Distribution of normal saline and 5% albumin infusions in cardiac surgical patients

Objective. To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) and the effect on oxygen delivery after infusing either normal saline or 5% albumin in cardiac surgical patients. Design. Prospective, randomized, unblinded, interventional study. Setting: Cardiac surgical intensive care unit in a 450-bed teaching hospital. Patients: Postoperative cardiac surgical patients (n = 40). Interventions. Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician. Measurements and Main Results. Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of I-131-albumin and [S-35]sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline and 5% albumin increased PV by 9 +/- 23% and 52 +/- 84% of the volume infused, respectively (p < .05), whereas there was no significant difference between saline and albumin in the change in ISFV per volume infused. Only 5% albumin significantly increased cardiac index, although oxygen delivery did not change significantly after either infusion. Conclusions: In postoperative cardiac surgical patients, infusion of 5% albumin is approximately five times as efficient as a PV expander but has comparable effects on changes in ISFV and oxygen delivery relative to normal saline.