M5 Flashcards
Why does a patient desaturates 5 min after retrobulbar block
Local anesthetic in CSF causing high spinal
Next best step in treatment of patient with likely corneal abrasion
Topical antibiotics
Protopathic sensation
Noxious (painful)
Epicritic sensation
Non-noxious (touch, pressure, temperature, proprioception)
Nociceptive pain is caused by activation of what type of receptors
High threshold peripheral nociceptive receptors
Nociceptive pain is transmitted via what types of nerves
A-delta and C nerve fibers
Pain fibers enter spinal cord via which nerve roots?
Mostly dorsal nerve root but some enter via ventral nerve root
Primary area of pain pathway that opioids act upon
Dorsal horn where 1st order neurons synapse with 2nd order neurons
How is resistance to flow related to length and radius?
Resistance proportional to 8 times length
Resistance inversely proportional to radius to 4th power
What’s an intrinsic property of a transplanted lung that is kept intact?
Hypoxia pulmonary vasoconstriction
Which procedure is hypotension most likely, insertion of venous cannulation or insertion of aortic cannulation?
Venous cannulation can significantly reduce preload
What are advantages to off pump cabg?
Decreased incidence of respiratory infection and afib postop, less inotrope use, fewer blood transfusions
Mechanism of heparin
Binds to anti-thrombin 3, which accelerates inhibition of thrombin and factors 9 and 10
Next best step if heparin causes no change in ACT prior to CPB
Give 2 units of ffp then give heparin. Pt likely has anti-thrombin 3 deficiency
Functions of thromboxane
1) Platelet aggregator, facilitating clot formation. 2) Vasoconstrictor that reduces blood flow to site of clot
Pulmonary artery pressure rise after protamine administration for heparin reversal
Heparin protamine complexes can cause thromboxane release from macrophages
Hypotension after protamine administration for heparin reversal
Dose dependent histamine release from mast cells
Best way to decrease time to rewarm patient
nitroglycerin infusion
Fast pain is carried by what type of nerve fibers?
A delta fibers (myelinated)
Delayed slow secondary pain is carried by what type of nerve fibers?
C fibers
Induction agents except for ketamine work on which type of GABA receptor?
GABA-A receptor
Propofol should be discarded after being drawn into a syringe after how many hours?
12 hrs, it used be 6 hrs before EDTA preservative was added.
What part of egg is used in propofol?
Egg lecithin from the egg yolk. People allergic to eggs are allergic to egg albumin which is in egg white.
Pretreatment with what drug can decrease etomidate associated myoclonus?
Opioids
Reason why etomidate causes burning pain
Propylene glycol solvent that etomidate is in
Etomidate causes increase in ICU mortality because of?
Prolonged infusions causing adrenal suppression
In what percent of patients does a single induction dose of etomidate cause adrenal suppression?
All patients
Hydrophilic or lipophilic drug has smaller volume of distribution
Hydrophilic
Induction agent that is completely metabolized by liver on a single pass
Propofol
2 pathways signaled by G protein coupled receptors
1) cAMP -> PKA
2) phospholipase C -> IP3
Where is propofol metabolized?
Liver and lung
How is fospropofol different than propofol?
Water soluble, prodrug that has to be metabolized by liver to release propofol and formaldehyde
How does barbiturates affect tolerance to pain?
Decrease tolerance to pain
Barbiturate injected in artery causes?
Limb gangrene due to arterial spasm and vasoconstriction, treatment is stellate ganglion block
Morphine metabolite
Morphine-6-gluconoride, major contributor to mu receptor mediated respiratory depression
Oversized BP cuff affects BP measurement how
BP will be underestimated
Correlation between central venous pressure and left ventricular end diastolic volume
None at all
Betadine or chlorhexadine use has lesser catheter related bloodstream infection
Chlorhexadine
How does insulin affect glycogen and protein synthesis?
Increases
Hypernatremia or hyponatremia is associated with hypothyroidism?
Hyponatremia: hypothyroid patients retain free water
Classic diuretic of choice to treat Cushing’s syndrome
Spironolactone
Anesthetic considerations with Cushing’s syndrome
Increased sensitivity to muscle relaxants, hypokalemic arrhythmias, difficult intubation for obesity and swelling
Healthy person can produce up to how much cortisol in a day when maximally stressed
300 mg of cortisol
Historically why is succinylcholine contraindicated with pheochromocytoma pts?
