Bi-level positive airway pressure (biPAP) for non-invasive respiratory support of foals

Abstract

Respiratory insufficiency and pulmonary health are important considerations in equine neonatal care, as the majority of foals are bred for athletic function. The administration of supplementary oxygen is readily implemented in equine practice settings, but this does not address respiratory insufficiency due to inadequate ventilation and is no longer considered optimal care for hypoxia in some settings. Non-invasive ventilatory strategies including continuous or bi-level positive airway pressure are effective in human and veterinary studies, and may offer improved respiratory support in equine clinical practice. The current study was conducted in two parts to investigate the use of a commercial bilevel positive airway pressure (biPAP) ventilator, designed for home care of people with obstructive respiratory conditions, for respiratory support of foals. In Part 1 a prospective observational study was conducted to evaluate the effect of sequential application of supplementary oxygen and then biPAP for respiratory support of five foals ≤ 4 days of age hospitalised with respiratory in sufficiency (Group 1) and four healthy, sedated foals < 28 days of age (Group 2). In Part 2, biPAP and supplementary oxygen were administered to six healthy foals with pharmacologically induced respiratory insufficiency in a two sequence, two phase, cross-over study (Group 3). Non-invasive ventilation by biPAP improved gas exchange and mechanics of breathing (increased tidal volume, decreased respiratory rate and increased peak inspiratory flow) in foals, but modest hypercapnia was observed in healthy, sedated foals (Groups 2 and 3). Clinical cases (Group 1) appeared less likely to develop hypercapnia in response to treatment, however the response in individual foals was variable, and close monitoring is necessary. Clinical observations, pulse oximetry and CO2 monitoring of expired gases were of limited benefit in identification of foals responding inappropriately to biPAP, and improved methods to assess and monitor respiratory function are required in foals.