EFFECT OF SYNCHRONIZED, SYSTOLIC, LOWER-BODY, POSITIVE PRESSURE ON HEMODYNAMICS IN HUMAN SEPTIC SHOCK - A PILOT-STUDY

The pathophysiologic disturbance observed in volume-resuscitated patie nts with septic shock is primarily that of hyperdynamic circulation wi th a markedly reduced systemic vascular resistance. We hypothesized th at external, mechanically applied, phasic lower body positive pressure could increase systemic vascular resistance and, thus, blood pressure in patients with refractory septic shock. A total of nine studies wer e performed on seven patients with septic shock refractory to volume r esuscitation and vasopressors. All pre-existing therapies were continu ed unaltered during the study period. Phasic lower body positive press ure was produced by rapid synchronized inflation of pneumatic fabric c uffs fitted around each lower extremity. The cuffs were inflated for 2 00 ms to a pressure of 150 mm Hg, and the timing of inflation was adju sted to coincide with the peak systolic arterial pressure. Hemodynamic measurements were obtained at baseline and after 15 min of phasic low er body positive pressure. This off-on cycle was repeated twice for ea ch study. Phasic lower body positive pressure increased mean arterial pressure by 12% and cardiac index by 14% (p = 0.01) over baseline (p l ess than or equal to 0.001). Heart rate, central venous pressure, pulm onary capillary wedge pressure, arterial pH, arterial pO(2), and mixed venous pO(2) were unchanged. Synchronized external systolic compressi on of the lower extremities increased mean arterial pressure and cardi ac output in seven patients with refractory septic shock. This hemodyn amic improvement was independent of changes in calculated systemic vas cular resistance.