Comparison of tidal ventilation and high-frequency jet ventilation before and after cardiopulmonary bypass in dogs using two-dimensional transesophageal echocardiography.
This study compared the use of high-frequency jet ventilation (HFJV) and tidal ventilation (TV) in a group of dogs with induced global myocardial ischemia before and after cardiopulmonary bypass. Transesophageal echocardiography was used to determine whether HFJV with its lower airway pressures could improve cardiac performance. The surgical procedure was separated into four study periods: closed chest before bypass, open chest before bypass, open chest after bypass, and closed chest after bypass. During each of these study periods, the dogs were randomly ventilated with alternate periods of TV and HFJV to maintain the PaCO2 at 34.3 +/- 3.3 mm Hg (mean +/- SEM). Cardiac output, stroke volume, systemic mean blood pressure, left ventricular ejection fraction, left ventricular end-diastolic volume, left ventricular dP/dt, left ventricular stroke work, and expiratory volumetric flows were higher during HFJV, whereas airway pressures and pulmonary vascular resistance were lower. Increases in cardiac output and stroke volume during HFJV were due to a combination of improved left ventricular contractility indicated by increased LV dP/dt and increased left ventricular end-diastolic volume accompanying decreased airway pressures. These data indicate that HFJV with its lower airway pressure is associated with significantly less impairment of cardiovascular function than TV in dogs with induced global myocardial ischemia.
Hayes
J K
JK
Department of Anesthesiology, University of Utah College of Medicine, Salt Lake City 84132.
Smith
K W
KW
Port
J D
JD
Jordan
W S
WS
D000818:Animals; D002302:Cardiac Output / Q000502:physiology; D002315:Cardiopulmonary Bypass; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004285:Dogs; D004452:Echocardiography / Q000379:methods*; D004947:Esophagus; D005260:Female; D005540:Forced Expiratory Flow Rates; D006611:High-Frequency Jet Ventilation; D008297:Male; D011312:Pressure; D012123:Pulmonary Ventilation / Q000502:physiology; D012121:Respiration, Artificial; D013318:Stroke Volume / Q000502:physiology; D013815:Thermodilution; D013908:Thoracotomy; D013990:Tidal Volume; D014655:Vascular Resistance / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology