True Learn Flashcards
Post thoracotomy multi modal pain management
- Paravertebral vs epidural local anesthetic
- PCA morphine
- Tylenol
Brachial artery line cannulation risks
Median n runs with brachial artery, usually insertion site is proximal to antecubital fossa and medial to biceps tendon
- nerve damage
- Distal ischemia from thrombosis formation
- Central line infection
Pathophysiology of rhabdo in muscular dystrophies
Succinylcholine can trigger cellular lysis from contraction of already weakened myocyte cytoskeleton from dystrophy
- increase in potassium, myoglobin, phosphate, CPK
Hyperkalemia leads to peaked t wave and subsequent wide QRS and eventual v fib
Fibromyalgia diagnosis
Dx of exclusion, rule out inflammatory diseases
Complex pain syndrome assoc with widespread pain, sleep disturbance, and depression
Can benefit from SSRI/SNRI, neuropathic meds
Rheumatoid arthritis is 3+ joints for more than 6 weeks
Treatments of cyanide poisoning
Hydroxycobalamin: combines with cyanide to form cyanocobalamin (aka vit B12), rapid onset and low risk profile
Amyl nitrite: can be used as inhaled agent if patient does not have IV access
Sodium nitrite: risk of hypotension
Sodium thiosulfate: significantly slow onset if action
How to dose succinylcholine and rocuronium (wt based) and also RSI dose
Succinylcholine is total BW and 1.5mg/kg
Rocurconium is ideal BW and 0.6mg/kg (1.2mg/kg RSI)
A1c goal prior to elective surgery, hyperglycemia post surgical effects
Goal 6-8% a1c which correlates to avg 125-180 mg/Dl
Must decrease insulin dose prior to surgery due to NPO status
Risk of poor wound healing and infection post op (leads to poor chemotaxis and phagocyte activity)
Nerve innervation of gag reflex
Afferent - glossopharyngeal N
Efferent - vagus nerve
What is strong ion difference and how does it pertain to high volume fluid infusion (NS vs half NS)
cation (Na, K, Ca) - anion (Cl, lactate) = SID (bicarb, phos, albumin, unmeasured anion)
SID usually is 40mmeq
large infusion of NS (ie SID = 0) will increase Chloride which in turn will cause bicarb to diffuse into cells to even out negative charge causing acidosis
large infusion of 1/2 NS (SID = 0) will cause metabolic acidosis because it will dilute the SID anions
***decrease SID will decrease pH
What electrolyte abnormalities occur with CKD?
hyperkalemia (impaired clearance)
hyponatremia (hypotonic)
hypermagnesemia (exogenous admin)
hyper/hypocalcemia (tertiary HPT vs low Vit D)
hyperphosphatemia
all the above will prolong QRS or QT except:
hypercalcemia will decrease QRS and QT
hyperphos has no effect on ECG
pathophys of myasthenia gravis and MOA of tx, what are considerations of NMB in these patients
pathophys: antibodies against nicotinic Acetylcholine receptor in the NMJ leading to reduced number of receptors
Tx: pyridostigmine inhibits butyrylcholinesterase (plasma cholinesterase) preventing the break down of acetylcholine
patients with MG who take pyridostigime prior to surgery: can render neo/glyco less effective, potentiate succinylcholine due to decreased breakdown by plasma cholinesterase, and potentiate non -depolarizing NMB
What do B lines of lung US represent
interstitial lung disease: Pna or contusion/ bleed
What is ficks principle and what is the equation
Describes relationship between uptake if a substance, blood flow, and the gradient of that substance
Used to measure CO
CO = VO2/(CaO2-CvO2)
VO2 is total oxygen uptake by measure difference of inhaled and expired O2
Ca/Cv O2 is the o2 content of arterial or venous blood, which is calculates by taking saturation x hgb x carrying capacity of blood which is 1.36 g O2/ml
Moa of methylergometrine and risks
Ergot alkaloid causes intense vasocontriction, given IM and onset is 10 min lasting 3-6hrs
Watch out for pre-eclampsia or hx HTN, can lead to strokes!
Last line tx in hemorrhage for uterine atony
What is moa of carboprost and misoprostol
Both are prostaglandin
Increases force and frequency of uterine contraction
If oxytocin does not work for uterine atony then use carboprost up to 8 doses, then try misoprostol
What types of nerve blocks produce highest serum peak local anesthetic concentration?
How does epinephrine affect this process?
“BICEPS”
Bier block > intercostal > caudal > epidural > brachial plexus > subcutaneous
Uptake phases
Phase 1 is installed rapid fluid phase which is slowed by epinephrine and phase 2 is slow resolution into high lipid compartments
Epi slows phase 1 and allows for lower peak serum levels and greater blockade at block site
What other anomalies are assoc with tracheoesophalgeal fisutlas?
VACTERL anomalies
Vertebral
Anal
Cardiac
TEF
Esophageal atresia
Renal
Limb
Mild vs severe bronchospasm treatment ladder
100% FiO2 and hand ventilate
Mild (smaller but adequate TV)
- Deepen anesthetic, gas vs propofol vs ketamine
- Albuterol if able to move air
Severe (no tidal volume)
Epi
Glycopyrrolate takes 20 min
Magnesium sulfate for refractory
Glucocorticoid takes 4-6 hr
Fasting recommendations:
Clear liquids
Breast milk
Infant formula
Nonhuman milk
Light meals
Fatty meals
Clear liquids 2hr
Breast milk 4hr
Infant formula 6hr
Nonhuman milk 6hr
Light meals 6hr
Fatty meals 8hr
Premedications that don’t affect intraocular pressure?
Which medications are contraindicated in ocular trauma?
Midazolam - no effect on IOP
Precedex - can prevent increase in IOP if succhincholine is being used
C/I
Etomidate - decreases IOM but can cause myoclonus and contraction of EOM
ketamine - nystagmus and blepharospasm
Nitrous oxide
Succinylcholine - risk of vitreous expulsion and vision loss
Physiologic response following ECT
Transient parasympathetic response including bradycardia followed by sympathetic response including hypertension and tachycardia
Etomidate increases seizure duration
Methohexital and ketamine do not effect seizure duration
Mechanism of aldosterone
Mineralocorticoid
Activates RAA in response to hypovolemia and renal hypoperfusion
Upregulates N/K pumps in distal renal tubules to reavsorb na and secrete k to retain fluid
Level of conus medularis in neonates vs adults
L3 neonates
L1-L2 adults
Nerves for sensory innervation to these parts of the leg:
Medial leg
Lateral leg
Anterior thigh/knee
Medial knee
Lateral thigh
Medial ankle
Lateral ankle
Medial leg- saphenous
Lateral leg- superficial fibular n
Anterior thigh/knee- femoral n
Medial knee- obturator n
Lateral thigh/hip- Lateral femoral cutaneous n
Medial ankle- saphenous
Lateral ankle- sural
Nerves for sensory innervation of these parts of the leg:
Medial thigh
Posterior thigh
Posterior calf
Lateral foot
Heel
Posterior thigh- Posterior cutaneous nerve of thigh
Medial thigh- obturator
Posterior calf- sural n
Lateral foot- sural n
Heel- tibial
Adductor canal block for saphenous block, pure sensory, common for total knee
Deep peroneal nerve innervation type
Mixed sensory and motor
Foot dorsiflexion
Cutaneous innervation to skin between 1st and 2nd toes
Lateral knee injury can cause deep peroneal n damage and result in foot drop
Superficial peroneal nerve innervation type
Motor: foot eversion
Sensory: lateral lower leg and most dorsum of foot
Effects of the following on metabolism:
Starvation
Insulin
Glucagon
Catecholamines
Starvation 24-48 hr: glycogenolysis, lipolysis, proteolysis
Insulin: glycolysis and glycogen synthesis, lipogenesis, protein synthesis
Glucagon: glycogenolysis, gluconeogenesis
Catecholamine: beta stimulation > lipolysis (TGs turn into glycerol and FFAs)
Substrates for gluconeogenesis include glycerol, lactate, and some amino acids
FFA undergo hepatic conversion into ketone bodies in setting of low Insulin or lack of glycogenolysis
Brain does not use amino acids only ketone and glucose
How to determine level of consciousness?
Minimal, moderate, deep, general
Depends on purposeful movements to specific stimuli, NOT airway
Minimal- normal response to verbal stimulation
Moderate- Purposeful response to verbal or tactile stimulation
Deep- response to repeated painful stimulation
General- no response to repeated painful stimulation
What are contraindications for LMA
High aspiration risk: delayed gastric emptying, hiatal hernia, gerd, full stomach, intestinal obstruction
Low Lung conpliance: restrictive lung disease, glottic or subglottic airway obstruction, limited mouth opening
How does placental abruption present and what are risk factors for it?
Painful vaginally bleeding, uterine tenderness, nonreassuring fetal heart rate pattern
Rfs: materal/paternal smoking, trauma, hypertension, advanced material age, parity
What is the composition of Normal Saline and its effect on pH at high doses?
154mmeq/L of Na and Cl
No potassium
Isotonic
Excess chloride causes impaired bicarbonate reabsorption, causing decreased serum bicarbonate. This creates electroneutrality resulting in non-ion gap metabolic acidosis with hyperchloremia
In terms of strong ion difference, sharp increase of chloride as compared to sodium increase will decrease the strong ion difference. Smaller SID will create an acidosis.
Milrinone MOA and effects
Phosphodiesterase 3 inhibitor
Positive inotrope and causes peripheral vasodilation
(Good for right heart failure but need to add vasoconstrictor to support peripheral bloodpressure/perfusion ie vasopressin to prevent pulmonary constriction)
Phases of emergence
Phase 1: cessation of gen anes, antagonism of NMB, increased CO2, spontaneous respiration returns
Phase 2: recovery of airway tone and pharygeal muscles, ETT becomes noxious stimulus, defensive posture, gagging, coughing, salivation, tachy, HTN
Phase 3: responds to verbal command, return of cortical function, eye opening
Areas sensing and response to hypoxia and hypercapnia
Carotid body chemoreceptor > aortic arch chemoreceptor for inducing ventilatory response to hypoxia
Central chemoreceptors more sensitive to hypercapnia
Carotid sinus has baroreceptors ro manage blood pressure
Spironolactone mechanism and effects on electrolytes
Competitive aldosterone antagonist, potassium sparing, wastes Na
Aldosterone usually upregukstes ENACs at the distal tubule with pumps in Na and in return potassium is usually dumped
Equation for total oxygen content in arterial blood
(1.36 mL O2/g hb x hgb value x oxygen saturation) + (0.003 mL O2/dL/mm Hg × partial pressure of oxygen)
NMB of muscles in relation to diaphragm
- corrugator supercilii
- adductor pollicis
- flexor hallucis
Adductor pollicis muscle is supplied by ulnar nerve and lags behind diaphragm recovery
Flexor hallucis is innervated by posterior tibial n on Medial side posterior to Medial maleolus, similar to adductor pollicis
Corrugated supercilii innervated by facial nerve and resembles laryngeal adductor but not reliable for diaphragm recovery
What is standard error of mean?
Describes the standard deviation and measures the precision with which a sample mean represents a population
SEM = standard deviation / Sq root of (n)
As the sample size increases the standard error decreases
Compared to standard deviation which is a description of sample data compared to sample mean and quantifies the variation or dispersion of the data
How much does MAC change per decade of life?
