The immediate and long-term effects of postoperative total parenteral nutrition on body composition

Abstract

The short and long-term effects of post-operative total parenteral nutrition (TPN) on body composition were studied in a randomised series of patients undergoing major colorectal surgery. Ninety-two patients (colorectal cancer: 50, ulcerative colitis or Crohn's disease: 42) were grouped according to diagnosis and clinical inflammatory activity. TPN was given for 9.7±1.1 days. The complication rate was not changed by the TPN. Nitrogen balance was studied during the first week. Body weight, total body potassium, triceps skinfold, serum albumin and body water were measured before and at intervals up to 24 weeks after the operation. Cumulative nitrogen balance in control patients at 7 days after surgery was −47.3 g. Patients given TPN balanced nitrogen intake and output (cancer patients and patients with quiescent inflammatory bowel disease, IBD) or were in positive balance (patients with active IBD). Weight loss at 1 week after surgery was less in TPN patients compared to controls and this difference remained statistically significant up to 6 months after termination of the nutritional treatment. A similar, although not statistically significant, difference was noted in total body potassium and triceps skinfold. Patients with active IBD regained pre-operative body composition earlier than cancer patients and patients with quiescent IBD. It is concluded that TPN after major colorectal surgery reduces postoperative weight loss and that this effect lasts after termination of the nutritional treatment. In the absence of increased body potassium and increased body water, we conclude that the long-term effect of TPN on body weight is most likely due to preservation of fat. Preservation of cell mass was only demonstrable at one week after surgery. The results show that weight loss continues after discharge from hospital irrespective of nutritional treatment. Patients with ongoing inflammatory activity showed a less profound catabolic response and regained pre-operative body composition earlier than patients with quiescent IBD. The normal neuro-endocrine response to major abdominal surgery includes a period of weight loss. This weight reduction is derived from loss of cell mass, fat and water [1]. The magnitude of the weight loss depends on the operative trauma, the individual patient's nutritional state and the nutritional therapy in the perioperative period [2]. It has been shown that postoperative total parenteral nutrition (TPN) prevents loss of body weight and negative nitrogen balance in the first postoperative week [3–6]. It is unclear, however, whether this short-term effect on body weight and nitrogen balance lasts beyond the immediate postoperative period.

The purpose of this investigation was therefore to study, prospectively and under controlled conditions, the effects of a limited course of postoperative TPN on body composition. A comparison was made between patients operated on for colo-rectal carcinoma and those operated upon for ulcerative colitis (UC) or Crohn's disease (CD). It was also considered of interest to assess whether postoperative TPN alters the metabolic response to surgery differentially in patients with varying degrees of inflammatory activity.