Effect of Smoking a Cigarette on the Density Dependence of Maximal Expiratory Flow

Abstract

We have shown that tobacco smoke causes an increase in airways resistance and a drop in expiratory flow at 50% of the vital capacity (FEF₅₀). To better define the nature and site of this bronchoconstrictive effect we measured maximal expiratory flow while breathing air and a low-density gas mixture (helium-oxygen), in 12 healthy volunteers, before and after smoking a cigarette. There was a significant drop in FEF₅₀ while breathing air (FEF₅₀Air) (5.52 ± 1.83–5.05 ± 1.86 liters/s; p < 0.001).No changes were observed in the helium-oxygen FEF₅₀ (FEF₅₀He) after smoking. The increase in FEF₅₀ after breathing the low-density gas as a percentage of FEF₅₀Air (ΔVmax₅₀) increased from 47.1 ± 11.4% before smoking to 57.0 ± 13.3% after smoking (p < 0.05). There were no changes in forced vital capacity (FVC), flow at 75% FVC and volume of isoflow. We discuss these observations in light of the equal pressure point (EPP) analysis and wave speed theory of flow limitation. We conclude that after smoking flow becomes more density dependent because there is constriction of a flow-limiting segment downstream from the EPP, located in lobar and segmental bronchi. No acute effect of tobacco smoke on the small airways could be demonstrated.

Organizational factors affecting smoking at work: Results from focus group interviews with smokers and ex-smokers

“…Earlier investigations have, however identified a need for addressing work environmental factors that affect employee health behavior. Gupta and Jenkins' model (1984), although developed as a tool for discussing substance use at work, is also appropriate to our discussion of smoking policy/behavior, since nicotine is a drug with immediate psychoneurological and physiological effects (Golding et al 1982;Taveira Da Silva et al, 1982). Emont and Cummings (1990) assessed the effects of worksite-level factors on clinic participation and smoking cessation at multiple work settings and concluded that, in addition to intervention efforts focused on employee behavior, manager and worksite characteristics should also be addressed.…”