STUDIES OF CYCLOPROPANE II. CONCENTRATIONS OF CYCLOPROPANE REQUIRED IN THE AIR AND BLOOD FOR ANESTHESIA, LOSS OF REFLEXES, AND RESPIRATORY ARREST

¹ From the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee

1. The cyclopropane concentrations in the inspired air required for anesthesia, loss of reflexes and respiratory arrest have been determined. The concentrations in the air agree remarkably well with those of Seevers et al. (3).

2. The blood cyclopropane concentrations for anesthesia, loss of reflexes and respiratory arrest have been determined. The average values for seventeen dogs are: 16.8 mgm. per 100 cc. blood for anesthesia with abdominal relaxation, 20.6 mgm. per 100 cc. for loss of wink or lid reflex, 25.5 mgm. per 100 cc. for costal paralysis, and 28.2 mgm. per 100 cc. for respiratory arrest.

3. The average distribution ratio in vivo at 38° for seventeen dogs was 0.492, which is between the values obtained in vitro on four blood samples which varied from 0.475 to 0.515.

4. The rate of elimination of cyclopropane after long periods of anesthesia has been determined.