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General Anesthetics
General Anesthetic Drugs
Question | Answer |
---|---|
Potency of the anesthetic agent is most related to? | lipid solubility |
Most anesthetics increase the sensitivity of? | GABA-A and glycine receptors to GABA and glycine, respectively |
Most anesthetics also generally inhibit the activity of excitatory transmitters such as? | acetylcholine (Nicotinic) and serotonin. |
Ketamine and nitrous oxide inhibit ____ activity? | glutamate |
Partial pressure is? | the pressure exerted by a gas in a mixture of gases (Dalton's Law). For our purposes it is a measure of the concentration of a gas |
Blood/Gas partition coefficient is? | measure of the solubility of an anesthetic gas in the blood |
The speed of induction and emergence (recovery) is determined by the rate of? | change of the partial pressure (concentration) of the gas in the brain, which is determined by the partial pressure of the gas in arterial blood |
The best correlation with speed of induction is? | with blood/gas partition coeffcient (inverse correlation) |
Halothane has blood/gas coefficient of ___ and a rapidity of onset of___? | 2.3, 3 |
N2O has blood/gas coefficient of ___ and a rapidity of onset of___? | .47, 1 |
MAC is defined as? | the Minimal Alveolar Concentration that will block movement of 50% of patients in response to incision |
How is the potency of anesthetic gases expressed? | MAC |
Lipid/Gas coefficient is related to? | potency |
Blood/gas coefficient is related to? | speed of onset |
MAC correlates with? | lipid/gas partition coefficient (low MAC indicates high lipid/gas solubility) |
N20 has MAC of ___ and a lipid/gas coefficient of___? | 105, 1.4 |
Why is N20 considered an "incomplete anesthetic"? | because it can’t produce all stages of anesthesia without producing hypoxia because its MAC is 105%. |
The therapeutic index for most general anesthetics is? | low, 2-4, which indicates low margin of safety |
What are the characteristics of an ideal general anesthetic? | Provide a smooth and rapid induction of unconsciousness; Produce amnesia; Block troublesome reflexes; Produce skeletal muscle relaxation; Produce analgesia; Provide a smooth and rapid emergence and recovery without long lasting adverse effects. |
What is the pre-anesthetic effect of midolazam? | Reduce anxiety, Sedation, Amnesia, “Conscious sedation” |
What is the pre-anesthetic effect of atropine/glycopyrollate (robinul)? | Inhibit secretion, bradycardia, vomiting, and laryngospasms |
What is the pre-anesthetic effect of Opioid analgesics? | Sedation to decrease tension, anxiety, and provide analgesia |
What are the general pharmacological effects of anesthetics gases on the CNS? | dose dependent depression of all portions of CNS. Order of sensitivity (most to least) is RAS and cortex > hippocampus > basal ganglia > cerebellum > spinal cord > medulla (irregularly descending anesthesia) |
What are the general pharmacological effects of anesthetics gases on the ANS? | Inhibition of sympathetics; Stimulation of parasympathetics; Nausea and vomiting |
What are the general pharmacological effects of anesthetics gases on the cardiovascular system? | Dose related negative inotropic effect; decreased BP; Arrhythmias; Sensitization to circulating catecholamines |
What are the general pharmacological effects of anesthetics gases on the respiratory system? | Dose dependent depression of medullary respiratory center |
What are the general pharmacological effects of anesthetics gases on the thermoregulatory system? | Altered thermoregulatory control induced hypothermia d/t anesthesia of the hypothalamus and reduced metabolic rate |
Anesthetic gas responsible for developing an induced hepatitis? | halothane |
First non-explosive alternative to ether? | halothane |
an isomer of enflurane that is a commonly used anesthetic for adults? | isoflurane |
A rarely used gas similar to isoflurane, except has increased risk of seizures? | enflurane |
Anesthetic gas similar to isoflurane except has faster emergence and increased airway irritation? | desflurane |
Anesthetic gas similar to desflurance but less irritating to airway? | sevoflurane |
dissociative anesthetic similar to PCP? | ketamine |
What is ketamines MOA? | blocks NMDA receptors inducing a "dissociative" state |
IV anesthetic agent used for brief procedures in ER | etomidate |
IV anesthetic used in ICU for patients requiring prolonged intubation | dexmedetomidine (Precedex) |
a carboxylated imidazole | etomidate |
a substituted isopropylphenol | propofol |
IV anesthetic that decreases the rate of dissociation of GABA from its receptors, thereby increasing the duration of GABA-activated opening of chloride channels, with resulting hyperpolarization of cell membranes | propofol |
How is propofol cleared? | tissue reuptake (redistribution) |
Dosage for propofol for induction? | 1.5 - 2.5 mg/kg IV |
MOA of barbituates? | mimic the activation of GABA receptors |
How is thiopental cleared? | redistribution and metabolism however large or repeated doses of thiopental may saturate inactive tissue sites resulting in prolonged effects. |
Which is cleared faster: thiopental or etomidate? | Etomidate is cleared 5 times faster |
a phencyclidine derivative? | ketamine |
What receptor does ketamine NOT interact with? | GABA |
T or F: All inhaled anesthetics depress the CV system. | F. N2O produces sympathetic stimulation |
What drug increases the neuromuscular blocking effects of isoflurane? | polymyxin B sulfate |