M5 2014 Flashcards
Innervation of posterior tongue, soft palate, and oropharynx
Glossopharyngeal n. (IX)
Innervation of anterior tongue
Trigeminal n., mandibular branch (V3)
Innervation of hypopharynx
Internal branch of superior laryngeal n. (X)
Innervation of larynx and trachea
Recurrent laryngeal n.
Topicalizing anterior tonsillar pillars with lidocaine will anesthetize what nerve?
Glossopharyngeal n. (Only tonsillar, lingual, and pharyngeal branches, not the whole n.)
External branch of superior laryngeal n. supplies motor innervation to what?
Cricothyroid muscle
Blocking inferior aspect of greater cornu of hyoid bone will anesthetize what nerve?
Internal branch of superior laryngeal n., which innervates the hypopharynx
Only muscle responsible for vocal cord abduction
Posterior cricoarytenoid muscle
Only vocal cord muscle NOT innervated by recurrent laryngeal n.
Cricothyroid muscle, innervated by external branch of superior laryngeal n.
Block of recurrent laryngeal n. results in vocal cords being affected how?
Partial adduction. Unilateral block = hoarseness. Bilateral block = stridor and possible airway obstruction
Most sensitive indicator for a difficult intubation
Mallampati class 3 or 4
2nd most sensitive indicator for difficult intubation
Reduced thyromental distance
Highest positive predictive value (PPV) for difficult intubation
History of difficult intubation
Function of type I and type II pneumocytes
Type I: gas exchange
Type II: produce surfactant, smaller and far more numerous than type I
Sensory innervation of lung is provided by which nerve
Vagus nerve
Long thoracic n. innervates what muscle
Serratus anterior
Winged scapula is a result of damage to what nerve
Long thoracic n.
Coronary a. supplying anterolateral wall of LV
Left circumflex
Coronary a. supplying anteroseptal wall of LV
LAD
Coronary a. supplying inferior wall of LV
RCA
Coronary a. supplying inferolateral wall of LV
RCA and LCx
Most patients with atrial flutter have a rapid circuit originating from which chamber of the heart
Right atrium and involving tissue near tricuspid valve
Aortic arch crosses up, over, and behind which main bronchus
Left main bronchus
Aortic dissection creates false lumen in which layer of the aortic wall
Media (intima, media, adventitia)
Risk factors for aortic dissection
Uncontrolled HTN, connective tissue disease, vasculitis, trauma
Course of subclavian vein in relation to anterior scalene muscle
Anterior
Course of subclavian artery in relation to anterior scalene muscle
Between middle and anterior scalene muscles
Course of subclavian vein in relation to first rib
Superior to first rib and inferior to clavicle
Continuation of internal carotid artery in circle of Willis is called
Middle cerebral artery
When does spinal cord move from L3 to L1
By 2 months of age
Superior aspect of iliac crest is at which vertebral level
L4
Innervation of facet joint between 2 vertebrae
Medial branch of the posterior division of spinal nerves
Celiac plexus is located at which vertebral level
L1
Which nerve is inadequately blocked following axillary block
Musculocutaneous nerve which innervates lateral forearm
Medial forearm is innervated by cutaneous branches of which nerve
Ulnar
Relationship of median nerve to brachial artery in the antecubital fossa
Median nerve runs medial to brachial artery
Parasympathetic fibers to the heart arise from
Dorsal vagal nucleus and nucleus ambiguous
The two plexuses arising from parasympathetic fibers to the heart are located between
Aortic arch and tracheal bifurcation
Nicotinic acetylcholine receptors are found in greatest concentration at which heart node
SA node
Sympathetic cardiac nerve fibers course with which coronary artery
Left main coronary artery
How and when is S3 heart sound made
Early diastole when atrial blood reverberates against poorly functioning ventricular walls. S3 is associated strongly with MACEs (major adverse cardiac events)
S1 sound is heard where on an EKG
Just after QRS complex
S2 sound is heard where on an EKG
Just after T wave
S4 sound is heard where on an EKG
Just after p wave. Sound is caused by atrial contraction ejecting blood into a noncompliant ventricle
Where is mixed venous oxygen saturation measured
Right atrium
ATP binding to myosin results in
Release of myosin tension from actin
Amiodarone is what class of antiarrhythmic agent
Class III, a potassium blocking agent which delays phase 3 repolarization.
