Piezoelectric belts as a method for measuring chest and abdominal movement for obstructive sleep apnea diagnosis

Distinguishing obstructive sleep apnea from central apnea depends upon accurate measure of chest and abdominal movement. American Academy of Sleep Medicine (AASM) polysomnography guidelines recommend the use of respiratory inductive plethysmography (RIP) belts but not piezoelectrode (PE) belts for measuring chest and abdominal movements. To compare these two sensors, we measured the signal amplitude for 10 RIP belts and 10 PE belts stretched by mechanical distraction across six distances (2.5 to 15.0 centimeters) and replicated 10 times for each belt. Amplitudes were measured using the Stellate Harmonie (Stellate Systems, Inc., Natus Medical, Inc., San Carlos, California, USA) recording system. A Pearson Product Moment Correlation coefficient was calculated. All RIP belts performed well at all distraction lengths and demonstrated linear performance. Eight of 10 PE belts performed well through all measures whereas, two showed nonlinear increase in signal on stretch of greater than 12.5 centimeters. Signals from PE belts highly correlated with the distance of distraction (r = 0.96 to 0.99) and the RIP belts (r = 0.98 to 0.99). These results suggest that PE belts perform similarly to RIP belts at distraction distances up to 10.0 centimeters. Further testing on biological models is needed to determine if PE belts are a suitable alternative for RIP belts in polysomnography.