Measuring Gastric Emptying in the Critically Ill: More Than a Gut Feeling

The correlation between gastric residual volumes and markers of gastric emptying: a post-hoc analysis of a randomized clinical trial

BACKGROUND

The correlation between gastric residual volumes (GRV) and markers of gastric emptying (GE) in critically ill patients is unclear. This is especially true for ICU surgical patients as they are underrepresented in previous studies.

METHODS

We conducted a post-hoc analysis of a multicenter trial that investigated the effectiveness of a promotility drug in increasing enteral nutrition intake. Pharmacokinetic markers of GE [3-O-methylglucose (3-OMG) and acetaminophen] were correlated with GRV measurements. High-GRV was defined as one episode of >400 mL or two consecutive episodes of >250 mL, and delayed GE was defined as <20^th percentile of the pharmacokinetic GE marker that had the strongest correlation with GE.

RESULTS

Out of 77 patients, 8 (10.4%) had high-GRV, and 15 (19.5%) had delayed GE. 3-OMG concentration at 60 mins had the strongest correlation with GRV (Rho: - 0.631), and high-GRV had low sensitivity (46.7%) but high specificity (98.4%) in discriminating delayed GE. The positive (87.5%) and negative (88.4%) predictive values were similar. There was a small sample of surgical patients (n = 14, 18.2%), and they had a significantly higher incidence of high-GRV (29% vs 6%, P: 0.032) and a trend towards delayed GE (36% vs 16%, p: 0.132) when compared to medical patients.

CONCLUSION

GRV reflects GE, and high-GRV is an acceptable surrogate marker of delayed GE. Based on our preliminary observation, surgical patients may have a higher risk of high-GRV and delayed GE. In summary, GRV should be monitored to determine if complex investigations or therapeutic interventions are warranted. This article is protected by copyright. All rights reserved.