Reduced Exercise Tolerance and Pulmonary Capillary Recruitment with Remote Secondhand Smoke Exposure

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

Atraumatic Acromioclavicular Dislocation: A Case Report and Review of the Literature

Acromioclavicular dislocation (AC dislocation) is a common injury of the shoulder. In contrast to a traumatic cause, nontraumatic dislocation is very rare. We report on a 17-year-old female that presented with voluntary recurrent dislocation of the right AC joint followed by recurrent pain without instability of the ipsilateral shoulder. Clinical examination showed crepitation as well as palpitation pain and dislocation of the AC joint. There were no symptoms of Marfan or Ehlers-Danlos syndrome as other joint examinations were also negative for hypermobility. Considering age as well as minor complaints, nonoperative treatment by postural therapy without taping was recommended. After one year, the patient experienced fewer symptoms and she was able to participate in daily activities

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

RationaleFlight 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.MethodsTo 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.ResultsThe 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&lt;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).ConclusionsThis 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

Exercise Capacity.

<p>Data is shown in mean ± standard deviation. N = 80; abbreviations: : Oxygen uptake; : carbon dioxide output; R: respiratory gas exchange ratio.</p

Association between within breath diffusing capacity (DcoWB) and workload.

<p>Generalized estimating equations were used to create linear regressions representing each association. Exercise-induced increase in diffusing capacity is decreased in flight attendants with lower diffusing capacity at rest. <b>A:</b> Stratification based on abnormal and normal diffusing capacity at rest. <b>B:</b> Stratification based on tertiles of diffusing capacity at rest. <b>C:</b> Stratification based on quartiles of diffusing capacity at rest. PE: Parameter estimate from regression models.</p

Characteristics of pre-ban flight attendants.

<p>Data is shown in mean ± standard deviation. Subjects were all female. Abbreviations: BMI: body mass index; DcoSB: single breath diffusing capacity; Hgb: hemoglobin; FEV₁: forced expiratory volume in 1 second; FVC: forced vital capacity; TLC: total lung capacity measured by body plethysmography; V_A: alveolar volume measured by single breath helium dilution.</p

Association between exercise capacity and airflow and diffusing capacity in pre-ban FAs.

<p>The exercise capacity as estimated by maximum oxygen uptake (VO₂) was directly associated with (<b>A</b>) FEV₁ (r = 0.33; p = 0.002) and with (<b>B</b>) diffusing capacity at rest (r = 0.29; p = 0.008); r: correlation coefficient.</p

Association between within breath diffusing capacity (DcoWB), pulmonary blood flow, and workload.

<p>Generalized estimating equations were used to create linear regressions representing each association. <b>A:</b> Pulmonary blood flow increase with workload is not significantly different between the flight attendants with abnormal or normal diffusing capacity at rest. <b>B:</b> Diffusing capacity increases less with increasing blood flow in flight attendants with abnormal diffusing capacity at rest. PE: Parameter estimate from regression models.</p

Association between within breath diffusing capacity (DcoWB) during exercise and years of cabin SHS exposure in flight attendants with ≥10 years pre-ban experience (N = 42).

<p>Percent predicted DcoWB at 40% maximum observed exercise was plotted against the residuals of adjusted pre-ban years employment. r: correlation coefficient.</p