Hypertonic saline for fluid resuscitation after cardiac surgery (HERACLES): study protocol for a preliminary randomised controlled clinical trial

Abstract

Background Intraoperative and postoperative management of cardiac surgery patients is complex, involving the application of differential vasopressors and volume therapy. It has been shown that a positive fluid balance has a major impact on postoperative outcome. Today, the advantages and disadvantages of buffered crystalloid solutes are a topic of controversy, with no consensus being reached so far. The use of hypertonic saline (HS) has shown promising results with respect to lower total fluid balance and postoperative weight gain in critically ill patients in preliminary studies. However, collection of more data on HS in critically ill patients seems warranted. This preliminary study aims to investigate whether fluid resuscitation using HS in patients following cardiac surgery results in less total fluid volume being administered. Methods In a prospective double-blind randomised controlled clinical trial, we aim to recruit 96 patients undergoing elective cardiac surgery for ischaemic and/or valvular heart disease. After postoperative admission to the intensive care unit (ICU), patients will be randomly assigned to receive 5 ml/kg ideal body weight HS (7.3% NaCl) or normal saline (NS, 0.9% NaCl) infused within 60 min. Blood and urine samples will be collected preoperatively and postoperatively up to day 6 to assess changes in renal, cardiac, inflammatory, acid-base, and electrolyte parameters. Additionally, we will perform renal ultrasonography studies to assess renal blood flow before, during, and after infusion, and we will measure total body water using preoperative and postoperative body composition analysis (bioimpedance). Patients will be followed up for 90 days. Discussion The key objective of this study is to assess the cumulative amount of fluid administered in the intervention (HS) group versus control (NS) group during the ICU stay. In this preliminary, prospective, randomised controlled clinical trial we will test the hypothesis that use of HS results in less total fluids infused and less postoperative weight gain when compared to the standard of intensive care in cardiac surgery patients. Trial registration ClinicalTrials.gov, NCT03280745 . Registered on 12 September 2017. Electronic supplementary material The online version of this article (10.1186/s13063-019-3420-6) contains supplementary material, which is available to authorized users.

Postoperative resuscitation with hypertonic saline or hyperoncotic albumin in patients following cardiac surgery: A review of the literature

“…While some degree of postoperative resuscitation is necessary, inappropriate fluid administration of crystalloids resulting in volume overload has been found to be associated with non‐anion gap metabolic acidosis, 63 acute renal dysfunction, 54 increased length of stay in the ICU, and increased mortality 3,13,54,55,63,64 . As such, to modulate the risks of volume overload with isotonic crystalloids, resuscitation with HS is of increased clinical interest in the perioperative setting 18,65 …”

“…In the literature currently available, the use of hyperoncotic albumin for postcardiac surgery resuscitation has been published on more extensively when compared with HS 18,23,24 . The objectives of both bodies of literature aim to delineate whether or not resuscitation with concentrated albumin and saline improved hemodynamics more efficiently than their iso‐oncotic counterparts 17,18,21,23,24 . In addition, these analyses further attempted to identify whether resuscitation with these concentrated intravenous fluids impacted overall fluid balance 17,18,23,24 …”

“…In this review, resuscitation with hyperoncotic albumin and HS in patients following cardiac surgery was explored. In the literature currently available, the use of hyperoncotic albumin for postcardiac surgery resuscitation has been published on more extensively when compared with HS 18,23,24 . The objectives of both bodies of literature aim to delineate whether or not resuscitation with concentrated albumin and saline improved hemodynamics more efficiently than their iso‐oncotic counterparts 17,18,21,23,24 .…”

“…Thus, when considering the sequelae of a positive fluid balance, 6,7,11 there has been growing interest in the utility of resuscitation with hypertonic and hyperosmolar fluids in postcardiac surgery patients 14–16 . As such, the use of hypertonic saline (HS) and concentrated albumin in patients following cardiac surgery will be reviewed from the current literature 17–21 …”

Fluid trials: searching for a solution to an age-old problem

“…The primary outcome was cumulative fluid input during ICU stay. The authors conducted a low-risk-of-bias trial with adequate randomization, blinding, and a published protocol [12]. As a single-center study, it has limited external validity, and since it was a phase II trial the primary outcome was not patient centered.…”