Cardiopulmonary effects of volume loading in patients in septic shock

The effect of volume loading in 20 patients with clinical and bacteriological evidence of generalized sepsis was studied. The patients were divided into two groups according to their response to volume loading. Group A included 9 patients in whom the initial pulmonary capillary wedge pressure (PWP) was lower than the central venous pressure (CVP). In this group the intravenous administration of 5089 ± 409 ml/24 hr fluids was accompanied by a significant rise in blood pressure from 94.4 ± 9.3 mm Hg to 118.9 ± 6.3 mm Hg with no significant change in pulse rate or CVP. PWP rose from 5.7 ± 1.8 to 10.0 ± 1.4. The rise in cardiac output from 8.0 ± 1.3 liter/min to 9.7 ± 1.1 liter/min was not statistically significant. Group B included 11 patients in whom the initial PWP was higher than the CVP. In this group, signs of fluid overloading appeared after administration of 3151 ± 540 ml/24 hr. There was no significant change in blood pressure, pulse rate, CVP, PWP or cardiac output. Urine output was adequate in both groups. This volume load did not affect pulmonary oxygenating capacity (PaO₂/F(I)O₂) and effective lung compliance in both groups, but the maintenance of an unchanged oxygenating capacity necessitated an increase in PEEP in some patients. Thus, synchronous monitoring of PWP and CVP in septic shock is helpful in selecting patients (Group A) who will best respond to fluid loading without deterioration of pulmonary oxygenating capacity. PEEP ventilation may be necessary in some patients to maintain the favorable effect of volume loading.