Ventilatory Constraint, Breathing Pattern and Ventilatory Responses in Obese Postmenopausal Women

Study Overview
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Brief Summary
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The purpose of this study was to examine the dynamic lung volumes in obese post-menopausal women (without hormone replacement therapy) during exercise and their correlations with dyspnea.

Detailed Description
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Obesity-related changes in lung volumes have shown to affect breathing mechanisms. During exercise, altered breathing mechanisms increase potential for expiratory flow limitation and compromise exercise capacity. Estrogen and progesterone are potent respiratory stimulants, and their effects in the physiologic regulation of breathing are down-regulated after menopause. Therefore, we theorized that the combined obesity and reduced sex hormone levels after menopause work as a double jeopardy to cause mechanical ventilatory constraint which aggravates dyspnea sensation during exercise, and thus a reduction in exercise capacity. The purpose of this study was to exam the dynamic lung volumes in obese post-menopausal women (without hormone replacement therapy) during exercise and their correlations with dyspnea. From doctoral referral and advertisement, 24 obese (BMI ≧ 27 kg/m2) and 26 lean post-menopausal women were recruited for the study. Pulmonary function and body composition were measured at rest. A maximal flow volume loop (MFVL) was obtained at baseline. All subjects then performed an incremental exercise test on a cycle ergometer with workload increasing 25 watts every 3 min. During exercise, at each workload, the tidal exercise FV loops were obtained and an inspiratory capacity (IC) maneuver was conducted to assess changes in end-expiratory lung volume (EELV) and end inspiratory lung volume (EILV). Dyspnea and leg fatigue were assessed using the Borg scale. Analysis of variance with repeated measurements was used to test the significance of the mean differences between the two groups during exercise. Linear regression analysis was used to determine whether changes in dynamic lung volumes during exercise were related to changes in Borg scores. Statistical significance was established at p<0.05.

Official Title
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Ventilatory Constraint, Breathing Pattern and Ventilatory Responses in Obese Postmenopausal Women

Conditions
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Obesity, Postmenopausal Women

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Postmenopausal women (for at least 1 year) Age below 69 y/o Not receiving hormone replacement therapy Exclusion Criteria: Cardiopulmonary disease Musculoskeletal disease affecting results of maximal exercise test

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 69 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Post-menopausal women<br>Post-menopausal women (without hormone replacement therapy) | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Dynamic lung volume: end-expiratory lung volume (EELV), end-inspiratory lung volume (EILV) |  | At least 1 year post-menopause | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pulmonary function |  | At least 1 year post-menopause | 
| Breathing pattern |  | At least 1 year post-menopause | 
| Ventilatory response |  | At least 1 year post-menopause | 
| Visual analog scale (VAS) for dyspnea and leg fatigue |  | At least 1 year post-menopause | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Obesity, Postmenopausal women, Mechanical ventilatory constraints, Dynamic lung volume, Expiratory flow limitation