High Flow Nasal Cannula Oxygen Therapy in Dogs




Jagodich, Tiffany

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University of Guelph


High flow nasal cannula (HFNC) oxygen therapy is a non-invasive respiratory support modality that warms and humidifies inspired gases to physiologic conditions and delivers flow rates up to 10 times that of traditional oxygen supplementation, while allowing for FiO2 titration. This system has demonstrated success in improving work of breathing (WOB) and averting intubation in people with respiratory failure. The purpose of this thesis was to determine whether OptiflowTM HFNC oxygen therapy could be applied to dogs safely with acceptable tolerance, and whether this modality could improve oxygenation and WOB in dogs with acute hypoxemic respiratory failure (AHRF) and in those with post-anesthetic upper airway obstruction (UAO). A comparison of HFNC to traditional nasal cannula (TNC) oxygen therapy in 8 healthy dogs was conducted in a randomized, incomplete block design. High flow oxygen rates of 0.4, 1, 2, 2.5 L/kg/min and standard TNC oxygen flow rates of 0.1, 0.2, 0.4 mL/kg/min were evaluated. Data collection included physiological variables, respiratory/tolerance/sedation scores, arterial blood gas analysis, as well as inspiratory/expiratory gases and airway pressures. HFNC therapy provided a less variable FiO2 than TNC, reliable FiO2 titration, acceptable tolerance and low-level continuous positive airway pressure (CPAP) at flow rates of 1-2 L/kg/min. There was a small increase in PaCO2 associated with HFNC use in addition to subclinical aerophagia in 8/8 dogs. There was no evidence of air-leak syndrome in any dog. High flow oxygen support was then applied to dogs with AHRF and UAO to determine whether HFNC could improve respiratory status. The investigations in AHRF and UAO were prospective, sequential clinical trials, with 22 and 6 dogs enrolled, respectively. There was an improved WOB and good tolerance in both clinical trials. In dogs with pulmonary pathology, there was improved oxygenation without an increase in PCO2; however, periodic hypercapnia was noted in dogs with UAO. Monitoring of PCO2 is recommended given the correlation with increasing flow rates. Overall, this research has revealed the potential for HFNC as a valuable respiratory support modality in veterinary medicine.



HFNC, oxygen, canine, respiratory failure, high flow nasal cannula, brachycephalic