17 Aug 08

Diagnosis and initial management of obstructive sleep apnea without polysomnography

Posted in Obstructive sleep apnea at 11:20 by Laci

By A T Mulgrew, N Fox, N T Ayas and C F Ryan

Ann Intern Med 2007;146:157-166

Polysomnography (PSG), despite limited availability and high cost, is currently recommended for diagnosis of obstructive sleep apnea and titration of effective continuous positive airway pressure (CPAP).

Objective
To test the utility of a diagnostic algorithm in conjunction with ambulatory CPAP titration in initial management of obstructive sleep apnea.

Design
A randomized, controlled, open-label trial that compared standard PSG with ambulatory CPAP titration in high-risk patients identified by a diagnostic algorithm.

Setting
A tertiary referral sleep disorders program in Vancouver, British Columbia, Canada.

Patients
68 patients with a high pretest probability of moderate to severe obstructive sleep apnea (apnea–hypopnea index [AHI] >15 episodes/h) identified by sequential application of the Epworth Sleepiness Scale (ESS) score, Sleep Apnea Clinical Score, and overnight oximetry.

Intervention
Patients were randomly assigned to PSG or ambulatory titration by using a combination of auto-CPAP and overnight oximetry. They were observed for 3 months.

Measurements
Apnea–hypopnea index on CPAP, ESS score, quality of life, and CPAP adherence.

Results
The PSG and ambulatory groups had similar median BMI (38 kg/m2), age (55 years), ESS score (14 points), and respiratory disturbance index (31 episodes of respiratory disturbance/h). Each episode is determined by a computer algorithm based on analysis of oxygen saturation measured by pulse oximetry. After 3 months, there were no differences in the primary outcome, AHI on CPAP (median, 3.2 vs. 2.5; difference, 0.8/h [95% CI, –0.9 to 2.3]) (P = 0.31), between the PSG and ambulatory groups, or in the secondary outcomes, ESS score, Sleep Apnea Quality of Life Index, and CPAP. Adherence to CPAP therapy was better in the ambulatory group than in the PSG group (median, 5.4 vs. 6.0; difference, –1.12 h/night [CI, –2.0 to 0.2]) (P = 0.021).

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