Assessment of thoracoabdominal bands to detect respiratory effort-related arousal.

It would be helpful to be able to identify respiratory effort-related arousal (RERA) without needing to measure oesophageal pressure. Thoracoabdominal movements yield an indirect flow measurement from which reduction of amplitude and alteration of the inspiratory flow curve can be detected. The aim of this study was to evaluate the accuracy of using the shape and amplitude of signals from thoracoabdominal bands (inductance plethysmography) to detect RERAs. Altogether, 94 subjects suspected of having sleep apnoea but with an apnoea/hypopnoea index < or = 10 in full polysomnography with oesophageal pressure were studied. A routine polysomnographical analysis was carried out. The polysomnographies were then reanalysed at random to determine which of the identified arousals were due to RERA, as determined either by oesophageal pressure or by induction bands without an oesophageal pressure signal. Altogether, 14,617 arousals were analysed. The sensitivity and specificity to find RERA (arousal by arousal) from bands versus oesophageal pressure were both 94%. The average difference of RERA index between oesophageal pressure and bands was -0.6. The correlation between RERA index determined by oesophageal pressure and bands was 0.98. To evaluate the intra and interobserver agreement, 1183 arousals were additionally analysed. The intraobserver agreement was 91% for RERAs by oesophageal pressure and 80% by bands. The interobserver agreement was 89% by oesophageal pressure and 85% by bands. The thoracoabdominal bands can be used to identify respiratory effort-related arousal (obstructive events not detected by thermistor) with similar efficacy to oesophageal pressure measurement. Since bands are routinely used in most polysomnographies, they can be used as the usual method to detect respiratory effort-related arousal, using a thermistor to evaluate apnoeas and hypopnoeas or as a complement to other methods, such as nasal cannula, which can detect apnoeas, hypopnoeas and respiratory effort-related arousal.