METABOLIC AND HEMODYNAMIC EFFECTS OF HYPERTONIC SOLUTIONS: SODIUM-LACTATE VERSUS SODIUM CHLORIDE INFUSION IN POSTOPERATIVE PATIENTS

Although hypertonic saline has been proposed as an intravenous resuscitation fluid, the beneficial effects of the sodium load are associated with potentially deleterious effects of chloride. Since the physiological lactate anion is well metabolized, hypertonic lactate solution could represent an interesting alternative. The aim of this study was to compare metabolic and hemodynamic effects of hypertonic infusion of sodium lactate versus sodium chloride in three groups of surgical patients who underwent elective coronary artery bypass grafting (CABG). Hypertonic lactate solution was infused to patients 14 to 16 h after surgery either involving a cardiopulmonary bypass (CPB-Lac, n = 20) or on-off pump (OPCAB-Lac, n = 20), whereas the third group consisted of patients undergoing cardiopulmonary bypass but receiving hypertonic saline solution (CPB-NaCl, n = 20). An equal fluid and sodium load (2.5 mL/2.5 mmol x kg(-1)) was infused in all patients over 15 min. Plasma glucose and sodium increased after infusion in the three groups, but the changes, although significant, were small. As expected, lactate rose only in CPB-Lac and OPCAB-Lac groups, the changes being more marked in CPB-Lac, indicating a slower lactate metabolism in this group compared with OPCAB-Lac. Although both solutions produced significant increases in cardiac index and oxygen delivery, there was a significant decrease in oxygen extraction only in groups receiving sodium lactate (CPB-Lac and OPCAB-Lac) and not in CPB-NaCl. Finally, hypertonic NaCl infusion induced a modest, although significant, decrease in arterial pH and bicarbonate, whereas hypertonic lactate infusion increased these two parameters in both CPB-Lac and OPCAB-Lac. This study demonstrates that hypertonic lactate infusion is safe and well tolerated in patients undergoing elective cardiac surgery.