Effects of Mechanical Insufflation-Exsufflation on Airway secretion removal
Summary
Mechanical insufflation-exsufflation (MI-E) devices aim to enhance mucus clearance in mechanically ventilated patients. A randomised study conducted from June to November 2017 in Porto Alegre, Brazil, assessed the effectiveness of MI-E compared to standard physiotherapy. Two groups of 90 patients were studied: one received only standard physiotherapy, while the other received MI-E in addition. The primary outcome measured was the weight of secretions coughed up, along with secondary outcomes including lung compliance, airway resistance, and work of breathing. Results indicated that MI-E significantly improved mucus clearance and lung compliance without causing respiratory or hemodynamic complications.
Introduction - Why MI-E?
In mechanically ventilated patients, airway clearance is often compromised due to endotracheal intubation, sedation, and pain management, leading to risks like pneumonia and atelectasis. Standard treatments include physiotherapy and suctioning, but suctioning may not effectively reach proximal airway sections. MI-E uses a combination of positive and negative pressure to facilitate mucus removal, mimicking a cough, which is beneficial for sedated or unconscious patients. Despite its potential, MI-E remains underused. This study aims to provide additional insights into its effectiveness.
Study Design - How Was the Study Conducted?
This randomised comparative study included patients over 18 who had been mechanically ventilated for at least 24 hours with stable respiratory and hemodynamic status. Exclusions were made for those with neuromuscular diseases, untreated pneumothorax, or in palliative care. The intervention group underwent three sets of 10 cycles of MI-E at specific pressures. The control group received standard physiotherapy. The primary focus was on the weight of aspirated secretions measured five minutes post-intervention, alongside assessments of lung compliance, airway resistance, and any adverse events. A total of 180 patients completed the study, with baseline variables considered for group allocation.
Study Results - MI-E Beats Manual Physiotherapy
The intervention group demonstrated a significantly higher average weight of aspirated secretions (2.42 ± 2.32 g) compared to the control group (1.35 ± 1.56 g). Lung compliance also improved in the intervention group (1.76 ± 4.90 mL/cm H2O vs. -0.57 ± 4.85 mL/cm H2O). However, there were no significant differences in the average work of breathing or airway resistance between groups. Importantly, no respiratory or hemodynamic incidents occurred throughout the study. Subgroup analysis indicated that patients over 65 years without COPD benefitted particularly from MI-E.
Outlook
The study suggests that MI-E devices can enhance airway secretion clearance in certain patient populations and appear to be a safe option. Future research should further evaluate MI-E's effectiveness and safety across diverse clinical conditions. This study serves as an initial exploration into MI-E functionality in clinical settings and underscores the need for ongoing investigation.