Comparative Study Between Conventional Fasting Versus Overnight Infusion of Lipid or Carbohydrate on Insulin and Free Fatty Acids in Obese Patients Undergoing Elective On-pump Coronary Artery Bypass Grafting. A Prospective Randomized Trial

The Role of Insulin Resistance in the Development of Complications after Coronary Artery Bypass Grafting in Patients with Coronary Artery Disease

The aim of the study was to investigate the effect of carbohydrate metabolism disorders and insulin resistance indices on the immediate results of coronary artery bypass grafting (CABG).

METHOD

Patients with coronary artery disease who underwent CABG (n = 383) were examined to determine glycemic status, free fatty acid and fasting insulin levels, and insulin resistance indices (Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), McAuley index, Quantitative Insulin Sensitivity Check Index (QUICKI), Revised-QUICKI). Patients were assessed for the development of perioperative complications and their length of stay in the hospital. Two groups were formed: group 1, patients with a combined endpoint (CEP, any complication and/or duration of hospital stay >10 days), n = 291; and group 2 (n = 92) without a CEP. Perioperative characteristics were analyzed, and predictors of hospital complications and prolonged hospital stay were evaluated.

RESULTS

Patients in the CEP group were older, and there were more women among them (p = 0.003). Additionally, in this group, there were more patients with diabetes mellitus (37.5% vs 17.4%, p < 0.001), obesity (p < 0.001), and a higher percentage of combined operations (p = 0.007). In the group with a CEP, the levels of glucose (p = 0.031), glycated hemoglobin (p = 0.009), and free fatty acids (p = 0.007) and the Revised-QUICKI (p = 0.020) were higher than in the group without complications. In a regression analysis, the independent predictors of complications were combined operations (p = 0.016) and the predictors of a long hospital stay (>14 days) were female gender, the left atrium size, and diabetes mellitus (p < 0.001). The predictors of a composite endpoint included female gender, age, the left atrium size, and free fatty acid levels (p < 0.001).

CONCLUSIONS

In the group with in-hospital complications after CABG, not only was the presence of diabetes mellitus more often detected, but there were also higher levels of free fatty acids and a higher Revised-QUICKI. Therefore, additional assessments of insulin resistance and free fatty acid levels are advisable in patients before CABG.

Effects of preoperative carbohydrate loading on recovery after elective surgery: A systematic review and Bayesian network meta-analysis of randomized controlled trials

Background

Preoperative carbohydrate loading is an important element of the enhanced recovery after surgery (ERAS) paradigm in adult patients undergoing elective surgery. However, preoperative carbohydrate loading remains controversial in terms of improvement in postoperative outcomes and safety. We conducted a Bayesian network meta-analysis to evaluate the effects and safety of different doses of preoperative carbohydrates administrated in adult patients after elective surgery.

Methods

MEDLINE (PubMed), Web of Science, EMBASE, EBSCO, the Cochrane Central Register of Controlled Trials, and China National Knowledge Infrastructure (CNKI) were searched to identify eligible trials until 16 September 2022. Outcomes included postoperative insulin resistance, residual gastric volume (RGV) during the surgery, insulin sensitivity, fasting plasma glucose (FPG), fasting serum insulin (Fin) level, the serum levels of C-reactive protein (CRP), postoperative scores of pain, patients' satisfaction, thirst, hunger, anxiety, nausea and vomit, fatigue, and weakness within the first 24 h after surgery and the occurrences of postoperative infection. The effect sizes were estimated using posterior mean difference (continuous variables) or odds ratios (dichotomous variables) and 95 credible intervals (CrIs) with the change from baseline in a Bayesian network meta-analysis with random effect.

Results

Fifty-eight articles (N = 4936 patients) fulfilled the eligibility criteria and were included in the meta-analysis. Both preoperative oral low-dose carbohydrate loading (MD: -3.25, 95% CrI: -5.27 to -1.24) and oral high-dose carbohydrate loading (MD: -2.57, 95% CrI: -4.33 to -0.78) were associated with postoperative insulin resistance compared to placebo/water. When trials at high risk of bias were excluded, association with insulin resistance was found for oral low-dose carbohydrate loading compared with placebo/water (MD: -1.29, 95%CrI: -2.26 to -0.27) and overnight fasting (MD: -1.17, 95%CrI: -1.88 to -0.43). So, there was large uncertainty for all estimates vs. control groups. In terms of safety, oral low-dose carbohydrate administration was associated with the occurrences of postoperative infection compared with fasting by 0.42 (95%Crl: 0.20-0.81). In the other outcomes, there was no significant difference between the carbohydrate and control groups.

Conclusion

Although preoperative carbohydrate loading was associated with postoperative insulin resistance and the occurrences of postoperative infection, there is no evidence that preoperative carbohydrate administration alleviates patients' discomfort.

Systematic review registration

[https://www.crd.york.ac.uk/PROSPERO/], identifier [CRD42022312944].

Preoperative carbohydrates: what is new?

PURPOSE OF REVIEW

The aim of this review is to give an overview of recently published articles covering preoperative carbohydrate loading in surgical patients.

RECENT FINDINGS

Between January 1, 2017, and December 31, 2019, 26 publications addressing the effect of carbohydrate load were retrieved through a systematic search. Seventeen were randomized clinical trials, three prospective observational studies and six retrospective series with case-control comparison. Most of the studies were underpowered, addressed surrogate endpoints, and variability among dose and timing of carbohydrate (CHO) treatment was high. The most recent literature endorses preoperative carbohydrate loading up to 2 h before operations as a safe treatment. The new evidence confirm that this strategy is effective in reducing perioperative insulin resistance and the proportion of hyperglycemia episodes, and improving patient well-being and comfort but without affecting surgery-related morbidity.

SUMMARY

Further properly designed randomized clinical trials, addressing more clinically relevant endpoints such as length of hospitalization and morbidity rate, are warrant.

Perioperative Heart-Brain Axis Protection in Obese Surgical Patients: The Nutrigenomic Approach

The number of obese patients undergoing cardiac and noncardiac surgery is rapidly increasing because they are more prone to concomitant diseases, such as diabetes, thrombosis, sleep-disordered breathing, cardiovascular and cerebrovascular disorders. Even if guidelines are already available to manage anesthesia and surgery of obese patients, the assessment of the perioperative morbidity and mortality from heart and brain disorders in morbidly obese surgical patients will be challenging in the next years. The present review will recapitulate the new mechanisms underlying the Heart-brain Axis (HBA) vulnerability during the perioperative period in healthy and morbidly obese patients. Finally, we will describe the nutrigenomics approach, an emerging noninvasive dietary tool, to maintain a healthy body weight and to minimize the HBA propensity to injury in obese individuals undergoing all types of surgery by personalized intake of plant compounds that may regulate the switch from health to disease in an epigenetic manner. Our review provides current insights into the mechanisms underlying HBA response in obese surgical patients and how they are modulated by epigenetically active food constituents.