High-Frequency and Conventional Positive-Pressure Ventilation Do Not Decrease Cardiac Output in Acute Cardiac Tamponade in Dogs

The effects of different modes of ventilation were studied in 7 dogs with acute cardiac tamponade. During steady-state light thiopental anesthesia, measurements were performed with increasing tamponade volumes during spontaneous breathing (SB), intermittent positive-pressure ventilation (IPPV) with a frequency (f) of 20/min, and high-frequency positive-pressure ventilation (HFPPV) with f of 60/min. With normocarbic ventilation, no differences were observed in the hemodynamic effect of SB, IPPV, or HFPPV. The airway pressures were low during all modes of ventilation. They did not affect pericardial pressure when tamponade volume increased. The results indicate that both IPPV and HFPPV may be used in acute cardiac tamponade without risk of further deterioration of cardiac output. (Breivik H, Koller M-E, Smith RB, Sjöstrand UH, Davis R. High-Frequency and Conventional Positive-Pressure Ventilation Do Not Decrease Cardiac Output in Acute Cardiac Tamponade in Dogs . Respir Care 1983;28:291-296.