Major surgical operations of the gastrointestinal tract, such as colorectal resections due to several diseases, lead to significant burden on the human body, which is expressed during the first postoperative hours with an intense inflammatory reaction and consumption of a large amount of energy, increasing nutritional requirements of the patients. Therefore, specific protocols have been implemented for the early initiation of oral feeding in patients undergoing colorectal resections. However, it is not feasible for every patient to meet them due to several reasons, such as old age and associated pathophysiological changes, use of opioid drugs for the management of postoperative pain, which is associated with postoperative ileus or nausea, as well as open resection which lead to gastrointestinal impairment during the first postoperative days. The energy deficit that occurs during the early postoperative period, which appears to be associated with adverse clinical outcomes, can be counterbalanced by the administration of parenteral nutrition. However, the conventional way of administration through central venous lines is associated with significant complications. For this reason, administration of parenteral nutrition through a peripheral venous catheter could be used alternatively, which avoids morbidity and has been also effective in maintaining the patients' energy balance, even during the first postoperative hours. Therefore, the main purpose of the present study is to investigate the efficacy of the administration of peripheral parenteral nutrition on the postoperative outcomes of patients undergoing colorectal resections. Moreover, the correlation of the administration of peripheral parenteral nutrition with the reaction to post-operative stress and with the nutritional status of the patients post-operatively, which are determining factors for the clinical course of these patients, will be investigated.

Inclusion Criteria:

• Colorectal resection surgery
• Open or laparoscopic procedures
• Anastomosis, end-stoma or defunctioning stoma formation after colorectal resection
• Elective or emergent procedures
• Diagnosis of colorectal cancer, inflammatory bowel disease, diverticular disease and bowel ischemia
• Small bowel resection combined with colorectal resection
• Age > 18 years old
• Informed consent

Exclusion Criteria:

• Small bowel resection without colorectal resection
• End-stoma or defunctioning stoma formation without colorectal resection
• Preoperative parenteral nutrition administration
• Administration of parenteral nutrition after the 4th postoperative day
• Peripheral parenteral nutrition initiation after the 1st postoperative day
• Contraindication for peripheral parenteral nutrition administration
• Age < 18 years old
• No informed consent