Anesthesia Pharm Test 1 Part 1 Flashcards
What are the different roles of IV anesthetics
- sedation spectrum 2. anxiolysis 3. hypnotic 4. general anesthesia
what is an IV anesthetic
substance that when administered directly to the patient IV it can be used to induce or maintain a state of general anesthesia
define induction
transition from a state of awareness to loss of consciousness
what is a sedative
agent used to exert an anxiolytic effect by reducing anxiety and causing calmness
what is a hypnotic
agent that causes drowsiness as well as the onset and maintenance of sleep
what is a sedative hypnotic
drug class that is capable of anxiety relief (sedation) as well as inducing sleep (hypnosis)
T/F: chemical structure is what classifies a medication as a sedative hypnotic
false; it is based on clinical use rather than chemical structure
what are the most frequently used classes of IV anesthetics
- barbiturates 2. nonbarbiturates 3. benzodiazepines 4. miscellaneous (precedex)
characteristics of the “ideal” IV anesthetic
- rapid and smooth onset and recovery 2. provides analgesia 3. minimal cardiac and respiratory depression 4. water soluble aqueous base 5. anti-emetic action 6. bronchodilation 7. lack of toxicity or histamine release 8. advantageous PK and PD (i.e. reference to therapeutic index)
T/F: propofol is defined as an “ideal” IV anesthetic
false; there is no ideal IV anesthetic (bc they all have their s/e and drawbacks)
the vessel rich group (brain, heart, liver, kidney, endocrine glands) are __________% of body mass and recieve _________% of CO
10; 75
IV anesthetics ________________ structure allow them to rapidly penetrate the blood brain barrier to exert central effects
lipophillic
T/F: IV anesthetics are inactive once they reach the muscle group
TRUE
distribution of a propofol bolus has 3 phases, what are they?
- rapid distribution (alpha phase) 2. slow distribution (beta phase) 3. elimination
the kinetics of propofol (and other IVA infusions) is described by the ___________________
three compartment model
describe the three compartment model
IVA infusion when administered begins in the central compartment and then distributes peripherally
IVA “steady state”
4 half-lives with administration rate = elimination rate
according to the three compartment model, when can the IVA infusion rate be lowered?
when the peripheral compartments begin to saturate an appropriate blood concentration
what is context sensitive half time
the time to achieve a 50% reduction in concentration after stopping a continuous infusion
__________________ have a pyrimidine center with either a sulfur or an oxygen in the number 2 position
barbiturates
barbiturates are associated with incidence of ________________ in 10-60% of patients
myoclonus
why did the popularity of barbiturates decline?
- hang over effect 2. narrow therapeutic index 3. evolution of newer safer drugs
what is the oldest IV anesthetic drug?
barbiturates
addition of a ______________ atom to barbiturates made the drugs more lipid soluble and increased potency
sulfur (in place of oxygen) (aka thiobarbiturate)
thiopental and methohexital are what types of drugs
barbiturates
primary metabolism of barbituates occurs in the ______________, but thiopental has some ____________ metabolism too
liver; renal
1/2 life of thiopental
12 hours (10x that of propofol)
when a barbiturate is administered as an IV bolus, it exhibits ________________ order kinetics
zero
1/2 life of methohexital
4 hours
T/F: barbiturates are not ideal as an infusion
true; due to the prolonged context sensitive half life
MOA of barbiturates
binds at the barbiturate specific site of the GABA-A receptor in the cortex and brainstem & inhibits excitatory pathways at the NMDA receptor
which medication class is neuroprotective due to flow metabolism coupling
barbiturates
_______________ is an ideal neuro protectant and anticonvulsant drug, however, at lower doses can be a pro-convulsants
thiopental (barb)
which drug is used for ECT due to pro-convulsant effects
methohexital
_________________ drugs can decrease CMRO2 by 50% with their “flow metabolism coupling” effects
barbiturates
the flow metabolism coupling of barbiturates leads to a reverse steal effect which is ideal for _____________ neuro injuries but not ___________ neuro injuries
focal; global
CV effects of barbiturates
- decrease MAP and CO post induction 2. negative inotropic effects 3. reflex increase in heart rate 2/2 baroreceptor
ventilatory response to CO2 2/2 barbiturate administration is noted after _______ minutes
6
respiratory effects of barbiturates
- dose dependent respiratory depression 2. apnea within 1 - 1.5 minutes 3. no bronchodilatory effect
thiopental has the risk of __________________ 2/2 histamine release
bronchospasm/laryngospasm
induction dose of thiopental in adults
2.5 - 5 mg/kg
induction dose of thiopental in children
5-6 mg/kg
methohexital induction dose IV
1-2 mg/kg
methohexital induction dose if given rectally
25 mg/kg
dose of methohexital infusion rate?
50 - 150 mcg/kg/min
using ____________ or ____________ as a pre-medication before induction with methohexital or thiopental (barbs) can reduce the required induction dose by _________%
precedex; versed; 50
what situations should the barbiturate dose administered be reduced?
- elderly 2. HF 3. liver failure 4. shock 5. anemia 6. obesity
all barbiturates are contraindicated in what patients?
those with intermittent porphyria (exaggerates the sx)
erronous thiopental arterial administration can lead to the formation of ______________ which causes ____________ and ______________
crystal; vasospasm; thrombus
s/e of methohexital
pain on injection
