Changes in Physiological Dead Space During Deliberate Hypotension

Alterations in physiological dead space have been calculated in 7 patients undergoing surgical procedures and subjected to nitrous oxide-halo-thane anesthesia with deliberate hypotension produced by pentolinium and head-up tilt. Mean blood pressure was lowered from an average of 87 mm. of mercury to an average of 50 mm. of mercury. Physiological dead space increased in all patients. The increase resulted from enlargement of both anatomical and alveolar dead spaces, but more especially the latter. The increase was greater in this group of patients as compared with another group anesthetized with the same agents but whose blood pressure was within normal limits.