Author(s): Meenakshi Narasimhan1, Radhika Sharma2, Aruna Shanmuganathan3, Viswambhar Vallabhaneni4, Ragulan Rajalingam5, Nisha Ganga6, Gangalamaran Mani7, Krishnaveni Renganathan8
Overlap syndrome was first described by David Flenley in 1980 refers to the coexistence of Chronic Obstructive Pulmonary Disease (COPD) and Obstructive Sleep Apnoea (OSA). The global prevalence of Overlap syndrome is 11-14% and 7.5% in India Overlap patients are at higher risk of developing Nocturnal desaturations, hypertension, congestive heart failure, stroke etc. resulting in greater mortality and morbidity. There are very few studies in India correlating factors like poor lung function, body mass index, high ESS score, MMRC dyspnea grading in COPD patients with OSA .Hence, this study was undertaken to correlate the association and severity of OSA using AHI with Forced Expiratory Volume in 1 sec (FEV1), Body Mass Index (BMI), Modified Medical Research Council dyspnea grade (MRC) and high Epworth Sleepiness Scale (ESS).
MATERIALS AND METHODS
A prospective observational study, done in 66 COPD patients in Department of Respiratory Medicine, CHRI, Chennai. The diagnosis of COPD was based upon GOLD guidelines 2016. The OSA was diagnosed based on the American Academy of Sleep Medicine guidelines (AASMA). All COPD patients were subjected to detailed clinical history, thorough physical examination, ENT examination to rule out Upper airway obstruction. All patients were asked to fill up the Epworth sleepiness questionnaire. BMI was recorded. Dyspnea grading was done using MMRC scale. Patient was also subjected to Spirometry and overnight Polysomnography,
In patients with overlap syndrome, no correlation of statistical significance between the AHI and FEV1. Though, the grade of AHI showed an increase as the FEV1 decreased. Significant positive correlation was observed between AHI and MMRC as well as AHI and ESS.
In COPD patients FEV1 did not correlate with AHI grade and hence lung function cannot be used as predictor of OSA in COPD. However, simple clinical parameters like ESS and MMRC which show a positive correlation with AHI grade may be utilized to assess the presence of OSA.