General Anesthetics Flashcards
Nitrous Oxide (N2O) class?
Inorganic gas. Hypnotic, analgesic, NO muscle relaxation
N2O mxn? Is it soluble in blood? What does this mean?
NMDA antagonist; relatively insoluble in blood; rapid induction of anasthesia
N2O for?
Mask induction in children
N2O side effects?
PONV, inactivates B12 (abnormal embryonic development), accumulates in closed air spaces (bowel, middle ear, pneumothoraces, air emboli) because N2O is insoluble in blood
MAC of N2O?
104%
Isofluorane class?
Volatile anasthetic, will somewhat relax skeletal muscles
Isoflurane for?
Gold standard for maintenance of general anasthesia
Isoflurane MAC?
1.17% – Most potent of the 3 volatile anesthetics
Isoflurane side effects?
Pungent (makes mask induction difficult)
Desflurane class?
Volatile anesthetic
Desflurane MAC?
6.6% – Least potent, least soluble (allowing for rapid emergence from anesthesia)
Desflurane side effects?
Most pungent – will cause airway irritation symptoms (coughing, copious salivation, breath holding, laryngospasm)
Sevoflurane class?
Volatile anesthetic
Sevoflurane MAC?
1.8% – Middle potency between Isoflurane & Desflurane. Also, middle solubility.
Sevoflurane for? Why?
Mask induction in children and adults because it is the least pungent.
Sevoflurane side effects?
Produces inorganic Fl- ions; In combination with CO2 forms “compound A” (nephrotoxic in rats); forms CO when exposed to strong bases; exothermic rxns can cause fires
Volatile anesthetics?
Isoflurane, Desflurane, Sevoflurane
Effects of volatile anesthetics on CNS?
Dose dependent depression of EEG, potentials (↑ latency,↓ amplitude), Cerebral metabolic rate. Dose dependent increase in Cerebral blood flow (CBF) (may be blunted by hypocapnia produced by deliberate hyperventilation), ICP
Effects of volatile anesthetics on cardiovascular system & blood flow?
Dose dependent decreases in: vascular resistance, BP
BUT: Minimal effects on myocardial contractility. Isoflurane and desflurane ↑ HR (Likely due to pungency stimulating airway receptors and eliciting reflex tachycardia). Redistribution of blood flow
↑ blood flow to brain, muscle and skin & ↓ blood flow to liver, kidneys, gut.
Effects of volatile anesthetics on respiratory function?
Dose dependent decrease in Tidal volume, Ventilatory response to hypoxia and hypercarbia. Dose dependent increase in respiratory rate, Relaxation of airway smooth muscles (bronchodilation)
Effects of volatile anesthetics on NMJ?
Direct relaxation of sk muscle; Potentiate the effects of NMJ blockers; Malignant hyperthermia
Methohexital class?
Barbiturate
Methohexital mxn?
GABAa binding, @ higher concentrations, direct antagonist at the GABAa receptor, inhibit excitatory NTs, antagonise NMDA; hypnosis, sedation, ANTI-analgesic
Methohexital for?
Induction of general anesthesia
How is methohexital effect terminated? What is the onset timing?
Rapid onset, short duration of action, effects terminated via redistribution away from the brain, metabolized by the liver
How is methohexital dosed?
Based on lean body mass?
Methohexital physiologic effects on heart and lungs?
Dose dependent decrease in BP due to vasodilation; negative inotropic; Dose dependent respiratory depression
Propofol class?
Alkylphenyl (a fatty acid)
Propofol mxn?
GABAa receptor agonist; antagonist NMDA; some alpha2 activity; directly depresses spinal cord neurons via GABAa and glycine receptors
Most commonly used IV anasthetic today?
Propofol
Propofol for?
anti-emetic at low doses; induction and maintenance of general anesthesia; sedation in ICU; procedural sedation
Propofol side effects?
Propofol infusion syndrome: metabolic acidosis, rhabdomyolysis, renal failure, BP, bradycardia, death (esp if given >48 hours at high-dose infusion along wtih catecholamine & glucocorticoid use); Pain at injection site; Supports bacterial growth; Allergies to egg and soy; NO malignant hyperthermia
Onset of propofol? How is it metabolized?
Rapid onset and offset; Met in liver and lung and mets excreted in kidney
Etomidate class?
Carboxylated imidazole