Detection of duodenal fluid in the oesophagus with a sodium ion selective electrode.

The assessment of duodeno-oesophageal reflux is difficult as, until recently, no technique has been readily available for continuous ambulatory monitoring. A sodium ion selective electrode placed in the stomach has been previously shown to detect duodenogastric reflux by using sodium as a marker. This relies on the difference in sodium concentration between gastric (5-60 mmol/L) and duodenal, biliary and pancreatic (150 mmol/L) fluids.

Identifying oesophageal contents using electrical impedance tomography.

Investigations have been carried out using the Sheffield mark II real-time EIT system, to look at changes in conductivity associated with swallowing. A ring of 16 electrodes was placed around the neck of 10 subjects, who then performed swallows with four liquids of different conductivities, ranging from water (sigma = 0.03 mS cm-1) to salty soup (sigma = 35.

Applied potential tomography in the measurement of gastric emptying in infants.

The aim of this study was to investigate the feasibility of using applied potential tomography (APT), a noninvasive and nonradioactive method, to measure the rate of gastric emptying in preterm babies and infants < 3 months old. APT, a form of electrical impedance tomography, creates tomographic images of tissue resistivity to a small electrical current and has been used to study gastric emptying in adults. The rate of gastric emptying of 53 preterm infants and 29 term infants was measured.

Transport of gastric contents.

A planar array of electrodes has been used to provide a longitudinal section of the stomach. Impedance changes at the gastric frequency of 0.05 Hz can be detected.

Measurement of gastric emptying in infants with pyloric stenosis using applied potential tomography.

Gastric emptying in a group of 49 vomiting infants with infantile hypertrophic pyloric stenosis (IHPS) was investigated using applied potential tomography. Fourteen asymptomatic infants were also studied as a control group. A Dioralyte test feed (25 ml/kg/feed) was used for all the studies.