The maximal expiratory flow rate of normal individuals.

A total of 167 individuals was studied which included 85 men and 82 women ranging in age from 20 to 59 years. The criteria for normalcy were based on the following requirements: 1) no history of cardiopulmonary disease, 2) normal chest x-ray film within six months. The total vital capacity was measured with a 6-liter Vitalometer having a 70centimeter noncorrugated rubber tube with an internal diameter of 2.0 centimeters, and the maximum breathing capacity was measured with a Collins 13.5-liter respirometer having a double 92-centimeter noncorrugated tube with an internal diameter of 3.3 centimeters. All of the individuals studied were either house staff or employees of the hospital or patients who were ambulatory. The flow rate was determined on a 6-liter Collins Vitalometer with a direct writing pen inscribing on a Gorell and Gorell monodrum rotating