Anesthesia Pharm Flashcards
1
Q
uptake = ?
A
uptake = solubility x CO x (PA-PV)
2
Q
2nd gas effect
A
- High volume uptake of 1 gas accelerates rate of increase of
PA of 2nd gas - N2O + sevo = faster increase of sevo concentration
- used for inhalational induction
3
Q
concentration effect
A
increasing the concentration of an agent increases the rate of rise of PA
4
Q
PA = ?
A
PA = Pi - uptake
5
Q
racemic mixtures
A
- 2 entantiomers present in equal proportions
- Etomidate and Thiopental
6
Q
division of CO
A
- VRG = 75% of CO and 10% of body mass
- muscle = 19% of CO and 50% of body mass
- fat = 6% of CO and 20% of body mass
- VPG = 0% CO and 20% body mass
7
Q
pKa
A
- pH at which 50% of a drug/molecule is ionized
- basic drugs ionize when pH < pK
- acidic drugs ionize when pH > pK
8
Q
pharmacokinetics
A
- what the body does to the drug
- absorption, distribution, elimination, metabolism
9
Q
pharmacodynamics
A
what the drug does to the body
10
Q
competitive antagonist
A
reversible – overcome by increasing the concentration of the agonist at the receptor site
11
Q
noncompetitive antagonist
A
irreversible
12
Q
Thiopental (Brevitol)
A
- barbituate
- contraindication: acute intermittent porphyria
- induction dose: 3-5 mg/kg
- supplied at 25 mg/ml
- onset: 30-40 s, peak: 1 min, duration: 5-8 mins
- protein binding: 80% Albumin
- great for burst suppression (dec. CMRO2 up to 55%)
- mechanism: dissociation of GABA from receptors leading
to chloride channel opening and hyperpolarization - decrease SBP, increase HR, vasodilates
- pH = 10.5 – bacteriostatic, thrombophlebitis
- hangover effect
- racemic mixture
13
Q
Etomidate (Amidate)
A
- water soluble in acid, lipid soluble in the body
- 35% glycerol – pain on injection
- racemic mixture
- 76% protein binding
- cardiovascular stability
- may induce seizures
- myoclonus, adrenocortical suppresion leading to
decreased cortisol levels, PONV, hiccups (rare) - induction dose: 0.2 - 0.6 mg/kg
- onset: 30 s, peak: 1 min, duration: 3-5 mins
14
Q
Propofol
A
- dose: MAC =
TIVA = 100-200 mcg/kg/min
induction = 1-2 mg/kg
- don't use > 3 days in ICU -- hyperlipidemia
- oil at room tempurature, aqueous insoluble
- 98% protein binding
- rapid redistribution
- contraindications: egg and soy allergy
- glycerol causes pain on injection
- preservative: disodium edetate
15
Q
Ketamine
A
- non GABA – NMDA
- PCP derivative
- low protein binding – 27%
- inc. ICP, inc. CMRO2, inc. CBF
- bronchodilation, increased secretions
- inc. BP, inc. HR, inc. CO, possible increase in release of
catecholamines leading to arrhythmias - Emergence Delerium (Tx = benzos)
- analgesic effects
16
Q
Midazolam (Versed)
A
- PO: 50% 1st pass metabolism
- potentiates opioid ventilatory depression
- dose: pediatric = 0.5 mg/kg PO (no grapefruit juice)
adult = - anticonvulsant
17
Q
Flumazenil
A
- benzo antagonist
- shorter half life than benzos
- metabolism: hepatic enzymes
18
Q
Solubility of inhaled anesthetics
A
halo > iso > sevo > N2O > des
19
Q
Desflurane
A
- 6.0% MAC
- needs a special vaporizer
- fast on/off
- B:G solubility: 0.42
- B:B solubility: 1.3
- tachycardia due to SNS stimulation
- apnea with 1.5-2 MAC
- airway irritant – avoid in asthmatics
- carbon monoxide formation from interaction with
absorbers
20
Q
Nitrous Oxide
A
- 105% MAC
- B:G solubility: 0.47 (highly insoluble)
- B:B solubility: 1.1
- increases CMRO2
- sympathomimetic
- increases PVR in patients with pulmonary HTN
- analgesic
- PONV
- diffusion hypoxia – Tx: supplemental oxygen
- bone marrow suppression
- drawn to air filled spaces – don’t use with middle ear,
eyes, laparoscopic, bowels, or insertion of a gas bubble
21
Q
Sevoflurane
A
- 2.0% MAC
- B:G solubility: 0.65
- B:B solubility: 1.7
- apnea with 1.5-2 MAC
- compound A: interaction with CO2 absorbers that can
