Pulmonary function in primary pulmonary hypertension

Reduced hemoglobin-corrected diffusing capacity in pulmonary arterial hypertension with preserved pulmonary function and morphology

BACKGROUND

The diffusing capacity and the transfer coefficient of the lung for carbon monoxide (DLCO and KCO, respectively) are reduced in pulmonary arterial hypertension; however, the effect of pulmonary arterial hypertension alone on these parameters and their clinical impact remain unclear. We aimed to elucidate the exclusive impact of pulmonary arterial hypertension on these two parameters and examine their association with other parameters.

METHODS

We retrospectively selected patients with pulmonary arterial hypertension with normal pulmonary function upon pulmonary function testing and with normal lung parenchyma upon chest computed tomography. We calculated the hemoglobin-corrected DLCO (DLCO-Hbc) and KCO (KCO-Hbc) and examined their association with established pulmonary hypertension-related parameters. An exploratory analysis of pulmonary vasculopathy was performed in an autopsy case.

RESULTS

We included 50 patients with pulmonary arterial hypertension for analysis. Their median %DLCO-Hbc and %KCO-Hbc were 62 % and 70 %, respectively. The DLCO-Hbc was associated with functional class, 6-min walk distance, alveolar-arterial oxygen tension difference, cardiac output, and pulmonary arterial hypertension-related death. The DLCO-Hbc and KCO-Hbc were also correlated with the lowest minute ventilation/carbon dioxide production ratio (ρ = -0.84 and -0.49, respectively), an index that represents ventilation-perfusion mismatch. The autopsy revealed pulmonary arterial hypertension-specific arteriopathy that was heterogeneously distributed in the lungs.

CONCLUSIONS

The DLCO-Hbc and KCO-Hbc were reduced to 60 %-70 % in patients with pulmonary arterial hypertension even when their pulmonary function and morphology were preserved. The decreases were associated with pulmonary hypertension-related clinical parameters and survival and may be caused by heterogeneous vasculopathy and subsequent ventilation-perfusion mismatch.

Management of Critically Ill Patients With Pulmonary Arterial Hypertension in Transport: A Narrative Review

Pulmonary arterial hypertension (PAH) is a unique disease process with a highly complex physiology. Patients with PAH are often on specialized medications that exert specific hemodynamic effects. Furthermore, when they become critically ill, the management strategy can be counterintuitive. Commonly accepted, evidence-based management for the general population, such as fluid boluses in the setting of sepsis, can be harmful to this patient cohort. Often, these patients require highly specialized care at tertiary and quaternary centers, which necessitates critical care transport. Therefore, it is important that critical care transport crews understand the distinctive pathophysiology and management of critically ill patients with PAH.

Cardiopulmonary Exercise Testing in Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) is a progressive pulmonary vascular disease that has a high impact on patients' quality of life, morbidity and mortality. PAH is characterized by extensive pulmonary vascular remodeling that results in an increase in pulmonary vascular resistance and right ventricular afterload, and can lead to right heart failure. Patients with PAH exhibit inefficient ventilation, high dead space ventilation, dynamic hyperinflation, and ventricular-arterial uncoupling, which can contribute to high dyspnea and low exercise tolerance. Cardiopulmonary exercise testing can help to diagnose PAH, define prognosis and treatment response in PAH, as well as discriminate between different pulmonary vascular diseases.

Pulmonary arterial hypertension: Navigating the pathways of progress in diagnosis, treatment, and patient care

Pulmonary arterial hypertension (PAH) is a form of precapillary pulmonary hypertension caused by a complex process of endothelial dysfunction and vascular remodeling. If left untreated, this progressive disease presents with symptoms of incapacitating fatigue causing marked loss of quality of life, eventually culminating in right ventricular failure and death. Patient management is complex and based on accurate diagnosis, risk stratification, and treatment initiation, with close monitoring of response and disease progression. Understanding the underlying pathophysiology has enabled the development of multiple drugs directed at different targets in the pathological chain. Vasodilator therapy has been the mainstay approach for the last few years, significantly improving quality of life, functional status, and survival. Recent advances in therapies targeting dysfunctional pathways beyond endothelial dysfunction may address the fundamental processes underlying the disease, raising the prospect of increasingly effective options for this high-risk group of patients with a historically poor prognosis.

Sleep-related disorders in patients with precapillary pulmonary hypertension

Precapillary pulmonary hypertension (PcPH) is associated with the development of sleep-related disorders and impairment of sleep quality. With growing recognition of the clinical relevance of sleep-related conditions in PcPH, this narrative review seeks to discuss the spectrum of disorders encountered in clinical practice, pathophysiological mechanisms linking PcPH with sleep-related disorders, and potential therapeutic considerations. Current evidence demonstrates a higher prevalence of impaired sleep quality, sleep-disordered breathing, sleep-related hypoxia, and restless leg syndrome in patients with PcPH. These sleep-related disorders could further lead to impairment of quality of life in a patient population with already a high symptom burden. Recent data suggest that sleep-related hypoxia is strongly linked to worse right ventricular function and higher risk of transplantation or death. However, limited studies have investigated the role of oxygen therapy or positive airway pressure therapy improving symptoms or outcomes. Abnormal iron homeostasis is highly prevalent in PcPH and may contribute to the development of restless legs syndrome/periodic limb movement of sleep. To improve sleep management in PcPH, we highlight future research agenda and advocate close collaboration between pulmonary hypertension specialists and sleep physicians.

Diagnosis and Management of Pulmonary Hypertension: New Insights

Over the last decades, significant progress has been achieved in the pulmonary hypertension (PH) field. Pathophysiology of PH has been studied, leading to the classification of PH patients into five groups, while the hemodynamic definition has been recently revised. A diagnostic algorithm has been established and awareness has been raised in order to minimize diagnosis delay. The pulmonary arterial hypertension (PAH) treatment strategy includes the established three pathways of endothelin, nitric oxide-phosphodiesterase inhibitor, and prostacyclin pathway, but new therapeutic options are now being tested. The aim of this review is to summarize the existing practice and to highlight the novelties in the field of PH.

Sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary disease

BACKGROUND AND AIMS

Sleep-disordered breathing (SDB) and nocturnal hypoxemia were known to be present in patients with chronic thromboembolic pulmonary hypertension (CTEPH), but the difference between SDB and nocturnal hypoxemia in patients who have chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) at rest remains unknown.

METHODS

Patients who had CTEPH (n = 80) or CTEPD without PH (n = 40) and who had undergone sleep studies from July 2020 to October 2022 at Shanghai Pulmonary Hospital were enrolled. Nocturnal mean SpO2 (Mean SpO2) <90% was defined as nocturnal hypoxemia, and the percentage of time with a saturation below 90% (T90%) exceeding 10% was used to evaluate the severity of nocturnal hypoxemia. Logistic and linear regression analyses were performed to investigate the difference and potential predictor of SDB or nocturnal hypoxemia between CTEPH and CTEPD without PH.

RESULTS

SDB was similarly prevalent in CTEPH and CTEPD without PH (P = 0.104), both characterised by obstructive sleep apnoea (OSA). Twenty-two patients with CTEPH were diagnosed with nocturnal hypoxemia, whereas only three were diagnosed with CTEPD without PH (P = 0.021). T90% was positively associated with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance in patients with CTEPH and CTEPD without PH (P < 0.001); T90% was also negatively related to cardiac output in these patients. Single-breath carbon monoxide diffusing capacity, sex and mPAP were all correlated with nocturnal hypoxemia in CTEPH and CTEPD without PH (all P < 0.05).

