title: Development of automated postoperative enteral nutrition: restricting feeding site inflow to match peristaltic outflow.
abstract: BACKGROUND
  Surgical stress accelerates postoperative metabolism, while simultaneously compromising gut activity. The dysfunction may be worsened by early feeding. These patients are not expected to fully meet their optimum metabolic requirements using current nutritional regimens. For optimum postoperative enteral nutrition, we must automatically match the patients' feeding site inflows to their impaired peristaltic outflows. An essential adjunct is virtually complete exclusion of swallowed air. The small diameter post-pyloric duodenum is an efficient site for both aspiration and feeding.
  
  
  METHODS
  A multi-lumen feeding-decompression tube is utilized to feed an "elemental diet" (1 kcal/ml) at the rate of 3000-5000 ml/day immediately postoperatively. Outflow from the feeding site, relative to inflow, is monitored. Excess aspirate is discarded automatically, so that the re-fed inflow exactly matches the peristaltic outflow. The aspirate (digestive secretions, feedings, and swallowed air) is degassed. The aspirate is then directed by one-way valves alternately, every 30 s, into a pair of 30 ml collection chambers for re-feeding. Simultaneously, the previously collected aspirate (less discarded volume, if required) is delivered by gravity into the slightly more distal duodenum.
  
  
  RESULTS
  Within 2 h, the return of the entire aspirate volume is tolerated. The patients' increased metabolic demands are met early on the initial day of surgery. They achieve positive protein balance, with documented enhanced healing (experimentally) and immune globulin synthesis (clinically). Breakfast is tolerated the morning following operation, with discharge soon thereafter. X-ray motility and nutrient absorption studies document the more rapid return of clinically normal peristalsis.
  
  
  CONCLUSIONS
  Automatically keeping the proximal duodenum and stomach continuously decompressed, while simultaneously re-feeding tolerated degassed duodenal aspirate, leads to more rapid return of clinically adequate G-I function postoperatively. In addition to maximizing immediately postoperative nourishment, the secretory globulins are salvaged, and spontaneously delivered into the colon, where they provide natural antimicrobial protection.
authors.affiliation: Rensselaer Polytechnic Institute, Troy, NY USA ; 1 Reynal Road, 10605 White Plains, NY USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Moss
keywords: Automatic feeding control; Immune competence; Peristalsis monitoring; Postoperative enteral nutrition; Wound healing