What will balanced anesthetia do?
relax muscles, relieve anxiety, prevent secretions, induce unconsciousness
- several drugs are used together
Why do you need to worry about formulations for IV anesthesia drugs?
- are lipophilic (stuck for injecting) so pH must be adjusted or a surfactant needs to be added to make them more suitable.
What are the side effects of adding surfactants?
thromblophlebitis
- concentration and speed sensitive
general MOA of IV anesthetics?
- reinforce inhibitory action of GABA and glycine
MOA of ketamine
activate GABA and glycine
-inhibit NMDA by physically occluding the channel
MOA of propofol
activate GABA and glycine
- inhibit NMDA by blocking the binding of glutamate to the receptor
MOA of barbiturates and benzodiazepine and etomidate
reinforce inhibiting effects produced by endogenous GABA binding
- barbs = prolong binding of GABA to R
- bezno = allosteric change in receptor activty
- both require endogenous GABA
time course of IV anesthetics
- effects are almost instantaneous
- drug rapidly distributes out of plasma and into high flow organs and then re-distributes to other organs –> skeletal muscle and fat tissue
pharmoknetic profiles of IV anesthetics
- awakening of the pts is due only to drug re-distribution making their clinical duration short but increasing length of elimination from non-active stores
context sensitive half lives of IV anesthetics
- some drugs half lives increase w/ longer infusion times (thiopental, diazepam)
what pharmacologic effects of thiopental
increase HR
- porphyria, enzyme induction
what pharmacologic effects of etomidate
no effect on CV
- inhibits steroidogenesis, not used in ICU
what pharmacologic effects of ketamine
increase CBF, ICP, MAP, HR, CO
- intact pharyngeal/laryngeal reflexes
- bronchodilator for refractory asthma
- hallucinations w/ emergence
- causes dissociative states (eyes open)
what pharmacologic effects of propofol
increase HR
- antiemetic, infusion syndrome
what is the long acting and short acting benzo
long = diazepam short = midazolam
What are the good attributes of benzodiazepine
- when analgesia not required
- anticonvulsants, amnesia
- wide therapeutic saftety margin
- minimal CV and respiratory depression if used alone
- Specific antagonists – Flumazenil
What the is elimination of benzodiazepines?
- Diazepam - 3 active metabolites
- Lorazepam - conjugated for elmination
- Midazolam - rapidly inactivated
Opioid use during surgery
- CV effects - bradycardia, HypoTN, HTN, respiratory depression (less response to increase in PaCO2), muscle rigidity, increase ICP and CBF
- coma triad
N/V, constipation
Neurolept analgesia
use of drug combination that produces pain relief and provides a state of indifference
- Droperidol - state of indifference
- Fentanyl - analgesia
- Add N20
- Atropine
How to chose opioid for surgery?
- for long lasting analgesia – morphine is ideal
- fentanyl for short duratio
What happens in malignant hyperthermia?
- increase in end tidal CO2
- total body rigidity
- unexpected tachycardia, tachypnea
- respiratory and metabolic acidosis
What is the cause of malignant hyperthermia?
succinylcholine - increases IC Ca release from SR
- can be caused by volatile gases
how to treat malignant hyperthermia?
Danrolene
Stop giving trigger agent, hyperventilate w/ O2
- correct hyperkalemia and acidosis, cool core temperature
