Objective: To evaluate the tolerance of a continuous positive airway pressure (CPAP) mask in tranquilized dogs and compare PaO₂ in arterial blood in dogs receiving oxygen with a regular face mask or CPAP mask set to maintain a pressure of 2.5 or 5 cm H₂O.
Design: Prospective, randomized clinical study.
Setting: University teaching hospital.
Animals: Sixteen client-owned dogs without evidence of cardiopulmonary disease were studied.
Interventions: Eight animals were randomly assigned to each of 2 treatment groups: group A received 2.5 cm H₂O CPAP and group B received 5 cm H₂O CPAP after first receiving oxygen (5 L/min) by a regular face mask. Animals were tranquilized with acepromazine 0.05 mg/kg, i.v. and morphine 0.2 mg/kg, i.m.. An arterial catheter was then placed to facilitate blood sampling for pHa, PaO₂, and PaCO₂ determinations before and after treatments. Direct mean arterial pressure, heart rate, respiratory rate, and temperature were also recorded after each treatment.
Measurements and main results: CPAP administration was well tolerated by all animals. The mean arterial pressure, heart rate, respiratory rate, temperature, PaCO₂, and pHa, did not differ at any time point between groups. Differences were seen in oxygenation; in group A, PaO₂ significantly increased from a mean of 288.3 ± 47.5 mm Hg with a standard mask to a mean of 390.3 ± 65.5 mm Hg with the CPAP mask and in group B, PaO₂ increased similarly from 325.0 ± 70.5 to 425.2 ± 63.4 mm Hg (P<0.05); no differences were detected between the 2 CPAP treatments.
Conclusions: In healthy tranquilized dogs noninvasive CPAP is well tolerated and increases PaO₂ above values obtained when using a regular face mask.
© Veterinary Emergency and Critical Care Society 2010.