CONCLUSION

Nocturnal hypoxemia was worse in CTEPD with PH; T90%, but not SDB, was independently correlated with the hemodynamics in CTEPD with or without PH.

Prognostic value of pulmonary diffusing capacity for carbon monoxide and ventilation-perfusion SPECT findings in pulmonary arterial hypertension

Reduced pulmonary diffusing capacity for carbon monoxide (DLCO) can be observed in pulmonary arterial hypertension (PAH) and associates with increased mortality. However, the prognostic value of DLCO when corrected for haemoglobin (DLCOc), an independent modifier of DLCO, remains understudied. Additionally, the prognostic role of ventilation (V)-perfusion (Q) emission computed tomography (V/Q SPECT) findings in patients with PAH, which may concurrently be performed to rule out chronic thromboembolic pulmonary hypertension, is uncertain. A retrospective cohort study was conducted on 152 patients with PAH referred to a tertiary hospital for evaluation from January 2011 to January 2020. Lung function tests, clinical data and V/Q SPECT were ascertained. Cox regression analysis was performed to evaluate the association between DLCOc, DLCO and V/Q SPECT defects at referral with all-cause mortality. In equally adjusted Cox regression analysis, each percentage increase in DLCOc % predicted (%pred) (hazard ratio (HR) 0.97; 95% CI: 0.94-0.99) and DLCO%pred (HR 0.97; 95% CI: 0.94-0.99) was similarly associated with all-cause mortality. There was no detectable difference in area under the curve for prediction of all-cause mortality by DLCOc%pred and DLCO%pred (C-index 0.71 and 0.72, respectively, P = 0.85 for difference). None of the defects noted on V/Q SPECT were significantly associated with mortality, but mismatched defects were associated with lower values of DLCOc%pred and DLCO%pred. DLCOc%pred and DLCO%pred perform equally as prognostic markers in PAH, supporting the use of either metric when available for prognostic stratification.

Pulmonary hypertension impairs vasomotor function in rat diaphragm arterioles

Pulmonary hypertension (PH) is a chronic, progressive condition in which respiratory muscle dysfunction is a primary contributor to exercise intolerance and dyspnea in patients. Contractile function, blood flow distribution, and the hyperemic response are altered in the diaphragm with PH, and we sought to determine whether this may be attributed, in part, to impaired vasoreactivity of the resistance vasculature. We hypothesized that there would be blunted endothelium-dependent vasodilation and impaired myogenic responsiveness in arterioles from the diaphragm of PH rats. Female Sprague-Dawley rats were randomized into healthy control (HC, n = 9) and monocrotaline-induced PH rats (MCT, n = 9). Endothelium-dependent and -independent vasodilation and myogenic responses were assessed in first-order arterioles (1As) from the medial costal diaphragm in vitro. There was a significant reduction in endothelium-dependent (via acetylcholine; HC, 78 ± 15% vs. MCT, 47 ± 17%; P < 0.05) and -independent (via sodium nitroprusside; HC, 89 ± 10% vs. MCT, 66 ± 10%; P < 0.05) vasodilation in 1As from MCT rats. MCT-induced PH also diminished myogenic constriction (P < 0.05) but did not alter passive pressure responses. The diaphragmatic weakness, impaired hyperemia, and blood flow redistribution associated with PH may be due, in part, to diaphragm vascular dysfunction and thus compromised oxygen delivery which occurs through both endothelium-dependent and -independent mechanisms.

Managing Pulmonary Arterial Hypertension With Cardiopulmonary Comorbidities

Pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with left-sided heart and lung diseases are most commonly easily discriminated and treated accordingly. With the changing epidemiology of PAH, however, a growing proportion of patients at the time of diagnosis present with comorbidities of varying severity. In addition to classical PAH, two distinct phenotypes have emerged: a heart failure with preserved ejection fraction-like phenotype and a lung phenotype. Importantly, the evidence supporting the currently proposed treatment algorithm for PAH has been generated mainly from PAH trials in which patients with cardiopulmonary comorbidities have been underrepresented or excluded. As a consequence, the best therapeutic approach for patients with common PAH with cardiopulmonary comorbidities remains largely unknown and requires further investigation. The present article reviews the relevant literature on the topic and describes the authors' views on the current therapeutic approach for these patients.

Pulmonary hypertension in connective tissue diseases: What every CTD specialist should know - but is afraid to ask!

Pulmonary hypertension (PH) is a possible complication of connective tissue diseases (CTDs), especially systemic sclerosis (SSc), systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). It is defined by an elevation of the mean pulmonary arterial pressure above 20mmHg documented during a right heart catheterization (RHC). Due to their multiorgan involvement, CTDs can induce PH by several mechanisms, that are sometimes intricated: pulmonary vasculopathy (group 1) affecting arterioles (pulmonary arterial hypertension, PAH) and possibly venules (pulmonary veno-occlusive-like disease), left-heart disease (group 2), chronic lung disease (group 3) and/or chronic thromboembolic PH (group 4). PH suspicion is often raised by clinical manifestations (dyspnea, fatigue), echocardiographic data (increased peak tricuspid regurgitation velocity), isolated decrease in DLCO in pulmonary function tests, and/or unexplained elevation of BNP/NT-proBNP. Its formal diagnosis always requires a hemodynamic confirmation by RHC. Strategies for PH screening and RHC referral have been extensively investigated for SSc-PAH but data are lacking in other CTDs. Therapeutic management of PH depends of the underlying mechanism(s): PAH-approved therapies in group 1 PH (with possible use of immunosuppressants, especially in case of SLE or MCTD); management of an underlying left-heart disease in group 2 PH; management of an underlying chronic lung disease in group 3 PH; anticoagulation, pulmonary endartectomy, PAH-approved therapies and/or balloon pulmonary angioplasty in group 4 PH. Regular follow-up is mandatory in all CTD-PH patients.

Diagnostic value of combined FVC%/DLCO% and echocardiography in connective tissue disorder‑associated pulmonary hypertension

The main objective of the present study was to investigate whether forced vital capacity (FVC)%/diffusing capacity of the lungs for carbon monoxide (DLCO)% can be used to predict the presence of pulmonary hypertension (PH) in connective tissue disorders (CTDs). For this purpose, a total of 53 individuals who were diagnosed with CTDs and had undergone right heart catheterization between July, 2019 and July, 2022 were included in the present study. Based on the mean pulmonary artery pressure (mPAP) measured during right heart catheterization, the participants were divided into the PH and non-PH groups. The differences in demographic characteristics, including sex, age, body mass index, smoking index, FVC%/DLCO% and pulmonary artery systolic pressure (PASP) were determined by echocardiography; moreover, the 6-min walk distance, plasma brain natriuretic peptide (BNP) levels, white blood cell count, red blood cell distribution width, erythrocyte sedimentation rate and C-reactive protein levels were compared between the two groups to identify independent predictors of PH. The independent predictors were subsequently evaluated for their correlation with mPAP to assess their predictive value for PH. FVC%/DLCO%, echocardiographic PASP, and plasma BNP levels were identified as independent predictors of PH. FVC%/DLCO% and echocardiographic PASP exhibited a significant correlation with mPAP, while the correlation between plasma BNP and mPAP levels was not statistically significant. The area under the curve (AUC) value for FVC%/DLCO% alone in predicting PH was 0.791, with an optimal diagnostic threshold of 1.35, a sensitivity of 0.794 and a specificity of 0.789. The AUC for echocardiographic PASP alone in predicting PH was 0.783, with an optimal diagnostic threshold of 39.5 mmHg, a sensitivity of 0.794 and a specificity of 0.684. When combined, the AUC of the two factors in predicting PH was 0.872, with a sensitivity of 0.941 and a specificity of 0.684. Collectively, the data of the present study indicate that FVC%/DLCO% may be used as a predictive factor for CTD-PH, and its combined application with echocardiographic PASP measurement may provide additional evidence for the clinical diagnosis of CTD-PH.

