The Effect of Preoperative Carbohydrate Loading on Clinical and Biochemical Outcomes after Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Trials

Abstract

Background and aim: Preoperative fasting leads to metabolic stress and causes insulin resistance in patients undergoing cardiac surgery. The aim of this study was to assess the effect of preoperative oral carbohydrate loading (OCH) on outcome in patients undergoing planned cardiac surgery by systematically reviewing the literature and synthesizing evidence from randomized controlled trials (RCTs). Methods: Systematic search of PubMed/MEDLINE/Embase/Cinahl/Web of Science/ClinicalTrials databases was performed to identify relevant RCTs from databased inception until 05/03/2020. We included studies that compared outcome measures between OCH with control (placebo or standard starvation). We conducted a random-effect meta-analysis of clinical and biochemical parameters. Results: Nine studies (N = 9) were included with a total of 507 patients. OCH significantly decreased aortic clamping duration (n = 151, standardized mean difference (SMD) = −0.28, 95% confidence interval (CI) = −0.521 to −0.038, p = 0.023 and differences in means (DM) = −6.388, 95%CI = −11.246 to −1.529, p = 0.010). Patients from treatment groups had shorter intensive care unit (ICU) stay (n = 202, SMD = −0.542, 95%CI = −0.789 to −0.295, p < 0.001 and DM = −25.925, 95%CI = −44.568 to −7.283, p = 0.006) and required fewer units of insulin postoperatively (n = 85, SMD = −0.349, 95%CI = −0.653 to −0.044, p = 0.025 and DM = −4.523, 95%CI = −8.417 to −0.630, p = 0.023). The necessity to use inotropic drugs was significantly lower in the OCH group (risk ratio (RR) = 0.795, 95%CI = 0.689 to 0.919, p = 0.002). All other primary outcomes did not reveal a significant effect. Conclusions: Preoperative OCH in patients undergoing cardiac surgery demonstrated a 20% reduction in the use of inotropic drugs, a 50% reduction of the length of ICU stay, a 28% decrease in aortic clamping duration and a 35% decrease of postoperative insulin requirement.

The impact of oral carbohydrate-rich supplement taken two hours before caesarean delivery on maternal and neonatal perioperative outcomes -- a randomized clinical trial

“…Our study used HOMA-IR index to access the metabolic state. The impact of preoperative carbohydrate supplement on the reduction of postoperative insulin resistance has been found in other types of surgeries [ 2 , 15 ]. Insulin resistance is one of the most fundamental reactions to injury and stress.…”

“…The traditional fashion that patients preoperatively fast from midnight to minimum 6 h for solid food and 4 h for fluids before an elective surgery to prevent vomiting and aspiration pneumonia has been challenged by various studies [ 1 , 2 ]. Therefore, several updated guidelines encourage patients to take clear fluids up to 2 h before an elective operation with strong grade recommendations [ 3 – 6 ].…”

Preoperative Carbohydrate Loading on Outcomes after Cardiac Surgery: A Flawed Meta-Analysis. Comment on: “The Effect of Preoperative Carbohydrate Loading on Clinical and Biochemical Outcomes after Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Trials”. Nutrients 2020, 12, 3105

“…We read, with interest, the publication in Nutrients on the effects of preoperative carbohydrate loading on outcomes after cardiac surgery [ 1 ] and wish to highlight several inconsistencies and shortcomings that make the conclusions unreliable.…”

“…In addition, there should be a single stated primary end-point, with the other predetermined end-points being secondary. The authors [ 1 ] have chosen a host of primary outcome measures, and it is difficult to envisage how preoperative carbohydrate loading could influence some of these. For example, the decrease in aortic cross clamping time is more likely to be a technical issue rather than a beneficial metabolic effect of carbohydrate loading and, in turn, could have influenced other outcomes such as durations of cardiopulmonary bypass, mechanical ventilation and intensive care unit (ICU) stay.…”

Reply to: “Preoperative Carbohydrate Loading on Outcomes after Cardiac Surgery: A Flawed Meta-Analysis. Comment on: The Effect of Preoperative Carbohydrate Loading on Clinical and Biochemical Outcomes after Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Trials. Nutrients 2020, 12, 3904”

“…We appreciate the thoughts and questions posed by Drs Dileep N Lobo and Girish P Joshi [ 1 ] in relation to our manuscript entitled ‘The Effect of Preoperative Carbohydrate Loading on Clinical and Biochemical Outcomes after Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Trials [ 2 ]. Regarding protocol and registration, we cannot agree with the conclusion that the study is non-compliant with the PRISMA statement.…”