Prevalence of Gastroesophageal Reflux in Cats During Anesthesia and Effect of Omeprazole on Gastric pH

Abstract

Background: Gastroesophageal reflux (GER) is poorly characterized in anesthetized cats, but can cause aspiration pneumonia, esophagitis, and esophageal stricture formation.

Objective: To determine whether pre-anesthetic orally administered omeprazole increases gastric and esophageal pH and increases serum gastrin concentrations in anesthetized cats, and to determine the prevalence of GER using combined multichannel impedance and pH monitoring.

Animals: Twenty-seven healthy cats undergoing elective dental procedures.

Methods: Prospective, double-masked, placebo-controlled, randomized clinical trial. Cats were randomized to receive 2 PO doses of omeprazole (1.45-2.20 mg/kg) or an empty gelatin capsule placebo 18-24 hours and 4 hours before anesthetic induction. Blood for measurement of serum gastrin concentration was collected during anesthetic induction. An esophageal pH/impedance catheter was utilized to continuously measure esophageal pH and detect GER throughout anesthesia.

Results: Mean gastric pH in the cats that received omeprazole was 7.2 ± 0.4 (range, 6.6-7.8) and was significantly higher than the pH in cats that received the placebo 2.8 ± 1.0 (range, 1.3-4.1; P < .001). Omeprazole administration was not associated with a significant increase in serum gastrin concentration (P = .616). Nine of 27 cats (33.3%) had ≥1 episode of GER during anesthesia.

Conclusions and clinical relevance: Pre-anesthetic administration of 2 PO doses of omeprazole at a dosage of 1.45-2.20 mg/kg in cats was associated with a significant increase in gastric and esophageal pH within 24 hours, but was not associated with a significant increase in serum gastrin concentration. Prevalence of reflux events in cats during anesthesia was similar to that of dogs during anesthesia.

Keywords: Esophagitis; Feline; Gastric pH; Impedance; Reflux.

Figure 1

Photograph of the 6.4‐French (2.1‐mm) esophageal multi‐use pH/impedance catheter showing impedance channels (arrow heads), each 2 cm in length in between the impedance sensors, each in the form of a 4‐mm cylindrical ring, and one pH sensor (arrow heads and arrow). The catheter is attached to the recording device (ZepHr) from which data are uploaded onto a computer using proprietary software.

Figure 2

Waveform depicting a strongly acidic reflux event (pH < 4.0 designated by black stars) in an 8.3‐year‐old male‐neutered domestic longhaired cat in the placebo group. The numbered Z channels on the y‐axis represent impedance channels spaced throughout the esophagus with Z channel 1 being the most proximal in the esophagus and Z channel 6 representing the most distal impedance channel. Bolus presence is identified by a drop in impedance by at least 50% of the pre‐episode impedance highlighted by the black arrows on Z channels 3–6. Direction of bolus movement in the esophagus is determined by the direction of the impedance change with reflux moving distal to proximal and swallow moving proximal to distal. The height of reflux is determined by the position of the most proximal channel showing a drop in impedance (Z channel # 3). Although channel # 7 is positioned on the tracing below the impedance channels, the position of the pH sensor in the esophagus is at the same level as the most distal impedance channel.

Figure 3

Distribution of gastric and esophageal pH in 23 cats undergoing elective dental procedures after oral administration of omeprazole (n = 10 cats) administered twice at 1.45–2.2 mg/kg 18–24 hours before induction and 4 hrs before induction, or placebo (empty gel cap) (n = 13 cats). The horizontal lines of the box represent, from bottom to top, the 25th, 50th, and 75th percentiles of pH values. Whiskers represent the maximum and minimum pH values, except for outlying observations (solid circles). The symbol “*” denotes the mean esophageal and gastric pH in the cats that received omeprazole was significantly higher than the pH in cats that received the placebo (P < .001)