Nocturnal Desaturation in Patients with Chronic Obstructive Pulmonary Diseases

Abstract

This study included 34 patients with stable COPD, of whom ten patients were also studied during an infective exacerbation. The aim of this study was to identify predictors of noctumal desaturation in patients with COPD who have daytime oxygen saturation levels (Sa02>91%).

All patients were underwent a thorough history including a questionnaire about sleep disturbance and the associated symptoms during arousals at night (including headache, dyspnoea, cough, irritability, nightmares, daytime sleepiness and others), thorough clinical examination, pulmonary function testing (spirometry, lung volumes measurements, CO-Transfer factor measurements and blood gas analysis), mouth pressure measurement (Inspiratory and expiratoty) and 6 minute walking test in addition to ovemight oximetry.

Desaturation was defined as a decrease by more than 4% in oxygenation from the baseline saturation awake, for a period of 5 min or more. Fifty percent of our patients developed noctumal desaturation.

The desaturators reported more difficulty getting to sleep and staying asleep, more dyspnoea, snoring, restlessness, daytime sleepiness moming headache and less cough, when compared with the non desaturators.

There was significantly positive correlation between mean noctumal Sa02 and the following daytime parameters: Pa02, Sa02 and IMP. On the other hand, there was significantly negative correlation with PaC02, FRC and RV.

As regard the minimal nocturnal Sa02, there was significant positive correlation with the following daytime parameters: Pa02, Sa02 and IMP. TI1ere was a significant negative correlation with PaC02 and FRC.

• TI1e fall in noctumal Sa02 and the duration of noctumal fall in Sa02 expressed as a % of total sleep time correlated significantly with PaC02, RV and FRC (positiYe correlation), and IMP (negative correlation).

From all these daytime parameters, daytime Sa02 was the only independent parameter predicted noctumal desaturation. TI1e daytime Sa02accounted for 62.03% of the variability in the mean noctumal Sa02.