Depressed spontaneous ventilatory response to carbon dioxide in man under halothane anesthesia appears to be mainly due to respiratory mechanical depression, according to a team of investigators at Roswell Park Memorial Institute, Buffalo.
Yong H. Han, MD, reported a study of 11 patients which differentiated between central and mechanical effects of anesthesia on respiration. Han and associates from both Roswell Park and from the University of Maryland compared patients in the awake resting control state and under anesthesia. He evaluated a comparison of the apneic threshold of ventilatory response to carbon dioxide in control and anesthetized groups.
The patients had no evidence of cardiovascular or respiratory abnormality. About half the patients received no preanesthesia medication, while the remaining group received morphine sulfate and scopolamine.
In the latter group, half were anesthetized with thiopental and halothane and oxygen, and half received only halothane and oxygen—as did the group which received no