Pulmonary Gas Exchange After Hemorrhage During Intermittent Positive Pressure Breathing

The Cardiorespiratory Effects of Haemorrhage and Overtransfusion in Dogs

“…However, it is noteworthy that in the latter study the mean cardiac output in 3 dogs was only 850 ml/min and that halothane, a known myocardial depressant, was used for the anaesthesia. In dogs bled under conditions similar to our own the increase in VD/VT (from 45 to 57 per cent) was very similar (Rehder et al, 1965). In humans it would seem that the increase in VD/VT ratio is only moderate if deliberate hypotension is accompanied by spontaneous ventilation (Askrog, Smith and Eckenhoff, 1964) and that, even after a head-up tilt and controlled ventilation, the VD/VT ratio may still be under 50 per cent (Askrog, Pender and Eckenhoff, 1964).…”