Potential Role of Computed Tomography Volumetry in Size Matching in Lung Transplantation

BackgroundAccumulated knowledge on the outcomes related to size mismatch in lung transplantation derives from predicted total lung capacity equations rather than individualized measurements of donors and recipients. The increasing availability of computed tomography (CT) makes it possible to measure the lung volumes of donors and recipients before transplantation. We hypothesize that CT-derived lung volumes predict a need for surgical graft reduction and primary graft dysfunction.MethodsDonors from the local organ procurement organization and recipients from our hospital from 2012 to 2018 were included if their CT exams were available. The CT lung volumes and plethysmography total lung capacity were measured and compared with predicted total lung capacity using Bland Altman methods. We used logistic regression to predict the need for surgical graft reduction and ordinal logistic regression to stratify the risk for primary graft dysfunction.ResultsA total of 315 transplant candidates with 575 CT scans and 379 donors with 379 CT scans were included. The CT lung volumes closely approximated plethysmography lung volumes and differed from the predicted total lung capacity in transplant candidates. In donors, CT lung volumes systematically underestimated predicted total lung capacity. Ninety-four donors and recipients were matched and transplanted locally. Larger donor and smaller recipient lung volumes estimated by CT predicted a need for surgical graft reduction and were associated with higher primary graft dysfunction grade.ConclusionThe CT lung volumes predicted the need for surgical graft reduction and primary graft dysfunction grade. Adding CT-derived lung volumes to the donor-recipient matching process may improve recipients’ outcomes.     

Experience of the Reina Sofia hospital in lobar lung transplantation

The number of patients awaiting lung transplantation has steadily increased over the past decade, but the number of donors has remained relatively stable. Owing to the increasing scarcity of donor lungs, especially for pediatric and small adult recipients, advanced operative strategies for the use of larger grafts for smaller recipients have been developed. Size matching between donors and recipients represents one of the organ distribution criteria widely accepted by lung transplantation teams. However, in some cases it is not possible to allocate a donor to the corresponding size-compatible recipient. To avoid possible complications derived from the implantation of oversized lungs into smaller recipients, various methods of downsizing are applied for cadaveric donor lungs, such as lobar transplantation. We review our experience in 6 patients undergoing volume reduction of the lung graft by lobar resection at the time of transplantation. Graft volume reduction by anatomic resection (lobar transplantation) is a reliable and safe procedure to overcome size disparities between the donor and the recipient of a lung transplant, and thus to maximize the number of donors.     

Pulmonary tailoring and lobar transplantation to overcome size disparities in lung transplantation

Size matching between donors and recipients represents one of the organ distribution criteria widely accepted by lung transplant teams. However, in some cases it is not possible to allocate a donor to the corresponding size-compatible recipient. To avoid possible complications derived from the implantation of oversized lungs into smaller recipients, surgical procedures such as pulmonary tailoring and lobar transplantation have been advocated. We review our experience in 13 patients undergoing volume reduction of the lung graft at the time of transplantation, either by nonanatomical lung volume reduction or by lobar transplantation. There were no significant differences between lung-downsized patients and standard lung transplantation patients in terms of donor characteristics, surgical and postoperative complications, functional outcome, and survival. We conclude that downsizing the lung graft either by nonanatomical resection or lobar transplantation is safe and reliable to overcome size disparities between donor and recipients, with no additional morbidity and with similar early and midterm outcomes to those in standard lung transplants.     

Chest size matching in single and double lung transplantation

We applied predicted vital capacity to chest size matching between donor and recipient in lung transplantation to 15 single-lung transplant recipients with pulmonary fibrosis and to 20 double-lung transplant recipients with emphysema or non-emphysema. The predicted vital capacity of the donor was significantly correlated with the predicted vital capacity of the recipient both in double-lung transplantation (r = 0.79, p = 0.001) and single-lung transplantation (r = 0.71, p = 0.003). In double-lung transplantation, the post-transplant vital capacity was correlated with the predicted vital capacity of the recipient (r = 0.74, p = 0.002). Emphysema patients and non-emphysema patients contributed equally to this correlation. In left single lung transplantation, there was a weak correlation between the post-transplant vital capacity and the predicted vital capacity of the donor in the allograft (r = 0.57, p = 0.1095). In right single lung transplantation, the post-transplant vital capacity of the allograft tended to be correlated with the predicted vital capacity of recipient (r = 0.77, p = 0.0735). We concluded that donors were actually selected based on the comparison of predicted vital capacity between donor and recipient. In double-lung transplantation, the post-transplant vital capacity was limited by the recipient’s normal thoracic volume and was not influenced by underlying pulmonary disease. In single-lung transplantation with pulmonary fibrosis, the allograft transplanted in the left chest could expand to its own size, and the allograft transplanted in the right chest could expand to the recipient’s normal thoracic volume as in double-lung transplantation.     

