Use of the WatchPAT to detect occult residual sleep-disordered breathing in patients on CPAP for obstructive sleep apnea

Study Objectives: To determine the accuracy of the apnea-hypopnea index (AHI) as measured by continuous positive airway pressure (CPAP) machines by simultaneously employing a home sleep apnea testing device (WatchPAT 200, Itamar Medical, Israel [WPAT]) in patients suspected of having residual sleep-disordered breathing (SDB). Methods: Patients with new, recurrent, or worsening signs, symptoms, or comorbidities associated with obstructive sleep apnea underwent home sleep apnea testing using WPAT while simultaneously using CPAP at their usual prescribed settings. CPAP AHI and WPAT AHI, respiratory disturbance index, and oximetry readings were then compared. Results: We identified an elevated AHI with WPAT testing in nearly half of patients with clinically suspected residual SDB and a normal CPAPAHI. WPAT detected additional respiratory events as well, including rapid eye movement-related apneas, respiratory effort-related arousals, and hypoxemia. Conclusions: WPAT AHI was significantly higher than simultaneous CPAP AHI in nearly half of those patients with clinically suspected residual SDB being treated with CPAP. Additional respiratory disturbances, including rapid eye movement-related respiratory events, respiratory effort-related arousals, and hypoxemia, were elucidated only with the use of the WPAT. Residual SDB may have potential clinical consequences, including reduced CPAP adherence, ongoing hypersomnolence, and other health-related sequelae. Simultaneous WPAT testing of patients with a normal CPAP AHI may represent a valuable tool to detect clinically suspected residual SDB or to ensure adequate treatment in high-risk patients with obstructive sleep apnea in general.