Diffusing Capacity for Nitric Oxide and Carbon Monoxide in Patients With Diffuse Parenchymal Lung Disease and Pulmonary Arterial Hypertension

There are limited published data defining survival and treatment response in patients with mild lung disease and/or reduced gas transfer who fulfil diagnostic criteria for idiopathic pulmonary arterial hypertension (IPAH).Patients diagnosed with IPAH between 2001 and 2019 were identified in the ASPIRE (Assessing the Spectrum of Pulmonary Hypertension Identified at a Referral Centre) registry. Using prespecified criteria based on computed tomography (CT) imaging and spirometry, patients with a diagnosis of IPAH and no lung disease were termed IPAHno-LD (n=303), and those with minor/mild emphysema or fibrosis were described as IPAHmild-LD (n=190).Survival was significantly better in IPAHno-LD than in IPAHmild-LD (1- and 5-year survival 95% and 70% versus 78% and 22%, respectively; p<0.0001). In the combined group of IPAHno-LD and IPAHmild-LD, independent predictors of higher mortality were increasing age, lower diffusing capacity of the lung for carbon monoxide (DLCO), lower exercise capacity and a diagnosis of IPAHmild-LD (all p<0.05). Exercise capacity and quality of life improved (both p<0.0001) following treatment in patients with IPAHno-LD, but not IPAHmild-LD. A proportion of patients with IPAHno-LD had a DLCO <45%; these patients had poorer survival than patients with DLCO ≥45%, although they demonstrated improved exercise capacity following treatment.The presence of even mild parenchymal lung disease in patients who would be classified as IPAH according to current recommendations has a significant adverse effect on outcomes. This phenotype can be identified using lung function testing and clinical CT reports. Patients with IPAH, no lung disease and severely reduced DLCO may represent a further distinct phenotype. These data suggest that randomised controlled trials of targeted therapies in patients with these phenotypes are required.

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Carbon monoxide diffusing capacity and mortality in pulmonary arterial hypertension

The Journal of Heart and Lung Transplantation ◽

10.1016/j.healun.2009.07.005 ◽

2010 ◽

Vol 29 (2) ◽

pp. 181-187 ◽

Cited By ~ 39

Author(s):

Sonal Chandra ◽

Sanjiv J. Shah ◽

Thenappan Thenappan ◽

Stephen L. Archer ◽

Stuart Rich ◽

...

Keyword(s):

Carbon Monoxide ◽

Pulmonary Arterial Hypertension ◽

Arterial Hypertension ◽

Diffusing Capacity ◽

Pulmonary Arterial

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A normal diffusing capacity of the lungs for carbon monoxide is rare in incidental pulmonary arterial hypertension in systemic sclerosis: Data from the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma cohort

Journal of Scleroderma and Related Disorders ◽

10.1177/2397198318778818 ◽

2018 ◽

Vol 3 (3) ◽

pp. 237-241

Author(s):

Rebecca S Overbury ◽

Maureen A Murtaugh ◽

Tracy M Frech ◽

Virginia D Steen

Keyword(s):

Carbon Monoxide ◽

Pulmonary Hypertension ◽

Pulmonary Arterial Hypertension ◽

Arterial Hypertension ◽

Natriuretic Peptide ◽

Right Heart Catheterization ◽

Heart Catheterization ◽

Diffusing Capacity ◽

Pulmonary Arterial ◽

Left Atrium Size

Objective: Our purpose was to determine the frequency of normal diffusing capacity for carbon monoxide defined as ⩾70% predicted, in those diagnosed with pulmonary arterial hypertension in the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma cohort. We compared those with normal diffusing capacity for carbon monoxide to those with reduced diffusing capacity for carbon monoxide <70% in order to better clarify the role of pulmonary function testing as a screening test for pulmonary arterial hypertension and to better understand this population. Methods: Entry criteria included a right heart catheterization with mean pulmonary artery pressure ⩾25 mm Hg and pulmonary capillary wedge pressure ⩽15 mm Hg. Demographics, echocardiogram variables, B-type natriuretic peptide levels, right heart catheterization findings, and survival were described for both groups. Results: Of (n = 202), 11 (5.4%) had a diffusing capacity for carbon monoxide of ⩾70% versus 191 (94.6%) who had a diffusing capacity for carbon monoxide <70%. There were no identified statistical differences between the groups. Left atrium size was 4.1 cm in the normal diffusing capacity for carbon monoxide patients compared to 3.7 cm in the low diffusing capacity for carbon monoxide group but did not reach statistical significance. There were no statistically significant differences in survival. On repeat testing, seven patients subsequently developed a diffusing capacity for carbon monoxide <70%. Conclusion: Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma data suggest that it is very rare for a patient to develop pulmonary arterial hypertension with a preserved diffusing capacity for carbon monoxide. The data support the importance of obtaining diffusing capacity for carbon monoxide and that a patient with a normal diffusing capacity for carbon monoxide while suspected to have systemic sclerosis-pulmonary arterial hypertension should be considered critically. Diffusing capacity for carbon monoxide >70% was present in too few patients to find significant differences in B-type natriuretic peptide and atrium size. Future research should seek to confirm abnormal B-type natriuretic peptide, increased left atrium size, and other evidence of myocardial involvement on diffusing capacity for carbon monoxide.

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