Prise en charge nutritionnelle périopératoire du patient obèse

Recommendations for perioperative nutrition in obese subjects require considering the following evidences. Obesity has long been falsely considered a risk factor for poor outcomes from a variety of surgical procedures, yet recent studies of critically and chronically ill patients suggest that overweight and obese patients may paradoxically have better outcomes than normal weight patients. Preoperative weight loss should be considered as a risk factor of postoperative complications in obese subjects as in normal weight patients. Obese patients could be malnourished because of vitamin deficiencies and of sarcopenia. The prevalence of vitamin deficiencies in the morbidly obese population prior to surgery is high, especially for vitamins B1, B12, B9, A, C, D and E. Standard of care should include perioperative thiamine replacement, especially in case of prolonged vomiting. Vitamin B12 deficiency could appear fast after gastric or ileal surgery, and iron deficiency is more frequent. Low caloric diet is not recommended in obese subjects before surgery, especially for the elderly, because of the frequent sarcopenia in this population. Energy and protein recommendations are not easy to be determined in obese subjects. Recommended allowance for protein should be defined according of the fat free mass, which is not easy to evaluate in clinical practice. So it is recommended to use a normalized weigh for a theoretic BMI between 25 and 30 kg/m². The loss of muscle mass can be very fast in the postoperative period in these subjects. The nutritional objective of care is to preserve skeletal muscle mass and to enhance the protein balance.