Monitoring gastric residual volume (GRV), a common practice in intensive care units (ICUs), is believed to decrease the incidence of ventilator-associated pneumonia (VAP). Jean Reignier and members of the Clinical Research in Intensive Care and Sepsis (CRICS) Group sought to test this belief and published their results in the January 16, 2013, issue of The Journal of the American Medical Association.
This multicenter, randomized, noninferiority trial included mechanically ventilated adults admitted to one of nine ICUs in France. Patients in the intervention group were fed enterally via a nasogastric tube, and nutrition was stopped only when vomiting occurred. The control group consisted of patients fed via a nasogastric tube, with cessation of feeding whenever either vomiting or GRV exceeded 250 mL. The primary endpoint was the incidence of VAP. Secondary endpoints included evaluations of whether absence of GRV monitoring affected enteral nutrition delivery. Additional patient outcomes were also assessed. Intent-to-treat (ITT) and per-protocol population analyses were conducted, and the number of VAP episodes was evaluated using negative binomial regression.
Four hundred forty-nine patients were included in the primary ITT analysis and 423 were included in the per-protocol analysis. In the ITT population, 16.7% in the intervention group developed VAP compared to 15.8% in the controls. The cumulative incidence of VAP in both groups was not significantly different (P=0.80). More patients vomited in the intervention group compared to the control group (odds ratio of vomiting, 1.86; 90% confidence interval, 1.32-2.61; P=0.003). Patients in the intervention group had a lower cumulative calorie deficit from day 0 to day 7 compared to the control group. There were no significant differences in mortality, lengths of stay, rates of diarrhea, and ICU-acquired infections between groups.
The results of this study challenge the practice of routinely checking GRVs in all mechanically ventilated patients receiving gastric feeds. A GRV cutoff of 250 mL was used; several other studies have evaluated higher GRVs (up to 500 mL). It is possible that more complications might occur at higher GRVs, but previous work has not shown VAP rates to be greater. Furthermore, the lack of blinding in this study might have caused nurses to over-report vomiting, even though patients not monitored clearly received a larger volume of enteral nutrition. Additionally, the majority of patients in this study had a medical diagnosis at admission (>90%), and patients who had abdominal surgery were excluded. Hence, the results are not necessarily externally generalizable to all ICU populations, including surgical and trauma populations. Based on the results of this study, the routine stopping of enteral nutrition for GRVs < 250 mL should be reconsidered in medical ICU patients receiving gastric feeds.
Concise Critical Appraisal is a regular feature authored by SCCM member Samuel M. Galvagno Jr., DO, PhD. Each installment highlights journal articles most relevant to the critical care practitioner.