title: Effect of feeding-tube properties on residual volume measurements in tube-fed patients.
abstract: BACKGROUND
  The effect of feeding tube size and port configuration on the ability to measure gastric residual volume (GRV) is poorly understood. In addition, there is confusion about the need to measure GRVs during feedings into the small bowel. This study sought to (1) compare the volume of gastric contents obtained from small-diameter feeding tubes and large-diameter sump tubes concurrently positioned in the stomach and (2) describe the distribution of GRVs during small-bowel feedings.
  
  
  METHODS
  For the first objective, GRV measurements were made from 10-Fr tubes (n = 645) and 14-Fr or 18-Fr sump tubes (n = 645) concurrently present in 62 critically ill patients. Sixty-milliliter syringes were used to measure GRVs from the 10-Fr tubes; the fluid was returned to the stomach and measurements were repeated from the large-diameter sump tubes. To address the second research objective, 890 GRV measurements were made from 14-Fr or 18-Fr gastric sump tubes (not connected to suction) in 75 critically ill patients who were receiving small-bowel feedings.
  
  
  RESULTS
  When GRVs were >50 mL, a linear regression equation indicated that volumes obtained from the large-diameter sump tubes were about 1.5 times greater than those obtained from the small-diameter tubes concurrently present in the stomach, p < .001. Gastric volumes > or =100 mL were found in 11.6% of the 890 measurements made in patients receiving small-bowel feedings; volumes > or =150 mL were found in 5.4% of the measurements.
  
  
  CONCLUSIONS
  The findings suggest that GRVs obtained from large-diameter sump tubes are about 1.5 times greater than those obtained from 10-Fr tubes. Large GRVs occur in at least 5% of patients receiving postpyloric feedings.
authors.affiliation: St. Louis University School of Nursing, 3525 Caroline Mall, St. Louis, MO 63104, USA. methenna@slu.edu
authors.forename: Norma A
authors.initials: NA
authors.lastname: Metheny
authors.forename: Jena
authors.initials: J
authors.lastname: Stewart
authors.forename: Gretel
authors.initials: G
authors.lastname: Nuetzel
authors.forename: Dana
authors.initials: D
authors.lastname: Oliver
authors.forename: Ray E
authors.initials: RE
authors.lastname: Clouse
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016638:Critical Illness / Q000628:therapy*; D004750:Enteral Nutrition / Q000295:instrumentation; D005260:Female; D005526:Food, Formulated; D005746:Gastric Emptying / Q000502:physiology*; D005766:Gastrointestinal Contents; D006801:Humans; D007441:Intubation, Gastrointestinal / Q000009:adverse effects / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged