Single-Breath Measurement Underestimates Ventilatory Volume According to Emphysema Severity

Status

Completed

Phases

Unknown

Study type

Observational

Source

ClinicalTrials.gov

Registry ID

NCT00528944

Enrollment

Registered

2007-09-14

Start date

2006-01-31

Completion date

2008-07-31

Last updated

2015-07-07

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Emphysema

Keywords

alveolar volume, pulmonary function testing, emphysema

Brief summary

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

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.

Interventions

None listed

Study design

Observational model

COHORT

Time perspective

PROSPECTIVE

Eligibility

Sex/Gender

ALL

Age

18 Years to 81 Years

Healthy volunteers

Yes

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.

Design outcomes

Primary

Measure	Time frame	Description
Difference between DLCO SB alveolar volume and the total lung volume measurement from plethysmography	10 seconds	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.
Difference between DLCO RB alveolar volume and the total lung volume measurement from plethysmography	10 seconds	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.

Countries

United States

Outcome results