Background. COPD and allied conditions rank as the 7th leading cause of mortality in the Philippines affecting approximately 24.3 per 100,000 Filipinos. (2) In patients with COPD, respiratory physiologic changes during sleep may have pronounced impact on gas exchange and profound hypoxemia may develop, especially during rapid eye movement (REM) sleep. (1) This study aimed to determine the occurrence of nocturnal oxygen desaturation among Filipino COPD and identified associated variables.
Methods. This is a prospective study involving Filipino COPD patients who underwent overnight polysomnography at the Philippine Heart Center Sleep Clinic. Sixteen stable COPD patients, underwent overnight polysomnography at the Philippine Heart Center, Sleep Clinic and were divided into desaturators (NOD) and nondesaturators (NNOD) on the basis of showing a percentage of total nocturnal recording time spent with an Sa02 of <90% (T90) of ~ 30% total sleep time.
Results. Six patients experienced nocturnal oxygen desaturation (NOD). Of these, three patients had overlap syndrome. Desaturators (NOD) are heavier, with increased BMI, had lower awake pa02, higher pC02, lower FEV1% and FEV1/FVC % , lower sleep efficiency, shorter REM sleep, longer percent wake duration, and had increased arousal index than non-desaturators (NNOD). There was a significant correlation between nocturnal oxygen desaturation and average awake Pa02 ( r= -0.7759 and p value=0.005), mean Pa02 (r= -0.6682 and P value= 0.005) average 02 at REM and NREM (r=-O.7272 and .-0.6655 , P value= 0.002 and 0.004 respectively), Sa02 <90% total sleep time REM and NREM (r=0.9978 , p value=O.OOOand r=0.8370 p value=O.OOO), and duration of REM and NREM sleep (r= 0.7970 and p value= .000, r =0.9523 p value= 0.00).
Conclusion. Nocturnal oxygen desaturation (NOD) occurs in 37.5% of Filipino COPD patients and overlap syndrome exists by 18.75%. Desaturators (NOD) had lower awake pa02, higher pC02 level, lower FEV1 % and FEV1/FVC %, with poor sleep efficiency, lower REM sleep, longer percent wake duration, and with increased arousal index.