December 11, 1981

The Quantitative Practice of Anesthesia: Use of Closed Circuit

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by Harry J. Lowe and Edward A. Ernst, 234 pp, with illus, $35, Baltimore, Williams & Wilkins Co, 1981.

JAMA. 1981;246(23):2748-2749. doi:10.1001/jama.1981.03320230064035

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A large proportion of anesthetics in this country are administered using a "semiclosed" gas delivery system. This technique presents an excess of drug to the lungs to achieve easily predictable alveolar (thus arterial, thus cerebral) anesthetic concentrations. It is analogous to running a rapid dopamine infusion with three fourths of the solution leaking out of a poorly connected intravenous tubing before entering the patient. Not only is the semiclosed system wasteful, but the absence of knowledge of total dose of drug given makes informed analysis of the response difficult. The act of sealing the anesthetic system (closing the circuit) has many advantages, the greatest being the skill and comprehension required to maintain safe anesthesia under this condition.

The authors of this book derive rules for closed-circuit anesthesia from basic physiology and pharmacology. Physical-chemical properties of anesthetics acquire new relevance. The authors emphasize practicality. Although they use differential calculus to present