Cardiorespiratory effects of high frequency intermittent positive pressure ventilation in the dog.
The cardiorespiratory effects of increasing respiratory frequency were investigated in two groups of dogs ventilated mechanically with a system which minimized apparatus and anatomical deadspace. In one group minute volume was constant whilst frequency was increased; in the second group minute volume was increased to maintain normal PaCO2. The reduction in tidal volume with increasing frequency was accompanied by a reduction in physiological deadspace. However, the reduction in deadspace was proportionally less than the decrease in tidal volume, so that the deadspace/tidal volume ratio increased. The peak airway pressures were minimal at a frequency of 45 b.p.m. At frequencies of 60 b.p.m. and more, the lung failed to empty so that peak airway pressures were increased and cardiac output decreased.
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output; D004285:Dogs; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods*; D011312:Pressure; D012119:Respiration; D012126:Respiratory Dead Space; D012143:Respiratory Physiological Phenomena; D013990:Tidal Volume
D002245:Carbon Dioxide