Ambulatory esophageal pH monitor

Claim 1

A self-contained diagnostic pH monitor for preliminary screening of gastroesophageal reflux disease and suitable for esophageal intubation without restriction of patient movement and activity, the monitor determining duration of exposure to pH levels clinically significant for gastroesophageal reflux disease, the monitor omitting use of external power, light and data processing sources, comprising: a nasoesophageal probe for selected esophageal intubation, the probe having a length permitting positioning of a distal end of the probe proximal to the gastroesophageal junction of the esophagus; at least one semipermeable envelope, the envelope being carried near the distal end of the probe, the envelope containing a composition including a cation exchange substance having an ionic dye bound thereto, the envelope being constructed of a material permeable to both hydronium ions and the ionic dye; said composition substantially and irreversibly discoloring in response to extended exposure to a pH of 4 or less and upon withdrawal of the probe the composition in said envelope being colorimetrically analyzable to semi-quantitatively determine the duration of exposure to pH levels being clinically significant for preliminary screening of gastroesophageal reflux disease.