Chest
Volume 141, Issue 2, February 2012, Pages 451-460
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Original Research
Transplantation
Lung Size Mismatch in Bilateral Lung Transplantation Is Associated With Allograft Function and Bronchiolitis Obliterans Syndrome

https://doi.org/10.1378/chest.11-0767Get rights and content

Background

Size mismatch between donor lungs and a recipient thorax could affect the major determinants of maximal expiratory airflow: airway resistance, propensity of airways to collapse, and lung elastic recoil.

Methods

A retrospective review of 159 adults who received bilateral lung transplants was performed. The predicted total lung capacity (pTLC) for donors and recipients was calculated based on sex and height. Size matching was represented using the following formula: pTLC ratio = donor pTLC / recipient pTLC. Patients were grouped according to those with a pTLC ratio > 1.0 (oversized) or those with a pTLC ratio ≤ 1.0 (undersized). Allograft function was analyzed in relation to the pTLC ratio and to recipient and donor predicted function.

Results

The 96 patients in the oversized cohort had a mean pTLC ratio of 1.16 ± 0.13 vs 0.89 ± 0.09 in the 63 patients of the undersized group. At 1 to 6 months posttransplant, the patients in the oversized cohort had higher FEV1/FVC ratios (0.895 ± 0.13 vs 0.821 ± 0.13, P < .01) and lower time constant estimates of lung emptying (0.38 ± 0.2 vs 0.64 ± 0.4, P < .01) than patients in the undersized cohort. Although the FVCs expressed as % predicted for the recipient were not different between cohorts, the FVCs expressed as % predicted for the donor organ were lower in the oversized cohort compared with the undersized cohort (at 1-6 months, 52.4% ± 17.1% vs 65.3% ± 18.3%, P < .001). Kaplan-Meier estimates for the occurrence of bronchiolitis obliterans syndrome (BOS) showed that patients in the oversized cohort had a lower probability of BOS (P < .001).

Conclusions

A pTLC ratio > 1.0, suggestive of an oversized allograft, is associated with higher expiratory airflow capacity and a less frequent occurrence of BOS.

Section snippets

Materials and Methods

This study was approved by the institutional review boards at the sites involved (e-Appendix 1A). We analyzed all BLTs for adult patients performed at Johns Hopkins Hospital from January 1, 1996, to March 1, 2010, and all BLTs performed at Inova Fairfax Hospital from January 1, 1996, to December 31, 2008. Recipients of single lung transplants were not assessed because of the potential effect of the native lung on overall lung function. All adult patients who received BLTs and were alive 3

Characteristics of the Stud

There were 159 adult patients who qualified for the analysis, of whom 154 received a BLT and five a heart-lung transplant (HLT). Donor and recipient characteristics are shown in Table 1. The follow-up period was completed at time of death or August 1, 2010, with a median follow-up period of 2.6 years (range, 0.3-14.2 years). The dataset included 3,783 FVL observations. The mean pTLC ratio for the study population was 1.06 ± 0.17. Patients who received transplants for COPD had the highest mean

Discussion

In this investigation of lung size mismatch and allograft function, a pTLC ratio > 1.0, suggestive of an oversized allograft, was associated with higher expiratory airflow capacity and a less frequent occurrence of BOS. A higher pTLC ratio was associated with a lower FVC, expressed as % predicted of donor lung. Expressing allograft function in relation to donor predicted lung function likely captured the actual restriction of an oversized allograft in a smaller recipient's thorax.

Prior studies

Conclusion

An oversized allograft is associated with higher expiratory airflow and lower occurrence of BOS. The oversized cohort is conceptually similar to CWS, an experimental condition known to cause higher expiratory airflow, likely from changes in surface tension. The mechanism linking an oversized allograft to delayed occurrence of BOS deserves further investigation.

Acknowledgments

Author contributions: Dr Eberlein is the guarantor of the entire manuscript.

Dr Eberlein: contributed to the conception and design of the study, acquisition of data, analysis and interpretation of data, drafting of the manuscript, and the revision of the article for important intellectual content.

Dr Permutt: contributed to the conception and design of the study, analysis and interpretation of data, and the revision of the article for important intellectual content.

Dr Chahla: contributed to the

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    Funding/Support: The authors have reported to CHEST that no funding was received for this study.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).

    *

    Dr Eberlein is currently at the Carver College of Medicine, University of Iowa, Iowa City, Iowa.

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