Single-Breath Measurement Underestimates Ventilatory Volume According to Emphysema Severity

Columbia University73 enrolled

Overview

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.

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.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Emphysema

Eligibility

Sex: ALLMin age: 18 YearsMax age: 81 YearsHealthy volunteers:

Medical Language ↔ Plain English

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.

Locations (1)

Columbia University Cardiopulmonary, Sleep and Ventilatory Disorders Center

New York, New York, United States

Outcomes

Primary Outcomes

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.

Time frame: 10 seconds

Difference between DLCO RB alveolar volume and the total lung volume measurement from plethysmography

Time frame: 10 seconds

Data from ClinicalTrials.gov

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