A Comparison of Cough Assistance Techniques in Patients with Respiratory Muscle Weakness

Abstract

Purpose: To assess the ability of a mechanical in-exsufflator (MI-E), either alone or in combination with manual thrust, to augment cough in patients with neuromuscular disease (NMD) and respiratory muscle dysfunction.

Materials and methods: For this randomized crossover single-center controlled trial, patients with noninvasive ventilator-dependent NMD were recruited. The primary outcome was peak cough flow (PCF), which was measured in each patient after a cough that was unassisted, manually assisted following a maximum insufflation capacity (MIC) maneuver, assisted by MI-E, or assisted by manual thrust plus MI-E. The cough augmentation techniques were provided in random order. PCF was measured using a new device, the Cough Aid.

Results: All 40 enrolled participants (37 males, three females; average age, 20.9±7.2 years) completed the study. The mean (standard deviation) PCFs in the unassisted, manually assisted following an MIC maneuver, MI-E-assisted, and manual thrust plus MI-E-assisted conditions were 95.7 (40.5), 155.9 (53.1), 177.2 (33.9), and 202.4 (46.6) L/min, respectively. All three interventions significantly improved PCF. However, manual assistance following an MIC maneuver was significantly less effective than MI-E alone. Manual thrust plus MI-E was significantly more effective than both of these interventions.

Conclusion: In patients with NMD and respiratory muscle dysfunction, MI-E alone was more effective than manual assistance following an MIC maneuver. However, MI-E used in conjunction with manual thrust improved PCF even further.

Keywords: Neuromuscular disease; cough augmentation; mechanical in-exsufflator; peak cough flow.

Fig. 1. Flow analyzer test system. When performing a cough-assistance technique, the air that is inhaled from the MI-E or Ambu bag through the patient connection part does not leak though the valve; when the patient exhales or coughs, the pushing bar is pressed at the same time, and the exhaled air is pushed through the pushing bar. (A) Disassembled view. (B) Complete view showing the inner parts. MI-E, mechanical in-exsufflator.

Fig. 2. Measurement of manually assisted peak cough flow following a maximum insufflation capacity maneuver.

Fig. 3. Measurement of mechanical insufflation-exsufflator-assisted peak cough flow.