Assessment of oesophageal emptying in achalasia patients by intraluminal impedance monitoring

Oesophageal emptying can be assessed by radiographic and scintigraphic tests with radiation exposure or by multichannel intraluminal impedance monitoring (MII). The aim of this study was to evaluate the applicability of MII for the assessment of oesophageal emptying in achalasia patients. In 10 achalasia patients, impedance tracings were scored independently by three observers after ingestion of a 100-mL barium bolus. Bolus clearance time (BCT) and height of barium column were scored using fluoroscopic images acquired at 20-s intervals. All patients showed a low baseline impedance level in the distal oesophagus. Air trapping in the proximal oesophagus was detected in nine patients. BCT on MII was similar to that on fluoroscopy in 40-70% of the patients. Correlations between height of barium on fluoroscopy and fluid level on MII were poor to moderate at different time intervals. Concordance (Kendall's coefficient) between the three observers for assessment of fluid level on MII was 0.31 (P = 0.04) at 1 and 5 min, 0.26 (P = 0.08) at 10 and 0.44 (P = 0.01) at 15 min. We conclude that in achalasia patients, low baseline impedance levels and air entrapment in the proximal oesophagus limit the value of intraluminal impedance monitoring as a test of oesophageal emptying.