Abstract
Background: DLCO differentiates asthma & chronic bronchitis from COPD. There is lack of clarity about DLCO measured by single breath (SB) or by rebreathe (RB) technique is better & the effects of bronchodilation on DLCO values are not known.Aim: To compare SB & RB techniques for measuring DLCO & to study the effect of bronchodilation in healthy, asthmatics & COPD subjects.Methods: In this ongoing study 3 healthy, 6 asthma & 4 COPD subjects underwent DLCO measurements by & RB methods, body plethysmography (BP) & spirometry before & after bronchodilation with 400 mcg of inhaled salbutamol.Results: The mean DLCO in healthy, asthmatics & COPD subjects were 8.88, 5.54 & 3.4 units by SB method & 2.42, 1.44 & 1.44 units by RB method respectively.
Similarly, total lung capacity (TLC) measured were 4.79, 3.27 & 4.41 L by SB & 4.68, 3.43 & 3.8 L by RB & 5.66, 4.48 & 7.15 L by BP respectively. Bronchodilation increased DLCO by -3.57%, 2.98% & 5.12% by SB & by 0.88%, 1.97 &-4.51% in healthy, asthmatics & COPD subjects respectively. Similarly, the TLC reduced by -6.93%, 0% and 0% by SB method & by 2.35%, 4.05% & 0% by RB method & by 1%, 9.37% and 6.15% respectively after bronchodilation. All changes due to bronchodilation were not significant (paired t-test, p > 0.05).Conclusion: SB measured higher DLCO values than RB. Bronchodilation did not increase DLCO. Body Plethysmography measure higher TLC than He-dilution techniques.
- © 2013 ERS