1996 OPEN FORUM Abstracts
THE EFFECT OF BRONCHODILATION ON SINGLE BREATH MEASUREMENTS OF DIFFUSING CAPACITY FOR CARBON MONOXIDE (DLCO)
MG SNOW, BD ANDERSON AND RJ FALLAT. California Pacific Medical Center, San Francisco, Ca
OBJECTIVE: Bronchodilation with albuterol is commonly performed to assess airway responsiveness. Since the onset of maximal response is not immediate, typically a 10-15 minute delay is interposed between pre and post bronchodilator testing. Many laboratories use this time period to assess lung diffusion rather than increase testing time. There is evidence that isoproteronol can cause an increase in DLCO. Albuterol, a highly beta-2 specific agent, is not believed to alter DLCO although there is no supporting literature. The purpose of this study is to document the effect of albuterol on the measurement.
Methods: Plethysmographic, spirometric and DLCO measurements were evaluated for 26 subjects before and after administration of three puffs albuterol MDI. All tests were performed as recommended by ATS guidelines and bronchodilator response was evaluated using ATS criteria. Data analysis used paired test comparisons with significance at the 0.05 level and cross correlation.
p value p value
FVC 0.0110 * DLCO 0.7085
FEV1 0.0001 * VA 0.6282
FEV1/FVC 0.0109 * DL/VA 0.9886
FEF2575% 0.0001 * Raw 0.0001 *
TGV 0.0077 * Sgaw 0.0001 *
RV/TLC 0.0001 * Sraw 0.0000 *
TLC 0.0002 * *=Statistically significant
DLCO versus FEV1 0.067
DLCO versus SGaw 0.006
6/26 subjects met ATS response criteria (200ml and 12%)
Conclusions: Spirometric and plethysmographic differences were statistically significant, although only 6/26 subjects met ATS criteria for response. DLCO was not significantly different and correlated poorly with changes in FEV1 and SGaw. There is no evidence for a resultant change in DLCO due to administration of albuterol MDI. As a result, testing sequences which interpose DLCO measurement after bronchodilator administration would not seem to introduce a bias.