Pulmonary hypertension (PHTN) is a rare and devastating disease characterized by progressive increases in pulmonary arterial pressure and pulmonary vascular resistance which eventually leads to right ventricular failure and death (Badesch et al., 2009; Farber and Loscalzo, 2004). It may due to various etiologies such as left heart disease, parenchymal lung disease, chronic thromboembolic disease, hematologic disorders or it may be idiopathic in nature though the clinical picture of these patients is similar (Simonneau et al., 2013). Patients with and advanced lung disease such as PHTN face symptomatology consistent with oxygen deprivation, including dyspnea, fatigue and exercise intolerance. Pulmonary rehabilitation (PR) in patients with PHTN patients is in fact important in the management as it improves outcomes (Sahni et al., 2015). This study is aimed at determining the effectiveness of structured PR program on exercise capacity in a population of PHTN patients.

Eighteen patients with PHTN met the criteria for the study. There were a total of 5 male and 13 female patients with a mean age 67.7±11.6 years. Of these patients there were six (33.33% who were considered WHO group 1 PAH), eight WHO group III PHTN (44.44%), two WHO group IV, and two WHO V PHTN (11.11%). Demographics have been outlined in Table 1. Of these patients, 14 (82.4%) were on supplemental oxygen. It was found that as a whole across all WHO groups of PHTN, treadmill speed improved following rehab (P<0.0001, Wilcoxon signed rank test). Median treadmill speed prior to rehab was 1.3 mph (interquartile range [IQR], 1.0–1.8 mph) and 2.2 mph (IQR, 1.3–2.8 mph) following rehab Fig. 1.

Prior to rehab, median exercise time was 27 min (IQR, 22–30 min), after rehab, median exercise time was 30 min (IQR, 24–30 min). The total exercise time also improved though not found to be statistically significant. Sixteen of the 18 participants improved (88.9%; 95% exact binomial confidence interval, 65.3%–98.6%).

PHTN treatment is centered on improved cardiopulmonary hemodynamics resulting in increased exercise tolerance as generally measured by the 6-min walk test. This emerging data has been seen specifically in the WHO group I PAH (Babu et al., 2016; Chan et al., 2013). Our study shows exercise tolerance improvements in terms of speed in mph and increased duration of exercise across multiple etiologies of PHTN after a course of structured PR. The results of this study also demonstrate that despite diagnostic etiology of PHTN and disease severity structured PR increases exercise tolerance.

The American Thoracic Society and the European Respiratory Society have defined pulmonary rehabilitation as an “evidence based, multidisciplinary and comprehensive intervention for patient with chronic respiratory diseases who are symptomatic and often have decreased daily life activities” (Nici et al., 2006). The principal purpose of PR programs is to improve function, disease related symptoms, optimize functional capacity and an overall improvement in quality of life.

The use PR as an adjuvant to pharmacotherapy is well established (Nici et al., 2006). PR has become a staple of therapy in advanced lung disease including chronic obstructive pulmonary disease (Casaburi et al., 2005), idiopathic pulmonary fibrosis (Raghu et al., 2011) and PHTN (Mereles et al., 2006) amongst others. Early thought process of exercise in PHTN was that it may be harmful, expedite the disease process and may even cause sudden death. However, evidenced based medicine has proven the opposite to be true (Sahni et al., 2015). The underlying mechanism of PR resulting in an increased exercise tolerance remains conjectural. Disease mechanism in PHTN heavily involves endothelin-1 (ET-1), the human body’s most potent vasoconstrictor. Studies have shown that chronic exercise causes an increase in the production of nitric oxide, a potent vasodilator and a decrease in the production of ET-1 which in turn may net a vasodilatory effect thereby decreasing pulmonary vascular resistances, increasing cardiac output and increasing exercise tolerance (Maeda et al., 2001). It is also important to note that the overall increase of speed in our pulmonary rehab patients points to an increase in exercise tolerance and endurance. Patients who were unable to increase their overall speed showed an increase in the duration of time there were able to exercise also pointing to an increased in endurance. A study by Otsuki et al. (2006) showed that ET-1 concentrations were lower in individuals who participated in strength or endurance training as compared to sedentary controls. As the knowledge and beneficial evidence of PR steadily increases the use in PHTN patients should continue to become part of standard of care.

In conclusion our study was able to show that patients with all types of PHTN and varying WHO functional class show improvement as measured by speed and time from a structured PR program. All PHTN patients should be enrolled in PR programs as part of their management in adjuvant to their pharmacotherapy and regardless of their WHO functional class.