Relationship between stroke volume and pneumocardiogram.
The intratracheal pressure oscillations produced by the heartbeat, called the pneumocardiogram, were recorded in 15 dogs. It was found that a linear relationship existed between the amplitude of the major negative deflection of the pneumocardiogram and the cardiac stroke volume, the latter determined either by indicator dilution (avg r = 0.94) or by use of an electromagnetic flow probe (avg r = 0.95). This relationship existed in animals with both an open and a closed chest. The vector of left ventricular wall motion directed toward the lungs, determined by high-speed cineradiography of the motion of a tantalum marker inserted in the wall of the left ventricle, looked very similar to the pneumocardiogram. This study showed that the pneumocardiogram can be used as a noninvasive technique to measure changes in stroke volume and is caused primarily by the motion of the cardiac walls.
D000818:Animals; D002302:Cardiac Output; D004285:Dogs; D006334:Heart Function Tests / Q000379:methods*; D009068:Movement; D009200:Myocardial Contraction; D011312:Pressure; D012129:Respiratory Function Tests / Q000379:methods*; D013318:Stroke Volume; D014132:Trachea / Q000502:physiology; D016276:Ventricular Function