Side effects of amiodarone
Pulmonary fibrosis, hypothyroidism or hyperthyroidism, transaminitis, peripheral neuropathies
How does glucagon treat beta blocker overdose
Glucagon increases cAMP and therefore protein kinase A
At what heart rate is stroke volume the greatest
60
At what heart rate is cardiac index maximized
120
Reflex when a hypovolemic pt has bradycardia and hypotension when moved from supine to upright
von Bezold-Jarisch reflex. Receptors in left ventricle
Mechanics of alpha 1 mediated vasoconstriction
Phenylephrine -> alpha 1 receptor -> activation of PLC (phospholipase C) -> formation of IP3 (inositol triphosphate) -> Ca release from sarcoplasmic reticulum -> increased contraction
Mechanics of beta 2 agonism
Beta 2 receptor -> cAMP -> uptake of Ca back to SR -> decreased contraction
Mechanics of NO activity
NO -> cGMP -> decreased contraction
Minimum number of days after coronary balloon angioplasty to wait before performing elective surgery
14 days
Slope of dose response curve is determined by
Receptor binding characteristics
Respiratory depression is mediated by which opioid receptor
Mu2
Muscle rigidity is mediated by which opioid receptor
Mu1
Hallucinations are mediated by which opioid receptor
Sigma
Opioid that decreases contractility, increases heart rate, and causes mydriasis
Meperidine, has atropine like structure causing anticholinergic response
Meperidine decreases shivering by agonism of what receptor
Kappa
Effects of opioids that are resistant to tolerance
Constipation and miosis
High doses of which opioid may induce acute opioid tolerance in the PACU
Remifentanil
Baclofen is an agonist of what receptor
GABA-B receptor
Aspirin sensitivity with nasal polyps is associated with what medical condition
Asthma. Samter’s triad
Reason for hypertension and bradycardia during infusion of dexmedetomidine
Cross reactivity with alpha 1 receptor at high doses
Benzodiazepine effects of amnesia is explained by hyperpolarization of
Post synaptic neurons primarily in the cerebral cortex
Benzodiazepine mediated muscle relaxation occurs through gamma subunit agonism of
GABA-A receptor specifically in the spinal cord
Hyperalgesia is mediated by what process
Opioid NMDA agonism, which explains why patients respond well to NMDA antagonists like ketamine, methadone, and dextromethorphan
How does activation of opioid receptors affect potassium conductance
Increase
Opioids that cause inhibition of serotonin reuptake
Meperidine, methadone, tramadol, dextromethorphan.
Pretreatment with what medication decreases incidence of etomidate associated myoclonus
Opioids
how much of etomidate is not metabolized after passing through liver
50%
Why is it that more active neurons are blocked to a greater extent than less active neurons
Sodium channels in the activated or inactivated state have a greater affinity for local anesthetics than in the resting state
rate of systemic absorption of local anesthetic from greatest to least
IV > tracheal > intercostal > caudal > paracervical > epidural > brachial plexus > sciatic > subcutaneous
Adding epinephrine to lidocaine will increase duration of peripheral nerve block by about how much?
50%
local anesthetics bind to which subunit of the voltage-gated sodium channels
alpha
2 ways that epinephrine enhances quality of a nerve block
1) vasoconstriction causing longer period of time that local is exposed to neuron
2) direct adrenergic activation of alpha-2 receptors
exception to the rule of pseudocholinesterase metabolism of ester local anesthetic
cocaine
Why is block onset faster by adding epi to plain local vs. using premixed local with epi?
Premixed solutions are more acidic to prevent degradation of epi
Basic drugs are usually bound to which protein?
Alpha-1-acid glycoprotein
Acidic drugs are usually bound to which protein?
Albumin
Preservative used with amide local anesthetic
Methylparaben
glutamate is an excitatory or inhibitory neurotransmitter?
excitatory
how does opioid agonism change the resting potential of a neuron
make it more negative
brain needs what percent of cardiac output to cover metabolic needs
15-20%
Is obesity a risk factor for POCD postop cognitive decline?
no
what area in the brain is pain sensed?
postcentral gyrus
Norepinephrine is metabolized by what?
Both MAO (monoamine oxidase) and COMT (catechol O-methyltransferase)
which opioid increases cerebral blood flow
sufentanil
external or internal intercostal muscles are used for inspiration?
external
external or internal intercostal muscles are used for expiration?
internal
dead space is what percent of tidal volume in a healthy mechanically ventilated patient?
50%
above what shunt fraction would supplemental oxygen not expect to increase PaO2 by more than 10 mmHg?
40%
Use ventilation-perfusion ratio (VQI) to calculate shunt
VQI = ( 1 - SaO2 ) / ( 1 - MvO2 ). Therefore 99% SaO2 with 75% MvO2 = 0.01 / 0.25 = 4% shunt in healthy person
Decreased FEF 25%-75% (forced expiratory flow) is indicative of what?
early indicator of medium airway obstructive disease. it is theoretically effort independent
FRC is classically lowest when after a surgery?
12 hours postop
General anesthesia will decrease FRC by what percent?
10%
maximal benefit from smoking cessation is how many weeks prior to surgery?
8 weeks or more
Classic EKG findings for a COPD patient
signs of right heart strain such as poor R wave progression, enlarged P waves, RBBB, right axis deviation, low voltage
Abdominal surgery affects residual volume (RV) how?
increases it by 10%. expiratory reserve volume is decreased by 25%
Best surface anatomic estimate for level of the carina
sternal angle
best marker for dynamic lung compliance
peak pressure
Ach receptor requires binding of how many Ach molecules to activate?
