The association between sleep-related breathing disorders and pre-capillary pulmonary hypertension: A chicken and egg question.

The level of knowledge about a direct link between sleep-related breathing disorders and pre-capillary pulmonary hypertension (PH) is low and there is a chicken and egg question to know which disease causes the other. On one hand, sleep-related breathing disorders are considered as a cause of group 3 PH, in the subgroup of patients with hypoxemia without lung disease. Indeed, isolated sleep-related breathing disorders can lead to mild pre-capillary PH on their own, although this is rare for obstructive sleep apnea and difficult to establish for obesity-hypoventilation syndrome, the evolution towards PH being observed especially in the presence of respiratory comorbidities. The hemodynamic improvement under treatment with continuous positive airway pressure or non-invasive ventilation also argues for a causal link between pre-capillary PH and sleep-related breathing disorders. On the other hand, patients followed for pre-capillary PH, particularly pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension, develop more sleep-related breathing disorders than the general population, especially sleep hypoxemia, central sleep apnea in patients with severe PH and obstructive sleep apnea in older patients with higher body mass index. The main objective of this article is therefore to answer two main questions, which will then lead us to discuss the bilateral link between these diseases: are sleep-related breathing disorders independent risk factors for pre-capillary PH and does pre-capillary PH induce sleep-related breathing disorders? In other words, who is the chicken and who is the egg?

[Liver diseases and pulmonary vascular disorders]. / Hépatopathies et maladies vasculaires pulmonaires.

About 70% patients waiting for liver transplantation have a dyspnea. Two pulmonary vascular disorders can be associated with portal hypertension or chronic liver diseases: portopulmonary hypertension (PoPH) related to pulmonary small arteries remodeling and obstruction and hepatopulmonary syndrome (HPS) characterized by pulmonary capillaries dilatations and proliferations. PoPH is defined by the combination of pulmonary arterial hypertension (PAH) (mean pulmonary artery pressure [PAP]≥25mmHg, with normal pulmonary artery wedge pressure≤15mmHg and pulmonary vascular resistance [PVR]>3 Wood units [WU]) and portal hypertension. HPS is a triad of intrapulmonary vascular dilatations, hypoxemia (increased alveolar-arterial oxygen gradient) and liver disease or isolated portal hypertension. The pathophysiology of both syndromes is complex and poorly understood. PoPH and HPS have a negative impact on functional and vital prognosis in patients with portal hypertension. Liver transplantation is the established treatment standard in HPS. PoPH treatment is improved over the years with the use of specific PAH treatment despite the lack of randomized assay in this indication. Liver transplantation could be considered in PoPH leading to stabilization, improvement or recovery in selected patients (mean PAP<35mmHg without severe right ventricular dysfunction and PVR<4 WU).

[Pulmonary manifestations of antisynthetase syndrome]. / Les manifestations pulmonaires du syndrome des antisynthétases.

Antisynthetase syndrome is an inflammatory myopathy frequently associated with pulmonary manifestations, especially interstitial lung diseases, and uncommonly pulmonary hypertension. In the context of a suggestive clinical and radiological picture, positive anti-RNA synthetase antibodies confirm the diagnosis. Anti-Jo1, anti-PL7, and anti-PL12 antibodies are the more commonly encountered. The presence of a number of extra-thoracic manifestations in association with pulmonary disease may suggest the diagnosis. These include: myalgia or muscular deficit, Raynaud's phenomenon, polyarthritis, fever, mechanics hands. Serum creatine kinase levels are usually increased. Electromyogram, muscular magnetic resonance imaging or muscle pathology are not mandatory to make the diagnosis. There is a high variability in symptoms and severity, between patients but also during the course of the disease in the same patient. The presence of an interstitial lung disease is a major prognostic factor and an indication for more intensive treatment, principally with systemic corticosteroids with or without immunosuppressive drugs. Improving respiratory physicians' knowledge of this disease, which is often revealed by its pulmonary manifestations, should help diagnosis, therapeutic management, and possibly prognosis.