NBCRNA Review
What are the two pathological variants of the nicotinic receptor?
1) episilon replaced by gamma subunit 2) 5 alpha subunits
Key side effects of kappa receptor stimulation
dysphoria, antishivering, diuresis
What drug noncompetitively inhibits acetylcholinesterase?
echothiophate/organophosphates
What drug inhibits acetylcholinesterase via electrostatic attachment?
edrophonium
Which beta-blocker can significantly decrease the amount of propofol required to prevent patient movement upon skin incision?
esmolol
What drugs are metabolized by nonspecific esterases?
esmolol, remifentanil, atracurium (+ hoffman), etomidate (+ liver)
What is the primary pathway of etomidate metabolism?
ester hydrolysis driven by plasma esterases and microsomal enzymes
What drugs must be avoided with acute intermittent poryphyrias?
etomidate, barbiturates, glucocorticoids, hydralazine
Treatment for acute intermittent poryphyrias
glucose and heme arginate
What are some examples of common enzyme inhibitors that decrease clearance of drugs?
grapefruit juice, cimetidine, omeprazole, SSRIs, isoniazid, erythromycin
What is unique about pancuronium?
has vagolytic properties making it good for bradycardia or regurgitant lesions
The Mu-2 receptor is primarily responsible for producing what side effects?
respiratory depression, physical dependence, and constipation
What muscarinic antagonist causes the most sedation?
scopolamine
Monoamine oxidase primarily serves to inactivate what through oxidative deamination?
serotonin, dopamine, epinephrine, norepinephrine
What drugs are metabolized by pseudocholinesterase?
succinylcholine, mivacurium, ester local anesthetics
What NMBs cause release of histamine?
sux, atracurium, mivacurium
A propofol syringe must be discarded when? infusion?
syringe = 6 hours infusion = 12 hours
pyridostigmine vs edrophonium dose
pyridostigmine = 0.3 mg/kg edrophonium = 1 mg/kg
The dose for IV or IM midazolam is __________ mg/kg
0.02-0.04
Rocuronium ED95
0.3 mg/kg
Its difficult to detect visual or tactile fade when the TOF > ____
0.4
Maximum dose of cocaine when used as a local anesthetic in adults
150-200 mg
vapor pressure of sevoflurane
157 mmHg
What are the five subunits on the nicotinic receptor?
2 alpha, 1 beta, 1 delta, 1 epsilon
EMLA cream components
2.5% lidocaine and 2.5% prilocaine
Approximately what portion of the total amount of body water is intracellular?
2/3rds
pulmonary HTN is defined as a mean PAP of ______ mmHg
25
Heterozygous deficiency is defined as a dibucaine number between ____-_____
30-70
PDE-___ inhibitors are useful for pulmonary HTN
5
What characteristic places the elderly at increased risk of 30 day mortality?
ASA physical status 4
What is Sampter's triad?
Asthma, nasal polyps and allergy to aspirin (aspirin exacerbated respiratory disease)
What causes fade during train of four stimulation?
antagonism of presynaptic Nn receptors
Pyridostigmine crosses the BBB making it useful for treating central anticholinergic syndrome. T or F
False, physostigmine crosses BBB (useful for anticholinergic syndrome)
With atypical plasma cholinesterase, pseudocholinesterase is not produced in sufficient quantities and will prolong the duration of action for succinylcholine. T or F
False, pseudocholinesterase is produced in sufficient quanities but the enzyme that is produced is not functional
Propofol induction dose should be based on ideal body weight for an obese patient. T or F
False, should be based on lean body weight
Opioids decrease the incidence of myalgias. T or F
False. pretreatment 1/10 dose of nondepolarizer, NSAIDs, lidocaine, and a higher dose of sux reduce the risk.
what drugs are in class I antiarrhythmics?
IA = quinidine, procainamide HCl, disopyramide IB = lidocaine, mexilitine HCl, tocainide, phenytoin IC = flecainide acetate, propafenone HCl
How much is MAC reduced in the full term parturient?
MAC is decreased by 40%
Why are patients with egg allergy probably safe to administer propofol too, despite lecithin being a component of propofol?
