INCREASED G-SUIT COVERAGE IMPROVES CARDIAC PRELOADING CONDITIONS DURING POSITIVE PRESSURE BREATHING

A miniaturized nuclear probe (MNP) and multiple gated cardiac blood pe el imaging (RCBI) were used to measure left ven tricular function duri ng positive pressure breathing (PPB) while wearing sin extended-covera ge (EC) vs. standard coverage (SC) anti-C-suit. Seven subjects were ex posed to 4.0 and 9.3 kPa PPB wearing each anti-G-suit during 3 min of PPB at ground level. Ejection fraction was unchanged using both techni ques. The atrial component to diastolic filling was greater with the S C suit (p < 0.02). Using the MNP, end-diastolic and end-systolic volum es declined non-linearly over time at both PPB levels; these declines were greater with the SC G-suit (p < 0.001). Left ventricular preload declines during PPB. This is attenuated with increased G suit coverage , confirming prior results using impedance cardiography. RCBI is less sensitive than MNP's for measuring non-steady-state cardiac physiology such as PPB.