TY - JOUR T1 - Remote exposure to secondhand tobacco smoke is associated with lower exercise capacity through effects on oxygen pulse, a proxy of cardiac stroke volume JF - BMJ Open Respiratory Research JO - BMJ Open Resp Res DO - 10.1136/bmjresp-2022-001217 VL - 9 IS - 1 SP - e001217 AU - Siyang Zeng AU - Michelle Dunn AU - Warren M Gold AU - Jorge R Kizer AU - Mehrdad Arjomandi Y1 - 2022/05/01 UR - http://bmjopenrespres.bmj.com/content/9/1/e001217.abstract N2 - Background Past exposure to secondhand tobacco smoke (SHS) is associated with exercise limitation. Pulmonary factors including air trapping contribute to this limitation but the contribution of cardiovascular factors is unclear.Objective To determine the contribution of cardiovascular mechanisms to SHS-associated exercise limitation.Methods We examined the cardiovascular responses to maximum-effort exercise in 245 never-smokers with remote, prolonged occupational exposure to SHS and no known history of cardiovascular disease. We estimated the contribution of oxygen-pulse (proxy for cardiac stroke volume) and changes in systolic blood pressures (SBP), diastolic blood pressures and heart rate (HR) towards exercise capacity, and examined whether the association of SHS with exercise capacity was mediated through these variables.Results At peak exercise (highest workload completed (WattsPeak)=156±46 watts (135±33 %predicted)), oxygen consumption and oxygen-pulse (O2-PulsePeak) were 1557±476 mL/min (100±24 %predicted) and 11.0±3.0 mL/beat (116±25 %predicted), respectively, with 29% and 3% participants not achieving their predicted normal range. Oxygen saturation at peak exercise was 98%±1% and remained >93% in all participants. Sixty-six per cent showed hypertensive response to exercise. In models adjusted for covariates, WattsPeak was associated directly with O2-PulsePeak, HRPeak and SBPPeak and inversely with SHS, air trapping (residual volume/total lung capacity) and rise of SBP over workload (all p<0.01). Moreover, SHS exposure association with WattsPeak was substantially (41%) mediated through its effect on O2-PulsePeak (p=0.038). Although not statistically significant, a considerable proportion (36%) of air trapping effect on WattsPeak seemed to be mediated through O2-PulsePeak (p=0.078). The likelihood of having baseline respiratory symptoms (modified Medical Research Council score ≥1) was associated with steeper rise in SBP over workload (p<0.01).Conclusion In a never-smoker population with remote exposure to SHS, abnormal escalation of blood pressure and an SHS-associated reduction in cardiac output contributed to lower exercise capacity.The data sets generated and analysed during the current study are available from the corresponding author on reasonable request. ER -