Formal evaluation and optimisation of nutritional status remains an often neglected element of modern preoperative assessment, despite a wealth of data linking malnutrition with poorer postoperative outcome. Surgical patients are at risk of malnutrition in the perioperative period for a range of reasons including: poor access to adequate nutrition whilst hospitalised, alimentary tract dysfunction, unmet calorific demand due to chronic neoplastic and inflammatory processes and disordered handling of nutrients from metabolic disturbance. The surgical insult itself constitutes a significant metabolic stress with documented increases in catabolism, insulin resistance and loss of muscle mass.
Defining the malnourished patient can be challenging. Body mass index (BMI) remain useful with malnourished patients presenting at both extremes of the BMI scale. At York Teaching Hospital, all patients are assessed using the Malnutrition Universal Screening Tool (MUST) and referred to the dieticians accordingly.
It would appear that it is mainly those patients with more advanced malnutrition, who most benefit from preoperative nutritional support. Supplementation by the oral route is preferred and is clinically more effective than the nasogastric route.
The supplementation of specific nutrients including omega-3-fatty acids, arginine, nucleic acids and antioxidants is thought to improve metabolic and immune responses in the perioperative period is of increasing interest. The evidence remains controversial but there may some clinical benefit in some patient subgroups i.e. major abdominal surgery.
- Nutritional risk should be assessed in all patients presenting for surgery.
- Caloric and nitrogenous supplementation by any route should only be used to treat severely undernourished patients and only then under the direct supervision of a dietician.
- Preoperative immunonutrition should be considered in patients presenting for major abdominal surgery.