Evolution of the respiratory function of professional divers over 15 years.

BACKGROUND: The study was aimed at assessing changes in respiratory function after 15 years of profes- sional diving, among scientific divers. MATERIALS AND METHODS: A retrospective study was performed on divers who underwent an initial visit and a visit 15 years later at the same medical centre, among divers who had a scientific activity (monitoring the coastline, fauna and flora). Pulmonary function tests were performed in the same laboratory with the same operating standards and using a Jaeger MasterBody plethysmograph. Each subject acted as his or her own control. The data were analysed by Student's t-test and Spearman's correlation coefficient. RESULTS: Twenty-six divers were included. Changes over 15 years included: a decrease in the forced expired volume in 1 second/functional vital capacity (FEV1/FVC) ratio (-6 for absolute value, p < 0.01; and -5% for theoretical value, p = 0.02); a decrease in forced expiratory flow (FEF)25% (-1.1 for absolute value, p < 0.01; and -21% for theoretical value, p < 0.01); a decrease in transfer factor for carbon monoxide (TLCO) (-0.7 for absolute value, p = 0.04); and an increase in vital capacity (VC) (+8% for theoretical value, p = 0.03). A significant correlation was found between the consumption of tobacco in packs per year (PY) and the variations in VC (r = 0.89; p < 0.01) and the variations in the theoretical FEV1 (r = 0.76; p = 0.03). There was a significant relationship between the number of dives and the variations in the percentage of the theoretical FEV1/FVC ratio (r = -0.42; p = 0.04). The same relationship was found for the average of dive duration (r = -0.59; p < 0.01) Conclusions: With increasing length of diving activities service, the pulmonary function displays a trend toward both a decrease in TLCO and a decrease in FEF25%.

Effects of inspiratory muscle training on dyspnoea in severe COPD patients during pulmonary rehabilitation: controlled randomised trial.

The benefit of inspiratory muscle training (IMT) combined with a pulmonary rehabilitation programme (PRP) is uncertain. We aimed to demonstrate that, in severe and very severe chronic obstructive pulmonary disease (COPD) patients, IMT performed during a PRP is associated with an improvement of dyspnoea.In a single-blind randomised controlled trial, 150 severe or very severe COPD patients were allocated to follow PRP+IMT versus PRP alone. The evaluations were performed at inclusion and after 4 weeks. The primary outcome was the change in dyspnoea using the Multidimensional Dyspnoea Profile questionnaire at the end of a 6-min walk test (6MWT) at 4 weeks. Secondary outcomes were changes in dyspnoea using the Borg (end of the 6MWT) and modified Medical Research Council scales and in functional parameters (maximal inspiratory pressure (PImax), inspiratory capacity, 6MWT and quality of life). All analyses were performed on an intention-to-treat basis.Dyspnoea decreased significantly in both groups; however, the improvement of dyspnoea was not statistically different between the two groups. We only found a statistically significant greater increase of PImax after IMT+PRP than after PRP alone.In this trial including severe or very severe COPD patients, we did not find a significant benefit of IMT during PRP+IMT as compared to PRP alone on dyspnoea, despite a significantly higher improvement of PImax in the IMT group.

Responsiveness and Minimally Important Difference of the 6-Minute Stepper Test in Patients with Chronic Obstructive Pulmonary Disease.

BACKGROUND: The validity and reproducibility of the 6-minute stepper test (6MST) have already been demonstrated in patients with chronic obstructive pulmonary disease (COPD). OBJECTIVES: The aim of this study was to evaluate the responsiveness of the 6MST to pulmonary rehabilitation (PR) in patients with COPD, to determine a minimal important difference (MID) for the 6MST, and to compare the 6MST and the 6-minute walk test (6MWT). METHODS: Sixty-two patients with COPD were included in a prospective experimental study. Participants underwent a 3-week inpatient PR program. The primary outcome was the change in the number of steps during the 6MST measured before and after PR. The secondary outcome included the change in the 6-minute walking distance (6MWD) pulse oximetry, heart rate, dyspnea, and leg discomfort during the tests measured before and after PR. MID was determined by anchor-based and distribution approaches. RESULTS: After PR, we observed a significant increase in the number of steps during the 6MST (22.5 steps; 95% CI 13.8-31.3; p < 0.0001) and in the 6MWD (26.6 m; 95% CI 17.6-35.5; p < 0.0001). The 6MST and 6MWT were improved by 10.1 and 6.5%, respectively. The number of steps during the 6MST was significantly correlated with the 6MWD before (r = 0.72; p < 0.0001) and after PR (r = 0.66; p < 0.0001). MID was estimated to be around 20 steps. CONCLUSION: The 6MST appears to be as responsive as the 6MWT in assessing functional improvement during PR in patients with COPD. The 6MST is a low-cost assessment and requires limited space.

Validation of improved recording site to measure phrenic conduction from surface electrodes in humans.

Phrenic nerve stimulation, electrical (ES) or from cervical magnetic stimulation (CMS), allows one to assess the diaphragm contractile properties and the conduction time of the phrenic nerve (PNCT) through recording of an electromyographic response, traditionally by using surface electrodes. Because of the coactivation of extradiaphragmatic muscles, signal contamination can jeopardize the determination of surface PNCTs. To address this, we compared PNCTs with ES and CMS from surface and needle diaphragm electrodes in five subjects (10 phrenic nerves). At a modified recording site, lower and more anterior than usual (lowest accessible intercostal space, costochondral junction) with electrodes 2 cm apart, surface and needle PNCTs were similar (CMS: 6.0 +/- 0.25 ms surface vs. 6.2 +/- 0.13 ms needle, not significant). Electrodes recording the activity of the most likely sources of signal contamination, i.e., the serratus anterior and pectoralis major, showed distinct responses from that of the diaphragm, their earlier occurrence strongly arguing against contamination. With ES and CMS, apparently uncontaminated signals could be consistently recorded from surface electrodes.