Single-Breath Measurement Underestimates Ventilatory Volume According to Emphysema Severity

Study Overview
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Brief Summary
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Although single breath helium (He) dilution measurement (VASB) is currently used in pulmonary function laboratories to assess functional alveolar volume and diffusing capacity for carbon monoxide, the extent to which VASB reflects ventilatory and thoracic volume has not been prospectively determined in emphysema. We hypothesized that VASB underestimates rebreathe helium dilution volume (VARB), and plethysmographic volume (VApleth) as clinical and physiologic severity of emphysema increases.

Detailed Description
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VASB, VARB, and VApleth were measured in 52 consecutive stable outpatients with clinical and radiographic emphysema. Thirteen patients with an obstructive ventilatory defect without emphysema (OVD) and 18 normal controls were similarly studied. All subjects underwent spirometry followed by whole body plethysmography and He dilution volume measurements; VASB and VARB order was randomized.

Official Title
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Single-Breath Measurement Underestimates Ventilatory Volume According to Emphysema Severity

Conditions
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Emphysema

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All outpatients between the ages of 18 and 81 years referred to the Columbia University Medical Center Pulmonary Diagnostic Unit between 1/18/06 and 7/30/07 for full pulmonary function evaluation, and with an obstructive ventilatory defect on spirometry, were considered eligible. Exclusion Criteria: Patients who did not want to undergo the re-breathe diffusing capacity testing Patients who could not give informed consent;and Patients who were too physically compromised to undergo full testing including the re-breathe maneuver as deemed by our technicians.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 81 Years

Sexes Eligible for Study
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All

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 |
| --- | --- |
| Cohort A<br>Patients with obstructive defects and radiological evidence of emphysema | |
| Cohort B<br>Patients with obstructive ventilatory defects and no radiological evidence of emphysema | |
| Cohort C<br>Non-smokers without obstructive ventilatory defects or history of cardiopulmonary disease | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference between DLCO SB alveolar volume and the total lung volume measurement from plethysmography | To test the hypothesis that DLCO SB underestimates DLCO derived by the re-breathe DLCO maneuver, and that VA SB similarly underestimates VA RB. Alveolar volume derived with the two maneuvers will be compared with body plethysmography, the gold standard of total lung volume measurement in patients with emphysema. | 10 seconds | 
| Difference between DLCO RB alveolar volume and the total lung volume measurement from plethysmography | To test the hypothesis that DLCO SB underestimates DLCO derived by the re-breathe DLCO maneuver, and that VA SB similarly underestimates VA RB. Alveolar volume derived with the two maneuvers will be compared with body plethysmography, the gold standard of total lung volume measurement in patients with emphysema. | 10 seconds | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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alveolar volume, pulmonary function testing, emphysema