2
Ach receptor uses a pair of alpha or beta subunits?
alpha subunits
what does ecothiophate do?
cholinesterase inhibitor
dibucaine number for normal person
80%
half life of esmolol
10-20 minutes
muscle fasciculations after succinylcholine have strongest association with which effect?
increased ICP
muscle relaxants metabolized by pseudocholinesterase
mivacurium and succinylcholine
steroid muscle relaxant that has no metabolites
rocuronium
Extubation criteria for RSBI (rapid shallow breathing index) should be less than
105 (RR/TV)
duration of neostigmine
1 hour
timing of peak effect of neostigmine
10 min
treatment for central anticholinergic syndrome
physostigmine, because its tertiary amine structure allows it to cross blood brain barrier, unlike neostigmine and edrophonium
A right to left cardiac shunt will slow the induction more in desflurane or isoflurane
desflurane because so very little desflurane is taken up so when it is further diluted with a right to left shunt, it slows induction
decreased cardiac output slows or speeds elimination of inhaled anesthetics
speeds
MAC value for ED95 for patient moving in response to surgical stimulus
1.3
which electrolyte abnormality increases MAC
hypernatremia
inhaled anesthetic that doesn’t increase apneic threshold
nitrous oxide, which also does not potentiate muscle relaxation
which of the modern inhaled anesthetics is metabolized to the greatest extent
sevoflurane, 5%
which modern inhaled anesthetic produces the greatest extent of coronary vasodilatation
isoflurane
at what MAC does isoflurane produce burst suppression of EEG
1.5 MAC
which modern inhaled anesthetic causes transient increases in sympathetic tone with rapid increases in concentration during induction
desflurane and isoflurane
desflurane can be degraded by dessicated CO2 absorbent to produce what?
carbon monoxide
A unit of insulin should decrease glucose by how much?
25 mg/dL
hypothyroidism is associated with hyper or hypo natremia?
hyponatremia because patients retain free water
Chance of cross-reaction between penicillin and cephalosporins
< 2%
why is ankylosing spondylitis patient at increased risk for neuraxial and general anesthesia?
GA: cervical neck stenosis
Neuraxial: reduced intervertebral spaces and ossification
minimum gas flow rate needed for a carbon dioxide absorber to prevent rebreathing of CO2
5L/min
least likely benefit of neuraxial anesthesia
decreased morbidity and mortality from myocardial ischemia
Neuraxial anesthesia can be done how many hrs after last dose of daily enoxaparin? And enoxaparin can be restarted how many hrs after block placed?
Block can be placed 12 hrs after last dose. Dose can be given 6 hrs after block is placed.
which epidurally given local anesthetic interferes with epidural opioid mediated analgesia
chloroprocaine
supraclavicular or interscalene block has higher incidence of transient hemidiaphragmatic paralysis
interscalene
which brachial plexus block has highest incidence of chylothorax
infraclavicular block
which brachial plexus block performed without ultrasound has highest risk of pneumothorax
infraclavicular block
axillary block likely misses what nerve and what sensory region of arm?
musculocutaneous, lateral forearm
relationship of ulnar, median, and radial nerves to the axillary artery for axillary block
ulnar is superior-medial
median is superior-lateral
radial is deep to artery
what proportion of sodium filtered by glomerulus is typically excreted in the urine
5%
Site of action of furosemide
ascending loop of Henle
ADH increases aquaporin-2 channels in what part of the nephron?
collecting duct
what part of nephron is most responsible for concentrating urine
collecting duct
what is the reason to prescribe ACE inhibitor for CHF patient?
interrupt pathological increases in sodium retention
mechanism of action of spironolactone
direct aldosterone receptor antagonist, leading to decreased Na/K ATPase activity so potassium-sparing
mechanism of action of acetazolamide
carbonic anhydrase inhibitor, leading to inhibition of bicarb uptake at proximal tubule
mechanism of action of loop diuretics
inhibit Na-K-2Cl transporter in the thick ascending limb of the loop of Henle
mechanism of action of thiazides
inhibit Na-Cl transporter in the distal convoluted tubule
furosemide’s effect on calcium level
furosemide leads to hypocalcemia
thiazide’s effect on calcium level
thiazide increase calcium reabsorption -> hypercalcemia
which is used to treat hypercalcemia? furosemide or thiazide?
furosemide
why do potassium-excreting diuretics increase risk of digoxin toxicity?
digoxin competes with potassium on Na-K ATPase, so hypokalemia worsens risk of digoxin toxicity
furosemide causes metabolic acidosis or alkalosis
metabolic alkalosis
why does a hyperosmolar state cause hyperkalemia?
Potassium follows water out of the intracellular compartment
An increased SIG (strong ion gap) demonstrates what metabolic abnormality
metabolic alkalosis
A decreased SIG (strong ion gap) demonstrates what metabolic abnormality
metabolic acidosis
Fatter or thinner people are at increased risk of ulnar neuropathy
fatter
fatter or thinner people are at increased risk of common peroneal injury
thinner
the only sure-proof way to treat “obturator reflex” in a cystoscopy under spinal anesthesia is to?
induce general anesthesia with neuromuscular blockade
What causes hyperammonemia in TURP syndrome?
glycine can be metabolized to ammonia