Decreases by 6% per decade of life starting after age 40
What is MOA of TCAs causing cardiac toxicity?
sodium channel blockade which causes QRS prolongation (>100ms) along with inhibition of potassium efflux during repolarization which flattens the T wave, QT is also prolonged but patients are often sinus tachycardic during TCA overdose.
post-op considerations after carotid endarterectomy
damage to carotid body can lead to low hypoxic induced ventilatory drive
damage to the carotid sinus can lead to hypertension or hypotension
risk of thromboembolism, cerebral hypoperfusion, and neck hematomas
difference between nicotinic and muscarinic cholinergic receptors
cholinergic receptors are a part of the parasympathetic system
nicotinic receptors are excitatory and are located in between the pre and post ganglionic neurons
muscarinic receptor activation depends on subtype. M1-3. M1 and M3 are excitatory, M2 is inhibitory and works on the heart.
what is the function of alpha-2 adrenergic receptors and where are they located?
inhibitory role when activated and located in presynaptic terminal betwee neurons of the sympathetic nervous system often in the CNS and peripheral blood vessels, act as a negative feedback system.
ie. clonidine is alpha-2 agonist and is used for both lowering blood pressure both peripherally and centrally which helps with migraines.
What type of patients are at risk of upregulated nicotinic acetylcholine receptors?
What is the difference between myasthenia gravis and guillaine Barre syndrome?
risk is increased in low mobility, nerve damage, or neuromuscular disorders
burn (1 day up to 1-2 yrs), stroke, spinal cord injury (worse after 16 days), muscular dystrophy, GBS, ALS, MS
MG is auto antibodies targeting nicotinic acetylcholine receptors
vs.
GBS is autoimmune destruction of myelin sheath of neuronal axons
excretion of NMB and acetylcholinesterase inhibitors in CKD
both are excreted by kidneys and will be prolonged in patients with CKD. extended duration of neostigmine provides a safety margin for the prolonged NMB.
No dose changes are indicated in CKD for neostigmine, glycopyrrolate, or rocuronium.
what is the target of an inter scalene block and what are the risks? What are limitations?
aimed at blocking ventral rami of C5-7 which covers the shoulder and proximal arm, but spares the distal arm and hand since C8-T1 is often not blocked
Common risks include almost 100% hemidiaphragm due to involvement of C5 that contributes to phrenic nerve, hoarseness if recurrent laryngeal n is blocked, and horner syndrome from sympathetic blockade
renal changes in pregnancy
increased cardiac output and increased blood volume leads to GFR and renal plasma flow increases by about 50% along with decreased tubular reabsorption leading to glycosuria
BUN and Cr are decreased and usually lower than pre-pregnancy levels
technical spinal cord level of injury classifying paraplegia vs quadriplegia
Above T1 vertebrae (C1-8) is quadriplegia
Below T1 vertebrae (T1-L5) is paraplegia
What are minimum criteria when following up a post-op patient in pacu (standards)
mental status
respiratory function
cardiovascular function
temperature
pain
hydration status
how does blood volume and CBC lab values change in pregnancy
blood volume increases by 45% by sodium retention through RAA system
Hemoglobin only increases by 30% but usually hgb will be above 11. CO increases in order to increases oxygen delivery to tissues.
oxygen dissociation curve shifts to the right in order to help facilitate offloading to the fetus
what dictates changes in baseline fetal heart rate tracing? What is normal range?
accel or decel lasting more than 10 minutes dictates a change in baseline FHRT
normal range is 110-160bpm
What is FHR baseline variability and what are the different types? what is sinusoidal pattern?
irregular fluctuations in peak/ trough of heart rate
absent
minimal <5bmp
moderate 6-25
marked >25
sinusoidal pattern is undulating fluctuations that occur 3-5 times per minute and last more than 20 minutes and is an ominous sign of placental abruption
FHR Accels/Decels and pathology:
Variable Decel
Early Decel
Accel
Late Decel
V = cord compression
E = head compression
Accel = ok
Late = placental insufficiency
what makes a carbon dioxide absorbent high risk of producing CO
Containing high amounts of strong bases like NaOH or KOH
Baralyme (discontinued) and sodalime both have higher amounts of strong bases
Desflurane breaks down into CO and sevoflurane breaks down into Compound A when ran thru carbon dioxide absorbents
If patient has symptomatic bradycardia what is the ACLS algorithm?
HR < 50
place ECG/cardiac monitoring, IV access
check for HD stability and signs of shock including angina, AMS, dizziness
- atropine IV 1mg q3-5min for maximum 3 doses
- transcutaneous pacing or dopamine gtt @5-20mcg/kg/min or epinephrine gtt @ 2-10mcg/min
- transvenous pacing/expert consult
how does partial pressure of desflurane gas change when elevation changes?
partial pressure decreases as elevation increases
sea level atmospheric pressure is 760mm hg (1 atm)
how does desflurane storage/delivery differ from other halogenated gases (ie sevo)
Desflurane has high vapor pressure and will boil at temp above 22C therefore must be pressurized and delivered via dual-gas blender which is calibrated at a certain elevation and will deliver anesthetic based on the change in elevation that it is currently at compared to storage
All other gases can be delivered through variable bypass vaporizer which delivers similar MAC at higher and lower elevations
Relevant structures when performing a femoral nerve block?
medially are the femoral artery and vein
nerve lies deep to the fascia lata and fascia iliaca with the sartorius muscle more lateral
nerve sits on top of the iliopsoas muscle
These structures are perfused by which branches of the coronaries:
anterior left ventricle
AV node
lateral right ventricle
posteromedial papillary
interventricular septum (thirds)
SA node
bundle of HIS
cardiac apex
posteroinferior wall
anterior left ventricle = Lateral anterior descending a.
AV node = AV nodal a.
lateral right ventricle = Right marginal a.
posteromedial papillary = Posterior descending a.
interventricular septum (thirds) =
- anterior 2/3 = LAD
- posterior 1/3 = PDA
SA node = SA nodal a.
bundle of HIS = AV nodal a.
cardiac apex = RMA + LAD
posteroinferior wall = PDA
what is first line txs for afib with RVR if HD is stable, and what are their mechanisms of action
beta blocker or CCB
avoid beta blocker in patients with reactive airway diseases. Esmolol/metoprolol is cardioselective for B1 anatagonism, esmolol would be more indicated in rapid correction of dysrhythmias ie HD instability
diltiazem better for HD stable patients. inhibits influx of Ca in cardiac and smooth muscle cells causing negative inotropy and vasodilation of cerebral, periphery, and coronaries
digoxin has low therapeutic window
mechanism of action of barbiturates and what are their function? How do they affect ventilation?
bind to GabaA receptors and increase the duration of opening of the chloride ion channels. They provide anesthesia by increasing inhibitory transmission and decreasing excitatory transmission (CNS depression). They do not produce analgesia.
Depresses the ventilatory center of the brain stem which blunts ventilatory response to hypoxia and hypercarbia.
mechanism of Vasopressin
aka antidiuretic hormone
released from the hypothalamus and transported into the posterior pituitary
release is triggered by hypovolemia or hyperosmolality
will activate V2 receptors in the collecting ducts of the kidney which increases free water reuptake via aquaporins
and will activate V1 receptors of peripheral vessels which causes vasoconstriction
how are ester vs amide LAs metabolized
ester = plasma cholinesterase
amide = hepatic metabolism
platelet recommended cutoffs for the following:
- prevent spontaneous bleeding
- minor procedure
- major procedure
- neurosurgery/neuraxial procedure
- prevent spontaneous bleeding = >10k
- minor procedure = 20-30k
- major procedure = 50k
- neurosurgery/neuraxial procedure = 100k
**take into account clinical context, platelet dysfunction can occur in times of acidosis or hypothermia (ie trauma/cardiac arrest)
pathophysiology and presentation of cushing syndrome vs addison disease
cushing = hypercortisolism
moonfacies, hyperglycemia/diabetes, osteoporosis, central obesity, easy brusing
addison’s = hypocortisolism
weight loss, fatigue, hypercalcemia, hyponatremia, hyperkalemia (via hypoaldosteronism)
hydrophilic vs lipophilic opioid pharmacology via epidural administration
hydrophilic (morphine, dilaudid)
slower onset, longer duration, greater CSF bioavailability and CSF spread, delayed respiratory depression
lipophilic (fentanyl)
faster onset, shorter duration, fat redistribution > systemic, less CSF spread/bioavailability
what properties affect a fluids state of laminar vs turbulent flow?
density, velocity, and size of tube are all directly associated with Re (reynolds number) and inverse with viscosity
Re <2000 = laminar
RE >4000 = turbulent
chronic HTN vs gestational HTN vs pre-eclampsia vs chronic HTN w/ superimposed pre-eclampsia
chronic HTN is elevated BP prior and up to 20 weeks of gestation
gestational HTN is elevated BP after 20 weeks gestation without severe features
Pre-clampsia is HTN after 20 weeks accompanied by proteinuria or severe features (think HELLP syndrome stuff, headache, migraine, RUQ pain, elevated liver enzyme, kidney dysfunction, thrombocytopenia, pulm edema)
control BP to prevent maternal stroke, Mg sulfate for neuroprotection from seizures
what are landmarks associated with the lower extremity dermatomes
L3
L4
L5
S1
L3 = medial knee
L4 = medial malleolus and anterior knee
L5 = dorsum of foot and 2nd/3rd digit
S1 = lateral foot and lateral malleolus
FYI C1 does not have dermatome
C2 covers posterior scalp and anterior neck under chin
ankle block nerve anatomy (5 nerves) and where do they branch from
posterior tibial nerve (1cm posterior to medial malleolus and posterior tibial artery) branches from tibial n and provides motor and sensory to plantar aspect of foot
Saphenous n (1cm anterior to medial malleolus) is a terminal branch of the femoral nerve and provides sensory to the medial ankle
Sural n (lies 1 cm distal to lateral malleolus) branches from both peroneal and tibial and provides sensory to the lateral foot and 4th and 5th digits
Deep peroneal n is medial of the dorsum of the foot while superficial peroneal n is more lateral on dorsum of the foot
Alternatively, sciatic (popliteal fossa) and saphenous n blocks will coverall the nerves in an ankle block as well
how to convert woods to dynes units for resistance?
what is normal range svr and pvr?
woods x80 = dynes
normal SVR 800-1200 dyne
normal PVR 30-180 dyne
arterial oxygen content equation
Ca O2 = (1.39 x SaO2 x Hgb) + (0.003 x PaO2)
digoxin mechanism of action, route of elimination, signs of digoxin toxicity and treatment
- reversible inhibition of Na/K pump in cardiac muscle producing high intracellular Na
- there is a Na/Ca exchanger which will retain Ca as Na leaves the cell
- this causes increased contractility and decreased conduction via AV and SA nodes, which helps in heart failure and for SVTs
eliminated mostly by kidneys, must be dose adjusted for renal function
toxicity is from slowing heart too much ie bradycardia, AV block, and PVCs and delirium and visual changes and is promoted by electrolyte abnormalities like hypoK, hypoMg, hyperCa
Tx is digoxin specific antibodies
what did POISE-2 trial find about clonidine and beta blockers perioperatively
initiating treatment with clonidine or betablockers prior to non-cardiac surgery had increased risk of clinically relevant hypotension and nonfatal cardiac arrest compared to placebo
ok to continue if patient is chronically on betablocker or clonidine
What is mechanism of ketamine
NMDA r antagonist in thalamus and indirectly affects reticular activating system
All other sedatives or anesthetics directly affects RAS including gas, etomidate, opioids
What is difference between type 1 error, type 2 error, alpha error, beta error?
