Dataset Information

Reduced exercise tolerance and pulmonary capillary recruitment with remote secondhand smoke exposure.

ABSTRACT:

Rationale

Flight attendants who worked on commercial aircraft before the smoking ban in flights (pre-ban FAs) were exposed to high levels of secondhand smoke (SHS). We previously showed never-smoking pre-ban FAs to have reduced diffusing capacity (Dco) at rest.

Methods

To determine whether pre-ban FAs increase their Dco and pulmonary blood flow (Qc) during exercise, we administered a symptom-limited supine-posture progressively increasing cycle exercise test to determine the maximum work (watts) and oxygen uptake (VO2) achieved by FAs. After 30 min rest, we then measured Dco and Qc at 20, 40, 60, and 80 percent of maximum observed work.

Results

The FAs with abnormal resting Dco achieved a lower level of maximum predicted work and VO2 compared to those with normal resting Dco (mean±SEM; 88.7±2.9 vs. 102.5±3.1%predicted VO2; p?=?0.001). Exercise limitation was associated with the FAs' FEV(1) (r?=?0.33; p?=?0.003). The Dco increased less with exercise in those with abnormal resting Dco (mean±SEM: 1.36±0.16 vs. 1.90±0.16 ml/min/mmHg per 20% increase in predicted watts; p?=?0.020), and amongst all FAs, the increase with exercise seemed to be incrementally lower in those with lower resting Dco. Exercise-induced increase in Qc was not different in the two groups. However, the FAs with abnormal resting Dco had less augmentation of their Dco with increase in Qc during exercise (mean±SEM: 0.93±0.06 vs. 1.47±0.09 ml/min/mmHg per L/min; p<0.0001). The Dco during exercise was inversely associated with years of exposure to SHS in those FAs with ?10 years of pre-ban experience (r?=?-0.32; p?=?0.032).

Conclusions

This cohort of never-smoking FAs with SHS exposure showed exercise limitation based on their resting Dco. Those with lower resting Dco had reduced pulmonary capillary recruitment. Exposure to SHS in the aircraft cabin seemed to be a predictor for lower Dco during exercise.

SUBMITTER: Arjomandi M

PROVIDER: S-EPMC3321018 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Publications

Reduced exercise tolerance and pulmonary capillary recruitment with remote secondhand smoke exposure.

Arjomandi Mehrdad M Haight Thaddeus T Sadeghi Nasrat N Redberg Rita R Gold Warren M WM

PloS one 20120406 4

<h4>Rationale</h4>Flight attendants who worked on commercial aircraft before the smoking ban in flights (pre-ban FAs) were exposed to high levels of secondhand smoke (SHS). We previously showed never-smoking pre-ban FAs to have reduced diffusing capacity (Dco) at rest.<h4>Methods</h4>To determine whether pre-ban FAs increase their Dco and pulmonary blood flow (Qc) during exercise, we administered a symptom-limited supine-posture progressively increasing cycle exercise test to determine the maxim ...[more]

PMID: 22493689

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Project description:BackgroundProlonged past exposure to secondhand tobacco smoke (SHS) in never-smokers is associated with abnormal lung function and reduced diffusing capacity suggestive of an associated lung tissue injury and damage. The mechanisms by which past SHS exposure may contribute to lung tissue damage are unknown. Elastin is a major constituent of extracellular matrix in lung parenchyma.ObjectiveTo determine whether past exposure to SHS is associated with ongoing lung tissue damage as indicated by elevated elastin degradation products that are linked to lung function.MethodsWe measured the plasma levels of elastin degradation markers (EDM) from 193 never-smoking flight attendants with a history of remote SHS exposure in aircraft cabins and 103 nonsmoking flight attendants or sea-level control participants without such history of cabin SHS exposure and examined those levels versus their lung function with adjustment for covariates. The cabin SHS exposure was estimated based on airline employment history and years of the smoking ban enactment.ResultsThe median [interquartile range] plasma EDM level for all participants was 0.30 [0.24-0.36] ng/mL with a total range of 0.16-0.65 ng/mL. Plasma EDM levels were elevated in those with a history of exposure to cabin SHS compared to those not exposed (0.33±0.08 versus 0.26±0.06 ng/mL; age- and sex-adjusted P<0.001). In those with a history of cabin SHS exposure, higher EDM levels were associated with a lower diffusing capacity (parameter estimate [PE] 95% [confidence interval(CI)]=4.2 [0.4-8.0] %predicted decrease per 0.1 ng/mL increase in EDM; P=0.030). Furthermore, EDM levels were inversely associated with forced expiratory volume in 1 second (FEV1), FEV1 to forced vital capacity (FVC) ratio , and forced expiratory flow rate between 25% and 75% ( FEF25%-75%) (PE [95%CI]=5.8 [2.1-9.4], 4.0 [2.2-5.7], and 12.5 [5.8-19.2] %predicted decrease per 0.1 ng/mL increase in EDM, respectively; P<0.001). Plasma EDM mediated a substantial fraction of the association of SHS with FEV1, FVC, and FEF25%-75% (P<0.05).ConclusionsLong after past exposure to SHS, there is ongoing elastin degradation beyond what is expected from the aging process, which likely contributes to lower lung function and a reduced pulmonary capillary bed as seen in chronic obstructive pulmonary disease (COPD).

Project description:BackgroundPast 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.ObjectiveTo determine the contribution of cardiovascular mechanisms to SHS-associated exercise limitation.MethodsWe 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.ResultsAt 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).ConclusionIn 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.

Project description:BackgroundAirports may represent significant sources of secondhand smoke (SHS) exposure for both travelers and employees. While previously common smoking rooms have largely disappeared from US airports, smoking continues to occur outdoors at terminal entrances. SHS may be especially high at arrival areas, since they oftentimes are partially enclosed by overhead departures, creating stagnant microenvironments. This study assessed particulate matter <2.5 microns in diameter (PM2.5), a common surrogate for SHS, at airport terminal locations to evaluate both outdoor exposure risk and possible indoor drift of SHS from outdoor sources.MethodsA convenience sample of nine airport terminal arrival areas in the US state of Florida was surveyed between February and July 2018. PM2.5 levels were assessed outdoors and indoors at terminal entrances and at control areas far into terminal interiors. We also examined the impact of smoking location on SHS exposure by correlating cigarette and passing vehicle counts with PM2.5 levels at terminals with contrasting proximity of designated smoking locations to terminal entrances.ResultsAlthough outdoor PM2.5 levels (mean 17.9, SD 6.1 µg/m3) were significantly higher than indoors (p < 0.001), there was no difference between indoor areas directly inside terminal entrances and areas much further interior (mean 8.8, SD 2.6 vs mean 8.5, SD 3.0 µg/m3, p=0.49). However, when smoking areas were in close proximity to terminal entrances, the number of lit cigarettes and vehicular traffic per minute predicted 70% of the variance of PM2.5 levels (p < 0.001), which was attributable mostly to the cigarette number (β = 0.83; 95% CI (0.55 to 1.11); p < 0.001). This effect was not observed at smoking areas further away.ConclusionPM2.5 data did not suggest indoor drift from outside smoking. Nevertheless, absolute exposure outdoors was high and correlated with the location of designated smoking areas. Further studies are needed to examine the effect of microclimate formation on exposure risk.

Dataset Information

Reduced exercise tolerance and pulmonary capillary recruitment with remote secondhand smoke exposure.

Rationale

Methods

Results

Conclusions

Publications

Reduced exercise tolerance and pulmonary capillary recruitment with remote secondhand smoke exposure.

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