Pulmonary hypertension alters blood flow distribution and impairs the hyperemic response in the rat diaphragm

Pulmonary hypertension (PH) is characterized by pulmonary vascular remodeling, respiratory muscle and cardiac impairments, and exercise intolerance. Specifically, impaired gas exchange increases work of the diaphragm; however, compromised contractile function precludes the diaphragm from meeting the increased metabolic demand of chronic hyperventilation in PH. Given that muscle contractile function is in part, dependent upon adequate blood flow (Q ˙ ), diaphragmatic dysfunction may be predicated by an inability to match oxygen delivery with oxygen demand. We hypothesized that PH rats would demonstrate a decreased hyperemic response to contractions compared to healthy controls. Methods: Sprague-Dawley rats were randomized into healthy (HC, n = 7) or PH (n = 7) groups. PH rats were administered monocrotaline (MCT) while HC rats received vehicle. Disease progression was monitored via echocardiography. Regional and total diaphragm blood flow and vascular conductance at baseline and during 3 min of electrically-stimulated contractions were determined using fluorescent microspheres. Results: PH rats displayed morphometric and echocardiographic criteria for disease (i.e., acceleration time/ejection time, right ventricular hypertrophy). In all rats, total costal diaphragm Q ˙ increased during contractions and did not differ between groups. In HC rats, there was a greater increase in medial costal Q ˙ compared to PH rats (55% ± 3% vs. 44% ± 4%, p < 0.05), who demonstrated a redistribution of Q ˙ to the ventral costal region. Conclusion: These findings support a redistribution of regional diaphragm perfusion and an impaired medial costal hyperemic response in PH, suggesting that PH alters diaphragm vascular function and oxygen delivery, providing a potential mechanism for PH-induced diaphragm contractile dysfunction.

The Diagnostic Approach to Pulmonary Hypertension

The clinical presentation of pulmonary hypertension (PH) is nonspecific, resulting in significant delays in its detection. In the majority of cases, PH is a marker of the severity of other cardiopulmonary diseases. Differential diagnosis aimed at the early identification of patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) who do require specific and complex therapies is as important as PH detection itself. Despite all efforts aimed at the noninvasive assessment of pulmonary arterial pressure, the formal confirmation of PH still requires catheterization of the right heart and pulmonary artery. The current document will give an overview of strategies aimed at the early diagnosis of PAH and CTEPH, while avoiding their overdiagnosis. It is not intended to be a replica of the recently published European Society of Cardiology (ESC) and European Respiratory Society (ERS) Guidelines on Diagnosis and Treatment of Pulmonary Hypertension, freely available at the Web sites of both societies. While promoting guidelines' recommendations, including those on new definitions of PH, we will try to bring them closer to everyday clinical practice, benefiting from our personal experience in managing patients with suspected PH.

[Diagnostic Algorithm and Screening of Pulmonary Hypertension]

The new guidelines for the diagnosis and treatment of pulmonary hypertension include a new diagnostic algorithm and provide specific recommendations for the required diagnostic procedures, including screening methods. These recommendations are commented on by national experts under the auspices of the DACH. These comments provide additional decision support and background information, serving as a further guide for the complex diagnosis of pulmonary hypertension.

Features of the Diagnosis of Pulmonary Hypertension in Outpatient Practice

For the past 20 years, there has been no significant decrease in the time from the onset of symptoms to the diagnosis of pulmonary hypertension (PH). Therefore, it is very important to improve the awareness of therapists about clinical manifestations of the disease, risk factors for the development of PH, and the major diagnostic stages for early detection of the disease and timely administration of appropriate therapy.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare and progressive disease characterised by remodelling of the pulmonary arteries and progressive narrowing of the pulmonary vasculature. This leads to a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure and, if left untreated, to right ventricular failure and death. A correct diagnosis requires a complete work-up including right heart catheterisation performed in a specialised centre. Although our knowledge of the epidemiology, pathology and pathophysiology of the disease, as well as the development of innovative therapies, has progressed in recent decades, PAH remains a serious clinical condition. Current treatments for the disease target the three specific pathways of endothelial dysfunction that characterise PAH: the endothelin, nitric oxide and prostacyclin pathways. The current treatment algorithm is based on the assessment of severity using a multiparametric risk stratification approach at the time of diagnosis (baseline) and at regular follow-up visits. It recommends the initiation of combination therapy in PAH patients without cardiopulmonary comorbidities. The choice of therapy (dual or triple) depends on the initial severity of the condition. The main treatment goal is to achieve low-risk status. Further escalation of treatment is required if low-risk status is not achieved at subsequent follow-up assessments. In the most severe patients, who are already on maximal medical therapy, lung transplantation may be indicated. Recent advances in understanding the pathophysiology of the disease have led to the development of promising emerging therapies targeting dysfunctional pathways beyond endothelial dysfunction, including the TGF-β and PDGF pathways.

The Current Role of Cardiopulmonary Exercise Test in the Diagnosis and Management of Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease with a poor prognosis if left untreated. Despite remarkable achievements in understanding disease pathophysiology, specific treatments, and therapeutic strategies, we are still far from a definitive cure for the disease, and numerous evidences have underlined the importance of early diagnosis and treatment to improve the prognosis. Cardiopulmonary exercise testing (CPET) is the gold standard for assessing functional capacity and evaluating the pathophysiological mechanisms underlying exercise limitation. As effort dyspnea is the earliest and one of the main clinical manifestations of PAH, CPET has been shown to provide valid support in early detection, differential diagnosis, and prognostic stratification of PAH patients, being a useful tool in both the first approach to patients and follow-up. The purpose of this review is to present the current applications of CPET in pulmonary hypertension and to propose possible future utilization to be further investigated.

Identification of immune-related hub genes and analysis of infiltrated immune cells of idiopathic pulmonary artery hypertension

Objectives

Idiopathic pulmonary artery hypertension (IPAH) is a rare but life-threaten disease. However, the mechanism underlying IPAH is unclear. In this study, underlying mechanism, infiltration of immune cells, and immune-related hub genes of IPAH were analyzed via bioinformatics.

Methods

GSE15197, GSE48149, GSE113439, and GSE117261 were merged as lung dataset. Weighted gene correlation network analysis (WGCNA) was used to construct the co-expression gene networks of IPAH. Gene Ontology and pathway enrichment analysis were performed using DAVID, gene set enrichment analysis (GSEA), and gene set variation analysis (GSVA). Infiltration of immune cells in lung samples was analyzed using CIBERSORT. GSE22356 and GSE33463 were merged as peripheral blood mononuclear cells (PBMCs) dataset. Immune-related differentially expressed genes (IRDEGs) of lung and PBMCs dataset were analyzed. Based on the intersection between two sets of IRDEGs, hub genes were screened using machine learning algorithms and validated by RT-qPCR. Finally, competing endogenous RNA (ceRNA) networks of hub genes were constructed.

Results

The gray module was the most relevant module and genes in the module enriched in terms like inflammatory and immune responses. The results of GSEA and GSVA indicated that increasement in cytosolic calcium ion, and metabolism dysregulation play important roles in IPAH. The proportions of T cells CD4 memory resting and macrophage M1 were significantly greater in IPAH group, while the proportions of monocytes and neutrophils were significantly lower in IPAH group. IRDEGs of two datasets were analyzed and the intersection between two set of IRDEGs were identified as candidate hub genes. Predictive models for IPAH were constructed using data from PBMCs dataset with candidate hub genes as potential features via LASSO regression and XGBoost algorithm, respectively. CXCL10 and VIPR1 were identified as hub genes and ceRNA networks of CXCL10 was constructed.

