Comparing methods for detection of gastro-oesophageal reflux in anaesthetized dogs.

Abstract

OBJECTIVE: To compare the sensitivity and specificity of pH with multichannel intraluminal impedance (pH-MII), pH-metry (pH) alone and MII alone to direct observation of GOR by endoscopy in anaesthetized dogs. STUDY DESIGN: A prospective comparative trial in a live canine model. ANIMALS: A group of 35 (22 females, 13 males) dogs of various breeds. The mean (range) body weight and age were 31.9 (14-40) kg and 5.6 (0.75-12) years, respectively. METHODS: All dogs were premedicated with medetomidine and morphine, anaesthesia was induced with propofol and maintained on isoflurane in oxygen. A monitoring assembly consisting of an endoscopy camera, endotracheal tube and a disposable flexible pH-MII catheter was used to measure oesophageal pH, MII and directly visualize reflux. Visual reflux score was (0-3) and pH was recorded on a data capture sheet. Reflux was considered to have occurred whenever oesophageal pH was < 4.0 or > 7.5, device software analysing MII data detected fluid or a visual reflux score of 2 or 3 were assigned. Receiver operator curves (ROC) analysis was used to determine sensitivity and specificity for each monitoring method to detect GOR. RESULTS: Endoscopy identified GOR in 20 dogs (57%), pH-MII in 19 dogs (54%), pH alone in 13 dogs (37%) and MII alone in 12 dogs (24%). ROC analysis showed fair accuracy for pH-MII and pH alone, whereas MII demonstrated low accuracy. CONCLUSIONS AND CLINICAL RELEVANCE: In conclusion, pH-MII is a reliable method for detecting GOR and emerges as a promising tool for future research. Endoscopy is reliable and provides the ability to subjectively quantify the volume of reflux; however, it lacks the ability to discern the pH of refluxate. pH alone misses reflux events with intermediate pH (4.1-7.4). Incorporation of impedance addresses some of the limitations associated with pH alone and enhances diagnostic accuracy.