Response to Braghiroli et al., regarding our study “Accuracy of a novel auto-CPAP device to evaluate the residual apnea-hypopnea index in patients with obstructive sleep apnea”

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

“…CPAP machine AHI was found to be accurate, but only 2 patients had AHI > 10 events/h on therapy. Nigro et al 27 found a slight underestimation of autoCPAP AHI vs PSG in 148 patients with OSA on CPAP, and absolute agreement between the 2 methodologies was low for obstructive apneas and hypopneas. In a bench model assessing 11 different commercially available autoCPAP devices in the treatment of simulated SDB, Zhu et al 28 demonstrated significant variability in bench-measured and CPAP device-reported residual AHI.…”

“…Although some studies have found CPAP machine quantification of residual respiratory events to be accurate, there is growing concern that both fixed and auto-adjusting CPAP machine reporting may be subject to error. 21,[23][24][25][26][27][28] We have observed patients with an acceptable CPAP data report in terms of compliance and machine-reported residual apnea-hypopnea index (AHI) who nevertheless manifest new, recurrent or worsening signs, symptoms, or comorbidities associated with OSA. These patients have a high clinical suspicion for having occult, residual SDB.…”

“…*P <.001 between Group 1 and Group 2 using Mann-Whitney U test. AHI = apnea-hypopnea index, CPAP = continuous positive airway pressure, ODI = oxygen desaturation index, RDI = respiratory disturbance index.SDB may occur in patients receiving either fixed CPAP (based on in-laboratory CPAP titration) or auto-adjusting CPAP, and the ability of CPAP machines to detect and treat these events has been increasingly scrutinized 21,[23][24][25][26][27][28]. We identified an elevated AHI with WPAT testing in nearly half of patients with clinically suspected residual SDB and a normal CPAP AHI.While previous studies have evaluated patients on CPAP with concomitant PSG to detect residual OSA, ours is the first to assess patients by comparing the CPAP data report derived AHI and WPAT AHI obtained simultaneously in the ambulatory setting.…”