Perioperative carbohydrate loading in patients undergoing one-day surgery. A systematic review of randomized controlled trials

Search strategy

The Medline, EBSCO, Scopus, Web of Science (WoS) and Cochrane databases were systematically and comprehensively searched in October 2021 according to Prisma guidelines. The search protocol was prospectively registered in the International prospective register of systematic reviews (PROSPERO) – CRD42021284397. Two reviewers (JK, KPS) independently evaluated each paper. If any disagreement occurred, the third reviewer (RO) was involved. The following data were extracted: title, first author, publication year, number of patients, patient age, sex, body mass index (BMI) and ASA status, inclusion criteria, exclusion criteria, intervention type, allocation, measured outcomes, amount of carbohydrates administered, type of surgery, duration of anaesthesia and surgery.

Search query

The following search query was used to extract articles from databases: ((preoperative or perioperative) and (carbohydrate or CHO or nutricia/nutrition or carbohydrates or maltodextrin or carbohydrate rich) and (drink or treatment or loading or oral or per os or load or administration)) and ((ambulatory or 1-day or elective or outpatient or ambu* or electiv* or fast-track) and (surgery or surgical procedures or procedure or sedation or anesthesia or surg* or general anesthesia)).

Type of studies

We included randomised clinical trials comparing carbohydrate loading with controls in patients over 18 years old undergoing elective ambulatory surgery. Patients undergoing ambulatory surgery receiving clear liquid or nothing were treated as controls.

Inclusion criteria

Exclusion criteria

Main outcome

Comparison of the effectiveness of preoperative oral carbohydrate and fasting.

Additional outcomes

Search results

Databases yielded 3467 results, from those 2385 were screened for eligibility criteria based on the titles which gave 240 papers. Those were screened for eligibility criteria based on abstracts which have left 74 papers which were read in full text. After careful consideration against inclusion criteria, 6 papers were included in the review. Prisma flow diagram presents study search in detail (Figure 1).

Figure 1

Prisma flow diagram

CHO – carbohydrates, LOS – length of stay, RCT – randomised controlled trial, WoS – Web of Science.

Characteristics of included studies

Six studies published in 2012–2020 were included in the study [12–17]. The studies were conducted in Finland, Turkey, India and Brazil. Majority of patients were females under 50 years old who underwent elective laparoscopic cholecystectomy. Patients had ASA status I–II. In all studies patients received the amount of carbohydrates recommended by ERAS guidelines. The comparator was either fasting placebo or carbohydrates + glycine (GLN group). Detailed characteristics of the studies are presented in Table I.

Quality assessment

We followed Cochrane Collaboration guidelines regarding bias assessment. Each paper was assessed independently by two reviewers. Five databases were searched to ensure that all matching papers were included. In risk of bias assessment, several parameters were included: (I) random sequence generation, (II) allocation concealment, (III) blinding of participants and personnel, (IV) blinding of outcome assessment, (V) incomplete outcome data, (VI) selective reporting, (VII) other potential threats to validity. All studies have met baseline criteria for quality assessment. Typically, there were no issues regarding random sequence generation, however in most cases allocation concealment was not described. Unfortunately majority of the studies were single blinded, or blinding was not reported, also only one study by Helminen et al. published the protocol. We have not found other potential risks within the studies. A summary of biased assessment for each study is presented in Table II.

Thirst and hunger

Three studies examined whether carbohydrate loading can alleviate thirst and hunger [14–16]. Helminen et al. used VAS scale (0–100) while Gok et al. and Yildiz et al. measured nausea incidence. In studies by Gök et al. and Yildiz et al., the carbohydrate-rich drink decreased thirst preoperatively or preoperatively and postoperatively. However, Helminen et al. did not support that result (Table III).

In studies by Gök et al. and Yildiz et al., administration of a carbohydrate-rich drink decreased hunger preoperatively or preoperatively and postoperatively. However, Helminen et al. did not support that result (Table IV).

Nausea and vomiting

For studies including nausea as examined outcomes [14–17], Helminen et al. and Singh et al. used VAS scale while Gök et al. and Yildiz et al. measured nausea incidence. Data are inconsistent as Helminen et al. and Yildiz et al. did not observe any significant changes in nausea intensity. Meanwhile Singh et al. reported that in the early postoperative period nausea was less intensive in the group which received carbohydrates preoperatively, oppositely Gök et al. determined that nausea was more frequent in the pre-op group. Detailed results are presented in Table V.

Singh et al. and Gök et al. examined impact of carbohydrate administration on emesis occurrence [15, 17]. Singh et al. determined that vomiting occurred less frequently only in the first 4 h postoperatively, however this observation was not supported by the study of Gök et al. It seems that pre-op carbohydrate loading does not have a significant impact on vomiting occurrence more than 4 h after surgery. Moreover, Helminen et al. reported that there were no differences regarding need for antiemetics administration between carbohydrates and fasting group (p = 0.84). Results are presented in Table VI.

Pain

Two studies included in the analysis determined the effect of carbohydrates administration on the pain level post-operatively [16, 17]. Helminen et al. measured pain with a visual analog scale (VAS; 0–100), Singh et al. also used VAS, however with a span of 0–10. In the study of Helminen et al., no changes between groups had been found. They also did not observe differences in demand for pain medication and opioids between groups (p = 0.94 and p = 0.95, respectively). Contrarily Singh et al. reported that pain intensity was lower in the CHO group in the first 12 h postoperatively. Based on those two studies it cannot be concluded whether the carbohydrate-rich drink administration has beneficial effects on pain alleviation. Detailed results of included studies are presented in Table VII.

Tiredness

Two studies included tiredness in their outcomes [14, 16]. Helminen et al. used the VAS scale (0–100), whereas Yildiz et al. measured tiredness incidence. It seems that the carbohydrate-rich drink did not impact tiredness after surgery. Data regarding the preoperative period are inconclusive as studies reported opposite results (Table VIII).

Impact on metabolism

Three studies measured impact of pre-op carbohydrate loading on glucose and/or insulin levels [12, 13, 16]. In all studies no differences between groups were found (Table IX).

Other outcomes

Some outcomes have been described only in one study, here we discuss the selected few. Helminen et al. did not observe any significant changes between groups regarding mouth dryness, time to be able to drink, eat, ambulate or discharge [16]. Dock-Nascimento et al. investigated selected biochemical parameters and they found significant differences between the groups in HOMA-IR, albumin, C-reactive protein and interleukin 6 levels [12]. Another study by Dock-Nascimento et al. found that there are no differences in gastric residual volume between groups [13]. Yildiz et al. have found that weakness, malaise and concentration difficulty are less prominent in patients receiving a carbohydrate-rich drink [14].