This article is accompanied by the following Invited Commentary:
Protic A, Tokmadzic VS, Sustic A. Oral carbohydrate treatment before surgery. Eur J Anaesthesiol 2012; 29:259–260.
Surgical trauma induces a catabolic response characterised by the release of stress hormones and inflammatory mediators.1 The use of regional anaesthetic techniques, maintenance of body temperature and minimally invasive surgery all aim to reduce stress. Postoperative pain control with minimal use of opioids, relying instead on epidural analgesia and nonsteroidal anti-inflammatory drugs has been shown to accelerate recovery after major surgery.2 Furthermore, there is a reduction in the effect of insulin and an increase in insulin release.1 Performing surgery on patients who have fasted overnight has several disadvantages including insulin resistance and prolonged length of hospital stay (LOS).1,3,4 Loss of muscle mass is greater among patients receiving placebo instead of oral carbohydrate solution perioperatively.5 It has been shown that preoperative gastric emptying is complete within 90 min and is unaffected by anxiety even if carbohydrate-rich beverages are used.6 A specially designed oral 12.5% carbohydrate solution has been developed for preoperative use,6 400 ml of which produces an insulin release approximately the same as seen after a standard meal.
Previous studies have focused on general surgery patients and we wished to determine the clinical benefit in orthopaedic patients. In particular, the aim of this study was to determine if the consumption of preoperative and early postoperative oral carbohydrate reduced discomfort in elective total hip arthroplasty patients.
This randomised, double-blind, controlled study was approved by the Research Ethics Committee at Lund University (No. 2009/218, Chairperson Göran Lingman) and was carried out at Hässleholm Hospital, Sweden. Written informed consent was obtained from all patients. Sixty consecutive patients were assessed for eligibility by two orthopaedic surgeons between September 2009 and March 2010. Patients were enrolled after a preoperative visit by an anaesthesiologist. The patients were randomly assigned to a carbohydrate group or a placebo group using sealed envelopes. Two nurses who were not otherwise involved in the care of the patient administered the drinks. All other care providers were blinded to group allocation. Exclusion criteria were obesity (BMI >35 kg m−2), diabetes mellitus, prior hip surgery to the same hip, ongoing infection, immunological deficiency, ASA physical status grade IV or higher, and age less than 50 or more than 80 years.
There were no drink or food restrictions the day before surgery. After midnight, nothing was given by mouth except the study beverages. The carbohydrate group received an iso-osmolar oral carbohydrate solution (12.5% carbohydrates, 50 kcal/100 ml, 290 mOsm kg−1, pH 5.0; Nutrica Preop; Numico, Zoetermeer, the Netherlands).6 To ensure that the groups were double-blinded and that the taste of the solution did not lead to bias, the placebo group received flavoured water.7 Four hundred millilitres of these solutions were administered 90 min before induction of anaesthesia and again 2 h after the end of surgery. In all patients, surgery started before noon, and time from 08:00 h until start of surgery was recorded.
Premedication consisted of celecoxib 200 mg, paracetamol 1 g, midazolam 2.5 mg and morphine 10 mg, given orally. Glucose-containing solutions were not permitted prior to surgery. An intravenous infusion of lactated Ringer's solution was started prior to anaesthesia and 2 l was administered over the next 24 h. All patients received intrathecal anaesthesia with bupivacaine 15 mg, fentanyl 25 μg and clonidine 30 μg. In addition, they were given an infusion of propofol during surgery to induce a light level of sedation. In the event of a drop in mean arterial blood pressure of 20% from baseline an intravenous bolus of ephedrine 10 mg was given. During the first 24 h after surgery rescue analgesia consisted of intravenous morphine 2.5 mg given on demand by a nurse.
Patients scored their subjective sense of discomfort and pain using a 100 mm visual analogue scale. The boundaries of the variable being measured were at each end of the scale.7 The variables measured were anxiety, hunger, nausea, pain, thirst, tiredness and headache. Pain was recorded preoperatively, on arrival in the recovery unit, every 4 h for the first 24 h, and then twice daily for the following 2 days. All the other parameters were recorded 60 min after administration of the first oral solution and on arrival in the recovery unit. From that time on, anxiety and thirst were recorded 1, 2, 3, 14 and 28 days after surgery; hunger and nausea were recorded twice daily for the first 3 days; and tiredness was recorded twice daily for the first 3 days and then at 14 and 28 days after surgery. Venous blood samples were analysed for plasma concentrations of haemoglobin, glucose, albumin and creatinine. Glucose was measured before the administration of the first oral solution, on arrival in the recovery unit, every 4 h for the first 24 h and then once daily. Haemoglobin, albumin and creatinine were measured before the first intake of the oral solution, on arrival to the recovery unit, once daily during the hospital stay and after 14 days. The Short Portable Mental State Questionnaire (SPMSQ) was used to assess the patients’ cognitive function preoperatively, at discharge and at the follow-up visit.8 LOS was defined as the time from end of surgery until discharge from the ward. We screened for episodes of deep venous thrombosis or wound infection by a phone call to the patient after 1 year.
