Use of Residual Volume as a Marker for Enteral Feeding Intolerance: Prospective Blinded Comparison With Physical Examination and Radiographic Findings

Abstract

High gastric residual volumes (RVs) are a frequent cause for cessation of total enteral nutrition (TEN). This study was designed to determine the RV that indicates intolerance or inadequate gastric emptying and to compare the RV findings in a blinded fashion with those findings obtained on physical examination and radiography. Twenty healthy normal volunteers (HNV), 8 stable patients with gastrostomy tubes (GTP), and 10 critically ill patients (CIP) were evaluated prospectively for 8 hours while receiving TEN. No subjects were clearly intolerant (ie, vomiting, aspiration). Of the total RVs recorded, 13.1% were ≥150 mL in the CIP group, whereas only 2.4% of the RVs were ≥150 mL in the HNV group. None of the RVs in the GTP group were ≥150 mL. Objective scores on physical examination failed to correlate with RV (p =.397), as did objective scores on radiography (p =.742). However, objective scores on physical examination were significantly related to scores on radiography (p =.016). Abnormal physical examination findings were found in 4 out of 11 patients (GTP + CIP) with RVs <100 mL and in 6 out of 7 with RVs ≥100 mL. Abnormal radiographic results were found in 6 out of 11 patients with RVs < 100 mL, in 7 out of 7 patients with RVs ≥100 mL, and in 4 out of 20 HNVs. There was no difference in RVs obtained from the supine or right lateral decubitus positions. Patients with gastrostomy tubes had lower RVs than did those with nasogastric tubes. Patients receiving higher infusion rates had higher RVs. Low RVs did not seem to guarantee tolerance and adequate gut motility because abnormalities still appeared on physical examination and radiography. A single high RV should not cause automatic cessation of TEN because it did occur in some cases in a setting with normal radiographic and physical examination results, where subsequent RVs were shown to decrease. An RV ≥200 mL obtained from a nasogastric tube (or ≥100 mL obtained from a gastrostomy tube) should raise concern about intolerance, but feedings may continue as physical examination, radiographs, and RV are monitored closely. (Journal of Parenteral and Enteral Nutrition 16:99—105, 1992)