Blast Basics Flashcards
What is the anatomical landmark for each level:
C7
T4
T7
T8
T10
T12 -L4
L2
L4
L4-S3
S2
C7 vertebra prominens
T4 nipple line
T7 xiphoid process
T8 inferior border of scapula
T10 umbilicus
T2-L4 lumbar plexus
L2 termination of spinal cord adults
L4 iliac crest
L4-S3 sacral plexus
S2 termination of subarachnoid space in adults
What is oculocardiac reflex (OCR)? Which nerves are involved?
10% decrease in heart rate associated with traction applied to extraocular muscles, direct pressure on the globe, ocular manipulation, and ocular pain.
Can lead to bradycardia , hypotension, junctional Rythm, ectopic beats, av block or asystole.
Reverted with atropine
Afferent Lomb mediated by trigeminal nerve. Efferent by vagus nerve.
What drug is echotiophate? What is it’s interaction with succinylcholine?
Anticholinesterase used for glaucoma.
Increase the duration of succinylcholine.
Which nerve innervates the larynx muscles? What’s the exception
All larynx muscles are innervated by the recurrent laryngeal nerve.
Exception to cricothyroid muscle, which is innervated by the external branch of superior laryngeal nerve.
Innervation of upper airway:
Anterior 2/3 of the tongue: mandibular branch of the tirgeminal nerve (v5)
Posterior 1/3 of the tongue, Soft palate and oropharynx: glossopharyngeal (IX)
Hypopharynx below level of epiglottis: internal branch of superior laryngeal nerve-> vagus nerve
Larynx bellow the vocal cords and trachea: recurrent laryngeal nerve.
Which blocks are used for regional Anesthesia for intubation?
Glossopharyngeal block:
- local anesthetic sunmucoaally at the caudal portion of the posterior tonsillar pillar.
Superior laryngeal nerve block:
- local anesthetic instilled are the level of the thyroid membrane at the inferior aspect of the greater Cornu of hyoid bone. (Blocks the internal branch of the superior laryngeal nerve)
Transtracheal block:
- recurrent laryngeal nerve blocked by instilling local anesthetic into the trachea at the level of crycothyroid membrane.
Landmarks for caudal anesthesia
Sacral hiatus - defect formed by failure to S4 and S5 to fuse midline.
Bound by sacral cornu
Sacral hiatus can be found between Posterior superior iliac spines (PSIS).
Pierce through sacrococcygeal ligament.
What’s the location of brachial plexus?
At or Bellow the level of clavicle.
Closely related to axillary artery.
Where is the supraclavicular block performed?
Above the clavicle , lateral to the subclavian artery, targeting the brachial plexus.
What is meralgia paresthetica?
Pain and/or dysesthesia in the anteriolateral thigh.
Caused by compression of femoral cutaneous nerve.
Which dermatomes are not adequately covered with iterscalene block?
C5-7
Intercostobrachial nerve block provide anesthesia to which dermatome?
Provides anesthesia to T2 dermatome. Proximal arm.
Respiratory centers functions?
Dorsal?
Ventral?
apneustic?
pneumotaxic?
Medulla
- Dorsal: ventilation rate by stimulating inspiration.
-Ventral: ends inspiration
Pontine:
- apneustic: sustain inspiration
- pneumotaxic: limits depth of inspiration.
Carotid body chemorecptors communicate with respiratory centers via which nerve?
Carotid body receptors senses oxygen, CO2, acidosis. Commuicate via glossopharyngeal.
Aortic arch chemorecptors communicate with resp centers via which nerve?
vagus nerve.
Senses changes in O2, CO2 and pH.
whats the function of each pathway:
Dorsal column
Spniothalamic
Corticospinal
Reticulospinal
Spinothalamic: carries pain and temperature
Dorsal column: Vibration, propioception, pressure, touch
Corticospinal: Motor fibers
Reticulospinal: Influences motor pathway and is involved in atonomic activity.
What is the effect of IV induction anesthetics to CBF? What’s the exception?
IV agents decrease CBF.
Ketamine is the exception that increases CBF.
What’s the effect of volatile anesthetics to CBF?
In general volatile anesthetics INCREASE CBF and decrease CMRO2.
halotane>desflurane>isoflurane>sevoflurane.
