Physiologic evidence for high-frequency chest wall oscillation and positive expiratory pressure breathing in hospitalized subjects with cystic fibrosis

Background and Purpose. This investigation identified ventilation distribution, gas mixing, lung function, and arterial blood oxyhemoglobin saturation (Spo₂) physiologic responses to 2 independent airway clearance treatments, high-frequency chest wall oscillation (HFCWO) and low positive expiratory pressure (PEP) breathing, for subjects who had cystic fibrosis (CF) and who were hospitalized during acute and subacute phases of a pulmonary exacerbation. Subjects. Fifteen subjects with moderate to severe CF were included in this study. Methods. Subjects performed single-breath inert gas tests and spirometry before and immediately after HFCWO and PEP breathing at admission and discharge. Arterial blood oxyhemoglobin saturation was monitored throughout each treatment. Results. At admission and discharge, PEP breathing increased Spo₂ during treatment, whereas HFCWO decreased Spo ₂ during treatment. Ventilation distribution, gas mixing, and lung function improved after HFCWO or PEP breathing. Discussion and Conclusion. High-frequency chest wall oscillation and PEP breathing are similarly efficacious in improving ventilation distribution, gas mixing, and pulmonary function in hospitalized people with CF. Because Spo₂ decreases during HFCWO, people who have moderate to severe CF and who use HFCWO should have Spo₂ monitored during an acute exacerbation.