be overcome with flows of > 2L/min, worse with baralyme - least AW irritant – good for inhalational inductions
- low flow for 2 MAC hours
22
Q
Isoflurane
A
- 1.1% MAC
- B:G solubility: 1.4
- B:B solubility: 2.6
- barely affects CBF – great for neurosurgery
- burst suppression with 1.5 MAC
- coronary steal
23
Q
Halothane
A
- 0.75% MAC
- B:G solubility: 2.4
- B:B solubility: 2.9
- increases CBF 200%
- decreases myocardial contractility – decrease CO
- most potent trigger of MH
- nephrotoxicity – 20% liver metabolism
- thymol preservative
- great for inhalational inductions
- high potency
- bronchodilation
24
Q
metabolism and elimination of inhaled anesthetics
A
- biotranformation, transQ loss, and exhalation (major)
- Halothane is most metabolized
- Nitrous is least metabolized
25
Q
MAC
A
- MACbar = 1.3 - 1.5
- 1.3 MAC prevents movement in 95% of patients
- MAC awake = 0.1-0.3 MAC
- MAC intubation = 2 MAC
- MAC amnestic = 0.25 MAC
- MAC decreases 6% per decade
- avoid more than 0.5 MAC with motor potential monitoring
26
Q
factors increasing MAC requirement
A
hyperthermia, drug-induced increase in catecholamines, hypernatremia
27
Q
factors decreasing MACrequirement
A
hypothermia, increased age, preop meds, hyponatremia, alpha-2 agonists, acute EtOH intoxication, pregnancy, immediate post-partum, lithium, lidocaine, neuraxial opioids, PaO2 < 38, BP < 40, CPB, opioids
28
Q
potency of inhaled anesthetics
A
halo > iso > sevo > des > N2O
29
Q
local anesthetic loss of sensation
A
autonomic > sensory > motor
30
Q
resting membrane potential
A
~ -70 mV
31
Q
membrane potentials
A
maintained by Na-K pump
32
Q
local anesthetics mechanism of action
A
bind Na channels in the activated state to decrease the rate of depolarization and therefore prevent action potential propagation
33
Q
easiest nerves to block
A
small diameter with greater myelination, sensory, basic environment, rapidly firing, decreased K and increased Ca
34
Q
metabolism of amides
A
CYP 450 (hepatic)
35
Q
metabolism of esters
A
- plasma cholinesterase hydrolysis
- metabolite PABA can cause allergic reactions
- exception: cocaine is metabolized in the liver
36
Q
methemoglobinemia
A
- caused by metabolite in prilocaine and benzocaine
- infants at greatest risk
- spO2 will read 85%, dark/chocolatey blood
- treatment: methylene blue
37
Q
epinephrine and LA
A
- limits systemic absorption and maintains concentration
of drug at the site - helps prevent toxicity
- does not affect onset
- 1:200,000 (5 mcg/ml)
- epi has a lesser effect on Bupivicaine because it has an
longer duration - contra: end arterial supply (Tx: nitroglycerin paste)
38
Q
systemic toxicity from LA
A
- causes: accidental IV injection, absorption from the
injection site (dose, vascularity, epi, drug itself) - symptoms: circumoral numbness, tinnitus,
lightheadedness, visual disturbances, muscle twitching,
unconsciousness, convulsions, respiratory depression,
cardiovascular collapse - signs: hypotension, decreased cardiac conduction, vent
arrhythmias
39
Q
Bupivicaine
A
- long duration
- highly toxic to CV system, especially in pregnant
patients and potentiated with hypoxia and acidosis - don’t use in upper extremity
40
Q
vascularity of injection sites
A
IV > tracheal > intercostal > caudal > paracervical > epidural > brachial plexus > sciatic > subQ
41
Q
maximum toxic dose
A
Lidocaine: 5 mg/kg
7.5 mg/kg with epi
Bupivicaine: 2.5 mg/kg
42
Q
Cocaine
A
- hepatic metabolism
- vasoconstriction and LA of mucosal membrane (ENT)
- intranasal onset: 30 mins
- IV/smoked onset: < 5 mins
- prevents reuptake of NE dopamine causing HTN, vent
arrhythmias, increased O2 demands of heart, coronary
vasospasm, decreased uterine blood flow, and seizures - no OD treatment, treat symptoms – NTG, benzos, etc.