Conclusion

Inflammatory response, increasement in cytosolic calcium ion, and metabolism dysregulation play important roles in IPAH. T cells CD4 memory resting and macrophage M1 were significantly infiltrated in lung samples from patients with IPAH. IRDEGs of lung dataset and PBMCs dataset were analyzed, and CXCL10 and VIPR1 were identified as hub genes.

Comprehensive Review of Pulmonary Hypertension and Treatment Options in the Paediatric Population

Pulmonary hypertension (PH) is a complex condition that can occur as a result of a wide range of disorders, including left heart disease, lung disease, and chronic pulmonary thromboembolism. Multiple improvements have been made in the diagnosis and treatment of pulmonary arterial hypertension (PAH) including a greater understanding of the involvement of extrapulmonary vascular organ systems, validated point of care, clinical assessment tools, and a focus on the initial exposure of numerous pharmacotherapeutics in the appropriate level of care. To achieve a minimal symptom burden, improve the patient's biochemical, hemodynamic, and functional profile, and reduce adverse impact, early diagnosis of PAH is a key objective today. The preferred method of management for thromboembolic PH, which is chronic, is pulmonary endarterectomy since the majority of affected patients are operable. The timing of pulmonary endarterectomy should never be delayed for medical reasons, and risk stratification can enable us to select patients who have a high chance of success. Patients who are not qualified for endarterectomy should be referred for drug trials. Even though there are more effective ways to guarantee a sufficient, long-lasting septostomy, atrial septostomy is promising but undervalued. The procedure's indications remain the same and need to be taken into account more frequently. Class III or IV patients who are not improving need to be consulted at a transplant centre as soon as possible as they may be candidates for potential recipients of bilateral sequential lung or heart-lung transplants, which is a significant choice for some people. PH is rarely linked to other conditions like connective tissue or thromboembolic disease. It is either idiopathic or linked to congenital heart disease. Infants and children with PH are more frequently recognised in conjunction with a congenital diaphragmatic hernia and developmental lung diseases like bronchopulmonary dysplasia. Although the underlying disease has not yet been treated and advanced structural changes have not yet been reversed, the value of natural life and survival have suggestively increased. Children's haemodynamic and functional outcomes have improved as a result of endothelin receptor antagonists, prostacyclin analogues, and phosphodiesterase type 5 inhibitors, which are examples of targeted pulmonary vasodilator therapies. The health maintenance of paediatric PH is still difficult because treatment decisions are largely based on the findings of adult studies that have been supported by evidence and the clinical expertise of paediatric specialists.

The Role of Pulmonary Function Test for Pulmonary Arterial Hypertension in Patients with Connective Tissue Disease

Objective: The study aimed to investigate the value of pulmonary function test (PFT) in evaluating and predicting pulmonary arterial hypertension (PAH) in patients with connective tissue disease (CTD). Methods: This was a prospective observational study recruiting patients diagnosed with CTD-PAH. Patients with interstitial lung disease and pulmonary hypertension induced by other causes were not eligible for enrollment. All patients were assessed for PAH every 1–3 months. A patient was considered to have clinical improvement if the grade of risk stratification declined or at least two parameters improved during follow-up, otherwise no improvement. Results: A total of 31 patients with CTD-PAH were recruited in this study. Nearly 70% of patients had declined forced vital capacity (FVC), 60% had declined total lung capacity and maximum expiratory flow at 50% of vital capacity, and 95% had normal or mild decline in forced expiratory volume in 1 second (FEV1)/FVC. A decline in diffusing capacity of the lung for carbon monoxide (DLCO) was present in 96% of patients, and 60% were moderate to severe. Furthermore, 50% of patients had an FVC/DLCO ratio of less than 1.4. Univariate analysis showed that FEV1/FVC, DLCO, and FVC/DLCO were associated with disease prognosis. After adjusting for age as a confounding factor, multivariate logistic regression analysis revealed that DLCO was an independent predictive factor for the prognosis of CTD-PAH. Conclusion: The pulmonary function of patients with CTD-PAH is abnormal in parameters such as lung volume, small airway, and gas exchange. PFT can reveal complex pathophysiological changes in the lungs of CTD-PAH patients and predict prognosis.

Exercise metabolomics in pulmonary arterial hypertension: Where pulmonary vascular metabolism meets exercise physiology

Pulmonary arterial hypertension is an incurable disease marked by dysregulated metabolism, both at the cellular level in the pulmonary vasculature, and at the whole-body level characterized by impaired exercise oxygen consumption. Though both altered pulmonary vascular metabolism and abnormal exercise physiology are key markers of disease severity and pulmonary arterial remodeling, their precise interactions are relatively unknown. Herein we review normal pulmonary vascular physiology and the current understanding of pulmonary vascular cell metabolism and cardiopulmonary response to exercise in Pulmonary arterial hypertension. We additionally introduce a newly developed international collaborative effort aimed at quantifying exercise-induced changes in pulmonary vascular metabolism, which will inform about underlying pathophysiology and clinical management. We support our investigative approach by presenting preliminary data and discuss potential future applications of our research platform.

Diagnosis and Treatment of Pulmonary Arterial Hypertension: A Review

IMPORTANCE

Pulmonary arterial hypertension (PAH) is a subtype of pulmonary hypertension (PH), characterized by pulmonary arterial remodeling. The prevalence of PAH is approximately 10.6 cases per 1 million adults in the US. Untreated, PAH progresses to right heart failure and death.

OBSERVATIONS

Pulmonary hypertension is defined by a mean pulmonary artery pressure greater than 20 mm Hg and is classified into 5 clinical groups based on etiology, pathophysiology, and treatment. Pulmonary arterial hypertension is 1 of the 5 groups of PH and is hemodynamically defined by right heart catheterization demonstrating a mean pulmonary artery pressure greater than 20 mm Hg, a pulmonary artery wedge pressure of 15 mm Hg or lower, and a pulmonary vascular resistance of 3 Wood units or greater. Pulmonary arterial hypertension is further divided into subgroups based on underlying etiology, consisting of idiopathic PAH, heritable PAH, drug- and toxin-associated PAH, pulmonary veno-occlusive disease, PAH in long-term responders to calcium channel blockers, and persistent PH of the newborn, as well as PAH associated with other medical conditions including connective tissue disease, HIV, and congenital heart disease. Early presenting symptoms are nonspecific and typically consist of dyspnea on exertion and fatigue. Currently approved therapy for PAH consists of drugs that enhance the nitric oxide-cyclic guanosine monophosphate biological pathway (sildenafil, tadalafil, or riociguat), prostacyclin pathway agonists (epoprostenol or treprostinil), and endothelin pathway antagonists (bosentan and ambrisentan). With these PAH-specific therapies, 5-year survival has improved from 34% in 1991 to more than 60% in 2015. Current treatment consists of combination drug therapy that targets more than 1 biological pathway, such as the nitric oxide-cyclic guanosine monophosphate and endothelin pathways (eg, ambrisentan and tadalafil), and has shown demonstrable improvement in morbidity and mortality compared with the previous conventional single-pathway targeted monotherapy.

CONCLUSIONS AND RELEVANCE

Pulmonary arterial hypertension affects an estimated 10.6 per 1 million adults in the US and, without treatment, typically progresses to right heart failure and death. First-line therapy with drug combinations that target multiple biological pathways are associated with improved survival.

