Abstract
Background Pulmonary hypertension (PH) is a progressive fatal disease thus, noninvasive prognostic tools are needed to follow these patients. The aim of our study was to evaluate fractional exhaled nitric oxide (FeNO) and exhaled breath temperature (EBT) values in patients with PH from different causes and to correlate them with respiratory functional data. Methods Twenty-four PH patients underwent spirometry, carbon monoxide diffusion (DLCO) test, transthoracic echocardiography, right-heart catheterization, and FeNO and EBT measurements. Results We studied 3 groups according to the type of PH: 10 patients with pulmonary arterial hypertension (PAH) (group A), 11 patients with PH due to chronic obstructive pulmonary disease (COPD) (group B), and 3 patients with PH associated with left heart disease (group C). Mean FeNO values tend to be higher in group B (15.0 ± 9.3ppb) compared with other groups (respectively, 9.9 ± 5.7 and 8.5 ± 5.2 ppb in groups A and C; p = 0.271) but no statistical significance has been reached. Mean values of alveolar NO concentration (CANO) were higher in groups A and B compared to group C (respectively, 16.9 ± 12.6; 13.9 ± 6.8; and 6.7 ± 2.0 ppb) (p = 0.045). EBT mean values were significantly lower in group C when compared with other groups (group C: 29.0 +- 1.3°C, groups A and B: 30.9 ± 1.3 and 31.2 ± 1.2°C, respectively: p = 0.041). EBT levels were inversely correlated to mean pulmonary artery pressure (PAPm) levels (Spearman coefficient -0.481; p = 0.017). Conclusions eNO, CANO, and EBT have been evaluated in three groups of PH patients. Interestingly EBT reduction was correlated with PAPm increase, whereas FeNO was higher in COPD patients and CANO in PAH and COPD groups. Further studies are needed to clarify EBT, FeNO, and CANO roles as biomarkers in the monitoring of patients with PH.
Highlights
Pulmonary hypertension (PH) is a progressive fatal disease noninvasive prognostic tools are needed to follow these patients
Patients were divided into 3 groups according to the classification of PH adopted by European Society of Cardiology guidelines [1]: group A was composed of 10 patients with pulmonary arterial hypertension (PAH) (3 patients with idiopathic PH, 6 patients with PH secondary to connective tissue disease, and 1 patient with portal hypertension)
We found lower mean exhaled breath temperature (EBT) values in the group C (PH associated with heart failure (HF)) if compared with groups A and B ones (30.9 ± 1.3∘C versus 30.6 ± 1.3 and 31.2 ± 1.2∘C, respectively, p = 0.041 Figure 3)
Summary
Pulmonary hypertension (PH) is a progressive fatal disease noninvasive prognostic tools are needed to follow these patients. The aim of our study was to evaluate fractional exhaled nitric oxide (FeNO) and exhaled breath temperature (EBT) values in patients with PH from different causes and to correlate them with respiratory functional data. EBT reduction was correlated with PAPm increase, whereas FeNO was higher in COPD patients and CANO in PAH and COPD groups. FeNO is usually used as a noninvasive marker of lung inflammation in asthma and other pulmonary diseases since it has been observed that its concentration in the exhaled air is related to the presence of eosinophilic infiltration of the airways [4]. The alveolar contribution to the exhaled NO (CANO) can be estimated by an extended NO analysis [11] This has been widely applied in a variety of lung diseases and in patients with PH founding increased alveolar NO concentrations probably reflecting dysfunctional alveolocapillary diffusion [12]. The clinical use of this parameter is still uncertain, this measurement is validated and clear reference limits in healthy subjects have been determined [16]
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