Prolonged pre-operative fasting increases postoperative hospital stay and current evidence recommends carbohydrate (CHO) drinks 2 hours before surgery. Our hypothesis is that the addition of hydrolized protein to a CHO-based drink not only reduces the inflammatory response but also diminish hospitalization.

This was a randomized, double-blind, clinical study carried out at the Julio Muller University Hospital (Mato Grosso State, Brazil). The study was approved by the hospital Research Ethics Committee registered under number 723/CEP-HUJM/09 and is in accordance with the ethics principals set out in the Helsinki Declaration (2000), and meets Brazilian national legal specifications.

Inclusion criteria includes adults (18-65 years-old), of both sexes, and candidates to elective major operations such as subtotal gastrectomy, colectomy, and anterior resection of the rectum for malignancies. Exclusion criteria were having diabetes mellitus, chronic kidney failure, chronic liver disease or serum bilirubin greater than 2 mg/dL, body mass index (BMI) above 35Kg/m2, American Anesthesiologists Association (ASA) score above 3, gastro-esophageal reflux, gastroparesis or intestinal obstruction. Patients with any non-compliance with the study protocol, or who had associated operations, or presented severe intraoperative complications (any type of shock, cardiac arrest, coagulations problems), or experienced prolonged operations (lasting more than 6 hours) were also excluded.

Patient randomization was carried out on admission to the hospital using random numbers issued by a computer program (www.graphpad.com). For the randomization the precepts of the CONSORT flow diagram were followed.

The patients were randomized into two groups: the study group and the control group. The patients were given a specific drink to their group on the evening prior to surgery and three hours before the operation. The study group received 400 ml (evening drink) or 200 ml (3h prior to operation drink) of a solution containing 11% de protein (pea hydrolized proptein), 89% de carbohydrates (maltodextrin 79% and saccharose 21%) e 0% of lipids (Providextra, Fresenius Kabi, São Paulo, Brasil) and the control group received conventional 6-8h fast. All the patients fasted for solids at least 6 hours from the operation.

On the day before the surgery and on the second postoperative day blood samples were collected for glucose, insulin, triglycerides, albumin, pre-albumin, CRP, and α-1-acid glycoprotein (α-1-GA) assays. The HOMA-IR (Homeostasis Model Assessment-Insulin Resistance) equation was used to assess insulin resistance according to the formula: HOMA-IR = insulin (µU/mL) x glycaemia (mg/dL) / 405. To assess inflammatory activity the PINI (CRP (mg/L) x α-1-GA (mg/L)/ albumin (g/L) x pre-albumin (mg/L) and the CRP/albumin ratio were used.

The mean outcome variable was the length of postoperative stay. Other endpoints included the infectious morbidity, the insulin resistance assessed by HOMA-IR, and the inflammatory indexes or markers mentioned above.

Inclusion Criteria:

• Adults (18-65 years-old),
• of both sexes, and candidates to elective major operations such as subtotal gastrectomy, colectomy, and anterior resection of the rectum for malignancies

Exclusion Criteria:

• Diabetes mellitus,
• chronic kidney failure,
• chronic liver disease or serum bilirubin greater than 2 mg/dL,
• body mass index (BMI) above 35Kg/m2, American Anesthesiologists Association (ASA) score above 3,
• gastro-esophageal reflux,
• gastroparesis or intestinal obstruction.
• Patients with any non-compliance with the study protocol, or who had associated operations, or presented severe intraoperative complications (any type of shock, cardiac arrest, coagulations problems), or experienced prolonged