Lung Size Mismatch In Bilateral Lung Transplantation Is Associated With Allograft Function And Bronchiolitis Obliterans Syndrome

Abstract

S ize mismatch between donor lungs and a recipient thorax could affect the major determinants of maximal expiratory airfl ow: airway resistance, propensity of airways to collapse, and lung elastic recoil. 1 The degree of mismatch can be estimated by the ratio of predicted total lung capacities (pTLCs), using the following formula: pTLC ratio 5 donor pTLC / recipient pTLC. [2][3][4] In a previous study, a fl ow volume loop (FVL) pattern in patients who received bilateral lung transplants (BLTs) that was characterized by supranormal expiratory airfl ow (SUPRA pattern) was associated with high pTLC ratios (likely the result of oversized allografts). 5 Although patients with and without the SUPRA pattern had comparable FVC and FEV 1 , expressed as % predicted for the recipient, there were signifi cant differences in expiratory airfl ow (FEV 1 /FVC ratios and time constant estimates for lung emptying). A mismatch of oversized transplanted Background: Size mismatch between donor lungs and a recipient thorax could affect the major determinants of maximal expiratory airfl ow: 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 5 donor pTLC / recipient pTLC. Patients were grouped according to those with a pTLC ratio . 1.0 (oversized) or those with a pTLC ratio Յ 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 Ϯ 0.13 vs 0.89 Ϯ 0.09 in the 63 patients of the undersized group. At 1 to 6 months posttransplant, the patients in the oversized cohort had higher FEV 1 /FVC ratios (0.895 Ϯ 0.13 vs 0.821 Ϯ 0.13, P , .01) and lower time constant estimates of lung emptying (0.38 Ϯ 0.2 vs 0.64 Ϯ 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% Ϯ 17.1% vs 65.3% Ϯ 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 airfl ow capacity and a less frequent occurrence of BOS.

Survival in Adult Lung Transplant Recipients Receiving Pediatric Versus Adult Donor Allografts

“…We believe that this supports the previous finding that a higher predicted total lung capacity ratio, which indicated oversized donor lungs, was associated with improved survival after LTx [21,22]. In addition, oversized lungs were found to improve allograft function and clinical outcomes [23]. Although many experts believe that standardized methods for matching lung size between donors and recipients are needed, the current study suggests that greater height in general improves long-term outcomes in adults after LTx.…”

Parameters of donor–recipient size mismatch and survival after bilateral lung transplantation

“…14 A higher pTLC ratio was associated with lower forced vital capacities (FVCs), expressed as percent predicted for the donor lung. 15 A mismatch between relatively large transplanted lungs restricted in recipients with a smaller thorax is conceptually similar to restriction of the chest wall by strapping (CWS). When FVC was limited via CWS to 50% of the unstrapped vital capacity, expiratory airflows increased by approximately 60%.…”

Transplant size mismatch in restrictive lung disease

“…Many donor characteristics including age, comorbidities, and smoking status have been examined with regard to their impact on outcomes following lung transplantation. More recently, some groups have examined the impact of donor and recipient lung size on survival following lung transplantation .…”