Supposedly fasciculations cause catecholamine release secondary to abdominal pressure
Historically why is pancuronium contraindicated with pheochromocytoma pts?
Pancuronium is vagolytic
Pheochromocytoma is associated with which syndromes?
MEN2A, NF1, Von Hippel-Landau
How are anaphylactoid reactions different from anaphylaxis?
Anaphylactoid reactions are NOT IgE mediated
MC type of vWD
Type I
Type of vWD that responds to DDAVP
Type I
One unit of plasmapheresis platelets will raise platelet count by how much?
60,000 because 1 unit equals a 6 pack of pooled platelets which comes from 6 donors
Cryoprecipitate contains what factors?
Factor 8, fibrinogen, vWF
Washing RBCs prevents what?
Anaphylaxis in IgA deficient patients by removing IgA from RBCs
Leukodepletion or leukoreduction of RBCs prevents what?
Febrile reactions and alloimmunization
Irradiation of blood products prevents what?
Graft vs host disease, irradiation destroys DNA
Febrile transfusion reaction is caused by?
Recipient antibodies toward donor WBCs
Post transfusion purpura is caused by
Immunologic complication towards platelet surface proteins presenting with thrombocytopenia a week after transfusion, very uncommon.
Typical onset of TRALI is within how many hrs?
2 hrs
Typically TRALI resolves within how many hrs?
48
What is the 2 hit theory of TRALI?
1) sequestration of neutrophils in lungs
2) activation of neutrophils and immune response causing transient leukopenia
Transfusing 4cc/kg of prbcs will raise hgb by how much?
1 g/dL
Blood volume for premature neonate
100 mL/kg
Blood volume for full term neonate
85 mL/kg
Blood volume for infant/toddler
75 mL/kg
Blood volume for adult
60-70 mL/kg
Risk of hep B infection from blood transfusion
1:200,000
Risk of hep C infection from blood transfusion
1:2,000,000
Risk of HIV infection from blood transfusion
1:2,000,000
Nerve root that provides motor innervations to triceps and back of hand and middle finger
C7
Nerve root that when damaged causes numbness of medial forearm and fifth finger and weakness in finger flexion
C8
Ulnar nerve injury is characterized by?
Handgrip weakness and fifth finger numbness
Main advantage of retrobulbar block over peribulbar block
Decreased onset time of block
Half life of dabigatran
12 hrs
Preop instructions regarding herbal meds that cause increased risk of bleeding
Discontinue 1 week prior to surgery
Herbal med that interferes with warfarin
Ginseng
When do u stop giving 100% oxygen to patient with carbon monoxide poisoning?
When asymptomatic and carboxyHb is below 10%. 100% Oxygen shortens elimination half life by 5 times, hyperbaric oxygen by 10 times
Vapor output equation for a given gas flow and vapor pressure of anesthetic gas
Vapor output = (CG X SVP) / (Pb - SVP)
CG = carrier gas flow SVP = saturated vapor pressure Pb = atmosphere pressure
Which partition coefficient is necessary for calculation of time constant for volatile anesthetics?
Brain/blood partition coefficient. Time constant equals double the coefficient
Midazolam, fentanyl, barbiturates are water or lipid soluble?
Lipid soluble.
Obese patient should be induced with propofol based on what type of weight?
Ideal body weight. Propofol infusion should be based on total body weight
Proportion of sodium filtered by glomerulus that is typically excreted in the urine
5%
Treatment for acute interstitial nephritis
Steroids
Digoxin toxicity symptoms
Ventricular arrhythmias, malaise, vision changes
For every increase of glucose of 100 mg/dL, the measured sodium falls by how much?
1.6 mEq/L
Normal value for urine sodium
Less than 20 mEq/L
Loss of cold discrimination under epidural anesthesia is how many levels above level of anesthesia?
