Background: Pulmonary function testing is an integral part of evaluating patients who are being considered for cardiac transplantation. The accurate measurement of diffusing capacity (Dlco) and alveolar volume (VA) is dependent on a 10-s breath-holding maneuver that may be difficult for patients with congestive heart failure to perform. The intrabreath (IB) technique is not dependent on a breath-holding maneuver and may provide more accurate pulmonary function testing results in chronically debilitated patients.
Methods: Seventy-five patients performed maneuvers with IB and single-breath (SB) techniques during evaluation for heart transplantation and at 3 and 12 months following transplantation. The Dlco, VA, and total lung capacity (TLC) were compared using Pearson correlation coefficients, a Student t test, and intercorrelation coefficients.
Results: The Dlco and VA, when determined with the IB technique, had excellent correlations to the SB technique over all ranges of Dlco values. VA values that were determined by the IB technique were greater than those determined by the SB technique and more closely approximated the TLC values. The satisfactory correlation between the two techniques was maintained when Dlco was corrected for VA. However, due to the lower values for VA as determined by the SB method, the corrected measurements were consistently higher for the SB technique.
Conclusion: Pulmonary function can be measured accurately in a population of patients with long-standing congestive heart failure, both before and after cardiac transplantation, using the IB technique. Furthermore, the IB technique may provide a more accurate measurement of VA.