Respiratory mechanics after heart-lung and bilateral lung transplantation

BACKGROUND: The factors determining respiratory mechanics following heart-lung transplantation (HLT) and bilateral lung transplantation (BLT) are incompletely understood. METHODS: The dynamic and static lung volumes of 15 patients after HLT (n = 6) and BLT (n = 9) with no evidence of obliterative bronchiolitis were analysed to assess the factors which determine lung volumes following transplantation. Post- transplantation total lung capacity (TLCpost) was compared with the size of the recipient's lungs (TLCpre), the predicted capacity of the thorax of the recipient (TLCpred), and the predicted size of the donor's lungs (TLCdon). In addition, the post-transplantation respiratory mechanics were investigated by measuring the static pressure-volume (PV) curve of the lungs and the maximum respiratory pressures in a subgroup of nine patients (four HLT, five BLT). RESULTS: TLCpost was closely related to TLCpred in both groups and showed no correlation with TLCpre. The mean (95% CI) TLCpost was 102.5 (90.2 to 115)% predicted for the recipient in the HLT group and 109 (97.6 to 120)% predicted for the recipient in the BLT group. Despite the near normal TLC, residual volume (RV) and functional residual capacity (FRC) remained increased after transplantation in both groups. These abnormalities were not attributable to either airflow obstruction or expiratory muscle weakness. On average, lung compliance expressed in terms of the shape constant of the static pressure-volume curve of the lungs was mildly reduced in both groups compared with values predicted for the recipient. CONCLUSIONS: These results suggest that at high lung volumes the chest wall adapts to the size of transplanted lungs, while at lower volumes the increase in FRC and RV might be due to a persistent change in the static pressure-volume curve of the chest wall.


     

Chest size matching in single and double lung transplantation.

We applied predicted vital capacity to chest size matching between donor and recipient in lung transplantation to 15 single-lung transplant recipients with pulmonary fibrosis and to 20 double-lung transplant recipients with emphysema or non-emphysema. The predicted vital capacity of the donor was significantly correlated with the predicted vital capacity of the recipient both in double-lung transplantation (r = 0.79, p = 0.001) and single-lung transplantation (r = 0.71, p = 0.003). In double-lung transplantation, the post-transplant vital capacity was correlated with the predicted vital capacity of the recipient (r = 0.74, p = 0.002). Emphysema patients and non-emphysema patients contributed equally to this correlation. In left single lung transplantation, there was a weak correlation between the post-transplant vital capacity and the predicted vital capacity of the donor in the allograft (r = 0.57, p = 0.1095). In right single lung transplantation, the post-transplant vital capacity of the allograft tended to be correlated with the predicted vital capacity of recipient (r = 0.77, p = 0.0735). We concluded that donors were actually selected based on the comparison of predicted vital capacity between donor and recipient. In double-lung transplantation, the post-transplant vital capacity was limited by the recipient's normal thoracic volume and was not influenced by underlying pulmonary disease. In single-lung transplantation with pulmonary fibrosis, the allograft transplanted in the left chest could expand to its own size, and the allograft transplanted in the right chest could expand to the recipient's normal thoracic volume as in double-lung transplantation.     

Donor-recipient lung volume matching in double lung transplantation. Value of left lower lobe graft]

For double lung transplantation, lung volume matching is easier comparing the predicted total lung capacities of the donor and recipient and the recipient's true TLC. The major concern in the inability to close the chest when the donor lungs are too large. The technique reported of left lower lobe implantation during bilateral single lung transplantation might be of great value in patients with small lung volume.     

