Impaired endothelial vasoreactivity and markers of systemic inflammation in overlap syndrome

Abstract

Introduction Impairment of systemic endothelial reactivity (SER) has been observed in Chronic Obstructive Pulmonary Disease (COPD) and Obstructive Sleep Apnea (OSA). The present study investigates the relation between SER and systemic inflammation in patients of Overlap Syndrome (OS) of COPD and OSA.

Methods The study was conducted on 31 COPD patients and 14 healthy controls. On the basis of polysomnography, the patients were divided into COPD only group [Apnea-Hypopnea Index (AHI)< 5] (n=16) and OS group (AHI > 5) (n= 15). SER was assessed by measuring changes in pulse wave amplitude (PWA), Maximum slope of upstroke (MSU) and Pulse Transit Time (PTT) derived from the photoplethysmographic waveform during reactive hyperemia (RH). Additionally, C-reactive protein(CRP) in serum was estimated by ELISA.

Results Maximum percentage change in PWA during RH was significantly lower in COPD only group [23.61% (12.02-34.07) p<0.001] as well as OS group [10.71%(6.196-21.95) p<0.0001] in comparison to controls [49.31%(46.44-62.01)], whereas the amplitude responses between the COPD and OS group were not significant (p>0.05).Similar responses were seen in MSU in all the groups. CRP levels were higher in COPD (p<0.001) and OS group (p<0.0001). Maximum percentage change in PWA negatively correlated with CRP levels in COPD(r= -0.5695) and OS group (r= -0.5214) and positively correlated with FEV1% predicted in COPD and OS group. AHI did not correlate with vascular function parameters in Overlap group.

Conclusion The patients with Overlap Syndrome have impaired SER which correlates with CRP levels. However, no additive effect of OSA was observed on impaired SER in patients with Overlap Syndrome.