Fasle positive is type 1 or alpha error (incorrectly reject null)
False negative is type 2 or beta error (incorrectly accept null)
Mechanism of precedex
Sedative hypnotic effect via alpha2 receptor agonist in the locus ceruleum and also can cause hypotension
What is absolute vs relative humidity and application to skin evaporation
Absolute: measure of gaseous water in gas and is reported as mass of water per unit area of gas, temp directly associated with maximum absolute humidity
Relative humidity is amount if water vapor in gas relative to temperature of the gas itself and is reported as a percentage of the maximum absolute humidity at a given temp
Lower ambient relative humidity results in more rapid water evaporation from skin
Recommended humidity in OR is 20-60% (lower limit for electrical equipment and upper limit for sterile barrier integrity)
Wilms tumor perioperative considerations in pediatrics
Embryonic tumor of kidneys can often metastasized thru IVC into right atrium and high risk of PE
Usually present with hypertension but volume down
Often have hematuria and chronic kidney dysfunction, excess renin release from mass compression of renal artery
Present with severe anemia and thrombocytopenia and acquired vWB disease but may be asymptomatic
Preoperative chemo therapy
What is biggest components of room air?
21% O2
78% nitrogen
Stages of drowning pathophys
- Holding breath while submerged
- water in hypopharynx causes laryngospasm
- hypercarbia from lack of ventilation
- release of laryngospasm from hypoxia
- aspiration of water causes washout of surfactant, decrease lung compliance, VQ mismatch
- multiorgan failure from global hypoxemia
Larynx nerve innervation (M and S)
Sensory: recurrent laryngeal is sensory to larynx from vocal cords and downward while superior laryngeal supplies above vocal cords
Motor is from recurrent laryngeal which supplies al intrinsic laryngeal muscles except the cricothyroid muscle
Circothyroid M is innervated motor by superior laryngeal n which tenses the vocal cords for pronation but has minimal disruption
What is definition of fluid responsiveness
Increase in stroke volume by 10-15% after 500cc bolus IV
Often volume depleted causes low preload and low CO.
Positive pressure Vent causes increases intrathoracic pressure and decreases venous return/preload of right ventricle. If LV stroke volume changes with cyclic vent then then ventricles are preload dependent
Stroke volume variation can be calculated from arterial pressure waveform when arterial compliance and SVR are known or can be determined by doppler
Must be paralyzed, Supine, ventilated with larger tidal volume >8cc/kg and in NSR with closed thorax and normal lung compliance
What is DIC and how does it present/lab findings
Wide spread Coagulation cascade activation thrombo-hemorrhagic disorder
Lab findings will commonly show thrombocytopenia
Presents with diffuse thrombosis leading to multi organ failure, consumption coagulopathy, and bleeding
Signs and symptoms of uterine rupture
Loss of fetal station due to loss of uterine tone
Pain uncontrolled by epidural analgesia
Vaginal bleeding
Abnormal change in fetal heart rate
Acute shoulder or abdominal pain
Triangle of petit for tap block land marks
Iliac crest inferior
Latissimus dorsi posteriorly
External oblique anterior
Vecuronium elimination
Mostly thru biliary system, but partially thru kidneys
Has active metabolite which has 80% potency and is also eliminated via kidneys
Prolonged duration in kidney failure and elderly
Viral needle stick transmission rates
HIV, Hep C, Hep B
HIV 0.3%
HEPC 0.5%
HEPB 30%
CormackLehane laryngoscopy views
Gr1 epiglottis, entire vocal cords, arytenoids
Gr2a epiglottis, partial posterior aspect of VCs, arytenoids
Gr2b epiglottis and aryteboids, no VCs visualized
Gr3 only epiglottis no arytenoids
Gr4 only soft tissue no epiglottis
Ultrasound image reflections are created by acoustic impedance chances between mediums, what factors is impedance dependant on?
Propagation speed and density of mediums
QSOFA criteria of icu sepsis likelihood (screen)
Need 2/3:
Altered mental status
SBP < 100
RR > 22/min
Septic shock definition
Sepsis with persistent hypotension
Requiring pressors to maintain map >65
Lactate > 2 despite adequate volume resuscitation
How does coagulability change during pregnancy
Increases
Fibrinogen levels double to limit postpartum hemorrhage
Increase in factors
Dilution if platelets, often <150k
Dilutions anemia, plasma vol increases by 40-50%
Perioperative considerations of cerebrovascular AVM
Hemorrhage - avoid hypertension
Ischemia from vasc steal- avoid hypotension
Normal perfusion pressure breakthru - inability to vasoconstrict after AVM removal
Occlusion hyperemia
Seizures
Avoid hypertension by mix of 0.5 Mac gas and opioid anesthesia especially on induction
What is blood volume ratio in adult male and female?
Male: 65-70cc/kg
Female: 60-65cc/kg
what are complications of cardiac ablation procedure?
tamponade showing pericardial effusion on echo
esophageal thermal injury , detectable with temp probe
MI can be detected on ECG, often in right coronary distribution
phrenic nerve damage, can detect with fluoro while stimulating phrenic nerve
what do SSEP do?
somatosensory evoked potential provide information on the integrity of ascending neurons during stimulation of peripheral or cranial nerves and measuring resulting cortical impulse on EEG
SSPE quantifiable by amplitude and latency of signal (aka delay between stim and signal)
decrease in amplitude or increased latency can indicate direct damage to nerve or ischemic insult (significant is 50% lower amp or 10%inc latency)
signal is worsened by inhaled volatile gases (keep mac below 0.5 and use multimodal anesthetic i.e. propofol)
other types of SSPE are brainstem auditory evoked potential and visual evoked potential
often used during spine surgery
how do motor evoked potentials work?
evaluate integrity of descending motor neuron pathways. Generate motor impulse by stimulating motor cortex and receiving signal from distal muscle groups
Require that NMB not be used to receive motor signals
inhaled volatile gases can reduce signal but not as sensitive as SSPE
what and where is the stellate ganglion
anterior to C7 transverse process but safer to block at C6 (below is risk of unprotected vertebral artery)
part of the sympathetic chain receiving T1-4 outflow and can be used for CRPS in the upper extremities
vascular and cardiac changes in morbid obesity
fat is metabolically active and therefore requires increase in total blood volume
excess blood volume leads tto increase cardiac output with inc SV and ventricular dilation resulting in deleterious hypertrophy of ventricles
also eventually develop hypertension due to increased sympathetic NS leading to increased SVR which contributes to cardiac hypertrophy and eventual failure
when are immature extrajunctional acetylcholine receptors present and how are they different from mature ones
in fetus, immobilized, burns, or motor neuron injury, sepsis
associated with larger efflux of potassium from depolarizing paralytics
they contain gamma subunit instead of mature epsilon one
mechanism of gabapentin and side effects
anticonvulsant and for neuropathic pain (DM, TGN, phantom limb)
inhibits alpha2 voltage gated calcium channel by decreasing release of glutamate
SFX: sedation, dizziness, ataxia, nystagmus, edema, weight gain
What did POISE-1 trial show about initiating Beta blocker therapy on day of surgery
decreased risk of perioperative MI but increased risk of stroke and increased mortality
recommended to start BB atleast week prior to surgery and continue taking chronically
equation for coronary perfusion pressure
CPP = AoDP - LVEDP
diastolic fillingtime/HR also contributes
what are the risk classifications of surgery types
High risk = intrathoracic, intraperitoneal, suprainguinal vascular procedure, aortic/major vessel vasc surgery
Moderate risk = head neck, carotid, orthopedic, urological, gynecologinal, EVAR
low risk = superficial, outpatient, breast, endoscopic, eye, thyroid
consider per-op ECG for cardiac/CVA risk factors and for moderate to high risk procedures
What does fresh frozen plasma contain?
all plasma factors involved in hemostasis
can be used to urgently reverse warfarin, in DIC, liver dysfunction
recommended dose is typically 10-15ml/kg which obtains level of 30-40% factor activity which is about INR 1.4-1.7 (INR1.0 is 100% factor function)
can calculate by equation:
Amt FFP needed (mL) = (target functional percent - present percent) * Kg
stored frozen and warmed prior to use
single unit is about 200-250 mL
usualy to reach INR 1.5
INR 2.5 needs 4u
INR 2.0 needs 3u
INR 1.8 needs 2u
what are usual tourniquet pressures, duration, and changes after deflation
arm: 50 above systolic
leg: 100 above systolic
up to 2 hours at a time before compression injury
changes after deflation:
metabolic acidosis
increased CO2
drop in systemic BP
what is left vs right shift on oxygen-hgb dissociation curve
left shift means at a given pO2 there is more Hgb saturation which means higher affinity and less unloading
right shift means less saturation at a given pO2 which means less affinity and more off loading
what are factors that cause left shift in O2-Hgb dissociation curve
less CO2 or H+
lower temp
less DPG
alkalinity (higher pH)
met-Hgb
CO-Hgb
fetal-Hgb
What are factors that cause right shift in O2-Hgb dissociation curve
increased pCO2
increased temp
increased DPG
acidosis (lower pH)
what is the first three-letter designation of pacemaker mode function, which mode to use peri-operatively
first letter: chamber paced
(A,V, Dual)
second letter chamber sensed
(O none, A, V, Dual)
third letter response to sensing
(O none, I inhibit, T trigger, Dual)
*inhibits pacemaker not actual heart
asynchronous modes are DOO,VOO,AOO
and often used in perioperative setting where electro cautery is being used and patient is pacemaker dependent such as complete heart block, often set between 80-100bpm
Danger is posed with patient’s intrinsic HR is greater than pacemaker rate and has chance of R on T phenomenon and can lead to VT or VF
safe if intrinsic heart rate is less than mode set
DDD is most commonly used since it can pace both chambers and also inhibit itself if detecting increase intrinsic hr
what are the four MRI zones?
Zone 1: all freely accessible public areas outside MR environment
Zone 2: interface between uncontrolled zone1 and strictly controlled zone 3, acts as holding area for unscreened patients
Zone 3: strict access to screened patients and equipment includes control room outside the scanner
Zone 4: MR magnet scanner room, restricted access to screened patients under constant supervision of MR personnel and MRI compatible equipment
cellular fluid content divisions, how do neonates and obesity change proportion to normal adult
Total mass is about 60% water
intracellular fluid 2/3
Extracellular fluid 1/3 (mostly interstitial about 3/4 and rest is CSF and intravascular fluid about 1/4)
neonates have higher total body water than adults about 3x (particularly ECF)
obesity has lower TBW, adipose tissue contains much less water compared to other tissues
response of pulmonary vascular and peripheral vascular tone to hypoxia
when oxygen tension is low:
peripheral resistance decreases/vasodilates
pulmonary resistance increases (hypoxic pulmonary vasoconstriction) often in focal lung diseases to shunt blood to better oxygenated alveoli, diffuse constriction can lead to pulmonary hypertension
PONV risk factors in pediatric population
age >3
duration of surgery >30min
type of surgery (eye, tonsil)
PMH and FHX of PONV
adequate hydration and reduce opioids, consider regional where able
acromegaly and systemic changes
enlarged internal organs
Heart failure
macroglossia
sleep apnea
epiglottis enlargement
HTN
DM
CAD
peripheral neuropathy
What did SAFE trial show for TBI patients and fluid resuscitation
increased mortality in GCS<13 patients with TBI who received albumin 4% compared to normal saline
What is the RIFLE criteria for classifying acute kidney risk, injury, and failure along with loss and endstage kidney disease
Risk: UOP < 0.5cc/kg over 6 hours
Injury: UOP <0.5cc/kg over 12 hours or GFR decrease by 50% or rise of Cr x2
Failure: UOP < 0.3cc/kg for 24hr, dec GFR by 75%, rise Cr by3x, or 12hr anuria
Loss: persistent renal failure lasting 4 weeks
End stage: needs renal replacement therapy
bradycardia following heart transplant, treatment?
transplanted hearts are dennervated and there is minimal baroreceptor reflex to counterbalance
need to use direct adrenergic agents (beta 1) such as isoproterenol which is nonselective beta agonist, can also use epi, norepi, dobutamine, and glucagon but save epi/norepi for reserve since baroreceptor reflex is severed and can have unopposed tachycardia
reinnervation of vagus nerve of the donor heart can take up to 24months to be re-established
chi square vs ANOVA use
chi square evaluates multiple categorical data sets while ANOVA analyzes the variance between multiple nominal or ordinal data
what type of weight to use for the following medication dosings:
prop gtt/push
fentanyl
thiopental
vec/roc/succ
Prop gtt, succ: total BW
thiopental, fentanyl, prop push: lean BW
roc/vec: ideal BW
estimated blood volume of the following ages:
premature infant
full term infant
infant 1-12 months
child 1yo-12yo
adult male
adult female
premature infant: 90-105cc/kg
fullterm infant: 80-90 cc/kg
infant 1-12 months: 70-80cc/kg
child 1yo-12yo: 70-75cc/kg
adult male: 65-70
adult female: 60-65
how to calculate allowable blood loss
ABL = EBV x (HCTi - HCTf)/HACTavg
means maximum blood loss prior to transfusion
What are the following lung volume and capacities?
