Increased Respiratory Effort During Sleep is Non-invasively Detected with Movement Sensor

Introduction: Measuring breathing effort during sleep with an oesophageal pressure sensor remains technically challenging and has not become routine practice. The aim of the present work was to investigate whether increased thoracic pressure during sleep can be detected with the Emfit movement sensor. Experimental data suggest that increased respiratory efforts with the intrathoracic pressure variation induce high-frequency spikes in the Emfit signal, but this has not been systematically examined.

Methods: Polysomnography, oesophageal pressure and Emfit signal were recorded in 32 patients with suspected sleep-disordered breathing. Increased respiratory effort was defined as oesophageal pressure below -8 cmH(2)O during inspiration. The epochs of normal breathing, periodic breathing patterns and sustained spiking labelled as increased respiratory resistance (IRR) were defined on the Emfit signal according to established rules.

Results: Compared to normal breathing, the proportion of increased respiratory effort was higher during all periodic breathing with spiking. The highest proportion (18-23%) occurred during IRR, which is characterised by sustained spiking.

Conclusion: The Emfit movement sensor is a non-invasive alternative to the oesophageal pressure sensor in the assessment of the respiratory effort during sleep. In particular, the Emfit sensor enhances detection of non-apnoeic sleep-disordered breathing, the significance of which should not be ignored.