QUANTITATIVE EVALUATION OF THE BRONCHOCONSTRICTOR ACTION OF CURARE IN THE ANESTHETIZED PATIENT: A PRELIMINARY REPORT

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Abstract
The broncho-constrictor action of curare in 9 anesthetized patients was measured by an apparatus which maintained automatic controlled respiration at a constant rate and force and recorded changes in the tidal volume. For endotracheal intubation and to procure controlled respiration, various preoperative drugs and anesthetic agents were used. At a constant depth of anesthesia and under conditions of controlled respiration while a kymographic tracing of the tidal volume was being recorded, 15-24 mg. of d-tubo-curarine chloride was administered rapidly by intraven. injn. In 3 patients an increase in the tidal volume due to an increase on the effective bronchial caliber was obtained. This was attributed to a decreased resistance to inflation of the lungs produced by relaxation of the chest, abdominal muscles, and diaphragm in the absence of bronchoconstriction. In 5 patients no change in the tidal volume occurred. In 1 patient after the injn. of 21 mg. of d-tubocurarine chloride, a drop in tidal volume from 560 to 400 cc. occurred. This was attributed to sufficient bronchoconstriction to increase resistance to respiration in spite of the respiratory muscular relaxation produced by d-tubocurarine chloride. It was concluded that the bronchial effect of intraven. curare was, in anesthetized humans, variable and unpredictable.