Gastric Residual Volume

OVERVIEW

• Gastric residual volume is the amount aspirated from the stomach following administration of enteral feed
• An aspirated amount of ≤ 500ml 6 hourly is safe and indicates that the GIT is functioning
• Whilst most patients will tolerate enteral nutrition (EN) via a gastric tube, some patients will experience delayed gastric emptying and raised GRVs as a result of sedation, pain medications, hypothermia, decreased  movement and the effect of being critically ill
• intolerance of enteral feeding is defined here as more than one GRV > 500mls
• GRV measurement is one of the most common practices in ICU nutrition therapy but there is little evidence for its efficacy

RATIONALE

• originally designed to reduce the risk of aspiration pneumonia
• now used to identify feeding intolerance early‚ thus high GRVs are a major barrier to enteral feeding

ASSUMPTIONS

The use of GRV is based on these assumptions – all of which may be false! (see problems/ limitations)

• Performing GRVs is well standardized
• GRVs reliably and accurately measure gastric contents
• distinguishes between normal and abnormal gastric emptying
• easy to interpret
• GRVs correlate with aspiration, and that continuing to provide EN once a high GRV above some designated level has been reached will inadvertently lead to pneumonia and adverse outcome
• inexpensive with little or no impact on allocation of health care resources

MEASURING GASTRIC RESIDUAL VOLUME

• Only gastric sump tubes should be aspirated. Jejunal and fine bore NGTs should not be aspirated
• EN should be turned off immediately prior to aspirating the sump tube
• When aspirating sump tubes or instilling fluid the spigot should be taken out of the air-vent lumen to prevent trauma to the gastric mucosa
• The aspirate should be returned in full when it is less than 500mls. This is important as the gastric aspirate contains essential gastric contents that are important for normal GIT  function, protection and digestion

AN APPROACH TO GASTRIC RESIDUAL VOLUMES

This approach is based on that of the Alfred ICU enteral feeding guideline 2013

• GRVs checked 6 hourly after initiation of EN

Gastric aspiration can be reduced to 8 hourly when:

• The patient is medically stable
• EN has been maintained at target rate for 48 hours with GRVs ≤ 500ml and without pro-motility drugs being administered

First GRV >500 mL:

• Replace all of the aspirate up to 500ml, discard the rest and flush with 10ml of water
• Commence metoclopramide IV 10mg q6h together with erythromycin IV 200mg bd for 24 – 72hrs
• Continue with EN at TARGET rate
• Continue to monitor GRV q6h

Second GRV >500 mL

• Replace all of the aspirate up to 500ml and discard the rest
• Halve the EN delivery rate for 6 hours
• Continue to monitor GRV q6h
• Increase the EN back to the TARGET rate after 6 hours if the GRV is < 500ml

Third GRV >500 mL:

• Cease EN via gastric delivery
• Request ICU medical review
• Consider nasojejunal tube placement
• Consider supplementing with PN

PROBLEMS/ LIMITATIONS OF GRV MONITORING

• wide variation in practice (some centers use GRV thresholds as low as 150mL)
• high GRVs typically occur after vomiting, not before
• use may paradoxically contribute to pneumonia by delaying enteral feeding
• GRVs are a poor predictor of aspiration
• measurement is inaccurate and varies with factors such as tube bore size,number of openings,  patient position, NGT position, size of syringe, and composition of tube
• measurement takes time and increases nursing workload
• high GRVs delays delivery of nutrition without clear evidence of benefit
•  not possible if fine bore tube in situ
• repeated removal of gastric contents may clog the tube
• risks of prokinetics if high GRV
• may not reflect feeding intolerance and measured GRV and is affected by flushes and endogenous secretions

EVIDENCE

• no high level evidence for the use of gastric residual volumes exists
• the assumptions underlying the use of GRVs are not evidence-based
• No clear consensus exists on what the appropriate GRV cutoff level should be nor how they should be used as a monitor for patients in the ICU
• 80% of the time an elevated GRV is an isolated event
• elevated GRV is the most common reason for interrupting enteral nutrition and not reaching goal enteral feeding rates
• The REGANE study by Montejo et al, 2010 (open-label spanish MCRCT; n=329 mechanically ventilated patients) found that there were no important differences in using a GRV limit of 500mL was no different to a GRV limit of 200mL in terms of diet volume ratio (diet received/diet prescribed), incidence of GI complications, ICU-acquired pneumonia, days on mechanical ventilation and ICU LOS
• The CRICS study by Reignier et al, 2013 (open-label MCRCT, n=452) found no difference in the risk of VAP when GRV monitoring (cut off of 250 mL q6h) was compared to no GRV monitoring in mechanically ventilated ICU patients. There was twice as much vomiting in the unmonitored group but they still received a higher percentage of their goal calories. Feeding was aggressive, starting at goal rates

References and Links

LITFL

• CCC — Prokinetics
• CCC — Intolerance to Enteral Nutrition

Journal articles

• Deane A, Chapman MJ, Fraser RJ, Bryant LK, Burgstad C, Nguyen NQ. Mechanisms underlying feed intolerance in the critically ill: implications for treatment. World J Gastroenterol. 2007 Aug 7;13(29):3909-17. PMID: 17663503.
• Hurt RT, McClave SA. Gastric residual volumes in critical illness: what do they really mean? Crit Care Clin. 2010 Jul;26(3):481-90, viii-ix. PMID: 20643301.
• Montejo JC, Miñambres E, Bordejé L, Mesejo A, Acosta J, Heras A, Ferré M, Fernandez-Ortega F, Vaquerizo CI, Manzanedo R. Gastric residual volume during enteral nutrition in ICU patients: the REGANE study. Intensive Care Med. 2010 Aug;36(8):1386-93. PMID: 20232036.
• Reignier J, Mercier E, Le Gouge A, Boulain T, Desachy A, Bellec F, Clavel M, Frat JP, Plantefeve G, Quenot JP, Lascarrou JB; Clinical Research in Intensive Care and Sepsis (CRICS) Group. Effect of not monitoring residual gastric volume on risk of ventilator-associated pneumonia in adults receiving mechanical ventilation and early enteral feeding: a randomized controlled trial. JAMA. 2013 Jan 16;309(3):249-56. PMID: 23321763.
• Rice TW. Gastric residual volume: end of an era. JAMA. 2013 Jan 16;309(3):283-4. PMID: 23321767