The effects of various antishock trouser inflation sequences on hemodynamics in normovolemic subjects

In an attempt to maximize the hemodynamic effects of antishock trousers, a pair of such trousers was modified to a five-bladder trouser (one abdominal, two thigh, and two calf bladders) and inflated using three different inflation sequences. These three sequences were simultaneous inflation of all five bladders; concurrent inflation of the calf and thigh bladders and then inflation of the abdominal bladder (standard inflation); and sequential inflation of the calf, thigh, and abdominal bladders. Simultaneous inflation resulted in the greatest increase in blood pressure and the smallest increase in end-diastolic volume, stroke volume, and cardiac output. The standard inflation sequence resulted in slightly higher increases in end-diastolic volume, stroke volume, and cardiac output than the sequential inflation sequence, and a significantly larger increase in cardiac output than the simultaneous inflation sequence. Our study indicates that of the three sequences used, the standard inflation sequence produces the greatest blood return to the heart.