Abstract
Introduction: High-flow humidified (HFH) oxygen is used for the management of acute respiratory failure. HFH could be used in patients with chronic hypercapnic respiratory failure. The aim of this study was to assess the physiological effect of HFH air on patients with chronic hypercapnic failure secondary to obesity-hypoventilation syndrome (OHS).
Methods: This was a physiological study enrolling patient with OHS established on long-term non-invasive ventilation. Trans-diaphragmatic pressure, diaphragmatic EMG and respiratory inductance plethysmography were recorded during self-ventilation, with HFH at a flow from 10 to 60L/min (10L/min steps). HFH was delivered using an Airvo2.
Results: Nine patients with an age of 59±10years and a BMI of 49±10kg/m2 were included. HFH significantly decreased diaphragmatic pressure time product (PTP), respiratory rate, minute ventilation and diaphragmatic EMG activity; it increased inspiratory and expiratory time (Figure 1). There was no significant change in comfort of breathing or breathlessness (Borg and visual analogue scale). TcCO2 decreased from 6.6±1.0kPa whilst self-venting to 6.1±0.9kPa on HFH 60L/min (p:0.01).
Conclusion: HFH improves respiratory mechanics and reduces neural respiratory drive of stable patients with OHS. Further studies are required to assess the clinical relevance of this physiological improvement.
- Copyright ©the authors 2017