Anesthetics Flashcards
stage 1 of anesthesia
- analgesia
- decreased activity in substantia gelatinosa
stage 2 of anesthesia
- excitaion
- disinhibition (undesirable)
stage 3 of anesthesia
- surgical anesthesia
- decreased spinal reflexes and reticular activating systems activity
stage 4 of anesthesia
- medullary depression
- respiratory and vasomotor depression
two mechanisms of general anesthetics
- enhance inhibitory receptor effects (GABA, Glycine)
- inhibit excitatory receptor effects (neuronal nicotinic, NMDA, K channel)
ED95 MAC value
1.3
1 MAC =
ED50
MAC
- minimum alveolar concentration
- concentration of inhaled anesthetic at which 50% of patients do not move in response to surgical incision
MAC awake value
~0.3
factors that speed induction and emergence
- increased anesthetic inspired concentration
- decreased anesthetic solubility
- increased minute ventilation
- decreased cardiac output
inhalation agents use
- usually maintenance
- sometimes for induction
IV agents use
- usually induction
- sometimes maintenance
context sensitive half-time (CSHT)
-time for plasma concentration to decrease by 50% after stopping an infusion targeting a steady state
things that alter CSHT
- duration of infusion
- redistribution rate
- fat accumulation
- metabolism/elimination
nitrous oxide
- inhaled
- inorganic gas, odorless, colorless
- MAC >105%
anesthetics that provide analgesia
- ketamine
- nitrous oxide
- dexmedetomidine
desflurane
- inhaled
- low solubility so rapid induction/emergence
- highly volatile
isoflurane
- inhaled
- moderate solubility
- pungent odor
sevoflurane
- inhaled
- non-pungent odor
- associated with emergence delirium in some pediatric patients
drugs associated with malignant hyperthermia
desflurane
isoflurane
sevoflurane
treatment for malignant hyperthermia
dantrolene
barbiturates (thiopental, methohexital, etc)
- IV
- rapid redistribution with a single dose
- accumulation with repeated doses
etomidate
- IV
- cardiovascular stability
- adrenocortical suppression
propofol
- IV (number 1 used in US)
- contraindicated in pts with egg allergy
- relatively flat CSHT curve (can use for maintenance)