Most people are allergic to the egg white proteins. Lecithin is found in egg yolk, soy, and peanuts (the latter two have their allergy proteins removed during the refinement process)
triggers of sickle cell crisis
Pain Hypothermia Acidosis Dehydration
What PIA is not metabolized to TFA?
Sevoflurane not metabolized to TFA, but is broken down to inorganic fluoride ions
A patient undergoing inhalation induction of anesthesia has a severe ventilation-perfusion defect. The speed of induction would be affected the most with what PIA: nitrous oxide, desflurane, isoflurane, or sevoflurane?
The effect is greatest in agents with a low blood:gas partition coefficient. Will effect N2O the most. The effect may be more visible in nitrous oxide than in desflurane despite the difference in blood:gas partition coefficients because of the extremely high concentrations of nitrous oxide normally used compared to that of desflurane.
In patients with scoliosis, what is the strongest predictor of need for postoperative ventilation
VC less than 40% of predicted
Body mass % of the four tissue groups
VRG 10% Muscle/skin 50% Fat 20% Vessel poor group 20%
Cardiac output % to the four tissue groups
VRG 75% Muscle/skin 20% Fat 5% Vessel poor group <1%
How can you calculate loading dose?
Vd x (desired plasma concentration/bioavailability)
TURP absorbed volume per minute vs blood loss per minute
absorbed 10-30 ml/min blood loss 2-5 ml/min
Lidocaine affects what phase of the action potential to serve as an antiarrhythmic?
affects phase 0 (influx of Na)
How long should N2O be avoided with air bubble, silicone oil, sulfur hexafluoride?
air bubble = 5 days silicone oil = 0 days Sulfur hexafluoride = 10 days
opioid potency compared to 10 mg morphine (alfentanil, fentanyl, remifentanil, sufentanil, ketorolac, meperidine, hydromorphone)
alfentanil = 1 mg fentanyl = 100 mcg remifentanil = 100 mcg sufentanil = 10 mcg ketorolac = 30 mg meperidine = 100 mg hydromorphone = 1.5 mg
What opioid has the fastest onset and why?
alfentanil has the fastest onset because it mainly exists in nonionized form (90%) and has a small volume of distribution
Volume of distribution calculation
amount of drug/desired plasma concentration
What is the major intracellular anion? cation?
anion = phosphate cation = potassium
Basic vs acidic drugs protein binding
basic = alpha 1 glycoprotein acidic = albumin
What are the three components of a local anesthetic molecule?
benzene ring, intermediate chain (ester vs amide), tertiary amine
What local anesthetics can cause methemoglobinemia?
benzocaine, cetacaine (contains benzocaine), prilocaine, EMLA cream (contains prilocaine)
Which term refers to the amount of the drug that is able to reach its target receptor after it is introduced into the circulatory system?
bioavailability
The Mu-1 receptor is primarily responsible for producing what side effects?
bradycardia, urinary retention, miosis
What diseases increase the risk of MH?
central core, minicore, and king-denborough syndome
When placed properly, where does the tip of an LMA lie?
cricopharyngeus muscle (upper esophageal sphincter)
Etomidate may cause a slight decrease in BP due to what?
decrease in SVR
How do multiple sclerosis affect depolarizers vs nondepolarizers
depolarizers = hyperkalemia nondepolarizers = sensitive
Which PIA is most associated with a transient increase in liver enzyme levels?
desflurane
What electrolyte disturbance can affect MAC?
hyponatremia = decreases MAC hypernatremia = increases MAC
What drugs are useful to treat pulmonary HTN?
iloprost, epoprostenol, PDE-V inhibitors (sildenafil), endothelin 1 antagonists (bosentan), inhaled nitric oxide
A low time constant will increase or decrease the rate of rise of FA/FI
increase rate of rise (faster onset)
Patients with hemophilia A will have what coagulation lab abnormalities?
increased PTT
What electrolyte disturbances potentiate neuromuscular blocking agents? (lithium, magnesium, calcium, potassium)
increased lithium, increased magnesium, decreased calcium, decreased potassium
Signs of cyanide toxicity with nitroprusside use
increased mixed venous O2, increased nitroprusside dosage requirements (tachyphylaxis), and metabolic acidosis.