What’s the effect of nitrous oxide on CBF and CMRO2?
If given alone: Increase both CBF and CMRO2.
If given with another volatile anesthetics, Nitrous Oxide effects are exacerbated.
If given with IV agents, has minimal or no effects.
What’s the effect of opioids on CBF?
Have no effect or decrease.
Remifentanil increases CBF at low sedative rates.
What’s the effect of Benzos to CBF?
Benzodiazepines reduce CBF.
What’s the effect of volatile anesthetics to formation and absorption of CSF?
Halotane impedes absorption of CSF, minimal decrease in CSF formation.
Isoflurane facilitates CSF absorption.
Where CSF is produced?
Whats the rate of production?
What’s the total volume?
Where is absorbed?
Produced by the coroid plexus.
20ml/h
Total volume 100-150mL
Absorbed at arachnoid villi in cerebral venous sinuses.
Which IV anesthetic class provides some protection against ischemia?
Barbiturates
What’s the effect of Ketamine on CSF?
Ketamine increases CSF production.
Whats the most ubiquitous material in the epidural space?
Fat
What it the gate control theory?
Non painful input results in attenuation of the pain sensation.
What is the effect of NMDA receptor activation?
Hyperalgesia
opioid tolerance
reduce central sensitization
Which drugs are NMDA receptor antagonist?
Ketamine
Methadone
memantine,
amantadine
dextromethorphan
activation of which opiod receptor is antipruritic?
Kappa
What to do if a vaporizer is tipped on it’s side?
Run high fresh gas flows with the dial set to a high concentration for 30 minutes
What happen to the output concentration of a volatile
anesthetic from a vaporizer if connected to 100% oxygen?
and 100% Nitrous Oxide?
100% nitrous oxide => decrease in the vaporizer output occurs, as the nitrous is more soluble in anesthetic liquid.
100% Oxygen => output concentration increases.
How very low or very high flow rates affects the output concentration of volatile anesthetic from a vaporizer?
Very low rates -> not enough turbulence to pick up the anesthetic vapors.
Very high flow rates => more than 15L/min => the flow is too fast, not enough time to concentrate the gas => will have a lower concentration than what’s on the dial.
T o decrease temperature fluctuations while delivering an anesthetic agent, manufacturers seek to use vaporizer materials that has which properties?
High specific heat, high thermal conductivity.
Less temperature variability means more stable concentration of volatile anesthetics vapors being delivered to the patient.
How to determinate how much time left in Oxygen Cilinder?
Pressure psig/(200 x flow rate).
A 2000 psig cilinder has 625L.
What is the definition of critical temperature?
Max temp which a gas can exist in liquid form
What does means to say a volatile anesthetic is at equilibrium in blood, CNS and alveoli?
It mean the the partial pressure in the blood, CNS and alveoli are the same.
which tissue group plays the greatest role in determining emergence time?
FAT
What should be the sequence of flowmeters on the anesthesia machine to prevent hypoxic mixtures?
Oxygen should be always to most downstream flow meter to prevent a backflow.
The sequence would be N2O, Air, O2.
What’s the function of a valve check on anesthesia machine?
Prevent backflow from the common gas outlet to the vaporizer.
What would cause a sudden Co2 decrease on capinography during surgery?
Sudden severe Hypotension, Massive PE, cardiac arrest.
Ultrasound sound wave characteristics properties:
Amplitude
Frequency
Wavelength
Velocity
Amplitude: How loud the sound is
Frequency: Number of cycles per second. Lower frequencies penetrate better tissues
Wavelength: Distance between two peaks of each wave
Velocity: product of wavelength and Frequency.
Ultrasound resolution:
Axial
Lateral
Elevational
Axial: evaluate objects lying on the axis of the US beam
Lateral: objects horizontal to the beam
Elevational: Objects vertical to the beam
How to maximize axial resolution on ultrasound?
Use short high frequency pulses.
Caviat: Has lower penetration.
What’s the function of a flow proportioning system in an anesthesia machine?
Prevent Hypoxic gas administration.
What’s Isolated Power System (IPS)?
