Gastro-oesophageal reflux during anaesthesia in the kitten: comparison between use of a laryngeal mask airway or an endotracheal tube

Abstract

Objective To compare the incidence of gastro-oesophageal reflux (GOR) during anaesthesia in the kitten when using a laryngeal mask airway (LMA) or an endotracheal tube (ET). Study design Prospective randomized cross-over experimental study. Animals Forty Domestic Short Hair laboratory cats, 19 females and 21 males, aged 12-15 weeks and weighing 0.57-1.73 kg (mean 1.13 +/- SD 0.26). Methods Kittens were anaesthetized twice, once using the LMA and once the ET. Following induction of anaesthesia with isoflurane in an anaesthetic chamber and intubation of the trachea with the ET or placement of the LMA, a pH-electrode was introduced into the lower oesophagus. Monitoring of the oesophageal pH was performed for 45 minutes while anaesthesia was maintained with isoflurane. At the end of the experiment, gastric pH was measured. Kittens that had GOR during the experiment were treated with sucralfate, cisapride and ranitidine for 15 days. Results Oesophageal pH was 6.51 +/- 0.76 and gastric pH was 1.54 +/- 0.59. GOR was observed in nine kittens when the ET was used, and in 20 kittens when the LMA was used, the difference being significant (p = 0.013). The refluxate nearly always was acidic, being alkaline in only one kitten. Most of the GOR episodes occurred shortly after induction of anaesthesia and the oesophageal pH remained below 4.0 until the end of the experiment. No regurgitation was observed. Conclusions and clinical relevance The use of the LMA is associated with an increased incidence of GOR during anaesthesia in the kitten, which is not detected by observation. That this may have occurred should be considered if the kitten demonstrates signs of oesophagitis in the postoperative period.