Respiratory muscle dysfunction in idiopathic pulmonary arterial hypertension

Open Access
Publisher Website
Google Scholar
Abstract
Idiopathic pulmonary arterial hypertension (IPAH) is a pulmonary vasculopathy of unknown aetiology. Dyspnoea, peripheral airway obstruction and inefficient ventilation are common in IPAH. Data on respiratory muscle function are lacking.This prospective single-centre study included 26 female and 11 male patients with IPAH in World Health Organization functional classes II–IV. Mean±sdpulmonary artery pressure was 48.6±16.9 in females and 53.1±22.9 mmHg in males; cardiac output was 3.7±1.3 and 4.2±1.7 L·min−1.Maximal inspiratory pressure (PI,max) was lower in the female patients than in 20 controls (5.3±2.0versus8.2±2.0 kPa). In the male patients,PI,max was lower than in 25 controls (6.8±2.2versus10.5±3.7 kPa). Maximal expiratory pressure (PE,max) was lower in the female patients than in controls (6.2±2.6versus9.5±2.1 kPa), and in male patients as compared to controls (7.1±1.6versus10.3±3.9 kPa). There was no correlation betweenPI,max orPE,max and parameters of pulmonary haemodynamics or exercise testing. The ratio of mouth occlusion pressure within the first 0.1 s of inspiration andPI,max was higher in IPAH than in controls (females 0.067±0.066versus0.021±0.008; males 0.047±0.061versus0.023±0.016).In conclusion, this study provides the first evidence of inspiratory and expiratory muscle weakness in idiopathic pulmonary arterial hypertension. The pathomechanisms and the prognostic significance should be further investigated.