Intravenous anesthetics Flashcards
How does Ketamine work?
It’s an NMDA receptor antagonist
Name 5 unique properties of Ketamine.
- profound analgesia
- stimulation of the SYM NS ( increases BP,HR, CO transiently)
- bronchodilation (relaxes bronchial SM)
- minimal respiratory depression
- unpleasant psychotomimetic effects
How is Ketamine metabolized?
By the liver-> active metabolite NORKETAMINE (has only 1/5 of potency)
What are some effects of Ketamine on the CNS?
It causes cerebral vasodilation
-> increased cerebral blood flow & CMO2 (cerebral metabolic rate of ox)
Hence it increases ICP
How can one avoid the undesirable effect of Ketamine on the CNS?
Increased ICP, can be limited by keeping normal arterial CO2 pressure (40mmHg)
How can the cardiovascular effect of Ketamine be minimized?
By co-administration of Opioids, BZD, inhaled anesthetics
How can the increased salivation and lacrimation caused by Ketamine be reduced?
Pretreatment with an anticholinergic agent
Name two advantages of using Ketamine.
- can be given I.m
- has a low protein binding compared to others
Explain “dissociative anesthesia” .
a characteristic state observed after an induction dose of Ketamine, wherein the Patient’s eyes remain open, with a slow nystagmic gaze (cataleptic state)
Usually characterized by catalepsy , analgesia, amnesia
How does etomidate work? What is it useful for?
It works on the GABA-A receptor - potentiates GABA-A mediated Cl- currents
It is used as in rapid i.v INDUCTION of anesthesia, especially useful in patients with compromised myocardial contractility
What is the advantage of using Etomidate?
- it preserves cardiovascular and respiratory stability
Name 4 undesirable effects of etomidate.
- causes adrenal suppression for hours
(decreased cortisol, decreased aldosterone)
Hence it is not used as a continuous infusion - pain on injection
- post op nausea
- Involuntary myoclonic movements (can be reduced using neuromuscular blocking agents)
