Concurrent expansion of plasma volume and left ventricular end-diastolic volume in patients after rapid infusion of 5% albumin and lactated Ringer's solution.

Study Objective: To examine the effects of plasma volume expansion on plasma volume, left ventricular end-diastolic volume (LVEDV), and cardiac index (CI) after rapid fluid infusion, as knowledge of the degree of concordance between plasma and cardiac preload expansion could optimize LVEDV expansion without administering excessive fluid.

Design: Randomized, double-blinded study.

Setting: Academic community hospital.

Patients: 20 patients undergoing elective coronary artery bypass surgery.

Interventions: Patients were administered either 5% albumin (5 mL/kg) or lactated Ringer's solution (25 mL/kg) over 30 minutes, just before incision.

Measurements: Serial measurements of plasma volume, LVEDV by transesophageal echocardiography, and CI were recorded.

Main Results: Albumin expanded plasma volume and LVEDV to a similar degree (11.3% and 13.2%). In contrast, lactated Ringer's solution increased plasma volume more than LVEDV (21.7% vs 14.4%; P = 0.0005). Increased LVEDV significantly but poorly correlated with increased CI (r(2) = 0.2, P < 0.0001) for both fluids. However, LVEDV expansion was brief and returned to baseline or less within 30 minutes for both fluids despite continued plasma volume expansion and increased CI. Correspondingly, rates of decline from peak expansion were significantly faster for LVEDV than plasma volume expansion for both albumin (-1.9% + 1.9%/min vs -0.1% + 0.1%/min; P = 0.0008) and lactated Ringer's (-1.1% + 0.8%/min vs -0.4% + 0.2%/min; P = 0.006).

Conclusions: Intravenous fluids increased LVEDV to a lesser extent and duration than did plasma volume expansion. Monitoring of LVEDV was a poor guide for fluid administration to maximize CI.