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), pHmetry (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 (14e40) kg and 5.6 (0.75e12) 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 (0e3) 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%), pHMII 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 (4.1e7.4). Incorporation of impedance addresses some of the limitations associated with pH alone and enhances diagnostic accuracy.