Noninvasive continuous positive airway pressure delivered using a pediatric helmet in dogs recovering from general anesthesia

Abstract Objective – To evaluate the feasibility and efficacy of noninvasive continuous positive airway pressure (CPAP) administered with a pediatric helmet in healthy dogs recovering from general anesthesia. Design – Randomized, cross-over, clinical study. Setting – University teaching hospital Animals – Fifteen healthy female, client-owned dogs recovering from general anesthesia following elective ovariohysterectomy. Interventions – All dogs received the same standardized anesthetic protocol (acepromazine, morphine, propofol, and isoflurane in oxygen). After extubation, a pediatric helmet was placed on all dogs and connected to a venturi valve supplied with medical air. In all patients, the gas flow was set to 50 L/minute and the FiO2 to 0.21. Dogs received the following sequence of treatments, each lasting 20 minutes: 0 CPAP (pre-CPAP), CPAP of 5 cm H2O (CPAP), and again 0 CPAP (post-CPAP). Measurements and Main Result – During the entire study, the following data were collected: pressure and FiO2 inside the helmet, mean arterial pressure, respiratory rate, heart rate, sedation score (0 = awake, 10 = deep sedation), and tolerance to the helmet (0 = excellent, 4 = poor). At the end of each phase, an arterial blood sample was sampled. As compared with the pre-CPAP and the post-CPAP periods, during the CPAP period, the PaCO2, alveolar-arterial oxygen gradient (P[A−a]O2), and respiratory rate significantly decreased. The PaO2 was higher at CPAP (105.6±4.0mmHg) compared with pre-CPAP (80.6±6.9mmHg) and post-CPAP (86.7 ± 5.8 mm Hg). Tolerance and sedation scores during the CPAP period were not different from those in the pre-CPAP and post-CPAP periods. Conclusions – Noninvasive CPAP applied through a helmet is a feasible and effective supportive technique in dogs recovering from general anesthesia.