This study evaluated the impact of a preoperative carbohydrate oral drink on the postoperative Neutrophil / Lymphocyte Ratio (NLR) and the incidence of postoperative complications after elective open colon surgery compared to the conventional preoperative fasting protocol. Hypothesis was: preoperative carbohydrate loading reduces postoperative NLR value and reduces the incidence and severity of postoperative complications in colorectal surgery.

This prospective randomized, controlled clinical study was carried out in the Department of Anesthesiology and Intensive Care Unit and Department of Surgery at the Cantonal Hospital Zenica, Bosnia and Herzegovina. The study protocol was approved by the local Ethics Committee.

A total of 60 participants who scheduled for elective open colon surgery and fulfilled study criteria were included into study. The purpose and procedures of the study were fully explained and voluntary, informed, written consent was obtained from each participant. The participants were randomly allocated into two equal groups, depending on the preoperative treatment. There were no reliable published data for effects of preoperative carbohydrate loading on postoperative NLR values. Based on our hypothesis, a pilot study was performed with ten patients per group. Mean postoperative NLR value was 8,67±4,98 in the participants with a conventional preoperative fasting protocol versus 4,76±2,83 in the participants with preoperative carbohydrate loading. Sample size was estimated using sample size calculator software and power analysis with 95% confidence interval and power of 80%. Statistical significance was considered as p< 0,05. The calculation indicated 27 participants per group would be sufficient to detect a difference of 3,91 with a standard deviation of 4,93 in NLR value between the groups. Assuming dropout of 10%, 30 participants per group were included. Block randomization was used with a block size of six and a 1:1 group ratio. A computer-generated random numbers indicating preoperative intervention, were sealed in opaque envelopes. An investigator who conducted randomization and opened the envelopes the night before surgery was blinded to the study protocol as well as the surgeons, nurses, anesthesiologists and staff involved in data collection.

The participants in the Fasting group (control group) stopped oral intake at 12:00 pm the night before surgery and underwent to a conventional preoperative fasting protocol. Participants in the Carbohydrate group (experimental group) consumed 400 ml of a clear carbohydrate solution at 10:00 pm the night before surgery and 200 ml of a clear carbohydrate solution, 2 hours prior induction of anesthesia. All participants underwent general anesthesia followed by colorectal surgery.

Fasting peripheral venous blood samples were collected at 06:00 am on the day of surgery (basal value), at 06:00 am on the first postoperative day, at 06:00 am on the third postoperative day and at 06:00 am on the fifth postoperative day. White blood counts were analysed with automated differential counts. The NLR value was obtained by dividing the absolute neutrophil count and the absolute lymphocyte count. All participants were followed up to 30 days post-surgery to assess postoperative complications and readmission rate. After discharge, participants were called by phone, once a week. Postoperative complications were graded for incidence and severity using the Clavien-Dindo Classification of Surgical Complications.

Demographic and surgical data of the participants were recorded: age, sex, body weight, body mass index, American Society of Anesthesiologists (ASA) physical status class, nutritional status of the participants according to Nutritional Risk Screening 2002 (NRS-2002), tumor localization and duration of surgery.

Inclusion Criteria:

• participants with diagnosed colorectal carcinoma scheduled for elective open colorectal surgery
• aged between 18 years and 70 years
• participants with ASA physical status class I-III

Exclusion Criteria:

• previous treatment of colon, rectum or any other cancer
• emergency or palliative colon and rectum surgery
• disseminated malignant disease
• body mass index below 20 and above 30 kg/mᶺ2
• overall score ≥3 after final assessment of the nutritional status according to Nutritional Risk Screening 2002 (NRS-2002)
• disease with increased risk of aspiration
• history of diabetes mellitus
• history of hematological disease
• evidence of systemic inflammation
• immunomodulatory therapy
• neuromuscular disease
• pregnancy
• mental disease
• allergy to any study drugs
• alcoholic or drug abuse
• patient's refusal to participate in the study.

The surgeons, anesthetists, and outcome assessors were masking to the treatment allocation.

A nurse from the Department of Surgery performed the allocation into groups. The night before the operation, the nurse managed the patients according to the assigned intervention, but was not included in the study protocol. The next morning, the surgeon and anesthetist performed open elective colon surgery under general anesthesia, but without knowledge of the type of intervention.

Independent outcomes assessors evaluated patients up to 30 days post-surgery and were also masked, without knowledge of the type intervention.