It’s a system that prevents macroshock (enough to cause V fib)
The power supply for the OR is ungrounded and isolated from ground potential.
What the most oxygen consuming event in cardiac cycle?
The most energy consuming event in the cardiac cycle is isovolumetric contraction
What is the earliest indicators of myocardial ischemia?
The earliest indicators of myocardial ischemia is increased left ventricle end-diastolic volime (LVEDV) and dreased compliance.
What is the E and A waves on echocardiography? What is their normal relationship?
E wave: flow across the mitral valve during early diastole. A wave : flow during atrial contraction.
-Normal diastolic function is E to A wave ratio more than 1.
- Diastolic dysfunction: A wave is more proeminent than E wave.
How to calculate MAP?
MAP = DBP + (0.33x pulse pressure)
What’s the effect of inhaled anesthetics to SA node automacity?
Depress SA node automacity.
Prolong conduction and increase refractoriness.
Why there is Junctional Tachycardia when anticholinergic is given for sinus bradycardia during inhalation anesthesia?
Inhaled anesthetics depress SA node automacity.
Therefore, anticholinergic stimulate Junctional pacemakers more then SA node.
What are the effects of opioids on heart conduction?
Opioids, specially fentanyl and sulfentanil, depress cardiac conduction, increase the time for AV node conduction and refractory period and prolong the duration of Purkinje fiber action potential.
What are the effects of Bupivacaine on the heart?
Longer effect then others local anesthetics.
Binds to open or inactivated sodium channels.
Can cause profound sinus bradycardia and sinus node arrest and malignant ventricular arrhythmias.
Can depress ventricular contractility.
How to treat local anesthesia systemic toxicity
20% lipid emulsion.
What’s the effect of volatile anesthestics on cardiac contractility?
Depress contraction due a decrease in Ca2+ entry into cells during depolarization.
Which factors can potentiate cardiac depression by volatile anesthetics?
hypocalcemia, B-block, ca channel bloq, Nitrous oxide.
What is compound A?
Compound A is a Sevoflurane degradation by-product, known to be nephrotoxic in rats.
Which factors increase compound A formation?
Dry barium hydroxide, increased respiratory gas temp, low-flow anesthesia, high sevoflurane concentration.
Which are the specific anesthetic considerations for Aortic Stenosis patients?
The patient should be kept with elevated SVR, low HR and optimized preload.
Which are the anesthetic considerations for a patient with Pulmonary HTN.
Should maintain right coronary well perfused.
1. High SVR
2. Decrease PVR.
3. increase inotropy.
Which medication should be avoided in a transplanted heart?
Neostigmine and other acetylcholinesterase inhibitors should be avoided as it can cause bradycardia dose-dependent. (responds well to atropine).
How long should a patient wait to go on a non-cardiac surgery after an MI?
60 or more days.
Which induction agent should be avoided in Hypertensive patients?
Ketamine can cause hypertension and should be avoided in HTN patients. Although when given with another agent as opioids or benzos, it’s sympathetic effects are blunted.
Function
C5-6
C6-7
C8
T1
C8-T1
L2-L3
L3-4
L4-5
L5-S1
S1-S2
C5-6
Arm flexion against resistance (musculocutaneous nerve)
C6-7
Wrist extension against resistance (radial nerve)
C8
Grip strength (median nerve)
T1
Finger abduction (fanning) against resistance (ulnar nerve)
C8-T1
Thumb opposition against resistance (median nerve)
L2-L3
Hip flexion against resistance (femoral nerve)
L3-4
Knee extension against resistance (femoral nerve)
L4-5
Ankle dorsiflexion against resistance (peroneal nerve)
L5-S1
Knee flexion against resistance (sciatic nerve)
S1-S2
Ankle plantarflexion against resistance (tibial nerve)
What is the Hering-Breuer reflex?
The slowing of breathing with activation of pulmonary stretch receptors.
Neuroleptic malignant syndrome symptoms
Muscle rigidity, trismus, tremor, hyperthermia, altered mental status and autonomic instability.
What is the meaning of each letter on a pacemaker? eg. DDD
The first letter means which chamber it paces (A-atrial, V- ventricular, D- dual, O-none).
2nd letter it senses.