43
Q
spinal anesthesia
A
- inject LA into subarachnoid space
- works on preganglionic fibers
- dose depends on patient height, segments of anesthesia
needed, and duration of action - dependent on concentration not volume
- faster onset than epidurals
- duration
lidocaine: < 1.5 hours
bupivicaine: 2-2.5 hours
tetracaine: 2-3 hours or 5 with epi - chloroprocaine is contraindicated because it is
neurotoxic
44
Q
Lidocaine
A
- add dextrose to a spinal to make it hyperbaric
- transient neurologic symptoms
- crosses dura mater quickly in epidural
45
Q
epidural anesthesia
A
- mechanisms of action: diffuse across dura mater and
absorbed intravenously - dependent on volume not concentration
- onset: 15-30 mins
- fetal effects: none unless baby is acidotic which could
create ion trapping and toxicity - typical volume used: 15-30 ml
46
Q
Bier block
A
- regional hand block
- duration of action is indicated by tourniquet time
- tourniquet must be let down slowly
- don’t use bupivicaine
- 50 ml of lidocaine or prilocaine
47
Q
peripheral nerve blocks
A
- diffusion occurs on a concentration gradient
- onsets and durations
Lidocaine: 3 mins, 1-2 hours or 2-3 hours with epi
Bupivicaine: 15 mins, 3-6 hours or 4-8 hours with epi
48
Q
topical anesthesia
A
- drugs used: tetracaine, cocaine, lidocaine, benzocaine
in hurricaine spray
49
Q
EMLA
A
- eutectic mixture of LA
- lidocaine 5% and priolocaine 5%
- local anesthetic absorbed through the skin
50
Q
cauda equina syndrome
A
- lumbar plexus block
- risk greatest with 5% lidocaine via catheter
- spinal anesthesia
51
Q
mechanism of action of opioids
A
- agonist at the opioid receptors and mimic the effects of
endogenous ligands - decrease neurotransmitter release
- location of action: pariaqueductal gray matter of brain
stem, amygdala, corpus stiatum, hypothalamus, spinal
cord
52
Q
mu 1 receptors
A
- supraspinal and spinal
- analgesia*, euphoria, N/V, pruritis, low abuse potential,
bradycardia - binds endorphins
53
Q
mu 2 receptors
A
- predominantly in spinal cord
- hypoventilation*, analgesia, euphoria, sedation, physical
dependence, constipation - binds endorphins
54
Q
kappa receptors
A
- supraspinal and spinal
- analgesia, respiratory depression (less than mu 2),
dysphoria, diuresis - binds dynorphins
- agonist-antagonists typically work here (Nalbuphine),
used in abuse potential patients - resistant to high intensity pain
55
Q
delta receptors
A
- supraspinal and spinal
- analgesia, respiratory depression, physical dependence,
urinary retention - enkephalins bind here
56
Q
neuraxial analgesia
A
- acts on mu receptors in the spinal cord
- some systemic absorption
- dose related analgesia and specific for visceral pain
- side effects: pruritis, N/V, urinary retention, ventilatory
depression - CV effects: decrease HR, BP, and sympathetic tone and
minimal contractility effects - increased apneic theshold, decreased RR and increase
tidal volume, decreased minute ventilation, cough
suppression - seizures with Meperidine use – normeperidine metabolite
- sphincter of oddi spasms – Tx: Glucagon 2 mg IV
- OD: miosis, ventilatory depression, coma
57
Q
potency of opioids
A
Meperidine: 0.1
Morphine: 1
Hydromorphone: 8
Alfentanil: 10-20 (1/5-1/10 more than fentanyl)
Fentanyl: 75-125
Remifentanil: 100 (similar to fentanyl)
