Effects of industrial respirator wear during exercise in subjects with restrictive lung disease

Abstract

Few studies have examined the response of individuals with restrictive lung disease (RLD) to respirator wear. Such information should be of theoretical and practical interest when the need to determine fitness to wear respirators is considered. Seventeen females performed progressive submaximal treadmill exercise. Twelve control subjects with total lung capacity (TLC) = 5.71 +/- .19L (mean +/- SEM) and DLCO = 25.8 +/- 1.0 mL/min/mmHg were compared to five RLD subjects with TLC = 3.70 +/- 0.22 and DLCO = 14.5 +/- 0.7. Mean age, height and weight were similar. Separate exercise trials were performed with no added resistance (NAR), and with 5 cm H2O/L/sec inspiratory and 1.5 cm H2O/L/sec expiratory resistance (R2) to stimulate widely used respiratory masks. Comparisons of exercise data were made at an oxygen consumption of 0.8 L/min. With NAR, RLD subjects had significantly higher minute ventilation (VE) (29.0 vs. 21.2 L/min for controls), higher respiratory rate (RR), and lower tidal volume (VT). Heart rate, end-tidal PCO2 (PETCO2), and mouth pressure swing (Poral) were not different from control values. With R2 compared to NAR, the controls had reduced RR and VE; and increased VT, PETCO2, and Poral. While changes with R2 for the RLD subjects were in the same directions as controls, only the increase in Poral was statistically significant. Analysis of the differences showed that none of the changes with R2 in RLD subjects was different from control changes except for the greater increase in Poral and the smaller increase in VT. The former was explained by the RLD subjects' higher VE and flow rates, and the non-linear nature of R2 at higher flow rates.(ABSTRACT TRUNCATED AT 250 WORDS)