3rd letter is the response (I-inhibited, T-trigged, D- Dual, O-none).
4th letter describes programmability (R-rate modulation, O-none).
Criteria for biventricular pacing in CHF.
NYHA class III or IV; EF < 35% and QRS > 120msec.
When epinephrine should be given in a non-shockable rhythm CPR?
For non-shockable rhythm should be given as soon as possible.
For shockable rhythm calls for defibrillation then 2 min of CPR then defibrillation then epinephrine.
What are approved uses for Hyperbaric oxygen therapy?
- Gas-bubble disease (air embolism and decompression sickness)
- Carbon Monoxide poisoning.
- Infections (soft tissue necrotizing infections, intracranial abscess, refractory chronic osteomyelitis.
- Acute tissue ischemia( crush injury, compromised skin flaps, central retinal artery or vein occlusion)
- Chronic ischemia (chronic ulcer, radiation necrosis)
- Acute hypoxia (blood loss anemia and blood can’t be given).
- Acute thermal burn injury,
- Idiopathic sudden sensorineural hearing loss.
Through each muscles the needle goes through on a infraclavicular block?
Pectoralis major and pectoralis minor.
What’s the level of blockade on a infraclavicular block?
Blocks at the level of the cords and provides analgesia to the arm below shoulder level.
Blocks also musculocutaneous and axillary nerves.
Lateral, medial, and posterior cords are around the the axillary artery. Block is performed depositing local anesthetic around the axillary artery.
How to identify C7 on physical exam?
It’s the most cephalad stationary spinous process when the patient flexes and extend their neck.
What are the normal values for parameters measured with a Pulmonary arterial catheter?
CVP: 2-6mm Hg
PCWP: 6-12mmHg
CI 2.5 - 4L/ min/m2
SVR 800-1200 dynes*sec/cm
How is CVP, PCWP, CI and SVR in cardiogenic shock?
CVP: high
PCWP: high
CI: low
SVR: high
How is CVP, PCWP, CI and SVR in hypovolemic shock?
CVP: low
PCWP: low
CI: low
SVR: elevated
How is CVP, PCWP, CI and SVR in distributive shock?
CVP: low
PCWP: low
CI: high
SVR: low
How is CVP, PCWP, CI and SVR in obstructive shock?
CVP: high
PCWP: high
CI: low
SVR: elevated
What is the land mark for a lateral femoral cutaneous block?`
Anterior superior iliac spine.
Difference between roller and centrifugal pumps in cardiopulmonary bypass?
Centrifugal pumps require flowmeters on the arterial portion, due to flow variation with with alterations in pump preload and afterload.
Roller pump flow depend only on the speed of the rollers.
Roller pump is more associated with blood element destruction, creation of plastic emboli, and elimination of tubing wear and spallation, and inflow and outflow obstruction.
What are the most common complications after subarachnoid hemorrhage?
The most common cause of death is the initial bleeding.
Rebleeding peaks in 24h.
Vasospasm starts occurring from the third day, but peaks in 5 to 10 days.
What is phosgene? cause of mortality/morbidity? treatment?
Chemical used in warfare. Cause pulmonary damage. Treatment is supportive.
Which block is performed for patients with CRPS of the lower extremity?
Lumbar sympathetic plexus block. Injection of local anesthetic at the anterolateral aspect of lumbar vertebral bodies (L1-L5).
What is the most common valvopathy associated with rheumatoid arthritis?
Mitral regurgitation.
Interscalene block. Indications? Complications
Shoulder, lateral clavicle and upper arm surgeries.
Complications: recurrent laryngeal nerve paralysis, Horner’s syndrome, diaphragmatic paralysis, intravascular injection in the vertebral artery, unitentional epidural or subarachnoid block, pneumothorax.
Supraclavicular block. Indications? Complications?
upper arm, elbow, and forearm.
Major complication is pneumothorax due to the close proximity to the pleura. And intravascular injection in suprascapular and transverse cervical arteries.
Horner’s.
Infraclavicular block. Indications? Complications?
upper arm, forearm, and hand.
Level of chords.
Complications similar to supraclavicular, but lesser chance of Horner’s and pneumothorax.
Needle goes through pectoralis major and minor.
