Pulmonary haemodynamics in patients with OSAS or an overlap syndrome

Abstract

Background. Alveolar hypoxia is the most important mechanism leading to pulmonary arterial vasoconstriction, remodelling and pulmonary hypertension. Patients with Obstructive Sleep Apnoea Syndrome (OSAS) experience multiple short periods of alveolar hypoxia during apnoeic episodes. However, the question as to whether these hypoxic episodes are responsible for the development of permanent pulmonary hypertension is still debatable. We aimed to investigate the relationship between the episodes of nocturnal desaturation and pulmonary haemodynamics in two distinct group patients: with pure OSAS or an overlap syndrome. Methods: We studied 67 patients with severe OSAS (means: age 45±8 years, AHI 62±22, FEV1 3.6±0.8 L = 97±16% of predicted PaO2 72±10 mmHg, PaCO2 40±4 mmHg) and 17 patients with an overlap syndrome (OS), means: age 51±5 years, AHI 64±19, FEV1 1.5±0.7 = 43±16% of predicted PaO2 57±9 mmHg). All subjects underwent pulmonary artery catheterisation with pressure and flow recordings and an overnight full sleep study. Results. On average patients with OSAS had nocturnal desaturation (mean overnight SaO2 = 87±5%) and normal PPA (15.8±4.6 mmHg). Only 11 out of 67 subjects (16%) presented with pulmonary hypertension. Patients with OS had nocturnal desaturation (mean overnight SaO2 = 80.2±8.5%) and mild pulmonary hypertension (PPA 24.2±7.4 mmHg). Only three out of 17 patients had normal pulmonary arterial pressure. Conclusions. In patients with severe OSAS, pulmonary hypertension is rare (16%) and is related best to the severity of the disease and to obesity. In OS patients diurnal pulmonary hypertension is frequent but does not correlate with the severity of nocturnal desaturation.

Sleep Disorders in Chronic Obstructive Pulmonary Disease: Etiology, Impact, and Management

“…131 In one case series, pulmonary hypertension was observed in 86% of those with COPD comorbid with OSA (n = 17) compared to only 16% of patients with OSA but no COPD (n = 67). 132 The incidence of right heart failure in comorbid COPD and OSA was 12% in another case series, and was associated with lower mean nocturnal oxygen saturation, lower awake PaO 2 , and higher PaCO 2 .…”

Supplemental Oxygen Needs During Sleep. Who Benefits?

“…[66][67][68][69][70][71][72][73] For example, Hawrylkiewicz and colleagues observed that 16% of those with OSA had pulmonary hypertension, compared with 86% of those with overlap syndrome. 74 Several pulmonary parameters have been shown to increase mortality in patients with OSA. Both the diagnosis of concomitant COPD and markers of COPD, such as a reduced FEV 1 or smoking history, have been shown to be markers for increased mortality in OSA patients.…”

The Right Heart Diaries in Sleep Disordered Breathing

“…Increased sympathetic surges associated with IH as compared to the continuous hypoxia (55) may reflect the oxidative stress produced by rebound hyperemia. Oxidative insult promotes the release of proinflammatory mediators, such as cyclo-oxygenase-2, tumor necrosis factor-alpha, and interleukins (56-58) leading to systemic inflammation, endothelial dysfunction and culminating in vascular non compliance (59). The dysfunctional endothelium has been observed in SDB patients without any overt vascular disease and is a precursor to atherogenesis, thrombogenesis, and reduced vascular lumen (54,55,60).…”