ERS International Congress 2021: highlights from the Pulmonary Vascular Diseases Assembly

This article aims to summarise the latest research presented at the virtual 2021 European Respiratory Society (ERS) International Congress in the field of pulmonary vascular disease. In light of the current guidelines and proceedings, knowledge gaps are addressed and the newest findings of the various forms of pulmonary hypertension as well as key points on pulmonary embolism are discussed. Despite the comprehensive coverage of the guidelines for pulmonary embolism at previous conferences, discussions about controversies in the diagnosis and treatment of this condition in specific cases were debated and are addressed in the first section of this article. We then report on an interesting pro-con debate about the current classification of pulmonary hypertension. We further report on presentations on Group 3 pulmonary hypertension, with research exploring pathogenesis, phenotyping, diagnosis and treatment; important contributions on the diagnosis of post-capillary pulmonary hypertension are also included. Finally, we summarise the latest evidence presented on pulmonary vascular disease and COVID-19 and a statement on the new imaging guidelines for pulmonary vascular disease from the Fleischner Society.

Factors related to instrumental activities of daily living in persons with chronic thromboembolic pulmonary hypertension

Instrumental activities of daily living (IADL) are significantly related to quality of life and mortality among individuals with heart disease. However, few reports have examined IADL in persons with chronic thromboembolic pulmonary hypertension (CTEPH). The aim of this study was to clarify factors related to IADL in persons with CTEPH. This retrospective, observational study enrolled 163 persons with CTEPH (mean ± standard deviation age = 65 ± 13 years; 68% female) admitted to the Department of Cardiology at Keio University Hospital between January 2015 and July 2019. The Frenchay Activities Index (FAI) was used to assess IADL. Age, sex, body mass index, World Health Organization functional class (WHO-FC), cardiac function (mean pulmonary arterial pressure, mean right atrial pressure, pulmonary capillary wedge pressure, and cardiac index), pulmonary function (percentage vital capacity, percentage forced expiratory volume in 1 s, diffusion capacity of carbon monoxide (DLCO)/alveolar volume (VA)), physical function (knee extension strength and walking speed), and 6-min walking distance (6MWD) were assessed. Multiple regression analysis was performed to identify factors significantly associated with FAI. Mean FAI was 25 ± 8. Univariate analysis showed that sex, WHO-FC, DLCO/VA, walking speed, and 6MWD were correlated with FAI. Multiple regression analysis showed that 6MWD (sβ = 0.338, 95% CI 0.014–0.034, p < .001), sex (sβ = 0.268, 95% CI 2.238–7.165, p < .001), and DLCO/VA (sβ = 0.257, 95% CI 1.011–3.528, p < .001) were significantly correlated with FAI (R² = 0.261). IADL were associated with exercise tolerance, sex, and DLCO/VA in persons with CTEPH. In the future, more details of IADL are expected to be clarified by analyzing individual components of IADL and investigating social background characteristics, including living environment.

The effects of pulmonary hypertension on skeletal muscle oxygen pressures in contracting rat spinotrapezius muscle

NEW FINDINGS

What is the central question of this study? Does impairment in the dynamics of O₂ transport in skeletal muscle during a series of contractions constitute a potential mechanism underlying reduced exercise capacity in pulmonary hypertension? What is the main finding and its importance? Pulmonary hypertension compromises the dynamic matching of skeletal muscle O₂ delivery-to-utilization following contraction onset in the rat spinotrapezius muscle. These results implicate a role for vascular dysfunction in the slow V ̇ O 2 kinetics and exercise intolerance present in pulmonary hypertension.

ABSTRACT

Pulmonary hypertension (PH) is characterized by pulmonary vascular dysfunction and exercise intolerance due, in part, to compromised pulmonary and cardiac function. We tested the hypothesis that there are peripheral (i.e., skeletal muscle) aberrations in O₂ delivery ( Q ̇ O 2 )-to-O₂ utilization ( V ̇ O 2 ) matching and vascular control that might help to explain poor exercise tolerance in PH. Furthermore, we investigated the peripheral effects of nitric oxide (NO) in attenuating these decrements. Male Sprague-Dawley rats (n = 21) were administered monocrotaline (MCT; 50 mg/kg, i.p.) to induce PH. Disease progression was monitored via echocardiography. Phosphorescence quenching determined the O₂ partial pressure in the interstitial space ( P O 2 is ) in the spinotrapezius muscle at rest and during contractions under control (SNP-) and NO-donor (sodium nitroprusside, SNP+) conditions. MCT rats displayed right ventricular (RV) hypertrophy (right ventricle/(left ventricle + septum): 0.44 (0.13) vs. 0.28 (0.05)), pulmonary congestion, increased RV systolic pressure (48 (18) vs. 20 (8) mmHg) and arterial hypoxaemia ( P a O 2 : 64 (9) vs. 82 (9) mmHg) compared to healthy controls (HC) (P < 0.05). P O 2 is was significantly lower in MCT rats during the first 30 s of SNP- contractions. SNP superfusion elevated P O 2 is in both groups; however, MCT rats demonstrated a lower P O 2 is throughout SNP+ contractions versus HC (P < 0.05). Thus, for small muscle mass exercise in MCT rats, muscle oxygenation is impaired across the rest-to-contractions transition and exogenous NO does not raise the Q ̇ O 2 -to- V ̇ O 2 ratio in contracting muscle to the same levels as HC. These data support muscle Q ̇ O 2 -to- V ̇ O 2 mismatch as a potential contributor to slow V ̇ O 2 kinetics and therefore exercise intolerance in PH and suggest peripheral vascular dysfunction or remodelling as a possible mechanism.

Evaluation, Diagnosis, and Classification of Pulmonary Hypertension

Pulmonary hypertension (PH) is a rare heterogenous disease characterized by elevated blood pressure in the lungs. Patients with PH require careful evaluation and management at an expert center. Understanding of the mechanisms underlying the development of PH has increased over the past two decades, and several treatment options for pulmonary arterial hypertension have emerged. Despite this progress, PH continues to carry high morbidity and mortality. The 6th World Symposium on Pulmonary Hypertension that occurred in late 2018 modified the clinical classification of PH into five groups. In this review, we focus on the evaluation and diagnosis of PH and discuss the updated clinical classification.

The Evolution of Risk Assessment in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a chronic debilitating disease that carries an unacceptably high morbidity and mortality rate despite improved survival with modern therapies. The combination of several modifiable and nonmodifiable variables yields a robust risk assessment across various available clinical calculators. The role of risk calculation is integral to managing PAH and aids in the timely referral to expert centers and potentially lung transplantation. Studies are ongoing to determine the role of risk calculators in the framework of clinical trials and to elucidate novel markers of high risk in PAH.

Perioperative Management of Pulmonary Hypertension. a Review

Pulmonary hypertension is a rare and progressive pathology defined by abnormally high pulmonary artery pressure mediated by a diverse range of aetiologies. It affects up to twenty-six individuals per one million patients currently living in the United Kingdom (UK), with a median life expectancy of 2.8 years in idiopathic pulmonary hypertension. The diagnosis of pulmonary hypertension is often delayed due to the presentation of non-specific symptoms, leading to a delay in referral to specialists services. The complexity of treatment necessitates a multidisciplinary approach, underpinned by a diverse disease aetiology from managing the underlying disease process to novel specialist treatments. This has led to the formation of dedicated specialist treatment centres within centralised UK cities. The article aimed to provide a concise overview of pulmonary hypertension's clinical perioperative management, including key definitions, epidemiology, pathophysiology, and risk stratification.