TLV, TV, VC, RV, ERV, IC, FRC
TLV = total lung volume
TV = tidal volume
VC = vital capacity (IC + ERV) what you can maximally inhale and exhale
RV = what is remaining after forced exhale
ERV = forced exhalation volume after tidal exhale
IC = tidal volume with forced inhale
FRC = remaining volume after exhaled tidal volume
How is hepatic artery blood flow modulated in conjunction with portal blood flow?
Hepatic artery buffer response is the increase or decrease in Adenosine that will contract or dilate hepatic arterioles when portal blood flow changes
What are the morphine equianalgesic conversion between intrathecal, epidural, IV, and oral? What determines the difference?
1mg Intrathecal = 10mg epidural = 100mg IV = 300mg oral
Very hydrophilic drug which means if given intrathecal, it will stay for long duration
It will occur to smaller extent if given epidural
Lipophilic drugs like fentanyl will redistribute back into fat, so shorter duration
what is the ecg changes with hypercalcemia
shortened QT interval
Normal qtc is 350-450ms
oxygen content equation
CaO2 = [(SaO2 * Hgb * 1.34 ml O2/gm Hgb, O2 carrying capacity of Hgb) + ( 0.003, O2 solub in plasma * PaO2)
SaO2 is fraction of Hgb saturated with O2
PaO2 is partial pressure of O2
causes of methemoglobinemia
benzocaine, dapsone, inhaled nitric ozide
relationship of pregnancy and anesthesia to multiple sclerosis
no evidence to show anesthesia affects long term course of MS
higher chance of relapse in the few months following pregnancy
what does an isolation transformer do for OR elecetricity
converts grounded power supply from electrical company into ungrounded isolated power for OR use
line isolation monitor purpose in OR electricity
checks integrity of the isolated (ungrounded) power supply and measures current flow from isolated power to the ground
purpose of ground fault circuit interrupter in OR electricity
GCFI prevents shocks from occurring in a grounded power system by detecting differences in current between the hot and neutral wires to immediately interrupt the power supply
What is macroshock vs microshock
macroshock is electrical shocks that traverse the skin and can cause muscle contractions or even Vfib at higher currents
microshock is electrical shocks that are applied directly to the heart (ie from indwelling catheters, pacing wires, or from leakage current)
phentolamine mechanism of action
alpha 1 and 2 blocker
causes vasodilation but also increase in catecholamine release from alpha 2 block (unihibits release of norepi)
sodium nitroprusside mechanism
nonselective vasodilator working on veins and arteries causing decrease preload and SVR
clonidine mechanism
alpha 2 agonist which activates negative feedback that decreases sympathetic outflow in CNS and causes vasodilation in periphery
labetalol mechanism
nonselective beta and alpha 1 blocker through competitive inhibition, with more beta than alpha about 4:1
onset of 10minutes and lasts 2-6hours
nitroglycerin mechanism
venodilator which functions when it is turned into nitric oxide
first line therapy for MI since it also causes dilation of epicardial coronary arteries
immediate onset of action and lasts up to 5 minutes
structures to consider in the antecubital fossa when obtaining vascular access (vein vs artery)
medial side includes median nerve, brachial artery, and basilic vein (brachial artery will split into the ulnar and radial arteries distal to the antecubital fossa and runs lateral to median nerve)
lateral side is the cephalic vein and the radial nerve
midline of the fossa deep to the biceps tendon is the musculocutaneous nerve
posterior/medial is the ulnar nerve near the olecranon (funny bone)
physiology of denervated heart, baseline HR, and responsiveness to drugs
maintains own nervous function separate from recipients but will not receive parasympathetic innervation
direct beta agonists and blockers will work on the denervated heart
parasympathetic-blocking meds such as glyco and atropine will not affect the HR
resting HR of a transplanted denervated heart is usually between 90-110
excretion of rocuronium vs vecuronium vs succinylcholine vs cisatracurium
Rocuronium: 30% renal, mostly biliary
Vecuronium: 10-50% renal
Cisatracurium: hoffman elimination and ester hydrolysis
Succinylcholine: plasma cholinesterases
normal fetal oxygen saturation %? when does metabolic acidosis occur? How is this measured?
normally 35-65% is normal fetal O2 saturation
Below 30% is considered to cause metabolic acidosis
This can be measured with fetal pulse oximetry but Fetal heart rate monitor is more often used where decreases in heart rate are thought to be due to fetal hypoxia and correlates with fetal distress
what are the fascial layers relevant to femoral nerve block at the inguinal crease and other relevant vascular/muscle anatomy?
fascia lata is most superficial layer that encases all musculature
fascia iliaca is second layer that encases the femoral nerve
femoral nerve is lateral to the femoral artery and femoral vein (most medial)
lateral muscle structure us the sartorius with the iliopsoas being deep to the femoral nerve
mechanism and onset of action of pantoprazole/omeprazole vs famotidine/cimetidine vs sodium citrate
pantoprazole/omeprazole: directly inhibit H+ atpase channels in gastric parietal cells which ceases acid release, takes about 1hr for onset
famotidine/cimetidine: histamine-2 receptor blockers which partially prevents parietal cells from release acid (but other mechanisms are still unblocked), requires about 30min for onset
sodium citrate immediately increases pH of gastric fluid but also increases amount of fluid in the stomach
what does pudendal nerve innervate and where does it originate?
originates from S2-4
sensation to clitoris/head of penis, labia, external anal sphincter
what is difference between stage 1-3 of labor?
stage 1 is divided into latent and active phases
latent is variable in time and includes onset of contractions and persistent dilation
active phase is when contractions are regular at 2-3 minutes and lasting about a minute and ends at complete dilation of 10cm
(can use paracervical block) Pain comes from inferior hypogastric plexus to the uterus and cervix (T10-L1)
stage 2 starts with complete cervical dilation and ends with delivery of fetus
(can use pudendal block) Pain comes from S2-4 and T12-L1 to the vaginal wall
stage 3 is delivery of the placenta
duration of action of naloxone and dosing
lasts 90 minutes
IV adult dose is 0.4mg to 2mg can repeat q2-3minutes until reversal of respiratory depression
how long does it take for N2O to double or triple an airbubble size? why does this occur?
10 min to double and 30min to triple
this occurs because N2O has MAC 105% and very insoluble in blood (ie has a low blood:gas coefficient) and thus will come out of solution
relationship of radiation exposure and distance from source
1/radius^2
ie if exposure is 8mrem/s, and if you move 2 feet away, then it reduces exposure by 1/4 resulting in 2mrem/s
how is apnea-hypoxia index calculated and what numbers qualify for normal, mild, moderate, and severe sleep apnea?
divide number of apnea episodes with hypoxia that last at least 10 seconds by the number of hours slept
normal is 0-4
mild is 5-14
moderate 15-29
Severe is 30+
how does parturient status increase risk of aspiration, what are prophylaxis meds recommended prior to RSI?
increased levels of progesterone will relax the lower esophageal sphincter
can give antacid (non particulate), H2 blocker, and metoclopramide (reglan) for patients >16weeks gestation
what level and depth can you place esophageal ultrasound to look at the descending thoracic aorta for cardiac output
30-35cm from incisors which will reach about level T5-6, this is where esophagus and descending thoracic aorta are in close proximity
you can also see the mid-esophageal 4 chamber view here with views of the thoracic aorta when you rotate left
names of GLP-1 agonists for weight loss/diabetes and administration route vs DPP4 inhibitors and SGLT2 inhibitors
exenatide
semaglutide (wegovy/ozempic)
liraglutide
administered as injectables
while DPP4 inhibitors (sitagliptin/januvia) and SGLT2 inhibitors (empagliflozin/jardiance) are oral
what is the relationship of blood flow between the portal vein and the hepatic artery?
hepatic arterial buffer system
adenosine is a byproduct of the liver and causes vasodilation
blood flow through the portal vein will determine how much adenosine is washed out from the liver, if blood flow is low then high amounts of adenosine will dilate hepatic artery to increase blood flow and the opposite will occur if high portal blood flow resulting in adenosine washout and less arterial dilation
considerations of reperfusion syndrome during liver transplant
repercussion syndrome:
acidosis from influx of hydrogen ion, can give 25 meq of bicarb preemptive
influx of potassium can result in peaked t waves and arrhythmia - preemptive CaCl (500mg-1gm) administration can stabilize myocyte membranes
increase preload and right heart strain
hypothermia due to organ being cooled to prevent organ ischemia
coagulopathy due to wash out of TPA when organ is reperfused
how to calculate uncuffed or cuffed ETT size for children >2yo
uncuffed is age/4 + 4
cuffed is age/4 +3.5
ie for a 2yo use a size 4.5mm uncuffed or 4mm cuffed
differentiate sinus tachycardia from supraventricular tachycardia
sinus tach has p waves present and rate is typically less than 150 for adults
SVT has either absent or abnormal pwave emorphology with rates usually >160
For SVT attempt vagal maneuver or adenosine then try cardioversion
sinus tach: treat underlying cause
name 5 risk factors for difficult mask ventilation
presence of beard
BMI >30
edentulous
age > 55
hx of snoring (occlusion present)
also, male and mallampati 3-4
when and how long to hold antiplatelet medications prior to surgery
aspirin only needs to be held prior to operations that involve increased risk of bleed in to confined spaces ie intraocular, middle ear, intramedullary
hold for 7 days
P2Y12 inhibitors ie ticagrelor or clopidogrel are stronger antiplatelets and generally are held 5-7 days prior to surgerys with high bleed risk
usually DAPT is given 6-12onths after PCI stent and then recommended to wait 3-6mo after stent placement for elective surgery
resume anticoagulants immediately after surgery
pulmonary hypertension definition criteria
pulmonary artery systolic pressure >35, or mean PA pressure >25 at rest or >30 during exercise
pulmonary hypertension ventilator considerations
keep tidal volumes low (6-8cc/kg)
avoid excess PEEP which can increase vascular resistance, increase RV afterload from inc intrathroacic pressure
avoid permissive hypercapnia which will result in increase pulmonary vascular resistance and possible right heart failure
What are the 5 classifications of pulmonary hypertension
Group 1: primary pulmonary artery hypertension (ie collagen disease, portal HTN, drugs/toxins)
Group 2: left side heart disease
Group 3: lung disease (ie COPD, OSA)
Group 4: chronic thromboembolic disease (PE or sickle cell)
Group 5: other (ie sarcoidosis, henolytic anemia)
risk factors for difficult intubation (start from teeth and move distal)
prominent incisor length
large overbite
poor prognath ability
<3 cm interincisor distance
mallampati 3 or 4
narrow or high arched palate
stiff mandible
<3 finger breaths thyromental distance
short neck
thick neck
limited neck flexion or extension
best analgesia methods for thoracotomy
paravertebral block or thoracic epidural
PCA with IV opioid has higher risk profile and less analgeisa efficacy
how much dose cerebral metabolic rate change with each degree of temperature drop
6-7% per each degree celsius
deep hypothermic cardiac arrest, temp target is around <25C
what are the pulmonary artery cath hemodynamic values for the following:
central venous pressure
right atrial pressure
right ventricular systolic pressure
RV end-dia pres
Pulm A systolic pres
Pulm A end-dia pres
mean pulm A pres
pulm cap wedge pres
central venous pressure 0-7
right atrial pressure 0-7
RV sys pressure 15-25 (systolic presence)
RV end-dia pres 3-12
Pulm A systolic pres 15-25
Pulm A end-dia pres 8-15 (dia step up)
mean pulm A pres 10-22
pulm cap wedge pres 6-15
general transfusion goals for DIC:
HGB
PT/PTT
Fibrinogen
Plt
Hgb > 7
PT/PTT <1.5 (give FFP)
Fibrinogen >300 (give cryo)
Platelets >50,000
alveolar gas exchange equation
PaO2 = FiO2(Patm-Ph2o) - (PaCo2/R)
patm sealevel = 760
Ph2o = 47
R quotient - 0.8
what does using leukocyte reduced blood product help prevent?
