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Correspondence |

Concerns Raised by Lung Size-Mismatched TransplantationSize-Mismatched Lung Transplantation FREE TO VIEW

Wenjun Mao, MD; Wei Xia, MD; Jingyu Chen, MD
Author and Funding Information

From the Department of Cardiothoracic Surgery, Wuxi People’s Hospital, Nanjing Medical University.

Correspondence to: Jingyu Chen, MD, Division of Cardiothoracic Surgery, Wuxi People’s Hospital, No. 299, Qing Yang Rd, Wuxi City, Jiangsu, China; e-mail: chenjy@wuxiph.com


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2012;142(2):542-543. doi:10.1378/chest.12-0737
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To the Editor:

We read with great interest the article by Eberlein et al1 in CHEST (February 2012), which concluded that an oversized lung allograft (predicted total lung capacity [pTLC] ratio >1.0) was associated with higher expiratory airflow capacity and a less frequent occurrence of bronchiolitis obliterans syndrome when compared with an undersized allograft (pTLC ratio ≤1.0). Undeniably, lung size mismatch is commonly encountered in pulmonary transplantation because donor allocation does not allow precise matching when a long list of patients is waiting for scarce donors. We are grateful to the authors for their important work. However, we would like to voice some significant concerns about the study design that need clarifications.

A heterogeneous population of 159 patients undergoing transplant from two different centers (Johns Hopkins Hospital from January 1996 to March 2010 and Inova Fairfax Hospital from January 1996 to December 2008) was included in this retrospective study. However, no data were available to show the comparability between the two centers, and it is unknown if significant bias was introduced by different transplant protocols, which play a vital role in the prognosis of these patients. As a consequence, potential confounding factors not accounted for, including recipient and donor characteristics, should have been compared between the two centers before a combined analysis was conducted; otherwise, a separate analysis for each center would be have been preferred.

The authors provide the pTLC ratio (donor pTLC/recipient pTLC) for their definition of size matching according to the regression equations.2 Although we indeed agree that the pTLC ratio is widely used to match donors with recipients, it is wrong to suggest that the pTLC ratio is a reliable marker of size matching, as stated by the authors, because no reference range of pTLC ratio was raised to address the ideal status of size matching. From our perspective, oversized allografts implanted into the smaller thorax cavity can lead to atelectasis and impaired airway clearance because of bronchial anatomy distortion.

Increasing evidence suggests that size-reduced lung transplants (graft volume reduction and lobar lung transplant) are beneficial to recipients receiving oversized allografts.3,4 Shigemura et al5 investigated lung volume reduction as an efficient tool for reducing short-term complications and improving pulmonary function in patients with size-mismatched allografts. A special approach for overcoming severe size disparities is lobar transplant, which is especially useful in pediatric lung transplants involving a small thorax cavity. Loizzi et al6 suggested the pTLC ratio as a marker of lobar transplant based on a receiver operating characteristic analysis: Patients with oversized allografts (pTLC ratio >1.2) were considered for a lobar transplant, for which the higher the pTLC ratio, the higher the possibility that the patients were likely to benefit from it. Date et al7 also stated that size disparity in lobar transplants can be accepted when the total FVC of the two grafts is >50% of the predicted FVC of the recipient, estimated by the following formula: Total FVC of the two grafts = measured FVC of the right donor ×5/19 + measured FVC of the left donor ×4/19 (the right lower lobe consists of five segments, the left lower lobe of four, and the whole lung of 19). Date et al7 suggested that in such a case, this is an alternative to conventional cadaveric lung transplant, resulting in a similar outcome. Additionally, comparable clinical outcomes were observed between patients who received size-matched allografts and size-reduced allografts.4,8 However, the authors did not describe in the article the situation of size-reduced lung transplantation for an oversized cohort, implying that lung trimming as a confounding factor may result in significant discrepancy. It would be helpful if this concern could be commented on, and further analysis of the study to address this important issue is required.

Eberlein M, Permutt S, Chahla MF, et al. Lung size mismatch in bilateral lung transplantation is associated with allograft function and bronchiolitis obliterans syndrome. Chest. 2012;141(2):451-460.
 
Stocks J, Quanjer PH. Official statement of The European Respiratory Society Official statement of The European Respiratory Society. Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Eur Respir J. 1995;8(3):492-506.
 
Fitton TP, Bethea BT, Borja MC, et al. Pulmonary resection following lung transplantation. Ann Thorac Surg. 2003;76(5):1680-1685.
 
Inci I, Irani S, Kestenholz P, Benden C, Boehler A, Weder W. Donor predicted post-operative forced expiratory volume in one second predicts recipients’ best forced expiratory volume in one second following size-reduced lung transplantation. Eur J Cardiothorac Surg. 2011;39(1):115-119.
 
Shigemura N, Bermudez C, Hattler BG, et al. Impact of graft volume reduction for oversized grafts after lung transplantation on outcome in recipients with end-stage restrictive pulmonary diseases. J Heart Lung Transplant. 2009;28(2):130-134.
 
Loizzi D, Aigner C, Jaksch P, et al. A scale for decision making between whole lung transplantation or lobar transplantation. Eur J Cardiothorac Surg. 2010;37(5):1122-1125.
 
Date H, Aoe M, Nagahiro I, et al. Living-donor lobar lung transplantation for various lung diseases. J Thorac Cardiovasc Surg. 2003;126(2):476-481.
 
Santos F, Lama R, Alvarez A, et al. Pulmonary tailoring and lobar transplantation to overcome size disparities in lung transplantation. Transplant Proc. 2005;37(3):1526-1529.
 

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References

Eberlein M, Permutt S, Chahla MF, et al. Lung size mismatch in bilateral lung transplantation is associated with allograft function and bronchiolitis obliterans syndrome. Chest. 2012;141(2):451-460.
 
Stocks J, Quanjer PH. Official statement of The European Respiratory Society Official statement of The European Respiratory Society. Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Eur Respir J. 1995;8(3):492-506.
 
Fitton TP, Bethea BT, Borja MC, et al. Pulmonary resection following lung transplantation. Ann Thorac Surg. 2003;76(5):1680-1685.
 
Inci I, Irani S, Kestenholz P, Benden C, Boehler A, Weder W. Donor predicted post-operative forced expiratory volume in one second predicts recipients’ best forced expiratory volume in one second following size-reduced lung transplantation. Eur J Cardiothorac Surg. 2011;39(1):115-119.
 
Shigemura N, Bermudez C, Hattler BG, et al. Impact of graft volume reduction for oversized grafts after lung transplantation on outcome in recipients with end-stage restrictive pulmonary diseases. J Heart Lung Transplant. 2009;28(2):130-134.
 
Loizzi D, Aigner C, Jaksch P, et al. A scale for decision making between whole lung transplantation or lobar transplantation. Eur J Cardiothorac Surg. 2010;37(5):1122-1125.
 
Date H, Aoe M, Nagahiro I, et al. Living-donor lobar lung transplantation for various lung diseases. J Thorac Cardiovasc Surg. 2003;126(2):476-481.
 
Santos F, Lama R, Alvarez A, et al. Pulmonary tailoring and lobar transplantation to overcome size disparities in lung transplantation. Transplant Proc. 2005;37(3):1526-1529.
 
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