Comparison of CPAP and oxygen therapy for treatment of postoperative hypoxaemia in dogs

Objective: To compare 5 cmH2O of continuous positive airway pressure with oxygen therapy in dogs recovering from general anaesthesia with low SpO2 values. continuous positive airway pressure is more effective than oxygen therapy in restoring normoxaemia (SpO2≥95%). Materials and Methods: Prospectively, dogs recovering from anaesthesia, with SpO2<95% after extubation (T0), were randomised and treated with continuous positive airway pressure (FiO2 0.21) or oxygen (O2; FiO2 0.35-0.40) therapy. Dogs were monitored with SpO2 every 15 minutes for 1 hour (T15, T30, T45, T60). Data from normoxaemic dogs (SpO2>95%) were used as control (CTR). Results: Of the 42 dogs enrolled, 34 completed the study. Eleven dogs were treated with O2, 10 with continuous positive airway pressure and 13 were CTR. The SpO2 values at T0 were similar in the continuous positive airway pressure and O2 groups and were lower than in the CTR group. At T15, T30, T45 and T60, the SpO2 values in the continuous positive airway pressure group were higher than at T0; these were similar to those of the CTR group at the same time-points. In the O2 group, SpO2 values were significantly higher at T45 and T60 than at T0; 45.5% of dogs became normoxaemic at T45 and the remaining dogs became normoxaemic at T60. The average time to reach normoxaemia in the O2 group (53.1±7.3 minutes) was longer than in the continuous positive airway pressure group (15.0±0.0 minutes). Clinical Significance: In dogs recovering from general anaesthesia with pulmonary gas exchange impairment, normoxaemia is restored more effectively and rapidly by using continuous positive airway pressure than by oxygen therapy.