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

Abstract

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 II score (APACHE II score) 21 SD 6; PaO2/FiO2 of 139 mmHg SD 51). There was a statistically, although not clinically significant reduction in PaO2/FiO2 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 (ΔPaw) 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. ΔPaw decreased for up to 1 h after intervention, but was not explained by the weight of sputum removed.