Axillary block. Indications? Complications?
procedures elbow, forearm and hand.
Block of the terminal branches.
Lesser chance of phrenic nerve paralysis or pneumothorax.
What are the borders of adductor canal?
Sartorious, vastus medialis, and adductor longus muscles.
Adductor canal block indications?
Surgery on the knee and/or cutaneous involvement of the medial leg or ankle.
Location of lateral femoral cutaneous nerve?
the lateral femoral cutaneous nerve originates from L2 and L3 and carries
only sensory fibers. The nerve is located inferior and medial to the anterior superior iliac
spine and supplies the anterolateral part of the thigh up to the knee.
Duration of local anesthetics:
lidocaine 2% and mepivacaine 1.5% w/ ropivacaine .2% or .5%?
Ropivacaine .2 to .5% solo
lidocaine 2% or mepivacaine 1.5% w/ ropivacaine .2% or .5%? -> 5 to 6h
Ropivacaine alone -> 12 to 14h.
CNS signs of local anesthetic toxicity:
Circumoral paresthesias, lightheadedness, dizziness, difficulty focusing, and tinnitus
Restlessness and agitation
Slurred speech, drowsiness, and unconsciousness
Shivering, muscular twitching, tremors, and generalized seizures
Respiratory depression and respiratory arrest.
Cardiovascular signs and symptoms of local anesthetic toxicity:
Bradycardia
Hypotension
Intractable arrhythmias (ventricular ectopy, multiform ventricular tachycardia, and
ventricular fibrillation)
Cardiovascular collapse and asystole.
Where the spinal cord terminates in infants?
The spinal cord terminates at L3 level, dural sac extends to S3.
why bradycardia is uncommon in infants undergoing spinal anesthesia?
Infants have a high vagal tone and immature sympathetic system. Infants do not rely on cardiac accelerating fibers for a resting heart rate.
Bradycardia occurs in adults when sympathectomy affects the cardiac accelerating fibers (T1-t4).
Whats the CSF volume ml/kg in infants, children and adults?
Infants 4mL/kg
Children 3mL/kg
Adult 1.5-2mL/kg
When a malpractice situation needs to be reported to National Practitioner Data Bank?
Any malpractice payment made by insurer must be reported to NPDB, whether is a pretrial settlement or the result of judgment.
What are the most common side-effects of administration of succinylcholine in children?
- Bradicardia
- Junctional rhythms
- Myalgias
- Hyperkalemia (if patient has muscular dystrophy).
- Malignant hyperthermia
- No significant clinical effect: increase ICP, intraocular pressure and intragastric pressure.
How to calculate maximum allowed blood loss?
EBV= weight KG x blood volume (ml/kg)
ABL= EBV x(Hct initial - Hct target)/ Hct initial
Average blood volumes for:
Premature neonates
Full term neonates
Infants
Adult men
Adult woman
Premature Neonates 95 mL/kg
Full Term Neonates 85 mL/kg
Infants 80 mL/kg
Adult Men 75 mL/kg
Adult Women 65 mL/kg
What are the effects to platelets in cirrhotic patients?
Platelets are usually decrease due to hypersplenism and due reduced production of thrombopoietin. Alcoholism can cause bone marrow suppression.
What’s the pattern on a flow-volume loop for a variable extrathoracic airway obstruction?
Has a plateau on the INSPIRATORY curve
What’s the pattern on a flow-volume loop for a variable intrathoracic airway obstruction?
Has a plateau on the EXPIRATORY curve
What’s the effect of NO in the smooth cells of the pulmonary vasculature?
Nitrous oxide activate guanylate cyclase, which converts GTP in GMP.
Increased cGMP causes smooth muscle relaxation.
which substance controls the hepatic arterial buffer system?
Adenosine.
Hepatic arterial buffer system, stands for the portal venous flow regulating hepatic artery flow.
Adenosine is produced and accumulated in the liver. When there’s reduced portal venous flow, it builds up and causes dilation of hepatic artery.
If portal vein flow is increased, less adenosine is accumulated and causes vasoconstriction of hepatic artery.
Which nerve needs to be blocked in addition to supraclavicular block to decrease tourniquet pain?
Intercostobrachial nerve (t2). Medial upper arm dermatome.