Sample size was determined using PS Power and Sample Size Program for PC version 3.034 (William D. Dupont and Walton D. Plummer; http://www.biostat.mc.vanderbilt.edu/PowerSampleSize). Pain was the primary outcome used. Data from previous randomised trials indicated that 28 patients were needed in each group to detect a 30% difference in pain score with a significance of 0.05 and a power of 0.80.9 To compensate for dropouts, 30 patients were included in each group. The Mann–Whitney test was used to analyse pain and discomfort scores, hospital stay and the results of the SPMSQ. Student's t-test was used to analyse blood sample data. A P value less than 0.05 was considered significant. All statistical analyses were undertaken using SPSS 17.0 (IBM Sweden AB, Stockholm, Sweden).
Recruitment started in September 2009 and the final follow-up was performed in April 2011 (see CONSORT participant flow diagram, Supplemental Digital Content 1, http://links.lww.com/EJA/A24). Demographic data and waiting time to the start of surgery are summarised in Table 1. There were no differences in LOS, anxiety, headache or thirst between the groups. Patients who received the placebo were more hungry preoperatively compared with those who received carbohydrate (P < 0.05); at the other times of monitoring there was no difference in the feeling of hunger between the two groups.
Pain scores are shown in Fig. 1. During the first 24 h of postoperative care, the median (interquartile range) demand for rescue morphine was 14 mg (5–20) in the placebo group and 12.5 mg (5–25) in the carbohydrate group (NS). Patients who received the carbohydrate solution were more tired from day 2 and onward (at 08:00 and 16:00 h on day 2, at 08.00 h on day 3, and at 4 weeks; Fig. 2). The patients in the placebo group were more nauseated immediately prior to surgery and at 36 and 48 h after surgery compared with those in the carbohydrate group [1 (9) vs. 0 (1), 7 (11) vs. 0 (8), and 2 (8) vs. 0 (7), for placebo and carbohydrate groups, respectively; P < 0.05].
There was no difference in the glucose estimations except at 20 h after the end of surgery when the median values were 9.36 and 6.55 mmol l−1 for the placebo and carbohydrate groups, respectively (P < 0.05). There were no differences in haemoglobin, albumin, creatinine or SPMSQ scores between the groups. There were no episodes of deep venous thrombosis or wound infection.
We have shown that patients receiving oral carbohydrate solution prior to total hip arthoplasty experience less hunger and nausea. Patients who received carbohydrate solution were more tired postoperatively. Pain scores were lower in the carbohydrate group at 12, 16 and 20 h after surgery. However, as pain scores were only lower at three of the 13 times when pain was assessed, we believe that oral carbohydrate solution has no significant effect on pain after such surgery. There was no difference in the demand for rescue morphine. Other studies have also failed to show any significant differences in pain.10
The differences in nausea and hunger between the groups are plausible. However, the numerical difference was low (7 mm for nausea and 12.5 mm for hunger) and such small differences are probably not clinically relevant. However, our findings are in accordance with previous studies.7 The carbohydrate-treated patients were more tired; this is more difficult to explain but may be due to postprandial fatigue, which is seen more often after pure carbohydrate meals as compared with predominantly fatty or mixed meals.11
We found no differences in anxiety and thirst in the two groups. This is in contrast with the results reported by Hausel et al.,7 who reported less anxiety in those patients given carbohydrate. They gave 800 ml of oral solution the evening before surgery followed by 400 ml 2 h prior to surgery, whereas we gave 400 ml 90 min prior to surgery and again 2 h after surgery. We considered 800 ml to be too much for patients to ingest comfortably. Furthermore, it has been shown that spinal anaesthesia could cause delayed gastric emptying.12 The administration of 200 ml of a carbohydrate solution orally has been shown not to impair gastric emptying in orthopaedic patients receiving spinal anaesthesia.13
We found that blood glucose concentrations were higher in the placebo group 20 h after surgery. Patients undergoing elective total hip arthroplasty develop insulin resistance resulting in a reduction of glucose uptake.3 This may continue for up to 2 weeks, and the degree of insulin resistance developed after surgery depends on the magnitude of the surgery.14 However, we failed to show any major difference in glucose concentrations, possibly because some degree of insulin resistance was present in both groups.
A search of PubMed using the parameters ‘preoperative carbohydrate loading’ revealed 50 publications. However, almost all of these have been performed on patients undergoing abdominal, thoracic, vascular or endocrine surgery. This is one of the few studies performed on orthopaedic patients. Previous studies performed on patients undergoing other types of surgery have shown that preoperative carbohydrate loading attenuates insulin resistance via effects on cellular gene and protein expression.15 Furthermore, oral perioperative provision of certain aminoacids may reduce infections and LOS. However, the effects on clinical outcomes remain unclear.15
One of the limitations of this study is that we compared oral carbohydrate solution with flavoured water, and not with fasting. Both intravenvous glucose and oral carbohydrate solution are better than fasting.16
In conclusion, we found only limited benefits in the perioperative period from the administration of oral carbohydrate solution to patients undergoing total hip arthroplasty compared with those receiving water.
The authors are grateful to Mrs Marie Davidsson for technical assistance and Saskia Titman (CRNA) for help with the manuscript. No external funding and no conflicts of interest declared.
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dietary carbohydrates; length of stay; perioperative care; postoperative pain; total hip replacement
Supplemental Digital Content
© 2012 European Society of Anaesthesiology