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KEY POINTS

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KEY POINTS

  1. Propofol (2,6-diisopropylphenol) is currently the most widely used intravenous sedative-hypnotic. In typical clinical doses, it can produce unconsciousness in as little as 10 to 15 seconds.

  2. Propofol decreases the cerebral metabolic rate for oxygen and cerebral blood flow. By causing vasoconstriction of central nervous system (CNS) blood vessels, propofol also significantly decreases intracranial pressure.

  3. Propofol produces a dose-dependent decrease in ventilatory drive. It decreases tidal volume and minute ventilation and increases Paco2. The ventilatory depressant effect is exaggerated in patients with underlying chronic obstructive pulmonary disease (COPD).

  4. Propofol decreases myocardial contractility, leading to a reduction in cardiac output. It reduces smooth muscle tone, causing vasodilation in both systemic arteries and veins. Propofol also blunts the barostatic reflex, resulting in a slower heart rate for a given decrease in blood pressure.

  5. Coexisting factors, such as other medications (eg, benzodiazepines or opioids), advanced age, or presence of concurrent disease (eg, cardiac dysfunction, COPD, hypovolemia), can increase the hemodynamic effects of propofol and decrease the amount needed to produce unconsciousness. Patients with acquired tolerance because of chronic use of other CNS depressants, anticonvulsants, or alcohol may require higher doses of propofol to produce unconsciousness.

  6. Propofol causes the lowest incidence of postoperative nausea and vomiting of any general anesthetic agent, injected or inhaled. Propofol also has intrinsic antiemetic activity and has been used successfully as an antiemetic.

  7. Propofol often causes pain on injection, which can sometimes be severe. Placing a tourniquet proximal to the injection site and administering lidocaine or using an antecubital vein are the most effective ways to prevent this pain.

  8. Propofol is a very short-acting intravenous anesthetic. It has a short, context-sensitive half-time even after long-duration infusions. Because of its rapid recovery characteristics, it is an extremely useful drug for maintaining general anesthesia by continuous infusion.

  9. The CNS effects of thiopental are qualitatively similar to those of propofol. There are data suggesting that thiopental will reduce the likelihood of CNS damage when it is given before a planned decrease in global cerebral perfusion. The cardiac and pulmonary effects of thiopental are qualitatively similar to those of propofol. Thiopental generally causes a smaller decrease in blood pressure.

  10. The CNS effects of etomidate are similar to those of thiopental and propofol. Etomidate is notable for its lack of cardiovascular effects. Given by itself, it has little effect on systemic arterial or venous vascular tone or on cardiac contractility, and usually little change in blood pressure or heart rate occurs. Cardiovascular stability is generally preserved in persons with hypovolemia or cardiac dysfunction.

  11. Etomidate inhibits the enzyme responsible for performing the 11β-hydroxylation reaction in cortisol synthesis. A single induction dose of 0.3 mg/kg inhibits cortisol synthesis and the normal response to adrenocorticotropic hormone for up to 12 hours. Infusions of several days’ duration in ventilated intensive care unit patients were associated with increased mortality. Investigational derivatives of etomidate produce much less adrenal suppression than etomidate.

  12. Sedative doses of midazolam cause patients ...

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