febrile nonhemolytic transfusion reaction
Mechanism is cytokine build up in stored blood
nitrous oxide effects of ICP, cerebral metabolic rate, and cerebral blood flow
increases ICP by increasing CMR and cerebral blood flow
effects of the following meds on seizure duration ie during ECT:
methohexital, propofol, midazolam, etomidate, remifentanil
methohexital: no change
propofol: decreases
midazolam: decreases
etomidate: increases
remifentanil: no change
fentanyl vs dilaudid for ESRD patients
fentanil is metabolized by the liver and is better for ESRD
dilaudid has metabolite and can cause seizures in ESRD
name the neurotransmitters released and the target receptors in the following:
preganglionic parasympathetic
preganglionic sympathetic
postganglionic parasympathetic
postganglionic sympathetic
motor neurons
preganglionic parasympathetic > Ach >nicotinic R
preganglionic sympathetic > Ach > nicotinic R
postganglionic parasympathetic > Ach > muscarinic R
postganglionic sympathetic > Norepi > adrenergic R
motor neurons > Ach > nicotinic R
how does 2,3 DPG change oxygen dissociation curve
it is a intermediate in glycolytic pathway and increasing 2,3DPG will shift the curve to the left
Common drugs that induce cyt p450 system
Carbamazepine
Phenytoin
Rifampin
Ethanol
Barbiturates
Common drugs that inhibit cytp450 system
Fluconazole
Valproic acid
Metronidazole
Cirpofloxacin
What are the associated eeg wave form with the following conscious levels:
Wide awake
Drowsy awake
Stage 1 light sleep
Stage 2 deep sleep
Stage 3 and 4 (deep non rem)
Rem sleep
Wide awake - beta
Drowsy awake - alpha
Stage 1 light sleep - theta
Stage 2 deep sleep - sleep spindles k complex
Stage 3 and 4 (deep non rem) - delta
Rem sleep - beta
Bis is simplified eeg
Isoelectric = Bis < 40
Non hemolytic febrile transfusion reaction, mechanism
Host antibodies against donor leukocytes
Or accumulation of cytokines in donor blood during storage
Most common transfusion reaction and incidence can be reduced by leuko reduction
What defines stage 5 ckd
Egfr < 15 (esrd)
what do the following herbal medications do:
gingko
ginseng
kava
st john wort
ginger
gingko - inhibit platelet activating factor (inc risk bleed)
ginseng - lowers glucose, antiplatelet (risk bleed, hypoglycemia)
kava - sedation/anxiolysis (increases anes req)
st john wort - used for depresison (induces Cytp450
ginger - anti-emetic/antiplatelet (inc risk of bleed)
pathophys of myasthenia gravis
Ab against alpha-subunit of the muscle-type nicotinic acetylcholine receptors
symptoms include diplopia, ptosis, dysarthria, and proximal limb muscle weakness that worsens with activity
when to hold and resume heparin gtt during neuraxial procedure
hold 4-6 hr before and can restart 1 hr after both insertion and pull
when to hold and resume prophylactic LMWH during neuraxial procedure
hold 12 hr before and resume 12 hour after insertion or 4 hr after removal
hold and resume heparin prophylaxis SQ during neuraxial procedure
hold 4-6hr prior and can resume immediately after insertion and pull
on ABG, how much should bicarb increase per change in PaCO2 for chronic COPD patients
bicarb increases about 4-5mEq per 10 mm Hg inc in PaCO2
how does transpulmonary pressure relate to compliance in patients with restrictive lung disease
transpulmonary pressure are highest in restrictive lung disease due to a decrease in lung compliance
what cardiac event is associated with S1, S2, S3, and S4 heart sounds on auscultation?
S1 closure of mitral and tricuspid valves
S2 closure of pulm and aortic valves
S3 (after S2) early ventricle filling
S4 (before S1) atrial contraction
what are common anesthesia-related drugs that do not cross the placenta
glycopyrrolate
heparin
nondepolarize NMB
succinylcholine
phenylephrine
sugammadex
how much dose serum potassium increase after succinylcholine administration
0.5mEq/L in healthy and in renal failure patients
(not in spinal cord, burn or neuromuscular disease)
which allergy has shown cross reactivity with latex allergy
kiwi, bananas, and avocados (many fruits)
which medication has shown cross reactivity with fish allergy
protamine
how does respiration volumes change during pregnancy and why
increase in progesterone leads to increase in minute ventilation by increasing tidal volumes
what are the 5 criteria of the adlrete scoring system for safe pacu release?
activity level (0, 2, 4 extremities)
respiration (deep breath, shallow breath, apneic)
circulation (>20, >20-50, >50% pre-anes bp)
consciousness (fully, arousable, unconscious)
o2 sat (92% on RA, O2 supp for >90%, <90% on support
what is the difference between aldrete score and PADSS for ambulatory pacu discharge
PADSS also incorporates nasua/vomiting, pain, and surgical bleeding
also requires patient have a driver
difference in pathophys of myasthenia gravis and lambert eaton
myasthenia gravis is Ab against postsynaptic nicotinic Ach receptors
LE is Ab against presynaptic Ca channels
what is the leak pressure of a properly fitted uncuffed ETT in pediatrics
20 cm H2O
what is the dose of dantrolene to treat MH
initial bolus of 2.5mg/kg and maintenance of 1mg/kg q6hr for 1-2 days
asa definition of difficult intubation
3+ attempts and taking longer than 10 min
Duration of action of flumazenil vs midazolam
flumazenil has quick onset 1-3 min but only lasts 45min
midazolam is shortest duration of all benzos and lasts 1-2hr
patient must be continuously monitored for resedation when given flumazenil to reverse benzos due to half life discrepancy
physiologic changes during abdominal insufflation/trendelenburg position
decreased lung compliance
increased inspiratory pressure
increased VQ mismatch from atelectasis
hypercarbia from CO2 insufflation and reduced ventilation
how long to wait after low-dose (5000u TID) vs high dose (7500-10000 BID) ppx SC dose of heparin for neuraxial/deep regional procedure or removal of catheter
For low dose:
4-6hours from last dose OR normalization of PTT. Can dose while catheter is in place immediately after placement
For high dose wait 12 hrs before insertion and avoid giving while catheter is in
For both doses, can immediately resume next dose of subQ heparin ppx catheter removal
how long to wait after IV heparin to do neuraxial/deep regional procedure
hold 4-6hrs AND normalization of PTT prior to catheter insertion and removal
Can resume heparin IV dosing 1 hour after procedure/removal
how long to wait after giving ppx lovenox daily dosing vs BID vs therapeutic dosingprior to neuraxial catheter insertion and how long prior to removal
BID dosing lovenox must wait 12 hours before insertion and wait 12 hours after to restart dosing. Can wait 4 hours after catheter removal but cannot be within 12 hours from insertion (ie catheter was inserted but removed within 12 hours)
daily dosing must wait 12 hours before insertion. Avoid dosing daily while catheter is in. wait 12 hours after single shot and can similar wait 4 hours after catheter removal but no sooner than 12 hrs after insertion
therapeutic dosing wait 24hrs (longest) after last dose prior to insertion. Avoid administering while catheter is in place. Can resume dosing after removal 4hrs after and must be atleast 24hrs since initial insertion.
how long to wait after giving therapeutic SC heparin (>20,000u daily) to perform neuraxial/regional procedures
wait 24hrs before insertion AND have normalization of PTT. Do not administer while catheter is in place. Can resume immediately after removal.
electrolyte disturbances from hydrochlorothiazide
loss of chloride causes hypochloremic metabolic alkalosis
hyponatremia
hypokalemia
hypercalcemia
what are ideal settings to utilize arterial PPV for fluid responsiveness?
mechanically ventilated, no PEEP, 6=8cc/kg TV, ECG = SR, supine
PPV>13% is likely fluid responsive
potency of inhaled anesthetics is correlated with what property
correlates directly with lipid solubility of that gas (meyer overton study). higher potency means less drug is needed to attain therapeutic effect. high lipid solubility means a high oil:gas parition coeffecient which resutls in a lower MAC of that gas. (ie higher potency)
This also gives reason that partial pressure of a gas describes its potency (ie MAC) and not percent of gas volume. given different atmospheric pressures, a given percent gas volume can be more or less potent than at sea level. higher elevation ie -0.5atm means half the number of gas molecules per volume in a similar percentage
what are the numbers for MAC derivatives:
MACamnesia
MACunconscious
MACbar (blunt autonomic response)
MACamnesia = 0.25
MACunconscious = 0.5
MACbar = 1.3
identify all parts of the scotty dog spine xray
transverse process: nose
pedicle: eye
ears: superior articular process
inferior articular process: front legs
pars interarticularis: neck
opposite superior/inferior articular processes: tail/hindlegs
spinous process/lamina: body
fractured pars interarticularis from spondylolysis will show a white band on scotty dog neck
lambert eaton vs myathenia gravis pathophys vs mechanism of dantrolene
LE is antibodies against VG Ca channels at the terminal end of motor neurons which prevents vesicles from fusing and release acetylcholine (paraneoplastic syndrome sometimes seen when small cell lung cancer)
MG is antibodies against acetylcholine receptors at the motor end plate rendering transmission less sensitive
Dantrolene prevents the release of calcium from the sarcoplasmic reticulum in skeletal muscles, depressing the excitation-contraction coupling
when comparing oscillometric BP monitoring to invasive BP monitoring which values are most accurate and which are less accurate
MAP is most accurate as this is what is directly measured
Systolic is the most inaccurate and is often overestimated especially in HTN
What is happening during each stage of emergence from general anesthesia
Stage 1
Stage 2
Stage 3
Stage 1:
- cessation of anesthetics
- reversal of NMB
- transition of respirations from apnea to irregular to regular (reactivation of respiratory centers of medulla and pons)
- increase in CO2 levels
Stage 2:
- Return of autonomic responsiveness (ie tachycardia, HTN iso recent surgical trauma and ETT stimulation), sensory and motor brainstem pathways recovery (ie reaching for tube)
- tearing, grimacing, salivating (return of CN 7, 9, 10 in pons and upper medulla)
- airway tone improves when pharyngeal muscles recover (risk of laryngospasm here)
Stage 3
- following commands denotes recovery from general anesthesia (shows recovered integration of higher brain functions along with CN8)
- however spontaneous eye opening is usually the last physiologic response to recover despite patient following verbal commands
medication considerations in the parkinson patient taking the following meds:
carbidopa/levodopa
sellegiline
donepezil
metoclopramide is a dopamine antagonist (along with antipsychotic like haloperidol, and even antinausea/antiemetic promethazine (phenergan) which can result in tremors and dyskinesias
caution sympathomimetics (ephedrine, ketamine) when patient is on levodopa therapy which can precipitate severe hypertension
avoid meperidine if patient is on selegiline (MAOis) due to risk of serotonin syndrome (rigidity, hyperautonomic state)
if patient is taking acetylcholinesterase inhibitor like rivastigmine or donepezil for parkinsons dementia, administration of succinylcholine can be prolonged and patient can be more resistant to nondepolarizing NMB
prone to dyskinesias with propofol and rigidity with opioids (morphine/fentanyl)
aspirin for primary or secondary prevention guidelines in the following pre-operative scenarios (NOT P2Y12 blocker secondary agents, just ASA as sole agent):
- minor surgery
- noncardiac surgery
- elective CABG
- prior PCI with upcoming CEA
- periph vasc disease s/f pop art endovascularization
- minor surgery:
continue ASA thru surgery - noncardiac surgery:
prescriber and surgeon must discuss bleed risk vs MI risk - elective CABG:
continue ASA thru surgery - prior PCI with upcoming CEA:
continue ASA thru surgery unless risk of bleed > risk of MI - periph vasc disease s/f pop art endovascularization:
continue ASA thru surgery (better outcomes)
**If holding ASA or P2Y12 blocker, must stop 5-7 days prior to the surgery
describe dermatome areas of L1-S1
what are the pin prick sites of each?
