Measurements of gastric emptying during continuous nasogastric infusion of liquid feed: electric impedance tomography versus gamma scintigraphy.

Background & Aims: Continuous nasogastric infusion is commonly used to deliver enteral feed but current methods used to assess tolerance based on aspiration and measurement of gastric residual volume have been criticised. Electric impedance tomography (EIT) measures gastric emptying by monitoring changes in epigastric impedance when a meal progressively empties from the stomach.

Aims: (1) to establish whether EIT was a valid method for measuring gastric emptying during continuous nasogastric infusion by comparing it with gamma scintigraphy (GS) and (2) to provide data on gastric emptying patterns during continuous nasogastric infusion.

Methods: Gastric emptying of 400 ml of enteral feed given over 200 min was measured simultaneously using EIT and GS in 10 healthy volunteers (five male and five female).

Results: Gastric emptying curves were obtained in 10 subjects by EIT but only eight by GS. Visual examination of the curves showed reasonable agreement. Patterns of emptying and filling during continuous nasogastric infusion were variable between individuals; the prevailing pattern was a trend towards a steady-state volume of approximately 50-125 ml.

Conclusions: While EIT does not provide an accurate estimate of gastric volume during continuous infusion, it does show patterns of gastric emptying over time. With further development this could make it a useful tool for monitoring gastric emptying in patients at risk of gastroparesis.