2 dermatomes
Major side effect of methergine
Hypertension (rhymes with methergine)
Major side effect of hemabate
Bronchospasm (avoid in asthmatics)
Ephedrine effect on fetus
Increases fetal metabolism and oxygen consumption
Active phase of labor affects which nerve roots and what type of nerve fibers account for pain
Lumbar nerve roots, small visceral afferent fibers
Side effect of ketorolac in pregnancy
Theoretical closure of ductus arteriosus, increased bleeding. Ketorolac is relatively ineffective to treat labor pain
Mortality of pregnancy in patient with eisenmenger’s syndrome
30-50%
Narcotic with weak local anesthetic properties
Meperidine
Chorioamnionitis increases fetus’ risk of?
Cerebral palsy
Risk of benzodiazepine use in pregnancy
Cleft palate
Normal CMRO2
3.5 mL/100 g/min
Normal cerebral blood flow
50 mL/100 g/min
How many times a day does entire CSF volume replace itself?
About 3 times a day. Avg adult CSF volume: 150cc.
Volume of venous air embolism that is fatal
300 cc
Hunt and Hess scale
0-5 for classifying severity of SAH
0: unruptured
1: mild
2: mod-severe
3: drowsy, confused
4: stupor, hemiparesis
5: comatose
Greatest risk over one week after ruptured cerebral aneurysm
Cerebral vasospasm (incidence is around 15%)
Triple H therapy for cerebral vasospasm prevention and treatment
Hypertension, hypervolemia, and hemodilution
Anti seizure medication should be continued for how long after a traumatic brain injury
7 days
How is neuraxial anesthesia controversial for patients with multiple sclerosis?
Small case studies show increased rate of MS flare ups compared to GA
Hot or cold temperatures exacerbates multiple sclerosis?
Hyperthermia
Why is succinylcholine relatively contraindicated for multiple sclerosis patients?
Since MS is an upper motor neuron demyelinating disease, patients are prone to hyperkalemia, especially in setting of paresis and paralysis
Myasthenia gravis patient’s response to succinylcholine being given
Resistance to succinylcholine because of lack of acetylcholine receptors, and then more sensitive to non depolarizers
Why is neuraxial anesthesia considered contraindicated for Guillian-Barre syndrome patients?
Weak evidence shows increased risk of GBS exacerbation
3 things to avoid in a myotonic dystrophy patient with contracture
Succinylcholine, neostigmine, and hypothermia
Risk factors for postop mechanical ventilation in myasthenia gravis patients
Pyridostigmine > 750 mg/day, vital capacity < 2.9L, disease duration > 6 yrs
What are the effects of succinylcholine and non depolarizers in patients with Eaton Lambert syndrome?
Both are more sensitive in ELS patients
Greatest cause of perioperative morbidity in Duchenne’s muscular dystrophy patients
Respiratory complications secondary to restrictive pulmonary disease and pulmonary hypertension
How does lithium affect muscle relaxants?
Lithium potentiates both depolarizing and nondepolarizing agents
Drug that is most commonly abused among anesthesiologist and most likely associated with relapse
Fentanyl
Normal vitals for preterm
HR 160
SBP 50
DBP 30
RR 50
Normal vitals for term newborn
HR 130
SBP 60
DBP 40
RR 50
Normal vitals for 1 yr old
HR 120
SBP 80
DBP 60
RR 25
Normal vitals for toddler
HR 90
SBP 100
DBP 60
RR 20
Eaton lambert syndrome and myasthenia gravis sensitivity to nondepolarizers is increased or decreased
Increased.
How does up regulation of extrajunctional acetylcholine receptors affect response to muscle relaxants
Resistance to nondepolarizers and more sensitivity to depolarizers
How does autoimmune disorders affect response to muscle relaxants
Increased sensitivity to both nondepolarizers and depolarizers
Metabolism of mevacurium
Pseudocholinesterase
Why doesn’t glycopyrrolate cause mydriasis?
It’s quaternary structure prevents it from cross blood brain barrier so CNS and pupillary effects are not seen
Treatment for central anticholinergic syndrome
Physostigmine (tertiary structure allows it to cross blood brain barrier to “reverse” effects of scopolamine
Systolic pressure is higher at aorta or radial artery?
Radial artery
What is ecothiophate and what anesthetic drug should be avoided?
Irreversible cholinesterase inhibitor used for chronic glaucoma. Avoid using succinylcholine and other drugs metabolized by plasma cholinesterases including pseudocholinesterase.