Hypoxemia during sleep and overnight rostral fluid shift in pulmonary arterial hypertension: a pilot study

Sleep-related breathing disorders, including sleep apnea and hypoxemia during sleep, are common in pulmonary arterial hypertension, but the underlying mechanisms remain unknown. Overnight fluid shift from the legs to the upper airway and to the lungs promotes obstructive and central sleep apnea, respectively, in fluid-retaining states. The main objective was to evaluate if overnight rostral fluid shift from the legs to the upper part of the body is associated with sleep-related breathing disorders in pulmonary arterial hypertension. In a prospective study, a group of stable patients with idiopathic, heritable, related to drugs, toxins, or treated congenital heart disease pulmonary arterial hypertension underwent a polysomnography and overnight fluid shift measurement by bioelectrical impedance in the month preceding or following a one-day hospitalization according to regular pulmonary arterial hypertension follow-up schedule with a right heart catheterization. Results show that among 15 patients with pulmonary arterial hypertension (women: 87%; median (25-75th percentiles); age: 40 (32-61) years; mean pulmonary arterial pressure 56 (46-68) mmHg; pulmonary vascular resistance 8.8 (6.4-10.1) Wood units), two patients had sleep apnea and eight (53%) had hypoxemia during sleep without apnea. The overnight rostral fluid shift was 168 (118-263) mL per leg. Patients with hypoxemia during sleep had a greater fluid shift (221 (141- 361) mL) than those without hypoxemia (118 (44-178) mL, p = 0.045). In conclusion, this pilot study suggests that hypoxemia during sleep is associated with overnight rostral fluid shift in pulmonary arterial hypertension.

Particulate matter inhalation and the exacerbation of cardiopulmonary toxicity due to metabolic disease

Particulate matter is a significant public health issue in the United States and globally. Inhalation of particulate matter is associated with a number of systemic and organ-specific adverse health outcomes, with the pulmonary and cardiovascular systems being particularly vulnerable. Certain subpopulations are well-recognized as being more susceptible to inhalation exposures, such as the elderly and those with pre-existing respiratory disease. Metabolic syndrome is becoming increasingly prevalent in our society and has known adverse effects on the heart, lungs, and vascular systems. The limited evaluations of individuals with metabolic syndromehave demonstrated that theymay compose a sensitive subpopulation to particulate exposures. However, the toxicological mechanisms responsible for this increased vulnerability are not fully understood. This review evaluates the currently available literature regarding how the response of an individual's pulmonary and cardiovascular systems is influenced by metabolic syndrome and metabolic syndrome-associated conditions such as hypertension, dyslipidemia, and diabetes. Further, we will discuss potential therapeutic agents and targets for the alleviation and treatment of particulate-matter induced metabolic illness. The information reviewed here may contribute to the understanding of metabolic illness as a risk factor for particulate matter exposure and further the development of therapeutic approaches to treat vulnerable subpopulations, such as those with metabolic diseases.

Systemic sclerosis and pulmonary arterial hypertension: A case report

Pulmonary arterial hypertension (PAH), which occurs in about 15% of patients with systemic sclerosis (SSc), is a progressive vasculopathy and despite modern therapeutic options is still one of the leading causes of death in these patients. We presented a patient diagnosed with the overlap syndrome (systemic sclerosis and rheumatoid arthritis) with a predominance of the clinical picture of systemic sclerosis (SSc), established in November 2018. She was initially treated by a rheumatologist with an antimalarial, which was soon discontinued by an ophthalmologist, followed by azathioprine which was excluded due to an allergic reaction. She has been continuously on corticosteroid therapy, and since January 2020, mycophenolate mofetil has been added to treatment. The patient was diagnosed with primary biliary cirrhosis by a gastroenterologist after clinical findings and additional examination methods; also, pulmonary fibrosis was diagnosed by a pulmonologist. In January 2020, deterioration of echocardiographic findings was registered (dilated right heart cavity, right ventricular systolic pressure (RVSP) 72 mmHg, tricuspid regurgitation 3+). Sildenafil was proposed by a responsible cardiologist for therapy that was not approved by gastroenterologist. Due to worsening of her symptoms in the form of pronounced fatigue, shortness of breath, in August 2020, a cardiologist of the Institute "Niška Banja" started bosentan therapy in a dose of 2 x 62.5 mg per day. After the applied therapy, the patient had a subjective improvement and reduction of symptoms. In November 2020, a control echocardiographic examination registered a decrease in RVSP to 55 mmHg. In addition to the therapy proposed by the responsible rheumatologist (mycophenolate mofetil 2 g daily, prednisolone 15 - 20 mg daily), the therapy prescribed by her cardiologist was also continued (bosentan 62.5 mg 2 x 1), with regular controls and monitoring of laboratory analyses. PAH in patients with SSc has a worse prognosis than idiopathic PAH, and additionally depends on RVSP and functional class. The process of treating PAH in patients with SSc requires a complex strategy that includes initial assessment of disease severity and subsequent responses to the therapy.

[Guideline for Long-Term Oxygen Therapy - S2k-Guideline Published by the German Respiratory Society]

Long-term oxygen therapy is of great importance both for reducing mortality and for improving performance in patients with chronic lung diseases. The prerequisites for Long-term oxygen therapy are adequate diagnostics and clearly defined indication. A causal distinction into chronic hypoxaemic and hypercapnic respiratory failure is reasonable, from which the differential indication for non-invasive ventilation results.The revised guideline covers the diagnostics and indication of chronic lung and heart diseases, the role of oxygen in terminal illness and gives a detailed description of available oxygen devices. The guideline is intended to help avoid undersupply, oversupply and false prescriptions. Furthermore, the chapter "Postacute Oxygen Therapy" discusses the procedure, relevant in everyday life, but not yet clearly defined, for prescribing oxygen therapy for the home at the end of an inpatient stay. Another important point, the correct prescription of mobile oxygen systems, is also presented in the guideline. This document is a revised version of the guideline for longterm oxygen therapy and replaces the version of 2008.

Diffusing capacity in normal-for-age spirometry and spirometric impairments, using reference equations from the global lung function initiative

BACKGROUND

Reference equations from the Global Lung Function Initiative (GLI) are now available for both spirometry and diffusion. However, respiratory phenotypes defined by GLI-based measures of diffusion have not yet been evaluated in GLI-based normal-for-age spirometry or spirometric impairments.

METHODS

We evaluated cross-sectional data from 2100 Caucasians, aged 40-85 years. GLI-based spirometric categories included normal-for-age and the impairments of restrictive-pattern and three-level severity of airflow-obstruction (mild, moderate, severe). GLI-based diffusion included diffusing capacity of the lung for carbon monoxide (D_LCO) and measured components of alveolar volume (V_A) and transfer coefficient (K_CO): D_LCO = [V_A]x[K_CO]. Using multivariable regression models, adjusted odds ratios (adjORs) for D_LCO, V_A, and K_CO < lower limit of normal (LLN) were calculated for spirometric impairments, relative to normal-for-age spirometry.

RESULTS

Relative to normal-for-age spirometry, the restrictive-pattern increased the adjORs (95% confidence intervals) for D_LCO and V_A < LLN-4.61 (3.62, 5.85) and 15.53 (11.8, 20.4), respectively, but not for K_CO < LLN-1.02 (0.79, 1.33). Also relative to normal-for-age spirometry, airflow-obstruction from mild to severe increased the adjORs for D_LCO < LLN-from 1.22 (0.80, 1.86) to 6.63 (4.91, 8.95), for V_A < LLN-from 1.37 (0.85, 2.18) to 7.01 (5.20, 9.43), and for K_CO < LLN-from 2.04 (1.33, 3.14) to 3.03 (2.29, 3.99). Notably, in normal-for-age spirometry, 34.5%, 19.7%, and 25.3% of participants had D_LCO, V_A, or K_CO < LLN, respectively.

