Effectiveness of noninvasive respiratory strategies for the management of postoperative hypoxaemia in dogs: a prospective, randomized clinical trial.

Abstract

OBJECTIVE: To evaluate the effectiveness, the time to restore normoxaemia (TRN), and the tolerability of face mask (FM), continuous-positive-airway-pressure helmet (CPAP), or high-flow nasal cannulae (HFNC) as noninvasive respiratory support strategies for treating transient postoperative hypoxaemia in dogs. STUDY DESIGN: Prospective, randomized, clinical trial. ANIMALS: A total of 600 client owned dogs anaesthetized for various procedures. METHODS: At the end of general anaesthesia, the haemoglobin oxygen saturation (SpO) on room air (SpAT) was used for assessment of oxygenation 10 minutes after extubation (T-POST). Hypoxaemic dogs (SpO< 95%) were randomly assigned to: FM-group [flow rate = 10 L minute; fraction of inspired oxygen (FIO) = 0.3-0.4], CPAP-group (flow rate = 10 L minute; FIO= 0.3-0.4; CPAP = 5 cmHO), and HFNC-group (flow rate = 2-2.5 L kgminuteat 37 &#xb0;C; FIO= 0.3-0.4). Treatments lasted 1 hour, divided into 15-minute intervals (T15, T30, T45, T60) with 10 minutes of treatment and 5 minutes of SpAT. The TRN during SpAT was recorded. Interface tolerance was assessed using a dedicated scale. SpOand TRN were compared with two-way ANOVA, Kruskal-Wallis was used to test for differences in tolerance score between groups. p < 0.05. RESULTS: At T-POST, 168 dogs (28%) were hypoxaemic, and 76 of them completed the study (CPAP-group n = 31, FM-group n = 24, HFNC-group n = 21). All treatments restored normoxaemia. TRN was faster in the CPAP-group compared with HFNC-group and FM-group (mean &#xb1; standard deviation: 16.9 &#xb1; 15.7, 27.8 &#xb1; 20.8, and 40.4 &#xb1; 12.8 minutes, respectively) (p < 0.05). Tolerance was good for all devices, without differences between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Postoperative hypoxaemia in dogs can be effectively treated with FM, HFNC, or CPAP, the latter restoring normoxaemia more rapidly.