An Electronically Modified Wet Spirometer

Abstract

IN a recent investigation of respiratory muscles, recordings were made simultaneously from multiple indwelling electrodes, along with spirometric tracings, so that electrical activity could be examined in a series of conscious rabbits during quiet respiration. Tho electrical signals from the muscles and the spirometric tracing are shown on a film record (Fig. 1). Attention is directed especially to the spirometric tracing which appears as a horizontal band which widens with expiration and narrows with inspiration. A primary interest was to secure an accurate reflexion of the movement of air into and out of the lungs of the rabbit, a factor dependent on the accuracy of the spirometer. Although many spirometers are available, a simple, inexpensive electronic modification of a wet spirometer (400-c.c. Phipps and Bird spirometer, Richmond, Va.) was developed (Fig. 2). The electronic modification of the spirometer, its application, and a method devised to determine its latency from the subject of this communication.