Physiologic changes of antishock trousers in relationship to external pressure.

The results of this study on dogs demonstrates that 60 millimeters of mercury counterpressure does not differ significantly from 100 millimeters of mercury counterpressure either in the increase in carotic pressure or in the mobilization of blood in the lower extremities and abdomen. Therefore, one could assume that vital organ perfusion is just as effective at 60 millimeters of mercury as at 100 millimeters of mercury. Sixty millimeters of mercury counterpressure produces less lactic acidosis and hyperkalemia than does 100 millimeters of mercury. It must be emphasized, however, that the blood pressure of the dogs was maintained at 80 millimeters of mercury, significantly below the 100 millimeters of mercury of the counterpressure. The results of previous studies have demonstrated that, when the blood pressure in animals is maintained at 100 millimeters of mercury, this metabolic acidosis and hyperkalemia are not as severe. Data from these experiments demonstrated that, when the blood pressure in animals is maintained at 120 grams and the external counterpressure is maintained at 100 millimeters, there is only a minimal to moderate accumulation of lactic acid and potassium. It can be inferred, therefore, that, when blood pressure is returned to within normal range, there is enough perfusion of the lower extremities and abdomen to prevent production of excessive lactic acid and potassium. Finally, the results of the present study demonstrated that a significant amount (up to 30 per cent of blood volume) is mobilized from the lower extremities and abdomen when the device is properly applied.