Respiratory muscle dysfunction in idiopathic pulmonary arterial hypertension

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¡SD pulmonary 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¡2.0 versus 8.2¡2.0 kPa). In the male patients, PI,max was lower than in 25 controls (6.8¡2.2 versus 10.5¡3.7 kPa). Maximal expiratory pressure (PE,max) was lower in the female patients than in controls (6.2¡2.6 versus 9.5¡2.1 kPa), and in male patients as compared to controls (7.1¡1.6 versus 10.3¡3.9 kPa). There was no correlation between PI,max or PE,max and parameters of pulmonary haemodynamics or exercise testing. The ratio of mouth occlusion pressure within the first 0.1 s of inspiration and PI,max was higher in IPAH than in controls (females 0.067¡0.066 versus 0.021¡0.008; males 0.047¡0.061 versus 0.023¡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.KEYWORDS: Exercise test, pulmonary hypertension, respiratory function test, respiratory muscles I diopathic pulmonary arterial hypertension (IPAH) is defined as a pulmonary vasculopathy of unknown aetiology, predominantly affecting females [1]. Minute ventilation (V9E) is increased at rest and during exercise [2]. The ventilatory response to exercise in IPAH patients, i.e. the ratio of V9E to carbon dioxide production (V9CO 2 ) during exercise (V9E/V9CO 2 slope), is also increased and is a predictor of poor prognosis [2,3]. The increased V9E/V9CO 2 slope indicates inefficient ventilation in IPAH, which can partly be attributed to pulmonary-perfusion abnormalities [2]. It has been shown by the current authors' group and others that, in congestive left ventricular failure, inefficient ventilation is associated with reduced inspiratory muscle strength [4][5][6]. Moreover, inspiratory muscle function has recently been identified as a prognostic predictor in congestive left ventricular failure [7]. Risk stratification of patients with congestive left ventricular failure is improved by using the combination of maximal inspiratory pressure (PI,max) and peak oxygen consumption (V9O 2 ) [7].Inspiratory and expiratory muscle strength have not been studied in IPAH. Therefore, this prospective study investigated respiratory muscle function and the mouth occlusion pressures in 37 patients with IPAH. PI,max and maximal expiratory pressure (PE,max) were prospectively assessed in IPAH patients with varying degrees of disease and exercise limitation. Moreover, invasive (right heart c...

Chronic Thromboembolic Pulmonary Hypertension: Effects of Pulmonary Endarterectomy

“…The combination of alveolar hyperventilation and increased (parallel) dead space ventilation is remarkable as it puts an extra ventilatory drive on an already increased effort of breathing. These findings are in unison with reports in patients with iPAH (Meyer et al, 2005;Wessel et al, 1964;Zoia et al, 2002). The alveolar hyperventilation seemed to be only in part hypoxic driven, as administration of 100% oxygen for at least 20 minutes increased but did not normalize Pa,CO 2 (4.50 ± 0.42 kPa vs. 4.58 ± 0.42 kPa).…”

“…In COPD and chronic (left) heart failure multiple mechanisms have been suggested to be involved in reduced muscle strength; changes in muscle fibre type ratio, abnormal intracellular Ca 2+ profile, impaired muscle perfusion, decreased number of mitochondria, decreased oxidative enzymes, electrolyte disturbance, steroid therapy, malnutrition, wasting and cardiac cachexia. Most of these mechanisms do not seem to apply in PH (Meyer et al, 2005). However, we observed an increase in body mass index (BMI) one year after PEA in patients with CTEPH; in 48 consecutive CTEPH patients the BMI increased from 29.7±5.6 preoperatively to 30.8±5.7 at 1 year after surgery (p=0.001).…”

“…The main focus of our studies has been on the cardiac and ventilatory contributing components. However, recently a reduction in respiratory and peripheral muscle strength has been observed in patients with iPAH which may be a determinant of exercise performance as well (Bauer et al, 2007;de Man et al, 2009;Mainguy et al, 2010;Meyer et al, 2005). The underlying mechanisms responsible for muscle weakness in PH patients are not yet known.…”

Evaluating respiratory musculature, quality of life, anxiety, and depression among patients with indeterminate chronic Chagas disease and symptoms of pulmonary hypertension

“…In addition, a prospective study of 20 control patients and 37 patients with idiopathic PH (class II-IV, 26 women and 11 men) revealed that the patients with PH had lower values for PImax and PEmax, as well as weakness in the inspiratory and expiratory musculature 10 . These patients may hyperventilate during rest, exercise, and sleep, which can cause increased respiratory muscle activity, overload the inspiratory musculature, and lead to muscular weakness.…”

Effect of Volume-Oriented Versus Flow-Oriented Incentive Spirometry on Chest Wall Volumes, Inspiratory Muscle Activity, and Thoracoabdominal Synchrony in the Elderly

“…[1][2][3] This decrease in the static elastic recoil of the lungs is related to changes in the quantity and composition of the supporting structures within the lung parenchyma. 4 The reduced physiological capacity of the respiratory system with aging can predispose vulnerable individuals to an increased risk for respiratory diseases, such as respiratory insufficiency, atelectasis, and respiratory infection. 5,6 Some breathing exercises are commonly used in the treat-ment and prevention of aging-related respiratory conditions.…”