It has been suggested that impaired respiratory muscle function occurs in patients with PH (pulmonary hypertension); however, comprehensive investigations of respiratory muscle function, including the application of non-volitional tests, needed to verify impairment of respiratory muscle strength in patients with PH have not yet been performed. In the present study, respiratory muscle function was assessed in 31 patients with PH (20 females and 11 males; mean pulmonary artery pressure, 51+/-20 mmHg; median World Health Organization class 3.0+/-0.5; 25 patients with pulmonary arterial hypertension and six patients with chronic thromboembolic PH) and in 31 control subjects (20 females and 11 males) well-matched for gender, age and BMI (body mass index). A 6-min walking test was performed to determine exercise capacity. Volitionally assessed maximal inspiratory (7.5+/-2.1 compared with 6.2+/-2.8 kPa; P=0.04) and expiratory (13.3+/-4.2 compared with 9.9+/-3.4 kPa; P<0.001) mouth pressures, sniff nasal (8.3+/-1.9 compared with 6.6+/-2.2 kPa; P=0.002) and transdiaphragmatic (11.3+/-2.5 compared with 8.7+/-2.5 kPa; P<0.001) pressures, non-volitionally assessed twitch mouth (1.46+/-0.43 compared with 0.97+/-0.41 kPa; P<0.001) and transdiaphragmatic (2.08+/-0.55 compared with 1.47+/-0.72 kPa; P=0.001) pressures during bilateral anterior magnetic phrenic nerve stimulation were markedly lower in patients with PH compared with control subjects. Maximal inspiratory mouth (r=0.58, P<0.001) and sniff transdiaphragmatic (r=0.43, P=0.02) pressures were correlated with the 6-min walking distance in patients with PH. In conclusion, the present study provides strong evidence that respiratory muscle strength is reduced in patients with PH compared with well-matched control subjects. Furthermore, the 6-min walking distance is significantly linked to parameters assessing inspiratory muscle strength.

Exercise and respiratory training as an adjunct to medical therapy may be effective in patients with PAH to improve respiratory muscle strength and exercise capacity. Future, randomized, controlled trials should be carried out to further investigate these findings.

Background: Physical activity is known to cause significant deoxygenation in patients with severe chronic obstructive pulmonary disease (COPD). Although noninvasive positive pressure ventilation (NPPV) has been shown to improve oxygenation and physical activity in these patients, no practical approach for the application of NPPV during walking has yet been established. Objective: To elucidate the most effective approach to preserving oxygenation during walking in patients with severe COPD receiving long-term NPPV. Methods: Three 12-min walking tests were performed in a randomized cross-over design on 3 consecutive days, comparing the usual and double dosages of oxygen versus NPPV plus the usual dosage of oxygen. The ventilator and oxygen tank were placed in a backpack. Results: Eleven patients (FEV₁ 26 ± 9% predicted) completed the study, while 8 patients refused to walk with NPPV, due to the weight of the ventilatory device (7.3 kg with NPPV vs. 3.1 kg without). PaO₂ changes during walking differed [p = 0.01, repeated-measures (RM)-ANOVA], whereas dyspnea was unchanged. The difference in PaO₂ change was 14.0 ± 16.6 mm Hg (unadjusted p = 0.0036, critical level = 0.017, RM-ANOVA) in favor of NPPV compared to the usual dosage of oxygen. Changes in FEV₁, tidal volume and inspiratory impedance were in favor of NPPV-aided exercise (all p < 0.05, RM-ANOVA). Walking distance was reduced under NPPV (555 ± 227 m) compared to the usual (619 ± 210 m) and double (622 ± 215 m) dosages of oxygen (p = 0.024, RM-ANOVA). Conclusions: NPPV plus supplemental oxygen, but not oxygen alone, preserves oxygenation during walking in patients with severe COPD. However, dyspnea and walking distance were not improved due to the burden of carrying the heavy ventilatory equipment in a backpack.

Aims/hypothesis Diabetes has a major negative effect on intensive care unit outcome. This has been partly attributed to impaired respiratory neuromuscular function. However, data on respiratory neuromuscular involvement in diabetes are lacking. This study therefore aimed to assess respiratory neuromuscular function related to diabetic polyneuropathy in patients with type 2 diabetes. Methods Respiratory neuromuscular function was assessed by the use of volitional tests and twitch mouth (TwPmo) and twitch transdiaphragmatic (TwPdi) pressures during non-volitional bilateral anterior magnetic phrenic nerve stimulation in 21 male type 2 diabetic patients without pulmonary disease and in 23 healthy, well-matched controls (forced expiratory volume in 1 s 103±11 vs 103±12% predicted; p=0.9). Results Both volitionally assessed maximal inspiratory and expiratory mouth pressures, and sniff nasal and transdiaphragmatic pressures were comparable between diabetic patients and controls (p>0

Although the drop of PaO2 was comparable, stair-climbing resulted in more prolonged hyperinflation of the lungs, higher blood lactate production and more dyspnea than walking. The walking distance was not related to the time needed to manage stair-climbing. Therefore, pathophysiological changes during the 6-min walking test do not anticipate those during stair-climbing in patients with severe COPD.