The study covered in this summary was published on MedRxiv.org as a preprint and has not yet been peer reviewed.
Past occupational exposure to secondhand smoke (SHS) from tobacco in nonsmokers contributes to a reduction in cardiac output and lower exercise capacity proportional to the number of years of exposure.
Abnormal cardiovascular responses to exercise in the participants suggest the presence of subclinical pathology that may lead to poor outcomes during times of increased cardiopulmonary demand caused by physiologic distress or disease.
Study of the long-term health consequences of SHS has been challenging.
This study may be first to describe the long-term cardiovascular health effects of past occupational SHS exposure.
In the observational Secondhand Smoke Respiratory Health Study of nonsmokers with past occupational SHS exposure, 245 US airline crew members with such a history and control subjects who had never been airline crew members were recruited between July 2007 and July 2015.
87% (n = 213) of participants were women.
All but three participants were never-smokers; the exceptions had been nonsmoking for at least 20 years.
Exclusions included any history of cardiovascular or pulmonary disease.
The post hoc analysis examined associations among exercise capacity, cardiovascular responses, pulmonary function, and years of airline cabin SHS exposure.
Exercise capacity was determined by highest workload completed, volume of oxygen uptake, and cumulative work achieved.
Air trapping, previously shown to be associated with exercise capacity, was used to assess pulmonary function.
All participants reported ceasing exercise because of dyspnea or leg fatigue.
At peak exercise, 29% of participants did not achieve predicted oxygen consumption, and 3% did not achieve predicted normal oxygen-pulse range.
Exercise capacity and abnormal cardiovascular responses to exercise were proportional to years of exposure to SHS.
Despite no history of hypertension in 95% of the cohort, 62% of SHS-exposed participants demonstrated a hypertensive response to exercise.
None of the participants reported chest discomfort or lightheadedness or had clinically significant electrocardiographic changes during exercise testing.
The SHS-exposure association with exercise capacity was dependent on oxygen-pulse peak (P < .038), suggesting an SHS effect on stroke volume and cardiac output.
Generalizability of the findings may be limited to women, who made up most of the cohort; women have been reported to be more susceptible to adverse SHS health effects.
The reported cardiovascular findings did not include imaging or further clinical assessments.
Funding was provided by the Flight Attendant Medical Research Institute, California Tobacco-Related Disease Research Program, the Department of Veterans Affairs, and the National Library of Medicine Training Grant.
This is a summary of a preprint research study, “Remote Exposure to Secondhand Tobacco Smoke Is Associated With Lower Exercise Capacity Through Effects on Oxygen Pulse, a Proxy of Cardiac Stroke Volume,” written by Siyang Zeng, MS, from the University of Washington and colleagues, published on MedRxiv.org and provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on MedRxiv.org.
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