CONCLUSION

Abnormal diffusion is most prevalent in spirometric impairments but also occurs in normal-for-age spirometry. These results further inform the respiratory phenotypes of GLI-based spirometric categories and, in turn, the spirometric evaluation of respiratory disease.

Lung function in relation to six-minute walk test in pulmonary hypertension

Background: Pulmonary hypertension (PH) is a progressive disorder of the pulmonary circulation, associated with diverse medical conditions. Exercise limitation is the most prominent symptom in PH. Exercise capacity, commonly assessed through a six-minute walk test (6MWT), correlates with both functional status and survival in PH. Few studies have analysed the relation between respiratory function and exercise limitation. Therefore, we investigated the relationship between resting pulmonary function, exercise capacity, and exertional desaturation, assessed through the 6MWT, in unselected PH patients.

Methods: Fifty consecutive patients with PH diagnosis, referred for pulmonary function testing (lung volume, spirometry, and diffusing capacity for carbon monoxide (DLCO)) and 6MWT, were recruited at Molinette University Hospital, Turin.

Results: The majority of the patients (54%) had PH due to left heart disease. Airway obstruction (FEV₁/VC-ratio < 0.7) was found in 46% of the patients and they performed significantly worse in the 6MWT than unobstructed patients (307 m vs. 377 m). Patients with PH due to left heart disease also performed significantly poorer 6MWT when airway obstruction was present (305 m vs. 389 m). Twenty-two patients (44%) presented exertional desaturation upon 6MWT. Lower DLCO divided by the alveolar volume (DLCO/VA), FEV₁/VC-ratios and resting PaO₂-values were significantly correlated with exertional desaturation after adjustments for age, sex, BMI, and smoking habits. DLCO/VA was the main determinant of exertional desaturation in a stepwise regression model.

Conclusions: Spirometric parameters of airway obstruction were related to walk distance and exercise-induced desaturation in PH patients. This suggests a place for spirometry in clinical monitoring of PH patients.

Lower DLco% identifies exercise pulmonary hypertension in patients with parenchymal lung disease referred for dyspnea

Exercise pulmonary hypertension is an underappreciated form of physical limitation related to early pulmonary vascular disease. A low diffusing capacity of lungs for carbon monoxide (DLco) can be seen in patients with resting pulmonary hypertension as well as parenchymal lung disease. It remains unclear whether low DLco% identifies early pulmonary vascular disease. We hypothesize that a reduced DLco% differentiates the presence of exercise pulmonary hypertension in patients with parenchymal lung disease. Fifty-six patients referred for unexplained exertional dyspnea with pulmonary function tests within six months of hemodynamic testing underwent exercise right heart catheterization. Exclusion criteria included resting pulmonary arterial or venous hypertension. Receiver operator characteristic curve determined the optimal DLco% cutoffs based on the presence or absence of parenchymal lung disease. Twenty-one (37%) patients had parenchymal lung disease, most common manifesting as chronic obstructive lung disease or interstitial lung disease. In patients with parenchymal lung disease, a DLco of 46% demonstrated 100% sensitivity and 73% specificity for detecting exercise pulmonary hypertension. In patients without parenchymal lung disease, a DLco of 73% demonstrated 58% sensitivity and 94% specificity for detecting exercise pulmonary hypertension. In both cohorts, DLco% below the optimum cutoffs were associated with higher peak mean pulmonary arterial pressure and peak total pulmonary resistance consistent with the hemodynamic definition of exercise pulmonary hypertension. Patients with a DLco < 46% were more often treated with pulmonary vasodilators and had a trend to higher mortality and lung transplant. DLco% is a simple non-invasive screening test for the presence of exercise pulmonary hypertension in our mixed referral population with progressive exertional dyspnea. DLco < 46% with parenchymal lung disease and DLco < 73% without parenchymal lung disease may play a role in differentiating the presence of pulmonary vascular disease prior to invasive hemodynamic testing.

Screening strategies for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is rare and, if untreated, has a median survival of 2-3 years. Pulmonary arterial hypertension may be idiopathic (IPAH) but is frequently associated with other conditions. Despite increased awareness, therapeutic advances, and improved outcomes, the time from symptom onset to diagnosis remains unchanged. The commonest symptoms of PAH (breathlessness and fatigue) are non-specific and clinical signs are usually subtle, frequently preventing early diagnosis where therapies may be more effective. The failure to improve the time to diagnosis largely reflects an inability to identify patients at increased risk of PAH using current approaches. To date, strategies to improve the time to diagnosis have focused on screening patients with a high prevalence [systemic sclerosis (10%), patients with portal hypertension assessed for liver transplantation (2-6%), carriers of mutations of the gene encoding bone morphogenetic protein receptor type II, and first-degree relatives of patients with heritable PAH]. In systemic sclerosis, screening algorithms have demonstrated that patients can be identified earlier, however, current approaches are resource intensive. Until, recently, it has not been considered possible to screen populations for rare conditions such as IPAH (prevalence 5-15/million/year). However, there is interest in the use of artificial intelligence approaches in medicine and the application of diagnostic algorithms to large healthcare data sets, to identify patients at risk of rare conditions. In this article, we review current approaches and challenges in screening for PAH and explore novel population-based approaches to improve detection.

Central airway compression by massively dilated pulmonary artery in a patient with pulmonary arterial hypertension: a rare entity

Patients with pulmonary arterial hypertension (PAH) usually die from progressive right ventricular failure. Mechanical complications due to pulmonary artery (PA) enlargement are rare and include tracheobronchial and left main coronary artery compression, and PA dissection. A 62-year-old female with PAH was seen in our office for follow-up. During the evaluation, spirometry was performed, which revealed a severe obstructive ventilatory limitation. Subsequent workup identified compression of bilateral mainstem bronchi from the dilated PA as the aetiology for the abnormal spirometry. Very few cases of this rare complication have been reported in the literature. A significant dilation of the PA is necessary (>4 cm) for the occurrence of these complications. Dilation of PA is an independent risk factor for sudden unexpected death in patients with PAH.

Exhaled nitric oxide is not a biomarker for idiopathic pulmonary arterial hypertension or for treatment efficacy

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is a fatal illness. Despite many improvements in the treatment of these patients, there is no unique prognostic variable available to track these patients. The aim of this study was to evaluate the association between fractional exhaled nitric oxide (FeNO) levels, as a noninvasive biomarker, with disease severity and treatment outcome.

METHODS

Thirty-six patients (29 women and 7 men, mean age 38.4 ± 11.3 years) with IPAH referred to the outpatient's clinic of Masih Daneshvari Hospital, Tehran, Iran, were enrolled into this pilot observational study. Echocardiography, six-minute walking test (6MWT), FeNO, brain natriuretic peptide (BNP) levels and the functional class of patients was assessed before patients started treatment. Assessments were repeated after three months. 30 healthy non-IPAH subjects were recruited as control subjects.

RESULTS

There was no significant difference in FeNO levels at baseline between patients with IPAH and subjects in the control group. There was also no significant increase in FeNO levels during the three months of treatment and levels did not correlate with other disease measures. In contrast, other markers of disease severity were correlated with treatment effect over the three months.

CONCLUSION

FeNO levels are a poor non-invasive measure of IPAH severity and of treatment response in patients in this pilot study.