L1
L2
L3
L4
L5
S1
L1 - femoral crease
L2 - anterior mid thigh
L3 - medial KNEE (THREE)
L4 medial maleolus
L5 top of fore foot
S1 lateral foot
what is occuring in this double peaked capnography
COPD patient s/p single lung transplant
healthy lung is initial peak and diseased lung is the second elongated peak
What is occurring in this capnography? blunted inspiratory slope?
incompetent inspiratory valve which results in the inspiration of CO2.
extended expiratory plateau due to the detection of CO2 during inspiration phase
blunted and shortened inspiration wave
ETCO2 may or may not return to 0 during inspiration
what is occurring during this capnography?
ETCO2 does not return to 0 due to incompetent expiratory valve which results in rebreathing expired air
How does morphine cause vasodilation/hypotension?
via histamine release
this will lower end diastolic volume and thus pressure in the ventricles
this will assist in coronary perfusion
which leads would show ST elevation in the following infarct locations:
anterior
septal
lateral
inferior
anterior: V3-4
Septal: V1-2
Lateral: I, aVL, V5-6
Inferior: II, III, aVF
list the cranial nerve afferent and efferent limbs of the following reflexes:
pupillary light
corneal
jaw jerk
gag
oculocephalic
pupillary light: II, III
corneal: V1 (ophthalmic), VII
jaw jerk: V3 (mandibular), V3 (masseter)
gag: IX (GPN, tongue base, post. pharynx wall), X (contract post. pharyngeal musc.)
oculocephalic: VIII, III/IV/VI
what is the structure of succinylcholine and where does it bind on acetylcholine receptor
two acetylcholine bound together
binds to the alpha subunit on nicotinic acetylcholine receptors
what is the most common perioperative peripheral nerve injury and how does it present
ulnar nerve injury
numbness/pain in the 5th/4th digits of hand and weakness on wrist flexion and thumb abduction
ensure adequate padding of medial epicondyle and supination of upper extremities
what factor influences dermatomal spread during intrathecal LA injection
what is added to make hypobaric vs hyperbaric LA injections
baricity
hypobaric: sterile water
hyperbaric: dextrose
(volume will determine spread for EPIDURAL injection)
what is the MAP range of the cerebral blood flow/blood pressure autoregulation
MAP 60-150
interactions of the following types of drugs with NMBs:
inhaled anesthetics
antibiotics
antiepileptics
electrolytes
gases: potentiate blockade
antibiotics: potentiate blockade except for penicillin and cephalosporins (ceftriaxone)
antiepileptics: potentiate blockade
electrolytes
Ca: decreases blockade
Mg and Li: potentiate blockade
reason for mild acute postoperative bleeding after trach placement vs large bleeding multiple weeks/months after procedure
initially due to veins supplying nearby organs such as jugular or inferior thyroid veins
large bleed multiple months out is due to tracheoinnominate fistula bleed where there is a fistula between trachea and the brachiocephalic trunk coming off the aorta
what is mechanism of nicardipine and what is half life duration
dihydropyridine calcium channel blocker mainly causing arteriolar vasodilation with minimal effects on cardiac inotropy (this allows for easier control of BP as compared to medications that cause both venous and arterial vasodilation like nitroglycerin)
short half life of about 3-14min
what is physiologic osmolality
290 mOSM/kg
what triggers the release of physiologic Antidiuretic hormone (vasopressin)?
increased body plasma osmolality which triggers ADH release to retain more free water
what is the difference between TACO and TRALI after transfusion and how do they present?
TACO: transfusion associated cardiovascular overload is volume overload that appears several hours after large volume transfusion and presents with dyspnea, tachycardia, hypertension, with bilateral infiltrates but is afebrile
TRALI: TR acute lung injury is an immune response where donor antibodies trigger recipient neutrophils to cause damage to pulmonary vascular capillaries leading pulmonary edema. Presents with fever, chills, hypotension, hypoxia, and frothy airway secretions
How do benzodiazepines work on the GABAa receptor?
they increase the conductance of chloride across the channel while GABA is bound to the receptor, therefore benzos are allosteric positive modulators of the receptor and not direct agonists
(flumazenil is the opposite and is considered a negative allosteric modulator)
What is a TENS unit and how does it provide analgesia
TENS = transcutaneous nerve stimulation and provides analgesia by activating A-beta mechanoreceptors which will inhibit A-delta and C nociceptive fibers (pain fibers)
what is the time window to avoid succinylcholine in burn patients
immature and mature nACHr upregulate starting 1-2 days after initial burn and becomes safe 1-2years after the initial injury
which of the following breask down in to para benzoic acid and whic has allergy inducing preservatives:
aminoamides vs aminoesters
aminoamides have preservatives (ie methylparaben) that can sometimes cause allergies but rarely cause anaphylactic rxn themselves
aminoesters break down into PABA which can induce anaphylaxis
which anti muscarinic crosses the blood brain barrier vs the placental barrier of the following:
- atropine
- glycopyrrolate
-scopalamine
atropine is a tertiary structure that is able to cross both BBB and placental barrier and can be used to prevent neonatal bradycardia from neostigmine for reversal of NMB
glycopyrrolate (quaternary structure) does not cross the blood brain barrier and minimally crosses the placental barrier (often used during reversal of NMB to prevent the side effects of neostigmine (ie bradycardia)
scopalamine can cross the blood brain barrier and placental barrier, allowing for CNS effects like antinausea along with the potential adverse effect of central anticholinergic toxicity (AMS)
Which acetylcholinesterase inhibitor can be used to treat central anticholinergic toxicity? which can cross placental barrier? which is used for myathenia gravis?
physostigmine since it is a tertiary structure and is able to cross the BBB unlike neostigmine and pyridostigmine
neostigmine can cross the placental barrier and has potential for neonatal bradycardia
pyridostigmine is used to treat myasthenia gravis but does not cross BBB
what is the safe range of current to determine if a regional block needle is in appropriate proximity to a nerve bundle, what does the higher and lower limits indicate?
0.2mAmp - 0.5mAmp
less indicates risk of intraneural injection and too close proximity
greater than 0.5 means needle may be too far for LA to provide adequate block after injection
what are the differences between glucocorticoids and mineralocorticoids and what is the ratio that each of these steroids contribute to the above types:
- hydrocortisone
- dexamethasone
- methylprednisolone
- prednisolone
- prednisone
glucocorticoids affect glucose metabolism, glycogen deposition
mineralocorticoids are for sodium and water retention
hydrocortisone is a naturally produced glucocorticoid that has a 1:1 ratio (standard equivalent benchmark)
Prednisone, prednisolone, methylprednisolone are all glucocorticoids with very minimal mineralocorticoid function with ratio approx 4-5:0.5-0.8
dexamethasone only has glucocorticoid function and has a ratio of 30:0 and is long acting
what are the side effects of corticosteroids? (extensions of its mechanism, metabolism, electrolytes, immunity, inflammation)
hyperglycemia from increased gluconeogenesis
muscle wasting used to feed gluconeogenesis
fat metabolism and redistribution centrally
anti-inflammatory by decreasing prostaglandins which takes away protective stomach lining leading to peptic ulcers
immunosuppression leading to infections and oral thrush
sodium and water retention causing edema and hypertension
negative feedback on adrenal gland causing secondary adrenal insufficiency
osteoporosis/fractures
peri-operative steroid supplementation is indicated for what dose of steroids and for how long
> 20mg prednisone for 3+ weeks, especially for moderate and major surgeries
give 100-150mg hydrocortisone during induction
what is physiologic plasma osmolarity vs NS vs LR vs plasmalyte
plasma: 291
NS: 308
LR: 280
Plasmalyte: 284
potassium content in physiologic plasma vs NS vs LR vs plasmalyte
plasma: 4-5
NS: 0
LR: 4.5
Plasmalyte: 5
what is the difference between goal directed fluid management and zero balance fluid management intraoperative?
goal directed means to use IV fluids to improve prelaod and to utilize fluid responsiveness measurements to track response such as pulse pressure variation, cardiac output and oxygen perfusion then once adequately euvolemic, fluid is restricted
zero balance is where euvolemic weight is minimized and IF fluids are used to replete 3rd space losses and avoid overhydration and weight gain
no differences have been identified in terms of outcomes between the two methods
available treatments for progressive stridor in PACU prior to initiating re-intubation
(upper airway occlusion)
supplemental oxygen
racemic inspired epinephrine
non-invasive PPV (BiPAP, CPAP, or HFNC)
humidified air
Heliox (laminar flow 70%helium, 30% oxygen)
Steroids
basics to hemostasis: what occurs during primary hemostasis as opposed to secondary hemostasis
primary hemostasis involves a vasospasm to reduce bleeding area and the aggregation of platelets of exposed collagen at a damaged vascular endothelial site to form a platelet plug
secondary hemostasis involves the coagulation cascade purposed to create activated fibrin polymers to form a fibrin mesh that will strengthen the platelet plug
what is the start of the common pathway of coagulation cascade
the start of the common pathway is the activation of factor X. Xa along with Va will activate the prothrombin activator complex which activated prothrombin into thrombin which will activate fibrinogen into fibrin
intrinsic and extrinsic pathways lead to the activation of factor X
fun facts:
- Ca is also known as Factor IV
- tissue thromboplastin is part of the extrinsic pathway and is known as Factor III
describe the extrinsic pathway of the coag cascade and how it leads to the common pathway
tissue damage causes a release of tissue thromboplastin (aka factor III) which activates factor VII into VIIa which then activates X into Xa, starting the common pathway.
this is very quick to activate (approx 30 secs) since there is a high amount of factor VII available.
describe the intrinsic pathway of coag cascade and how it leads to common pathway
tissue damage/inflammation leads to activation of Factor XII then factor XII which activates Factor IX then factor VIII which directly activates factor X of the common pathway
this is a slower but more robust cascade that takes a few minutes but produces more fibrin than the extrinsic pathway
which pathway is measured by PT vs aPTT vs INR (
PT/INR measure extrinsic pathway by measuring Factor VII, X, V, II (prothrombin), and Factor I (fibrinofgen)
INR is a standardized way of expressing PT across different countries
Warfarin is monitored using INR
aPTT measures intrinsic pathway and common pathway by measuring all factors excpet for VII
Heparin is monitored using PTT (or ACT)
(both drugs affect both pathways but each is more sensitive for a particular drug)
what does von willebrand factor do? How is DDAVP relevant?
present in both primary and secondary hemostasis
Primary hemostasis: in the creation of platelet plug, VWF is used for platelet adhesion to the exposed collagen of the damaged endothelium, without vWF platelets cannot adhere and therefore cannot activate and therefore cannot aggregate
Secondary hemostasis: VWF acts as a carrier of Factor VIII and significantly extends the half-life of it, without VWF, you will have extended PTT
DDAVP will increase the amount of VWF expressed by the subendothelial tissue
what are the effects of volatile anesthetics on the cardiovascular system?
peripheral vasodilation
decreased cardiac contractility
coronary vasodilation (especially isoflurane)
cardiac preconditioning (decrease loading of Ca into myocardial cells)
what are the effects of propofol on respiratory system?
