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 (GRVs) and markers of gastric emptying (GE) in critically ill patients is unclear. This particularly applies to critically ill 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. 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 <20th percentile of the pharmacokinetic GE marker that had the strongest correlation with GE.

RESULTS: Of 77 patients, 8 (10.4%) had high GRV, and 15 (19.5%) had delayed GE. The 3-OMG concentration at 60 min had the strongest correlation with GRV (ρ = -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. Compared with medical patients, surgical patients (n = 14, 18.2%), had a significantly higher incidence of high GRV (29% vs 6%, P = .032) and a trend toward delayed GE (36% vs 16%, P = .132).

CONCLUSION: GRV reflects GE, and high GRV is an acceptable surrogate marker of delayed GE. From our preliminary observation, surgical patients may have a higher risk of high GRV and delayed GE. In summary, GRV should be monitored to determine whether complex investigations or therapeutic interventions are warranted.