Comparison of the Effects of a CPAP-Helmet Versus Oxygen Therapy Alone on the Postoperative Period in Brachycephalic Dogs Undergoing Surgery

Principal Investigator: Joaquin Araos

Co-PI: Galina Hayes, Manual Martin-Flores

Department of Clinical Sciences
Sponsor: American College of Veterinary Emergency and Critical Care
Grant Number: AC026
Title: Comparison of the Effects of a CPAP-Helmet Versus Oxygen Therapy Alone on the Postoperative Period in Brachycephalic Dogs Undergoing Surgery
Project Amount: $10,000
Project Period: July 2021 to June 2022

DESCRIPTION (provided by applicant): 

Brachycephalic obstructive airway syndrome (BOAS) describes a combination of anatomical abnormalities resulting in upper airway obstruction. BOAS-affected dogs can develop major post-anesthetic complications, including emergency reintubation, tracheostomy or death. Continuous positive airway pressure (CPAP) increases the laryngeal area and end-expiratory lung volume and improves oxygenation in dogs. Its use in brachycephalic dogs could improve their postoperative outcomes. This proposal aims to evaluate the postoperative effects of oxygen (O2) delivered via 5 cmH2O of CPAP versus traditional O2 therapy in brachycephalic dogs. We hypothesize that O2 via 5 cmH2O of CPAP, as compared to O2 alone, lowers rectal temperatures and improves gas exchange and distribution of ventilation in the postoperative period. Brachycephalic dogs scheduled for elective surgery will be randomly assigned to 0 (group Control) or 5 cmH2O of CPAP (group CPAP) immediately after surgery. A custom-made electric impedance tomography (EIT) belt will be placed in the thorax before anesthesia induction. Immediately after extubation, a CPAP-helmet will be placed in all dogs. In Control dogs, the spring-loaded valve of the helmet will remain open. In the CPAP dogs, the spring-loaded valve will be adjusted to provide 5 cmH2O of CPAP immediately after obtaining the first set of EIT recordings. In both groups, a flow of 10-15Lpm of O2 will be administered through the venturi valve at the inlet port of the helmet. Each treatment will be maintained for 2 hours post-extubation. Arterial blood gases, pulse oximetry and respiratory rates will be obtained to evaluate oxygenation and ventilation. Thermoregulation will be assessed by measuring rectal temperature. Regional distribution of ventilation and lung aeration will be assessed with EIT. Each variable will be recorded prior to helmet placement, immediately after placement of the helmet and at predefined times points thereafter. We anticipate CPAP to result in significant improvements in oxygenation, ventilation and thermoregulation. Moreover, we anticipate CPAP to improve the regional distribution of ventilation and to increase the end-expiratory lung impedance. We expect to generate population-based high quality and novel clinical data that will help clinicians to determine whether a non-invasive CPAP helmet could be used to improve postoperative outcomes of brachycephalic dogs.