A scoping review considering potential biomarkers or functional measures of gastrointestinal dysfunction and enteral feeding intolerance in critically ill adults

Gastric residual volume monitoring practices in UK intensive care units: A web-based survey

Background and aim

Monitoring of gastric residual volume (GRV) to assess for enteral feeding intolerance is common practice in the intensive care unit (ICU) setting; however, evidence to support the practice is lacking. The aim of this study was: (i) to gain a perspective of current practice in adult ICUs in the UK around enteral feeding and monitoring of GRV, (ii) to characterise the threshold value used for a high GRV in clinical practice, (iii) to describe the impact of GRV monitoring on enteral feeding provision and (iv) to inform future research into the clinical value of GRV measurement in the adult ICU population.

Methods

A web-based survey was sent to all UK adult ICUs. The survey consisted of questions pertaining to (i) nutritional assessment and enteral feeding practices, (ii) enteral feeding intolerance and GRV monitoring and (iii) management of raised GRV.

Results

Responses were received from 101 units. Ninety-eight percent of units reported routinely measuring GRV, with 86% of ICUs using GRV to define enteral feeding intolerance. Threshold values for a high GRV varied from 200 to 1000 ml with frequency of measurement also differing greatly from 2 to 12 hourly. Initiation of pro-kinetic medication was the most common treatment for a high GRV. Fifty-two percent of respondents stated that volume of GRV would influence their decision to stop enteral feeds a lot or very much. Only 28% of units stated that they had guidelines for the technique for monitoring GRV.

Conclusions

Measurement of GRV is the most common method of determining enteral feeding intolerance in adult ICUs in the UK. The practice continues despite evidence of poor validity and reproducibility of this measurement. Further research should be undertaken into the benefit of ongoing GRV measurements in the adult ICU population and alternative markers of enteral feeding intolerance.

Citrulline, Intestinal Fatty Acid-Binding Protein and the Acute Gastrointestinal Injury Score as Predictors of Gastrointestinal Failure in Patients with Sepsis and Septic Shock

Gastrointestinal (GI) failure can be both a cause of sepsis and a consequence of the systemic pro-inflammatory response in sepsis. Changes in biomarkers of enterocyte damage, citrulline and I-FABP (intestinal fatty acid binding protein), may indicate altered intestinal permeability and damage. The study group consisted of patients with sepsis (N = 28) and septic shock (N = 30); the control group included patients without infection (N = 10). Blood samples were collected for citrulline and I-FABP and a 4-point AGI score (acute GI injury score) was calculated to monitor GI function on days 1, 3, 5, 7, and 10. Citrulline concentrations in the study group were lower than in the control. Lower values were also noted in septic patients with shock when compared to the non-shock group throughout the study period. I-FABP was higher in the septic shock group than in the sepsis group only on days 1 and 3. Citrulline was lower in patients with GI failure (AGI III) when compared to AGI I/II, reaching significance on days 7 (p = 0.034) and 10 (p = 0.015); moreover, a higher AGI score was associated with an increased 28 day mortality (p = 0.038). The results indicate that citrulline measurements, along with the AGI assessment, have clinical potential in monitoring GI function and integrity in sepsis.

The need for biomarkers to determine response to enteral nutrition during and after critical illness: an update

PURPOSE OF REVIEW

Biomarkers proposed to provide prognosis or to determine the response to enteral nutrition have been assessed in a number of experimental and clinical studies which are summarized in the current review.

RECENT FINDINGS

There are several pathophysiological mechanisms identified which could provide biomarkers to determine response to enteral nutrition. Several biomarkers have been studied, most of them insufficiently and none of them has made its way to clinical practice. Available studies have mainly assessed a simple association of a biomarker with outcomes, but are less focused on dynamic changes in the biomarker levels. Importantly, studies on pathophysiology and clinical features of gastrointestinal dysfunction, including enteral feeding intolerance, are also needed to explore the mechanisms potentially providing specific biomarkers. Not only an association of the biomarker with any adverse outcome, but also a rationale for repeated assessment to assist in treatment decisions during the course of illness is warranted.

SUMMARY

There is no biomarker currently available to reliably provide prognosis or determine the response to enteral nutrition in clinical practice, but identification of such a biomarker would be valuable to assist in clinical decision-making.