[Estimation of respiratory muscle endurance using an inspiratory threshold loading device in patients with chronic pulmonary emphysema and in elderly subjects].

Abstract

We studied respiratory muscle endurance with an inspiratory threshold loading (ITL) device using Martyn's method (2-min incremental loading test) in 9 patients with chronic pulmonary emphysema (CPE patients) and in 9 elderly subjects with no lung disease (NE subjects), and their endurance was compared with that of 9 normal young subjects (NY subjects). In 11 cases (8 CPE patients and 3 NE subjects) a treadmill exercise test was performed and cardiopulmonary parameters obtained from the ITL and treadmill tests were compared. The maximum weight tolerated for 2 minutes (Wmax) and the mean peak inspiratory mouth pressure/maximum inspiratory mouth pressure ratio at the maximum load (Ppk/MIP at Max Load) were used as indices of respiratory muscle endurance. CPE patients had significantly decreased Wmax compared with those of NE and NY subjects. Wmax in all cases positively correlated with Ppk/MIP at Max Load, and endurance time of both the ITL and treadmill tests. During both tests, SaO2 significantly decreased, and heart rate and mean blood pressure significantly increased. There was less change in SaO2 and heart rate during the ITL test than during the treadmill test, and neither arrhythmias nor ST changes on ECG were observed during the ITL test. These results indicate that the ITL test can be easily and safely employed in CPE patients and elderly subjects to estimate respiratory muscle endurance.