Sufentanil: 1000 (5-125 more than fentanyl)
58
Q
Morphine
A
- onset: 15-30 mins, duration: 3-4 hours
- dose: 2-10 mg
- hepatic, extrahepatic, and renal metabolism
- metabolite morphine-6-glucaronic– allergic reaction
59
Q
Meperidine (Demerol)
A
- potency: 0.1
- IV, IM, PO
- peak: 5-7 mins, duration: 2-3 hours
- local/atropine like side effects
- 90% hepatic metabolism and renal elimination
- seizures in renal patients
- treatment for post op shivering: 12.5 mg
60
Q
Fentanyl
A
- IV, transdermal, PO, intranasal
- potency: 75-125
- peak: 3-5 mins, duration: 30-60 mins
- 75% fist pass pulmonary uptake
- highly lipid soluble and protein bound, cross BBB fast
- hemodynamically stable
- induction dose: 2-6 mcg/kg with sedative hypnotic
- additional dose: 25-50 mcg every 15-30 minutes
- infusion rate: 0.5-5 mcg/kg/hr
61
Q
Sufentanil
A
- potency: 1000 (5-10x more than fentanyl)
- peak: 3-5 mins, duration: 30-60 mins
- dose: induction: 0.3-1 mcg/kg 1-3 mins before induction
additional: 0.5 mcg/kg
infusion: 0.5 mcg/kg/hr - good for neuro cases, no HTN from intubation, helps
with Mayfield stimulation
62
Q
Alfentanil
A
- potency: 10-20 (1/5-1/10x more than fentanyl)
- peak: 1.5-2 mins, duration: 10-20 mins
- renal failure doesn’t alter clearance
- rapid on/off of intense analgesia
- great for retrobulbar block and DL
- dose: 5-10 mcg/kg
63
Q
Remifentanil
A
- potency: 100 (similar to fentanyl)
- peak: 1.5-2 mins, duration: 6-12 mins
- metabolism: plasma and tissue esterases
- dose: 0.5-1 mcg/kg (+propofol) for DL
0. 25-0.5 mcg/kg/min following - caution: patient won’t breathe on remi infusion
64
Q
Codeine
A
antitussive, analgesia for mild to moderate pain
65
Q
Methadone
A
long term relief from chronic pain and opioid withdrawal
66
Q
Hydromorphone (Dilaudid)
A
- potency: 8
- shorter acting than morphine
67
Q
Percodan
A
aspirin and oxycodone
68
Q
agonist/antagonists
A
- pentazocine, butorphanol, nalbuphine
- produce analgesia with minimal respiratory depression
- ceiling effect
69
Q
Naloxone (Narcan)
A
- opioid antagonist
- pure mu antagonist
- treats overdose and respiratory depression
- duration: 30-45 mins
- dose: 1-4 mcg/kg
- side effects: N/V, pain, tachycardia, increase SNS activity
- dilute the 400 mcg vial into 10 ml and give 1-2 ml every
2-3 mins
70
Q
Succinylcholine
A
- 2 ACh molecules bound together
- dose: 1-2 mg/kg
- onset: 30-60 seconds, duration: 3-5 mins
- laryngospasm dose: 0.1 mg/kg IV
- mechanism of action: binds to and activates receptors
- fasiculations
- metabolism: plasma cholinesterases
- decreased metabolism: hypothermia, hypthyroidism,
high estrogen mom at term, liver failure - phase I blockade: decreased single twitch response,
decreased amplitude with tetany without fade (box-like
appearance), enhanced with Neostigmine - phase II blockade: resembles NDNMBD (stair-case), fade,
post-tetanic potentiation, antagonized by Neostigmine - side effects: brady/tachycardia, hyperkalemia*, increased
IOP/ICP, MH trigger, increased intragastric pressure,
myoglobinuria - hyperkalemic conditions: 3rd degree burns, trauma,
severe intraabdominal infection, spinal cord injury,
encephalitis, Guillan-Barre, Parkinson’s, tetanus, prolonged
total body immobilization, ruptured cerebral aneurysm,
polyneuropathy, closed head injury, hemorrhagic shock,
metabolic acidosis
71
