Hypertonic saline for fluid resuscitation in ICU patients post-cardiac surgery (HERACLES): a double-blind randomized controlled clinical trial

Purpose Recent evidence questions a liberal approach to fluid resuscitation in intensive care unit (ICU) patients. Here, we assess whether use of hypertonic saline applied as single infusion at ICU admission after cardiac surgery can reduce cumulative perioperative fluid volume. Methods Prospective randomized double-blind single-center clinical trial investigates effects of a single infusion of hypertonic saline (HS) versus normal saline (comparator). Primary endpoint was the cumulative amount of fluid administered in patients in the hypertonic saline versus the 0.9% saline groups (during ICU stay). Upon ICU admission, patients received a single infusion of 5 ml/kg body weight of 7.3% NaCl (or 0.9% NaCl) over 60 min. Patients undergoing cardiac surgery for elective valvular and/or coronary heart disease were included. Patients with advanced organ dysfunction, infection, and/or patients on chronic steroid medication were excluded. Results A total of 101 patients were randomized to receive the study intervention (HS n = 53, NS n = 48). Cumulative fluid intake on the ICU (primary endpoint) did not differ between the HS and the NS groups [median 3193 ml (IQR 2052–4333 ml) vs. 3345 ml (IQR 2332–5043 ml)]. Postoperative urinary output until ICU discharge was increased in HS-treated patients [median 2250 ml (IQR 1640–2690 ml) vs. 1545 ml (IQR 1087–1976 ml)], and ICU fluid balance was lower in the HS group when compared to the NS group [296 ml (IQR − 441 to 1412 ml) vs. 1137 ml (IQR 322–2660 ml)]. Conclusion In a monocentric prospective double-blind randomized clinical trial, we observed that hypertonic saline did not reduce the total fluid volume administered on the ICU in critically ill cardiac surgery patients. Hypertonic saline infusion was associated with timely increase in urinary output. Variations in electrolyte and acid–base homeostasis were transient, but substantial in all patients.