Evaluation and classification of pulmonary arterial hypertension

In early 2019, the 6th World Symposium on Pulmonary Hypertension (WSPH) released an updated document highlighting the advances in the last five years. During the quinquennial event many experts worked together to suggest new changes in the disease diagnosis and management. Since inception of the WSPH in 1973, this is the first time when the hemodynamic definition of pulmonary hypertension (PH) has been updated. These proceedings have re-defined the different hemodynamic types of PH that occur with the left heart disease along with introduction to the genetic testing as part of pulmonary arterial hypertension (PAH) evaluation. Objective of this review is to highlight the evaluation and diagnosis of PAH based on the proceedings of the 6th WSPH. Accurate early diagnosis and subsequent management of PH is necessary, as despite of treatment advances, survival remains suboptimal.

Sensory consequences of critical inspiratory constraints during exercise in pulmonary arterial hypertension

We aimed to assess detailed ventilatory and sensory responses to exercise contrasting subjects with and without PAH. 20 non-smoking patients with PAH (37.5 ± 12.1 ys; FEV₁/FVC = 0.77 ± 0.04; mPAP by heart catheterization = 50.6 ± 18.1 mmHg) and 10 matched controls performed cycling cardiopulmonary exercise test with serial assessments of dyspnea, airway occlusion pressure during the first 0.1 s (P0.1) of tidal volume and inspiratory capacity (IC). Patients showed lower spirometric variables compared to controls. Dyspnea and ventilation (V_E) were significantly higher in patients for a given work rate. Dyspnea persisted more intense in patients even when expressed as a function of V_E. Lower IC at rest (in non-hyperinflators; n = 10) or exercise-induced reduction in IC (in hyperinflators) predisposed patients to achieve earlier and at lower workloads a critical inspiratory reserve volume (IRV). At this point, there was a sudden rise in P0.1 and dyspnea perception. Attainment of a critical IRV at premature workloads leads to neuromechanical dissociation with an abrupt increment in exertional dyspnea.

Clinical characteristics in lymphangioleiomyomatosis-related pulmonary hypertension: an observation on 50 patients

Lymphangioleiomyomatosis (LAM) is a rare diffuse cystic lung disease. Knowledge on LAM-related pulmonary hypertension (PH) is limited. This study aimed to analyze the clinical characteristics of LAM with elevated pulmonary artery pressure (PAP) and evaluate the potential efficacy of sirolimus. The study involved 50 LAM patients who underwent echocardiography. According to the tricuspid regurgitation velocity (TRV), these patients were divided into the TRV ⩽ 2.8 m/s group and TRV > 2.8 m/s group. Both groups comprised 25 females with an average age of 38.6 ± 8.1 and 41.5 ± 8.9 years. In the TRV > 2.8 m/s group, the estimated systolic PAP (SPAP) was significantly elevated (52.08 ± 12.45 mmHg vs. 30.24 ± 5.25 mmHg, P < 0.01). Linear analysis showed that SPAP was correlated with forced expiratory volume in 1 s (FEV₁), diffusing capacity of the lungs for carbon monoxide, alveolar arterial oxygen gradient (P_A-aO₂), and 6 min walking distance (r =-0.392, -0.351, 0.450, and -0.591, respectively; P < 0.05), in which P_A-aO₂ was a risk factor for SPAP elevation (β = 0.064, OR = 1.066, P < 0.05). Moreover, in 10 patients who received sirolimus therapy, SPAP decreased from 57.0 12.6 mmHg to 35.2 ± 11.1 mmHg. The study showed that LAM patients with PH exhibit poor pulmonary function and hypoxemia and may benefit from sirolimus treatment.

End-Tidal Carbon Dioxide as a Prognostic Feature in Pulmonary Arterial Hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) is characterized in part by increased dead space ventilation, which can be estimated noninvasively at the bedside by measurement of end-tidal CO₂ (ETco₂).

OBJECTIVES

Prior work has demonstrated that ETco₂ is lower in patients with PAH than in control patients, but whether ETco₂ has prognostic value is unknown. We hypothesized that lower measurements of ETco₂ in patients with PAH correlate with worse long-term outcomes.

METHODS

Patients with PAH seen in our referral clinic were prospectively recruited for ETco₂ measurement between September 2009 and February 2010. Vital status as of July 2015 was documented using medical records and the Social Security Death Index.

RESULTS

Eighty-two patients were followed for a median of 60 months. Twenty-six patients died, and two were lost to follow-up. Patients who died were more likely to be older (58.5 ± 14.9 vs. 47.6 ± 12.2 yr; P < 0.05) and to have shorter 6-minute walk distance (296 ± 127 vs. 401 ± 92 m; P < 0.05). Mean ETco₂ in survivors was 30.5 ± 4.8 mm Hg, whereas mean ETco₂ in patients who died was 27.1 ± 4.2 mm Hg (P = 0.004). After stratification by median baseline ETco₂ of 29 mm Hg, survival in each group was analyzed. Patients with lower ETco₂ had shorter survival (P = 0.006). Cox regression analysis with ETco₂ as a continuous variable revealed the hazard ratio to be 0.88 (95% confidence interval, 0.80-0.97; P = 0.006). In 52 patients with more than one measurement a median of 17 months apart, ETco₂ was unchanged.

CONCLUSIONS

Our single-center data suggest that lower ETco₂ is associated with shorter survival and that ETco₂ is stable over time in patients with PAH.

Spirometric impairments, cardiovascular outcomes, and noncardiovascular death in older persons

BACKGROUND

In prior work involving older persons, the reported associations of spirometric impairments with cardiovascular outcomes may have been confounded by age-related changes in lung function. Hence, using more age-appropriate spirometric criteria from the Global Lung Function Initiative (GLI), we have evaluated the associations of spirometric impairments, specifically restrictive-pattern and airflow-obstruction, with cardiovascular death (CV-death) and hospitalization (CV-hospitalization). In these analyses, we also evaluated the competing outcome of noncardiovascular death (nonCV-death) and calculated measures of relative and absolute risk.

METHODS

Our study sample was drawn from the Cardiovascular Health Study (CHS), including 4232 community-dwelling white persons aged ≥65 years. Multivariable regression models included the following baseline predictors: GLI-defined restrictive-pattern and airflow-obstruction, age, male gender, obesity, waist circumference, current smoker status, ≥10 pack-years of smoking, hypertension, dyslipidemia, diabetes, and cardiovascular and cerebrovascular disease. Outcomes included adjudicated CV-death, CV-hospitalization, and nonCV-death, ascertained over 10 years of follow-up. Measures of association included hazard ratios (HRs), rate ratios (RRs), and average attributable fraction (AAF), each with 95% confidence intervals.

RESULTS

Restrictive-pattern and airflow-obstruction were associated with CV-death (adjusted HRs: 1.57 [1.18, 2.09] and 1.29 [1.04, 1.60]) and with nonCV-death (adjusted HRs: 2.10 [1.63, 2.69] and 1.79 [1.51, 2.12]), respectively. Airflow-obstruction, but not restrictive-pattern, was also associated with CV-hospitalization (adjusted RRs: 1.18 [1.02, 1.36] and 1.20 [0.96, 1.50], respectively). The adjusted AAFs of restrictive-pattern and airflow-obstruction were 1.68% (0.46, 3.06) and 2.35% (0.22, 4.72) for CV-death, and 3.44% (1.97, 5.08) and 7.77% (5.15, 10.60) for nonCV-death, respectively.

CONCLUSION

Assessment of GLI-defined spirometric impairments contributes to broad geriatric risk stratifications for both cardiovascular and non-cardiovascular outcomes.