[Postoperative hypophosphoremia in digestive surgery. Influence of the parenteral diet]

Twenty-seven non emaciated patients undergoing major visceral surgery were randomly divided into two different groups according to the postoperative parenteral diet (100% glucose versus 50% fat 50% glucose). All patients received the same anaesthetic protocol and, peroperatively, none received any glucose. In the postoperative phase, parenteral feeding was started on the day of operation (18.5-21.8 kcal X kg-1) and was continued for a minimum of four days (37-44 kcal X kg-1 X 24 h-1). All patients received intravenous insulin and phosphorus (0.15 mmol X kg-1 X 24 h-1). During five days, daily measurements of serum phosphate and glucose levels were made and nitrogen balance was studied. For all these parameters, there was no evidence of any significant difference between the two groups. A significant fall in plasma phosphate occurred in each group on the first postoperative day, was maximum on the second and lasted until the fourth. This fall was not influenced by parenteral diet. No patients in this study developed symptoms of phosphate depletion. The glucose levels increased significantly and the nitrogen sparing effect was similar in both groups. The mechanism of hypophosphataemia seemed to be an intracellular transfer under the influence of hyperglycaemia and high plasma insulin levels rather than an increase in urinary phosphate excretion. The advantage of using lipid solutions did not appear under the dietary conditions studied. Indeed a glucose supply greater than or equal to 3 mg X kg-1 X min-1 seemed to induce a maximum intracellular transfer of phosphorus. Because of this, phosphate supplementation and frequent measurement of serum phosphate are recommended for patients undergoing major visceral surgery and postoperative intravenous feeding.