Propofol works as an anesthetic by potentiating the GABAa receptor
quick onset and termination are due to its lipid solubility allowing for quick re-distribution into other body compartments
dose dependent associated decreases in tidal volume and eventual apnea
bronchodilation
increases sensitivity of hypoxic vasoconstriction
What effects do each of these properties have on local anesthetics:
added epinephrine
sodium bicarb
lipid solubility
epinephrine increases the duration of the block by causing vasoconstriction and decreasing uptake of the LA
sodium bicarb will decrease the pH and allow for more LA to be in the nonpolarized form which allows for faster onset via faster diffusion across cell membranes
increased lipid solubility equates to more potent medication and denser block
what are the 5 neurotransmitters that contribute to nausea/vomiting
5HT3 (serotonin)
Histamine
Dopamine
muscarinic M1
Substance P/Neuokinin 1
what is the equation for calculating allowable blood loss?
ABL = [EBVx(starting Hct - minimum Hct)]/starting hematocrit
minimum Hct is about 20-25 for healthy adults/kids and 30 for active cardiac comorbidities
describe what breathstacking is (ie in COPD on ventilator) also known as dynamic pulmonary hyperinflation and the presence of auto/intrinsic PEEP
occurs when there is not enough time for adequate exhalation of lung volumes before the start of next inspiration
this is often due to inappropraite settings on the ventilator I:E time and frequency in patients with increased lung compliance suchas COPD where it takes longer for the chest to recoil and exhale to remove lung volumes
this leads to progressive build up of end inspiration and expiration lung volumes
auto/intrinsic PEEP is the notable by the presence of persistent end expiratory flow at the end of expiration and is due to hyperinflation of the lungs generating pressure moving outwards
what are the 5 criteria measured in the aldrete score to determine clearance for discharge from PACU
consciousness
activity (moves extremities)
O2 saturation (>90%/supp req)
respiration (quality of resp)
circulation (BP)
what functions does the superior laryngeal nerve provide (ie all branches) and where does it originate from?
superior laryngeal nerve originates from the vagus nerve (CN X) and divides into the external and internal branches
External provides motor function to the cricothyroid muscle which tenses the vocal cords
Internal branch provides sensory innervation to laryngeal/epiglottic structures above the vocal cords
how is propofol metabolized?
almost entirely by the liver (even with liver function at 50%, can metabolize 100% of propofol) however this means propofol metabolism is also dependent on adequate hepatic blood flow
about 30% of propofol is extrahepatic at the site of the kidneys
what are the 2 wavelengths of the pulse ox and what are the absorbed by?
940nm (infrared) more absorbed by oxyhemoglobin
660nm (red) more absorbed by deoxyhemoglobin
what are the three mechanisms of methadone that contribute to its analgesia and how is it metabolized?
opioid agonist, NMDA antagonist, and serotonin reuptake inhibitor
metabolized by liver enzyme CYP3A4
can cause QT prolongation that can progress into torsades de pointes
(normal QTc is 350-450ms)
effects of additives to bupivicaine and ropivicaine:
- epinephrine
- dexamethasone
- clonidine
-bicarbonate
epi does not increase duration of bupi or ropi for either peripheral nerve blocks or neuracial blocks
dexamethasone and clonidine have both been shown to increase duration of block for both ropi/bupi
dicarbonate is thought to increase speed of onset of local anesthetic block but it has the potential to cause LA precipitation at higher pH
what is the mechanism of delayed hemolytic transfusion reaction and when/how does it usually present?
occurs due to recipient antibodies targetting minor antigens on donor red blood cells (rhesus, kidd, kell) and hemolysis usually presents days to weeks after transfusion with mild or minimal symptoms (ie mild fever, jaudice or back pain)
what is a neuron’s resting potential
-60 to -90 mV and is largely due to K why it is negative
what is the bohr effect vs the haldane effect
Bohr effect pertains to the shift in the oxygen-hemoglobin dissociation curve due to changes in CO2 and pH
Haldane effect pertains to hemoglobin’s ability to carry more CO2 in the deoxygenated state
What are the US gas color labels for the following:
Air
Oxygen
Carbon Dioxide
Nitrous Oxide
Nitrogen
Helium
Air = yellow
Oxygen = Green
CO2 = grey
NO = blue
Nitrogen = black
Helium = brown
what is an osmolarity gap and what is the equation for measured osmolarity?
2 x Na + Glucose/18 + BUN/2.8
normal gap is <10
increased gap can be due to solutes that are unmeasured such as ethanol, mannitol, sorbitol, lactate, ketones
how do the following physiologic states contribute to changes in cerebral blood flow
- temperature
- blood pressure
- PaO2
- PaCO2
temperature: directly related to cerebral blood flow and will decrease with decrease in temp (CMRO2 decreases by 6% with every drop in 1 degree)
blood pressure is connected to blood flow thru the cerebral perfusion autoregulation curve that exists between maps of 50-150
PaO2: cerebral blood flow is inversely related t oPaO2 when < 50, does not change when PaO2 is > 50
PaCO2: increases in PaCO2 will result in increased cerebral blood flow
What is the purpose of the following additives into stored pRBC prior to transfusion:
citrate
phosphate
adenine
dextrose
citrate = anticoagulant
phosphate = pH buffer
adenine = ATP source and maintains membrane integrity
dextrose = sugar source
what is approx B:G coefficient of the following gases:
halothane
Isoflurnae
Sevoflurane
nitrous oxide
desflurane
halothane = 2.5 (very soluble)
iso = 1.4
sevo = 0.6
nitrous = 0.47
des = 0.42 (not soluble)
increasing minute ventilation will most increase the Fa/Fi of what property of inhaled anesthetics
increase the most in highly soluble gases (ie halothane then second is isoflurane)
what nerves are blocked in a TAP block and what do they innervate?
subcostal, ilioinguinal, and iliohypogastric nerves which provide sensation to lower abdominal walls
Neurophysiologic changes that result from etomidate
lowers cerebral metabolic rate, cerebral blood flow, and intracranial pressure
what muscle abducts the vocal cords. what nerves provide efferent innervation of the laryngospasm reflex
cricothyroid muscle adducts the vocal cords and is innervated by the external branch superior laryngeal nerve
all other intrinsic muscles are innervated by the recurrent laryngeal nerve (along with sensation below the vocal cords, internal branch of SLN provides sensation above the vocal cords)
both of these nerves provide efferent innervation of the laryngospasm
What are labs that check synthetic liver function? What are common symptoms that can indicate undiagnosed liver disease?
bilirubin, albumin, prothrombin time (PT or INR)
fatigue, nausea/vomiting, jaundice, dark urine, biliary colic, ascites, encephalopathy
what is the hoffman degradation reaction and which neuromuscular blockers undergo this reaction for elimination
enzyme-independent reaction of breakdown that occurs in the plasma which allows for a relatively predictable offset time especially in liver failure patients (this can be affected by acidosis or hypothermia). cisatracurium and atracurium undergo this elimination route.
how much fibrinogen is in a typical unit of cryoprecipitate? how much will this raise serum fibrinogen levels?
200mg of fibrinogen per unit of cryoprecipitate which will tend to raise the serum levels by about 70mg/Dl
in addition to fibrinogen, cryo has high concentrations of Factor VIII and XIII and vWBF
effects of propofol, ketamine, and etomidate on airway physiology
relaxes airway tone,, depresses airway reflexes, and attenuates hyperconstrictive responses to bradykinin and acetylcholine
what are alternative treatments for severe bronchospasm refractory to hand ventilation and anesthetics
anticholinergics such as atropine or glycopyrrolate
short acting beta agonist inhaler (albuterol)
magnesium
epinephrine
glucocorticoids
what factors contribute to reynolds number for determining turbulent vs laminar flow?
factors that increase tendency for turbulent flow include velocity, density, and length of travel (tubing)
while viscosity decreasing tendency of turbulent flow
what is the mechanism of action of unfractionated heparin (and LMWH) why is the difference in size clinically relevant?
both augment antithrombin III which inhibits factor Xa and thrombin
however in order to inhibit thrombin, the heparin molecule must be long (ie unfractionated heparin) while LMWH will preferentially only inhibit factor Xa which allows for lower risks of HIT and platelet dysfunction due to the role of thrombin in inflammatory and immune pathways
what is considered severe hyponatremia and if symptoms are present what is the treatment? How fast can you correct sodium per hour and over the course of 24hr?
sever hyponatremia is < 120 mmeq
give hypertonic saline if severe or symptoms are present
correct by 1-2mmeq per hour with maximum 12 per day due to risk of pons demyelination syndrome
what is the first stage oxygen regulator used for in the anesthesia machine? What is the second stage regulator for?
it allows for the preferential use of the higher pressured pipeline oxygen source (50 psig) over the lower pressure oxygen tank (40psig) source
using oxygen flush can allow high flow that lowers pipeline pressure below tank pressure
second stage regulators reduce pressure to just above atmospheric and provide constant flow to downstream components
how to distinguish prerenal azotemia from renal azotemia with labs
Prerenal:
BUN:Cr >20
Urine Na <20
FENa <1%
Renal:
BUN:Cr <20
Urine Na >20
FENa>2%
how does clonidine reduce blood pressure and how does withdrawal present?
centrally acting alpha2 agonist which decreases sympathetic activity in the medulla oblongata (vitals control)
this reduces the production of renin and catecholamines in plasma
withdrawal presents with rebound hypertension, tachycardia, flushing, agitation, palpitations
What is the timeline for the following types of surgeries:
emergent
urgent
time sensitive
elective
emergent = risk of life or limb if not operated within 6 hours
urgent = within 24 hrs
time sensitive is from 1 week to months
elective = within a year
what is the difference between incompetent inspiratory vs expiratory valve on the capnography curve
incompetent inspiratory valve will show an extended down stroke due to inappropriately allowing CO2 back into the inspiratory limb
incompetent expiratory valve will show residual CO2 during inspiration phase, such that EtCO2 will not return to baseline of 0.
what does an exhausted CO2 absorber do to the capnography and where is the CO2 absorber within the breathing circuit
ETCO2 will not return to 0 during inspiration phase
it lies after the expiratory valve and APL valve and just before the inspiratory limb (exhausted absorbent will cause CO2 to spill over into the inspiratory limb)
what are the mechanisms of amiodarone
primarily class 3 antiarrhythmic by blocking potassium channels
also acts as blocks calcium, sodium channels and to lesser extent alpha and beta adrenergic receptors
it can be used to treat ventricular arrhythmias and sustained SVT such as afib
what is the oxygen consumption rate in adults vs infants
adult: 3-5 ml/kg/min
infant 7-8 ml/kg/min
what are the blood:gas coefficients for the following gases:
isoflurane
sevoflurane
nitrous oxide
desflurane
desflurane 0.42
nitrous oxide 0.46
sevoflurane 0.65
isoflurane 1.46 (much more soluble)
“DNSI = Desflurane Not Soluble In..blood”
effects of thiazides vs loop diuretics on calcium levels
thiazides = hypercalcemia
loop = hypocalcemia
glucagon mechanism and effects
activates GCPRs to increase adenylyl cyclase and increases cAMP and causes increased inotropy and chronotropy in cardiac cells and which also leads to counter effects to insulin which increases blood sugar by increasing glycogenolysis and gluconeogenesis, and inhibiting glycogen synthesis in the liver
what are the vapor pressures of the following gases:
sevoflurane
isoflurane
desflurane
nitrous oxide
sevoflurane: 167
isoflurane: 238
desflurane: 669
nitrous oxide: 38000
vapor pressure increases and boiling point decreases
“SID-NEE has lots of vapor from aquatics”
what are the borders of the adductor canal and what contents lie within the adductor canal
anterior = sartorius
lateral = vastus medialis
posteromedial = adductor longus (superior portion), adductor magnus (inferior portion)
contents include saphenous nerve, femoral artery and vein
ultrasound halfway between ASIS and patella
what is the standard pressure and volume of a full “E-size” gas cylinder? How do you measure time remaining if given a flow rate of gas?
standard pressure is 2000 psig and volume is 625L
convert the new remaining pressure in to a volume and divide it by the flow rate
ex. 1500psig/2000psig = X/625L
then divide the new volume by the flow rate to get time in minutes
how does nitrous oxide differ from oxygen when stored in a tank?
nitrous oxide will be partially liquid and partially vapor when it reads pressure of 745psig. At this point only by weighing the tank will tell how much gas is left. Once <75% is remaining then the amount of nitrous oxide will parallel the decrease in pressure
what is the intubation dosing of cisatracurium, how long does it typically last
intubation dose: 0.1-0.15mg/kg and lasts 30-60min with half life about 25min
undergoes hoffman degradation dependent on temperature and pH (not kidney or liver)
what are the components of the MELD vs childs-pugh scores?
