Influence of capnoperitoneum on intraocular pressure in spontaneously breathing dogs undergoing ovariectomy

Abstract

The objective of this study was to evaluate potential changes in intraocular pressure in spontaneously breathing dogs undergoing laparoscopic ovariectomy with capnoperitoneum. Twenty bitches undergoing laparoscopic ovariectomy were enrolled in a prospective clinical trial. The dogs were under general anaesthesia and were breathing spontaneously throughout the entire period of the procedure. Capnoperitoneum was then established with an intra-abdominal pressure setting of 10 mmHg. Collected data included intraocular pressure, pupil size, heart rate, respiratory frequency, systolic and diastolic arterial pressure, end-tidal CO₂, oxygen saturation of haemoglobin and tidal volume. Data were recorded 5 min before starting CO₂-insufflation (baseline), after capnoperitoneum establishment (T0), and at further 5-min intervals (T5, T10, T15, T20, T25, T30). Compared to baseline, pupil size was increased at T30 (P = 0.03) and respiratory frequency at T25 (P < 0.01) and T30 (P = 0.02). No other significant changes were found regarding intraocular pressure. Our data show that the induction of an intra-abdominal pressure of 10 mmHg for a 30-min laparoscopy with the use of medetomidine-butorfanol-propofol-isoflurane in spontaneously breathing dogs in the horizontal position does not result in any important changes in intraocular pressure or end-tidal CO₂.