Influence of atracurium on selected cardiovascular and respiratory variables and surgical times in dogs undergoing laparoscopic ovariectomy with standardized ventilation pattern

Respiratory and cardiovascular changes in normocapnic dogs undergoing laparoscopic ovariectomy are described in this report. To-date, changes during a standardised ventilation pattern, irrespective of end-tidal CO2 (EtCO2) levels, have not been reported. This study was undertaken to describe these changes. Forty bitches undergoing laparoscopic ovariectomy were enrolled in a prospective double-blind randomised clinical trial. They were first anaesthetised with medetomidine-butorphanol-propofol and then maintained with isoflurane in oxygen-air. Ventilation pattern was pressure-controlled, volume-limited. After stabilisation, atracurium 0.4 mg/kg (ATR group, n = 20) or saline 0.04 ml/kg (SAL group, n = 20) was administered intravenously. Capnoperitoneum was then established with an intra-abdominal pressure setting of 10 mmHg. Collected data included heart rate (HR), non-invasive blood pressure, EtCO2, oxygen saturation of haemoglobin, and tidal volume and neuromuscular blockade (train-of-four). Data were recorded before administration of atracurium or saline, and at 2, 5, and 10 min thereafter. Subsequently, insufflation of CO2 was commenced. After capnoperitoneum was established, data were recorded at 2, 5 and 10 min. Time of capnoperitoneum induction and duration, time of ovary searching and excision and total time of capnoperitoneum and surgery were also recorded. For statistical analysis, the Shapiro Wilk test, ANOVA with repeated measures and Student's t-test for independent samples were used (P < 0.05). Significant increases in EtCO2 were observed in patients 5 min after atracurium administration and 5 min after capnoperitoneum was established in the ATR group, when compared to the SAL group. No other differences were found. Administration of atracurium in dogs undergoing laparoscopic ovariectomy with a standardised ventilation pattern did not result in clinically important differences in selected cardiovascular and respiratory variables and surgical times in comparison with non-relaxed dogs. Thus, the use of atracurium in laparoscopic ovariectomy does not result in any benefit for patients or surgeons.