General Anesthetics Flashcards
Nitrous Oxide
- gaseous general anesthetic
- GABA Cl- channel most sensitive
- cannot reach stage 3 surgical anesthesia
- low solubility- faster onset (3-5 min)
- low potency anesthetic, excellent analgesic
- used in balanced analgesia: NO2 combined with barbiturate + opioid
- causes 2nd gas effect: allows halothane to be taken in more quickly than expected when given with NO2
Halothane
-volatile general anesthetic
-GABAa receptor mediated inhibitory synaptic current is prolonged by Halothane
-high solubility- slower onset
-highly potent, poor analgesic
Side Effects: resp/cardio failure, hepatotoxic, malignant hyperthermia
Dantrolene
-tx for malignant hyperthermia caused by general anesthetics
A general anesthetic that has a high oil/gas partition coefficient is ______ potent.
More
Minimum alveolar concentration (MAC) ______ as oil/gas partition coefficient increases.
Decreases
-anesthetic potency = 1/MAC
Effect of ventilation on GA action.
- inc ventilation -> inc GA partial pressure
- rate of induction of anesthesia can be inc. by overventilation
- depth of anesthesia is not affected
GA uptake rate is determined by:
- the solubility in blood of GA
- pulmonary blood flow = cardiac output
* Induction of anesthesia is SLOWER for more soluble GAs.
Inc. pulmonary blood flow _____ arterial GA concentration.
Dec.
GA Tissue Solubility
-GAs are more soluble in fatty tissues, therefor inc. fatty tissue provides greater reservoir for GAs
Tissue Blood Flow
-inc. tissue blood flow -> fast delivery of anesthetic to tissues
True/False
GA’s freely permeate the blood/brain barrier.
True
Major route of removal of volatile anesthetics.
Clearance by lungs.
Adverse reaction to volatile anesthetics.
-products of hepatic metabolism of volatile anesthetics often instigate adverse reactions
Solubility of Anesthetic in Blood
- defined by blood:gas partition coefficient
- the lower blood solubility of gas the faster the rate of induction
