Elsevier

Clinical Nutrition

Volume 32, Issue 1, February 2013, Pages 34-44
Clinical Nutrition

Meta-analyses
A meta-analysis of randomised controlled trials on preoperative oral carbohydrate treatment in elective surgery

https://doi.org/10.1016/j.clnu.2012.10.011Get rights and content

Summary

Background & aims

Whilst preoperative carbohydrate treatment (PCT) results in beneficial physiological effects, the effects on postoperative clinical outcomes remain unclear and were studied in this meta-analysis.

Methods

Prospective studies that randomised adult non-diabetic patients to either PCT (≥50 g oral carbohydrates 2–4 h pre-anaesthesia) or control (fasted/placebo) were included. The primary outcome was length of hospital stay. Secondary outcomes included development of postoperative insulin resistance, complications, nausea and vomiting. Methodological quality was assessed using GRADEpro® software.

Results

Twenty-one randomised studies of 1685 patients (733 PCT: 952 control) were included. No overall difference in length of stay was noted for analysis of all studies or subgroups of patients undergoing surgery with an expected hospital stay ≤2 days or orthopaedic procedures. However, patients undergoing major abdominal surgery following PCT had reduced length of stay [mean difference, 95% confidence interval: −1.08 (−1.87 to −0.29); I2 = 60%, p = 0.007]. PCT reduced postoperative insulin resistance with no effects on in-hospital complications over control (risk ratio, 95% confidence interval, 0.88 (0.50–1.53), I2 = 41%; p = 0.640). There was significant heterogeneity amongst studies and, therefore, quality of evidence was low to moderate.

Conclusions

PCT may be associated with reduced length of stay in patients undergoing major abdominal surgery, however, the included studies were of low to moderate quality.

Introduction

Preoperative fasting and surgery cause metabolic-stress and insulin resistance,1 which is characterised by hyperglycaemia and decreased responsiveness of tissues (mainly skeletal muscle and liver) to the biological actions of insulin.1 Development of insulin resistance is associated with increased morbidity,2 mortality2 and length of hospital stay.3 Measures to attenuate development of insulin resistance, such as preoperative oral treatment with complex carbohydrates may, therefore, be clinically beneficial. A number of studies have examined the effects of preoperative carbohydrate treatment on postoperative insulin resistance and glucose kinetics,4, 5 protein balance and body composition,5, 6 postprandial hormonal and metabolic responses,7, 8, 9 immune function,10 gene and protein expression,8, 11 residual gastric volume,7, 12 drink-related complications,6, 13, 14 patient well-being15, 16 and length of hospital stay.6, 14, 17 Whilst the safety6, 14 and physiological benefits of preoperative carbohydrate treatment have been demonstrated,1 data regarding the effects on important clinical endpoints such as length of hospital stay are conflicting; with some studies demonstrating a reduction17 and others no reduction6, 14 in length of stay. Reasons for these inconsistencies include small numbers of participants and study of heterogeneous groups of patients undergoing surgical procedures of differing magnitudes.18

Meta-analysis of studies on the effects of preoperative carbohydrate treatment on clinical endpoints has hitherto not been performed. The aims of the present meta-analysis were to determine the effects of preoperative carbohydrate treatment in patients undergoing elective surgery on: 1) length of hospital stay; 2) development of postoperative insulin resistance; 3) occurrence of drink-related (vomiting, aspiration and pneumonia) and postoperative complications; and 4) occurrence of postoperative nausea and vomiting.

Section snippets

Inclusion criteria

We included prospective studies that randomised adult patients undergoing elective surgery to either preoperative oral treatment with complex carbohydrates using ≥50 g oral carbohydrate in the preoperative morning serving of the drink or a control arm. The latter may have been either ingestion of an equivalent volume of placebo drink containing no nutrients or preoperative fasting.

Exclusion criteria

Randomised controlled trials that administered intravenous carbohydrate, utilized <50 g oral carbohydrate in the

Eligible studies

Twenty-one randomised controlled trials published between 1998 and 2012 fulfilled the inclusion criteria, leading to a total of 1685 patients (range 14–252 patients per study), 733 in preoperative carbohydrate treatment group, 952 in control group (Table 1 and Fig. 1). Characteristics of included studies are shown in Tables 1 and 2. Randomisation methods (computer random number generator,16, 19, 20, 21 coded lots of study drinks,4, 22, 23 sealed envelope10, 13, 14, 17, 24, 25 and block

Principal findings

This meta-analysis of 21 randomised controlled trials evaluating the effects of preoperative carbohydrate treatment on patients undergoing elective surgery demonstrated a significant reduction in length of stay amongst patients undergoing major open abdominal surgery. Preoperative carbohydrate treatment was safe (no occurrence of drink-related complications), associated with reduced development of postoperative insulin resistance but the latter was not associated with any effect on surgical

Funding sources

KKV was supported by Research Fellowships from the Nottingham Digestive Diseases Centre National Institute for Health Research Biomedical Research Unit and the Enhanced Research After Surgery® Society. The funders had no role in the design or execution of this study, data analysis or the writing of the manuscript.

Author contributions

Study Design: SA, KKV, OL, DNL.

Data Collection: SA, KKV, OL.

Data Analysis: SA, KKV, OL, DNL.

Data Interpretation: SA, KKV, OL, DNL.

Writing of Manuscript: SA, KKV, OL, DNL.

Critical Revision: SA, KKV, OL, DNL.

Final Approval: SA, KKV, OL, DNL.

Overall Supervision: DNL.

Conflict of interest

SA has received research funding and travel expenses from Fresenius Kabi, and educational support from Nutricia Clinical Care. OL and DNL have received research funding from Nutricia Clinical Care and Fresenius Kabi. OL held the patent rights to Nutricia preOp® (the patent expired in 2011). OL has served as an advisor to Nutricia Clinical Care. KKV has no conflicts of interest to declare.

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    Preliminary findings from this paper were presented at the Annual Conference of the Society for Academic and Research Surgery, Nottingham, January 2012 and were published in abstract form [Br J Surg 2012; 99(S4):43]. The final dataset was presented at the Annual Congress of the European Society for Clinical Nutrition and Metabolism, Barcelona, September 2012 and was in abstract form in Clin Nutr Suppl 2012; 7:29.

    d

    SA and KKV have contributed equally to this paper.

    e

    OL and DNL are joint senior authors.

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