Developing Control Algorithms of a Voluntary Cough for an Artificial Bioengineered Larynx Using Surface Electromyography of Chest Muscles: A Prospective Cohort Study

Abstract

Objective

This prospective cohort study investigates the prediction of a voluntary cough using surface electromyography (EMG) of intercostal and diaphragm muscles, in order to develop control algorithms for an EMG controlled artificial larynx.

Setting

The Ear Institute, London.

Main outcome measures

EMG onset compared to voluntary cough exhalation onset and to 100ms (to give the artificial larynx the time to close the bioengineered vocal cords) before voluntary cough exhalation onset, in twelve healthy participants.

Results

In the 189 EMG of intercostal muscle detected voluntary coughs, 172 coughs (91% CI 70-112) were detected before onset of cough exhalation and 128 coughs (67.6% CI 33.7-101.7) 100ms before onset of cough exhalation. In the 158 EMG of diaphragm muscle detected voluntary coughs, 149 coughs (94.3% CI 76.3-112.3) were detected before onset of cough exhalation and 102 coughs (64.6% CI 26.6-102.6) 100ms before onset of cough exhalation. More coughs were detected before onset of cough exhalation when combining EMG activity of intercostal and diaphragm muscles and comparing this to intercostal muscle activity alone (183 coughs [96.8% CI 83.8-109.8] v 172 coughs, p=0.0294). When comparing the mentioned combination to diaphragm muscle activity alone, the higher percentage detected coughs before cough exhalation onset was not found to be significant (183 coughs v 149 coughs, p=0.295). In addition, more coughs were detected 100ms before onset of cough exhalation with the mentioned combination of EMG activity and comparing this to intercostal muscles alone (149 coughs [78.8% CI 48.8-108.8] v 128 coughs, p=0.0198) and to diaphragm muscles alone (149 coughs v 102 coughs, p=0.0038).

Conclusions

Most voluntary coughs can be predicted based on combined EMG signals of intercostal and diaphragm muscles and therefore these two muscle groups will be useful in controlling the bioengineered vocal cords within the artificial larynx during a voluntary cough.

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