Q
characteristics of muscle relaxants
A
- small, rapidly moving muscles are the first to go
- diaphragm is one of the last to relax
- onset depends on fiber type and ACh receptor density
- adductor pollicis can be blocked before larynx
- orbicularis occuli correlates most with VC and
diaphragm - limited volume of distribution similar to extracellular
fluid - can’t cross lipid membranes – no CNS effects, minimal
renal absoprtion, PO is ineffective, no fetal effect - decreased clearance with age, volatiles, and disease
72
Q
Pancuronium
A
- long acting
- dose: 0.08-1.2 mg/kg
0. 01 mg/kg maintenance - onset: 3-5 mins, duration: 60-90 mins
- 80% renal excretion – bad for renal patients
- ED95 = dose for CV effects
73
Q
Benzylisoquinoliniuma
A
-curiums
74
Q
Aminosteroids
A
-roniums
75
Q
ACh
A
- binds to cholinergic receptors (nicotinic and muscarinic)
- postynaptic membrane receptors
- metabolized by anticholinesterase into acetic acid and
choline
76
Q
Dibucaine
A
- LA that decreases function of plasma cholinesterase and
prolongs Succ duration - # 80
77
Q
NDNMB characteristics
A
- compete with ACh at alpha subunits
- decreased single twich, fade, TOF ratio < 0.7,
posttetanic potentiation,antagonized with Neostigmine - rare histamine release (curiums)
- large margin of safety
- prolonged block with volatiles, aminoglycosides (AB),
and high doses of LA, anti-dysrhthmics, diuretics,
ganglionic blockers (trimethaphan), hypothermia,
increased Mg - shortened block with seizure meds (Phenytoin)
78
Q
Atracurium
A
- intermediate acting
- onset: 3-5 mins, duration: 20-35 mins
- good for renal failure patients – Hoffmann degradation
- will form crystals when used with Thiopental
- pH: 3.2
- dose: 0.5 mg/kg (over 30-60 seconds)
- increased degredation with alkalosis
- side effects: histamine release
- decrease pediatric dose 50%
- laudanosine metabolite can cause seizures from
continuous use
79
Q
Cisatracurium
A
- dose: 0.1-0.15 mg/kg, infusion: 1-2 mcg/kg/min
- Hoffman degradation
- intermediate acting
- onset: 2-3 mins, duration: 20-45 mins
- no histamine release or metabolite
80
Q
Rocuronium
A
- can mimic the onset of SCh if you use 1.2 mg/kg
- dose: 0.6-1.2 mg/kg, 5-12 mcg/kg/min
- intermediate acting
- onset: 2.5 mins, duration: 20-45 mins
- cleared unchanged by liver and kidneys – no metabolites
81
Q
Vecuronium
A
- 10 mg poweder reconstituted to 1 mg/ml
- dose: 0.08-0.12 mg/kg
0.01 mg/kg q 15-20 mins maintenance
1-2 mcg/kg/min infusion - intermediate acting
- onset: 2-3 mins, duration: 20-45 mins
- liver and kidney clearance
- faster onset with pediatrics and longer duration
- longer duration in elderly
82
Q
Mivacurium
A
- short-acting
- used to be used for pediatric intubations
- dose: 0.15-0.2 mg/kg, 4-10 mcg/kg/min
- onset: 2-3 mins, duration: 10 mins
- plasma cholinesterase clearance
- no longer made
83
Q
Anticholinesterase drugs
A
- reverse muscle relaxants
- antagonism of CNS effects of other drugs (atropine
overdose) , treatment of MG or glaucoma - increase ACh in the NMJ and everywhere else
- renal clearance is 50-70% of elimination
- lower dose and faster onset with kids
- increased duration with elderly
- BBLUDS
84
Q
Edrophonium
A
- reversible inhibition
- short onset, quaternary amine
- onset: 1-2 mins
- shortest duration
- Mysathenia Gravis test
