PhilSPEN Online Journal of Parenteral and Enteral Nutrition

(Article 58 | POJ_0053.php) Issue

Thesis Abstract

Comparison of Gastric Residual Volumes among Critically Ill Patients receiving Peptide versus Intact-protein enteral formula using Refractometry in a Private Tertiary Hospital

Introduction | Methodology | Results | Conclusion | PDF () |Back to Articles Page

Submitted: March 2013

AUTHOR: Eliza Mei Perez-Francisco, MD

INSTITUTION WHERE STUDY WAS DONE: Philippine Women's Univeristy, Metro-Manila, Philippines



In clinical practice, gastric residual volume is used as a parameter to determine gastric emptying and feeding intolerance. However, the traditional practice of gastric residual volumes may be flawed and is not an accurate measure of gastric emptying. Relying on aspirated GRVs to guide management may result in unnecessary interruption of enteral feeding and lead to inadequate nutrient intake. Jhere is no current consensus in the Philippines on the cut-off levels for GRVs and what enteral formula to use in the event of high GRVs.

To compare the gastric residual volume of tube fed patients on intact protein formula versus that of patients on peptide-based formula as a parameter for gastric emptying.


This is a prospective, non-randomized, cohort study using Intact protein formula as the non-exposed arm and peptide-based formula (Peptamen) as the exposed arm. All tube fed patients admitted at Mary Mediatrix Medical Center intensive care unit and referred to the Nutrition Support Team during the study period July 2012 to June 2013 were consecutively recruited to the study. Patients receiving intact protein were placed in Group 1 (n=47) and patients receiving peptide based formula were placed in Group 2 (n=33). Gastric residuals were routinely measured every 4 hours. The aspirated GRV was recorded and the Brix Value was obtained using a refractometer. Mathematical equations were used for calculated GRV and Formula remaining in the stomach.


There was no significant difference between the two groups in terms of age (p=0.54), sex (p=0.36), mean concentration of feeding, (p=0.89), mean tube feeding volume (p=0.39), and mean SOFA score (p=0.85). Mode for SOFA score was 8 pts for both groups. The mean aspirated GRV was lower in the intact protein group compared to · the peptide-based group (159.47±52.67 vs 190.31±108.52 ), although this was not statistically significant (p=0.23). The mean calculated GRV of patients receiving intact protein formula ((256.99 ± 149 .52 ml) was significantly higher than that of patients receiving peptide-based formula (137.74 ± 106.76ml); (p<0.01). The mean calculated formula volume remaining in the stomach was significantly higher in the intact protein group (277.55±193.73) versus that in the peptide-based group (65.58 ± 45.7 ml); (p<0.01).


Patients fed with peptide based formula had lower gastric residual volumes and formula volume compared to those patients fed with intact protein formula. Patients fed with peptide based formula may have better· absorption, gastric emptying and feeding tolerance compared to those patients fed with intact protein, formula as determined by calculated GRVs using refractometry. Hopefully, the findings in this study will guide in the formulation of GRV protocols that include refractometry as a simple, inexpensive, reproducible bedside tool in interpreting gastric residuals. This may help create local clinical practice guidelines on GRV interpretation, using the mathematical equations as bases for deciding whether the gastric residual is composed mostly of feeding formula or of gastric secretions.

Introduction | Methodology | Results | Conclusion | Back to Articles Page