MELD predicts mortality in mortality in End stage liver disease but is purely objective criteria and components compared to childs-pugh and can be used to prioritize patients for transplant
MELD: “I crush several beers daily = INR, Cr, Sodium, bilirubin, dialysis
Childs-pugh: “Pour Another Beer At Eleven” = prothrombin, ascites, bilirubin, albumin, encephalopathy
What are contraindications to LMA placement?
morbid obesity
uncontrolled GERD
recent GI surgery
improper NPO
> 14 weeks pregnant
hiatal hernia
delayed gastric emptying (opioids, diabetes)
what percent of nicotinic Ach R blocked is associated with loss of 1, 2 ,3, 4 twitches on nerve stimulator?
if the following is present:
0 twitches = 95% blocked
1 twitch = 90% blocked
2 twitches = 80% blocked
3 twitches 75% blocked
4 twitches = 0-60% blocked
what is phase 1 biotransformation vs phase 2 biotransformation of drug metabolism?
phase 1 is polarizing with the addition of polar side groups (uses CYP enzymes to undergo oxidation/reduction etc)
phase 2 is addition of endogenous compounds to enlarge the molecule and uses transferase enzymes
list the neurotransmitter/receptor types for the following neuron pathways:
- PSNS: pre and post ganglionic neurons
- SNS: pre and post ganglion (sweat glands, smooth muscle cells, and preganglion to the adrenal gland)
PSNS is both cholinergic
SNS is cholinergic for preganglionic (including the single synapse to the adrenal gland) and postganglionic is all adrenergic including organs and smooth muscle (except for sweat glands which is cholinergic)
what are the non-metabolic effects that can be caused by glucagon
increased inotropic and chronotropic effect by increasing adenylyl cyclase in cardiac muscle cells (similar to catecholamines) but bypasses any inhibition by beta blockers (which is why it is considered Betablocker reversal)
dose is 1-5mg IV bolus followed by infusion
what is the intubating dose for rocuronium, vecuronium, and cisatracurium
what is the time to onset for these induction doses?
roc 0.6mg/kg, 1-2min
vec 0.12mg/kg, 3-5min
cis 0.2mg/kg, 2-3 min (hoffman degradation)
what are the urine labs in the setting of hypovolemia AKI?
urine will be concentrated but Na content will be low due to the body attempting to reuptake Na to retain voume
BUN:Cr ratio > 20:1
FENa <1%
UrNa < 20meq
Urine osm > 400
what is the time cutoff for recent cardiovascular event to differentiate between ASAIII and IV?
for recent MI, stroke, or TIA that occurs more than 3 months ago is considered ASA3 and within 3 months is considered ASA 4
what is droperidol used for and what is its mechanism?
what are the risks and black bow warning?
D2-antagonist used for antiemetic
can cause QT prolongation and is C/I in anyone with prolonged QT, patients with hypomagnesemia have higher risk of prolonged QT and developing torsades
other potential sideeffects include anxiety, restlessness, dystonia
describe blood flow to the liver. what percent of total blood flow, what percent of hepatic blood flow is portal vs arterial, what about oxygenation
30% of total blood output
3/4 blood flow to liver is thru the portal vein, 1/4 is thru the hepatic artery (origin celiac trunk)
50/50%
which tests have high sensitivity vs specificity for detecting heparin induced thrombocytopenia
sensitive = anti-platelet factor 4 antibody
specific = serotonin release assay
how does heparin induced thrombocytopenia present and what is the pathophysiology
when heparin binds to platelets and exposes platelet factor 4, then antibodies develop to PF4
10x more likely from UF hep compared to LMWH
presents 4-10 days after initiating heparin and often has reduction of 50% of pre-heparin platelet levels
other risk factors include surgical patient > medicine, UF heparin, appropriate timing, and thrombosis
what electrolyte abnormality will potentiate digoxin? what is the mechanism of digoxin?
hypokalemia will potentiate effects of digoxin
MOA: digoxin binds to K spot on the Na/K ATPase and causes inhibition. this leads to higher levels of Na in the cardiac cells. Higher levels of intracellular Na will then be exchanged outward in return for Ca to increase in the cell. This causes increased contractility (inotropy) and slower electrical conduction (decreased HR)
By decreasing K levels in the state of hypokalemia, there will be less competition for digoxin in the binding of ATPase
what is the parkland formula for fluids resuscitation of burn patients?
4ml x total body weight x %SA burn
half of this should be given over the first 8 hrs then the second half over the next 16hrs
what is the relationship between wall stress and tension (la place law) in the setting of LV hypertrophy from aortic stenosis vs dilated LV from regurgitation
ventricle dilation leads to increased afterload (higher volume to push), wall stress and also increased O2 consumption.
thick walled hypertrophy will develop a smaller ventricle chamber and will have lower wall stress
wall thickness is inversely related to wall tension. as chamber radius increases along with wall pressure then wall tension increases (thin dilated walls have high tension). when the chamber radius is decreased and wall thickness is increased then wall tension decreases
In cases of acute hyperkalemia intraoperative, what are the steps for the following: myocardial protection, intracellular shift, and excretion
- give calcium gluconate and increase pH with bicarb to immediately cause intracellular shift of K into cells
- insulin takes 15min, albuterol takes 30min to shift potassium intracellularly
- dialysis/RRT can be ordered, lasix can be given but must be euvolemic, polystyrene helps with GI excretion but takes days
What are considerations when determining whether to do MAC or GA?
- patient pathologies
- morbid obesity
- improper NPO or high aspiration risk
- difficult airway/intubation
- neck immobility, recent H/N radiation
- inability to lay flat/lay still for duration of surgery (anxiety/tremors/coughing)
2.type of surgery
-accessibility to airway (180 turn/prone)
- high pain stimulation surgery
- need for paralysis
- fire risk
what are some of the scorings for calculating the glasgow coma scale (what are the three categories)
eyes (4), mouth (5), movement (6)
Eyes:
4 = spontaneous eye movement
3 = opens to command
2 = opens to pain
1 = no response
mouth/verbal:
5 = spontaneous conversation
4 = confused speech
3 = incongruent speech
2 = incoherent speech
1 = no response
movement:
6: spontaneous movement
5: localizes painful stimuli
4: withdraws from pain
3: decorticate (flex) posture
2: decerebrate (extended) posture
1:no response
what is normal CBF, CPP, and ICP?
cerebral blood flow is 50ml/100g/min
cerebral perfusion pressure is 80-100mmhg
ICP is <10mmhg
why do anticonvulsants decrease the duration of neuromuscular blockers while use of aminoglycosides prolongs their duration?
What role does magnesium, potassium, and calcium play in duration of NMBs?
anticonvulsants such as carbamazepine and phenytoin wil induce the CUP450 system which increases metabolism of NMBs, shortening the duration
aminoglycosides prevent the release of acetylcholine in alpha neurons and potentiate NMB duration
hypercalcemia antagonizes NMBs
hypermagnesemia will prolong NMBs
hypokalemia will prolong NMBs
what are the 6 criteria in the revised cardiac risk index and what does the score mean?
1 point each:
high risk surgery, hx of ischemic heart disease, congestive heart failure, cerebrovascular disease, DM2 requiring insulin, Cr >2
score equates to risk of major cardiac event
0 = 0.4%
1 = 1%
2 = 2.4%
3+ = 5%
what is the effects of volatile anesthetics on CBF and CMR, what about at low vs high MAC?
initially causes both decrease in CBF and CMR, but above 1.1 MAC it will cause vasodilation that increases CBF while decreasing CMR
What is the use of paired t test vs unpaired t test
Paired t test is for when comparing outcomes from a single group who acts as their own control
Unpaired t test is used to compare nonordinal outcomes of two groups
what are the maximum doses for the following LAs:
- lidocaine plain
- lidocaine w epi
- bupivicaine plain
- bupi w epi
ropivicaine
- chloroprocaine
- lidocaine plain: 5
- lidocaine w epi: 7
- bupivicaine plain: 2.5
- bupi w epi: 3
ropivicaine: 3 - chloroprocaine: 12
what is the byproduct from hepatic metabolism of sevoflurane and enflurane
fluoride
what characteristics are considered to be low-risk type of surgery vs moderate risk vs high risk
low: outpatient, superficial, breast, eye, endocrine (thyroid)
moderate: head and neck, orth, uro/gyn, endovascular (aneurysm), carotid endarterectomy
high: intrathoracic, intraperitoneal, suprainguinal endovascular, large vessel (ie aorta)
what ratio of urine:serum mOsm is indicative of a pre-renal cause of oliguria?
Urine:serum > 1.5 , meaning the kidneys preserve the ability to concentrate the urine
What are the drugs that undergo zero order elimination?
“PEA”: phenytoin, ethanol, aspirin
describe the pressure/volume of nitrous oxide E cylinder and at what volume will pressure begin to change
total volume is 1590L of N2O at a pressure of 745psig much of it contained in liquid form under high pressure (actual internal volume of the cylinder is 5L)
pressure will continue to read the same until about 16% volume left or 250L, this is when all liquid N2O is used up
what are the 9 cartilages of the larynx (paired vs unpaired)
unpaired: cricoid, thyroid, epiglottis
paired: arytenoid, cuneiform, corniculate
describe anatomy of the trachea
- start/end point compared to spine
- cartilage/muscle
- cells
starts at the cricoid cartilage C6 and ends at the carina T5
has 15-20 U-shaped cartilage rings with the posterior wall consists of the posterior trachealis muscle that aids in expectoration
lined with ciliated pseudostratified columnar cells
describe the pathophysiologic changes of the myocardium during LVH in terms of wall tension LaPlace equation
Oxygen consumption of myocardium factors: wall tension, heart rate, and contractility
LaPlace Equation:
Wall tension = (Pxr)/2H, where H is wall thickness
from increased systemic pressure ie AS or HTN, wall tension increases from an increase in afterload pressure. The heart will hypertrophy the LV walls to increase thickness and subsequently decrease wall tension and thus decrease O2 consumption
Deleterious effects of this change is that the ventricles become less compliant and can develop diastolic dysfunction and becoming more reliant on left atrium kick to maintain LV end diastolic volume for adequate CO.
