Neural respiratory drive during apnoeic events in obstructive sleep apnoea

¹ Guangzhou Medical College, The State Key Laboratory of Respiratory Disease, China
² King's College Hospital, London, UK
³ Royal Brompton Hospital, London, UK

^* To whom correspondence should be addressed. E-mail: yuanmingluo9431{at}yahoo.co.uk.

	Abstract

For a given neural drive, oesophageal pressure during apnoeic episodes may differ from that during airflow, because inspiratory airflow and increased lung volume both reduce pressure generation. We therefore hypothesised that diaphragm electromyography may provide additional data to oesophageal pressure when used for the assessment of neural drive in patients with OSA whose breathing is associated with variable airflow and changes in lung volume.

We assessed neural respiratory drive with diaphragm EMG recorded from multipair oesophageal electrodes in twelve patients with OSA. Oesophageal pressure was also recorded.

The mean (SD) inspiratory oesophageal pressure swing was 11.0±3.7 cm H₂O during wakefulness, 38.2±15.7 cm H₂O at the end of the apnoea and reduced to 28.5±10.4 cm H₂O at the beginning of arousal. The mean peak inspiratory diaphragm EMG was 21.8±6.5 µV during wakefulness, and 38.6±14.0 µV at the end of the apnoea and further increased to 59.6±32.0 µV at the beginning of arousal.

We conclude that the pattern of neural drive assessed by oesophageal pressure differs from neural drive measured by diaphragm EMG during apnoeic events and, therefore, that diaphragm electromyography may be a useful adjunct to measurement of oesophageal pressure for assessment of neural drive in patients with OSA.

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