Effects of manually-assisted cough combined with postural drainage, saline instillation and airway suctioning in critically-ill patients during high-frequency oscillatory ventilation: A prospective observational single centre trial

Background: Chest physiotherapy may aid sputum clearance during conventional ventilation. However, the role of chest physiotherapy during high-frequency oscillatory ventilation (HFOV) is unclear. This study aimed to determine the effects manually-assisted cough (MAC), postural drainage, saline instillation and airway suction during HFOV. Methods: This was an observational study of a chest physiotherapy intervention in adult critically ill patients during HFOV. Measures included gas exchange, HFOV and haemodynamic variables 1h before, immediately before, and 15min, 1h, 6h and 12h after intervention. Wet weight of airway secretions was also measured. Linear mixed modelling compared pre-intervention gas exchange, HFOV and haemodynamic variables with the four specified time-points after intervention. Results: Seventeen adults (ten females) with moderate to severe respiratory failure were studied (age, 49 years SD 14; Acute Physiology and Chronic Health Evaluation II score (APACHE II score) 21 SD 6; PaO2/FiO2 of 139mmHg SD 51). There was a statistically, although not clinically significant reduction in PaO2/FiO2 for up to 1h after intervention, but no significant changes in oxygenation index, PaCO2, pH, or haemodynamic parameters up to 12h after intervention. A reduction in delta pressure (ΔPaw) at 15min (p<0.05) and 1h (p