Pre-pyloric versus post-pyloric feeding

Summary

Optimal management of the critically ill patient involves the initiation and rapid advancement of early enteral nutrition (EN). Compared to parenteral nutrition or no nutritional support, early enteral feeding favorably impacts patient outcome by reducing infectious morbidity and shortening hospital length of stay. Controversy exists over the true risks and benefits of pre-pyloric versus post-pyloric feeding. Placement of nasogastric tubes is easier than nasojejunal tubes, initiation of EN is more expedient, and intragastric feeds may provide greater physiologic benefits. Post-pyloric feeding, on the other hand, is associated with fewer interruptions once EN has been started, may reach goal calorie provision sooner, and may reduce risk for gastroesophageal reflux and aspiration. Overall differences in outcome between the two methods of feeding, however, are minimal. Thus, the final choice for the practicing clinician on the level of infusion of enteral feeding is based on institutional factors (related to protocols and available expertise) and the degree of risk and potential tolerance of the individual patient.

Introduction

Clinical nutrition is a rapidly evolving field of interest for physicians and patients, with new techniques and feeding formulas continually being developed. The maintenance of appropriate nutrition in patients with acute and chronic illness is well recognized as a fundamental part of optimal medical and surgical care. Malnourished patients are more likely to have complications, infection, and poor clinical outcome than similar patients who remain well nourished.1, 2 Physicians caring for patients with nutritional deficits, critical illness, or primary gastrointestinal diseases are facing an array of choices regarding the design and manner of delivery of enteral and parenteral formulations.

Enteral nutrition (EN) is generally preferred over parenteral nutrition (PN) in critically ill patients because of its relative simplicity and lower cost.³ Compared to PN, EN shortens duration of hospital length of stay and improves patient outcome.³ EN supports the structural integrity of the gut wall by maintaining the mass of gut-associated lymphoid tissue, keeping the tight junctions between the epithelial cells closed, and supporting the role of commensal bacteria.⁴ EN prevents bacterial adherence to the gut wall by stimulating release of secretory IgA immunoglobulin.⁵ Clinical studies have shown improved epithelial function with enhanced mucosal immunity from EN in critically ill patients, leading to decreased infectious morbidity.³

EN is generally delivered into the stomach or small bowel via nasogastric, nasoenteric, percutaneous endoscopic gastrostomy (PEG), percutaneous endoscopic gastrojejunostomy, or direct percutaneous endoscopic jejunostomy tube. The latter three tubes alternatively may be placed by open or laparoscopic surgical technique. For short-term periods of <30 days, nasogastric or nasoenteric tubes are preferred over endoscopic/surgical gastrostomy or jejunostomy tubes. Gastric feeding may be problematic in the intensive care setting, as gastroduodenal motility is often impaired in critically ill patients, especially when sedatives and pressor agents (like catecholamines) are used.6, 7 Impaired motility causing delayed gastric emptying may result in retention of enteral formula and endogenous secretions, large gastric residual volumes, vomiting, aspiration, and ultimately reductions or delays in achieving adequate nutrition. Mentec et al.⁸ in their prospective observational study of critically ill patients in an intensive care setting, showed that feeding intolerance (defined by high gastric residual volume and/or vomiting) was associated with a higher incidence of nosocomial pneumonia, prolonged length of stay in the intensive care unit (ICU), and higher mortality. Feeding distally into the duodenum or jejunum may potentially increase the volume of formula infused, decrease gastric residual volumes, and reduce risk for reflux, regurgitation, and aspiration. Placing a nasoenteric tube, however, may be technically difficult at the bedside, and may require specialized technique and expertise. Endoscopists or radiologists may be required to place tubes endoscopically or fluoroscopically, which may delay initiation of EN. In this review, we will look into detail at both the benefits and risks of pre-pyloric and post-pyloric feeding and review those studies which have compared these two strategies of feeding.