Why do nondepolarizers cause a phase II block?
inhibit the presynaptic nicotinic receptor Ach mobilization is impaired
Which body fluid normally has a higher concentration of protein?
intracellular fluid
How many fluoride atoms are located on desflurane, isoflurane, and sevoflurane
isoflurane = 5 desflurane = 6 sevoflurane = 7
A right to left shunt will slow an inhalation induction with what PIA the least (N2O, Des, Iso, Sevo) and why?
isoflurane effected the least since it has a high solubility (more uptake in blood which partially offsets the dilution effect)
Which organ is primarily responsible for excreting opioids and their metabolites?
kidneys
calculation for therapeutic index
lethal dose 50 / effective dose 50
max dosages of local anesthetics
lidocaine/mepivacaine = 4 mg/kg or 7 mg/kg with epi bupivacaine/ropivacaine = 2 mg/kg or 3 mg/kg with epi 2CP = 15 mg/kg or 20 mg/kg with epi
What benzo is the most potent amnestic?
lorazepam
What 3 common drugs are used to increase uterine tone and what are their side effects?
methergine is ergot derivative - avoid in hypertensive pts carboprost is a PGE2 - avoid in reactive airway disease oxytocin = can cause hypotension/tachycardia with rapid administration
What PIAs are methyl isopropyl ethers? methyl ethyl ethers?
methyl isopropyl ether = sevoflurane methyl ethyl ether = isoflurane and desflurane
What drugs reduce pseudocholinesterase activity?
metoclopramide, esmolol, neostigmine, echothiophate, oral contraceptives, MAO inhibitors, cyclophosphamide, nitrogen mustard
What primary cause of hypoxemia is unlikely to respond to increases in FiO2?
pulmonary edema (right to left shunt)
What are the endogenous ligands of mu, kappa, and delta receptors?
mu = endorphins kappa = dynorphins delta = enkephalins
What muscarinic receptor causes bradycardia?
muscarinic 2 receptor
What neuromuscular disease causes a resistance to sux
myasthenia gravis
examples of nongap vs gap metabolic acidosis
nongap - diarrhea, renal tubular necrosis, excessive NaCl administration gap - lactic acidosis, ketoacidosis, renal failure
best place to measure onset of blockade (intubation conditions) vs recovery of blockade (return of upper airway muscle function)
onset = orbicularis oculi or corrugator supercilii (facial nerve) return = adductor policis (ulnar nerve) or flexor hallucis
Opioid receptor MOA
opioid binds to receptor, activates G protein, adenylate cyclase is inhibited, cAMP is inhibited, Ca conductance is decreased, K conductance is increased
Which Phase 1 reaction is characterized by reactions that remove electrons from a molecule?
oxidation
What NMB is long-acting?
pancuronium (85 min duration)
The study of the intrinsic responsiveness of the body to a drug is known as ___________
pharmacodynamics
What term refers to the dose of a drug required to produce a given effect in 50 percent of subjects?
potency
What local anesthetic is metabolized to O-toluidine?
prilocaine
Rank IV anesthetics from most to least plasma protein binding
propofol, midazolam, dexmedetomidine, etomidate, ketamine
What are some examples of common enzyme inducers that increase clearance of drugs?
tobacco, ethanol, phenytoin, barbiturates, rifampin
What TEE view is best used for monitoring the filling and contractile function of the LV?
transgastric short view
Studies have shown that C fibers (which are unmyelinated and transmit pain and temperature impulses) are more resistant to blockade than A-delta fibers and B fibers. T or F?
true
What subunits must be occupied to open the nicotinic receptor at the motor end plate?
two alpha subunits
Risk of mendelson syndrome when aspirate volume and pH is what?
volume over 25 cc and pH less than 3
LA's exist as weak (acids or bases) with a (positively or negatively) charged amine group
weak bases and positively charged amine group
Who is at highest risk of myalgias after sux administration?
young adults undergoing ambulatory surgery (women>men)
