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Accuracy of Auto-CPAP in Estimating the Residual Apnea-Hypopnea Index in Patients With Obstructive Sleep Apnea FREE TO VIEW

Facundo Nogueira, MD; Sofía Grandval, MD; Pablo Micci
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Instituto Argentino de Investigación Neurológica, Buenos Aires, Argentina

Chest. 2010;138(4_MeetingAbstracts):887A. doi:10.1378/chest.10926
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PURPOSE: Auto-CPAP devices may be used to determine a fixed CPAP pressure for patients with Obstructive Sleep Apnea (OSA). Integrated circuits can record data from CPAP machines (CPAP pressure and usage, leak) and are able to estimate the Apnea-Hypopnea Index (AHI) under CPAP. One potential way to objectively determine efficacy of auto-CPAP treatment or titration is to follow the estimated residual AHI. The aim of our study was to determine the accuracy of auto-CPAP in estimating the residual AHI in patients with OSA who are being treated or titrated with auto-CPAP.

METHODS: Patients with polysomnographic (PSG) diagnosis of moderate to severe OSA, who returned to our sleep unit for an attended PSG using auto-CPAP (ResMed). Expert scorer manually analyzed every PSG and data from auto-CPAP were collected (CPAP pressure, air leak and residual AHI). Studies with a leak bigger than 0.6 L/sec were discarded. AHI from auto-CPAP were compared with those obtained by manual PSG scoring. Differences were calculated in every case and patients were classified in two groups according to these differences (> or < 5 ev/h). Correlation between manually scored PSG and auto-CPAP in classifying patients with a residual IAH > and <5ev/h was also calculated.

RESULTS: Over 80 cases 68 patients were recruited and 12 were discharged due to excessive leak. 52/68 males; 54.0 ± 12.5ys; BMI 33.3 ± 7.5; basal AHI 35.1 ± 24.8 ev/h; P95 CPAP 11.4 ± 2.8 cmH2O. Mean AHI calculated by auto-CPAP was 6.15 ± 10.3 vs. 4.4 ± 9.9 by PSG. In 55/67 patients (80.8%) the difference between both AHI was < 5 ev/h. Correlation in categorization of patients by their residual IAH for two methods was 0.76 (p=0.05). Populations of patients with differences > or <5ev/h were similar.

CONCLUSION: Auto-ACPAP machines are able to calculate residual AHI quite accurately.

CLINICAL IMPLICATIONS: Auto-CPAP residual AHI could be considered a very useful tool to evaluate the auto-CPAP efficacy when we titrate o even treat OSA patients with these devices.

DISCLOSURE: Facundo Nogueira, No Financial Disclosure Information; No Product/Research Disclosure Information

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