Not covered by any brachial plexus blocks.
Anterior spinal chord ischemia will effect which evoked potential?
Motor evoked potential.
50% decrease in amplitude and 10% increase in latency.
Posterior spinal chord ischemia will effect which evoked potential?
Somatosensory evoked potential.
Which opioids should be avoided in CKD patients?
Morphine and meperidine.
Morphine metabolite, morphine-6-glucoronide, is more potent then morphine is excreted by the kidney.
Meperidine metabolite, normoperidine, is neurotoxic and can cause seizure.
What are the most common causes of atlantoaxial instability?
- trauma
- achondroplasia
- down syndrome
4rheumatoid arthritis
How to manage auto-PEEP?
- Disconnect the expiratory limb from the ventilator to allow complete exhalation.
- Adjust vent settings: a. increase expiratory time. b. decrease respiratory rate. c. decrease tidal volume.
- Reduce demand: reduce pain, anxiety, fever, give sedation/ NMR, reduce dead space.
- reduce flow resistance: give broncho dilators, suction the tube.
- increase external PEEP.
What’s the effect of mu-opioid receptors?
- miosis
- dependence
- respiratory depression
- sedation
- nausea
- euphoria
obs: all opioid receptors have analgesic effects.
What’s the effect of kappa-opioid receptor?
- miosis
- diuresis,
- dysphoria
what’s the effect of delta-opioid receptors?
- respiratory depression
- inhibits dopamine release
- modulates mu receptor.
On which receptors Nalbuphine works?
Kappa-opioid agonist and partial mu-opioid antagonist.
Has similar analgesic effect as morphine, but has a ceiling effect around 30mg where it does not produce further respiratory depression.
Buprenorphine receptors?
Mu-opioid partial agonist and kappa-antagonist.
Butorphanol works on which receptors?
Mu-opioid agonist-antagonist and a kappa-opioid receptor partial agonist.
Helps to treat pain, post-op shivering, and neuroaxial opioid-induced central pruritus.
How to treat extrapyramidal symptoms caused by antidopaminergic (metoclopramide) medications?
- Anticholinergic medications (benzotropine, diphenhydramine, atropine).
Second line treatment: benzos, beta-blockers, antihistamines, and dopamine receptors agonist.
Which drugs are metabolized by pseudocholinesterase?
Succinylcholine, mivacurium, ester local anesthetics( procaine, chlorprocaine, cocaine, tetracaine), aspirin, and heroin.
Which enzyme is inhibited by etomidate?
11B-hydroxylase, which is responsible for synthesis of cortisol and aldosterone.
What causes ichemia-reperfusion syndrome?
The ischemia time during the liver transplant causes disruptions on Na-K channels due to lack of ATP and glycogen. When the liver is reperfused, more sodium enters the cell causing swelling and more damage.
What’s the mechanism behind Cushing reflex?
Increased intracranial pressure, causes increase intramedullary pressure resulting in medullary ischemia. Ischemia of the vasomotor center will cause a increase in systemic vascular tone, myocardial contractility, and heart rate, to improve cerebral perfusion. The increase in vascular tone causes reflex bradycardia mediated by baroreceptors.
Why elderly patients have slower onset of NMB and longer duration?
Potency is the same. Slower onset due to reduced cardiac output, therefore takes longer to distribute the drug. Longer duration because most of NMB depends on liver or renal clearance to be eliminated. The exception is cisatracurium which depends on Hofmann elimination.
What’s the main cause for shortness of breath after interscalene block?
Diaphragmatic hemiparesis, which occurs in 100% of the patients undergoing interscalene blockade.
What are the main differences of spinal anesthesia in infants compared to adults?
- Faster onset due to a higher cardiac output, highly vascular pia mater, and loose myelination.
- Decreased duration of action, due to increased diffusion and clearance.
- increased spread due to a lack of thoracic kyphosis.
- Cardiovascular collapse is rare, because their sympathetic system is immature, so they don’t depend on it.
Factors that promote leftward-shift of hemoglobin-oxygen dissociation curve?
- CO poisoning
- hypothermia
- Hypocapnia
- reduced concentration of 2,3 BPG.
- Alkalemia.