Effects of hypertonic saline (7.5%) on extracellular fluid volumes compared with normal saline (0.9%) and 6% hydroxyethyl starch after aortocoronary bypass graft surgery

Objective: To compare the effects of hypertonic (7.5%) saline (HS), normal (0.9%) saline (NS), and 6% hydroxyethyl starch (HES) on extracellular fluid volumes in the early postoperative period after cardiopulmonary bypass. Design: A prospective, randomized, double-blind study. Setting: University teaching hospital. Participants: Forty-eight patients scheduled for elective coronary artery b ypass graft surgery. Interventions: Patients were randomly allocated to receive 4 mL/kg of HS, N S, or HES during 30 minutes when Volume loading was needed during the posto perative rewarming period in the intensive care unit. Plasma volume was mea sured using a dilution of iodine-125-labeled human serum albumin. Extracell ular water and cardiac output were measured by whole-body impedance cardiog raphy. Measurements and Main Results: Plasma volume had increased by 19 +/- 7% in the HS group and by 10 +/- 3% in the NS group (p = 0.001) at the end of the study fluid infusion. After 1-hour follow-up time, the plasma volume incre ase was greatest (23 +/- 8%) in the group receiving HES (p < 0.007). The in crease of extracellular water was greater than the infused volume in the HS and HES groups at the end of the infusion. One-hour diuresis after the stu dy infusion was greater in the HS group (536 +/- 280 mL) than in the NS (26 7 +/- 154 mL, p = 0.006) and HES groups (311 +/- 238 mL, p = 0.025). Conclusion: The effect of HS on plasma volume was shortlasting, but it stim ulated excretion of excess body fluid accumulated during cardiopulmonary by pass and cardiac surgery. HS may be used in situations in which excess free water administration is to be avoided but the intravascular volume needs c orrection. Copyright (C) 2001 by W.B. Saunders Company.