Comparison of Mucus Clearance Between Biphasic Cuirass Ventilation Device and Mechanical Cough Assist Device on the Differences of Rheological Property and Lung Mechanics

Abstract

Background:

The biphasic cuirass ventilation device (HAYEK HRTX) and the mechanical cough assist device (Comfort Cough II) are used to improve pulmonary function and airway clearance. The purpose of this study was to clarify differences of airway clearance efficacy in two types of airway clearance devices.

Methods:

HAYEK HRTX and Comfort Cough II were compared the movement distance of different viscoelastic mucus stimulants (MS) in tube length 1m internal diameter 1cm on restrictive and obstructive condition. Ten healthy volunteers 21.7 ± 0.6 y old, %VC103 ± 12.5%, FEV₁%92.2 ± 4.4% were measured on restrictive ventilatory condition %VC65. 3 ± 6. 3%, FEV₁%91.0 ± 5.9% by fixed chest belt and obstructive ventilatory condition %VC91.2 ± 8.8%, FEV₁%39.1 ± 2.6% by loaded airway resistance. MS were prepared using thickener 1% (purulent sputum of chronic bronchitis) and 4% (plug mucus of asthma attack). HAYEK HRTX and Comfort Cough II were set in the same way. After performing the vibration mode at 13 Hz and vibration pressure -5/5 cm H₂O for 1 minute, the inspiratory pressure/expiratory pressure was set to -40/40 cm H₂O, and the inspiration/pause/expiration time was set to 1.5/1/1.5 s in the cough mode. Measured 5 times for each condition and compared with average value. Data analysis was performed by using software SPSS version17 and JMP version12, P values <0.05 were considered statistically significant.

Results:

For normal lung and restrictive ventilatory condition, the migration distance of MS in Comfort Cough II (Normal 28. 7 ± 13.7 cm, Restrictive 26.3 ± 12.7 cm) was significantly greater in 1% of MS than in HAYEK HRTX (Normal19.6 ± 9.0 cm, Restrtictive15.8 ± 6.8 cm) (P<0.01), but no difference was observed with 4% MS. For obstructive ventilatory condition, 1% MS of the migration length was significantly greater than 4% in Comfort Cough II (1% 9.0 ± 5.4 cm, 4% 4.8 ± 4.6 cm) (P<0.01), but not in HAYEK HRTX.

Conclusions:

Comfort Cough II was more effective for sputum with lower viscoelasticity in normal lung and restrictive ventilatory condition than HAYEK HRTX. The reason for this was that air leakage from the cuirass and actual pressure did not reach the set pressure.