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 1 h before, immediately before, and 15 min, 1 h, 6 h and 12 h 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 ll score (APACHE II score) 21 SD 6; PaO2/FiO(2) of 139 mmHg SD 51). There was a statistically, although not clinically significant reduction in PaO2/FiO(2) for up to 1 h after intervention, but no significant changes in oxygenation index, PaCO2, pH, or haemodynamic parameters up to 12 h after intervention. A reduction in delta pressure (Delta P-aw) at 15 min (p <0.05) and 1 h (p <0.05) post intervention was not correlated with sputum wet weight. Conclusions: MAC, postural drainage, saline instillation and airway suctioning during HFOV in critically ill patients was well tolerated with no clinically significant effect on arterial blood gases or haemodynamics. Delta P-aw decreased for up to 1 h after intervention, but was not explained by the weight of sputum removed.