Submitted on May 31, 2007
Accepted on October 29, 2007
Single-breath test in lateral decubitus reflects function of single lungs grafted for interstitial lung disease
Alain Van Muylem1, Pierre Alain Gevenois2, Elizabeth Kallinger3, Alexander A. Bankier4, Christiane Knoop1, G Verleden5, and Marc Estenne1*
1 Chest Service, Erasme University Hospital, Brussels, Belgium
2 Department of Radiolgy, Erasme University Hospital, Brussels, Belgium
3 Department of Radiology, Kaiser-Franz-Joseph Hospital, Vienna, Austria
4 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States
5 Chest Service, Gasthuisberg Hospital, Leuven, Belgium
* To whom correspondence should be addressed. E-mail: mestenne{at}ulb.ac.be.
After single-lung transplantation (SLT) for emphysema, heterogeneity of ventilation distribution in the graft can be assessed by measuring the slope of the alveolar plateau computed from a single-breath test performed in lateral decubitus with this lung in non-dependent position. We tested the validity of this technique in patients with SLT for interstitial lung diseases (ILD). Twelve patients with SLT for ILD, 12 non-transplanted patients with ILD, and 10 controls performed single-breath washouts in right and left lateral decubitus; nitrogen slope (SN2) and the difference between SF6 and He slopes (SSF6-SHe) were measured between 75 and 100% of expired volume. In 10 transplant recipients, the volume of each lung was measured in both postures by computerized tomography. Slopes were unaffected by posture in normal controls and patients with ILD. On the other hand, SN2 and SSF6-SHe in transplant recipients were smaller with the graft in non-dependent than in dependent position (0.366 ± 0.445 vs. 1.035 ± 0.498 for SN2; 0.094 ± 0.201 vs. 0.218 ± 0.277 for SSF6-SHe). Values of SN2 and SSF6-SHe obtained in the former position were similar to those obtained in normal controls, while values obtained the latter position were similar to those obtained in non-transplanted patients with ILD. Computerized tomography studies with the graft in non-dependent position indicated that this lung contributed 82% of the volume expired below functional residual capacity. We conclude that, in patients with SLT for ILD, SN2 obtained with the graft in non-dependent position reflects heterogeneity of ventilation distribution in this lung.