Evaluating the Use of CT-Derived Lung Volumes in Donor-Recipient Lung Size Matching for Lung Transplantation in Patients With Interstitial Lung Disease and/or Idiopathic Pulmonary Fibrosis

PurposeThis study aims to assess the efficacy of current measurement strategies for lung sizing and the feasibility of future use of computed tomography (CT)-derived lung volumes to predict a donor-recipient lung size match during bilateral lung transplants.MethodsWe reviewed the data of 62 patients who underwent bilateral lung transplantation for interstitial lung disease and/or idiopathic pulmonary fibrosis from 2018 to 2019. Data for recipients was retrieved from the department's transplant database and medical records, and the donor's data was retrieved from the DonorNet. The data included demographic data, lung heights, measured total lung capacity (TLC) from plethysmography for recipients and estimated TLC for donors, clinical data, and CT-derived lung volumes in both pre- and post-transplant recipients. The post-transplant CT-derived lung volume in recipients was used as a surrogate for donor lung CT volumes due to inadequate or poor donor CT data. Computed tomography–derived lung volumes were calculated using thresholding, region growing, and cutting techniques on Computer-Aided Design and Mimics (Materialise NV, Leuven, Belgium) programs. Preoperative CT-derived lung volumes in recipients were compared with the plethysmography TLC, Frustum Model, and donor-predicted TLC. The ratio of the recipient's pre-and postoperative CT-derived volumes, the ratio of preoperative CT-derived lung volume, and donor-estimated TLC were studied to detect a correlation with 1-year outcomes.ResultsThe recipient preoperative CT-derived volume correlated with the recipient preoperative plethysmography TLC (Pearson correlation coefficient [PCC] of 0.688) and with the recipient Frustum model volume (PCC of 0.593). The recipient postoperative CT-derived volume correlated with the recipient's postoperative plethysmography TLC (PCC of 0.651). There was no statistically significant correlation between recipients' CT-derived pre- or postoperative volume with donor-estimated TLC. The ratio of preoperative CT-derived volume to donor-estimated TLC correlated inversely with the length of ventilation (P value = .0031). The ratio of postoperative CT-derived volume to preoperative CT-derived volume correlated inversely with delayed sternal closure (P = .0039). No statistically significant correlations were found in evaluating outcomes related to lung oversizing in the recipient (defined as a postoperative to preoperative CT-derived lung volume ratio of >1.2).ConclusionsGenerating CT-derived lung volumes is a valid and convenient method for evaluating lung volumes for transplantation in patients with ILD and/or IPF. Donor-estimated TLC should be interpreted carefully. Further studies should derive donor lung volumes from CT scans for a more accurate evaluation of lung size matching.     

Problems in donor lung evaluation for transplantation with regard to airway infection

The shortage of donor organs has been 1 of the major obstacles to solid organ transplantation. Typical lung donor criteria include clear lung field on chest radiograph, adequate oxygenation, acceptable lung compliance, and satisfactory bronchoscopic findings. To extend usage of available donors, liberalization of donor lung selection criteria has been facilitated, however, marginal donor lungs must be used with discretion, because donor lung injury, especially that related to infection, has a potential leading to early post-operative death of the recipient. From March 2000 to December 2006, we evaluated 15 braindead donors and at least 1 of the lungs from 9 donors was judged suitable for transplantation. One of 9 recipients developed severe pneumonia cased by carbapenems-resistant Pseudomonas aeruginosa possibly originating from the donor lungs, eventually leading to death. The chest radiograph and oxygenation of the donor had been satisfactory, however, a moderate amount of mucopurulent secretions was observed by bronchoscopic inspection and the donor had been given a cefozopran for 9 days before the procurement operation. Remaining 8 recipients were free from air-way infection in the early postoperative period. We discuss the status and problems of donor lung evaluation for transplantation with regard to donor lung infection.     

Perioperative assessment of oversized lobar graft downsizing in living‐donor lobar lung transplantation using three‐dimensional computed tomographic volumetry

A 15‐year‐old boy with bronchiolitis obliterans after bone marrow transplantation successfully underwent bilateral living‐donor lobar lung transplantation (LDLLT) with segmentectomy of the superior segment of an oversized right lower lobe graft. As the recipient was small for his age, the predicted value of his functional vital capacity of the recipient was difficult to determine preoperatively. Three‐dimensional computed tomography (CT) volumetry revealed that the ratio of donor graft volume to recipient hemithorax volume was 159% on the right side and 82% on the left side. The patient is alive and well 7 months after transplantation, and three‐dimensional CT volumetry revealed that the right and left donor lungs were still compressed to 73% and 84% of the original size, respectively. In LDLLT, segmentectomy of the superior segment of the lower lobe is a useful option for downsizing an oversized graft and three‐dimensional CT volumetry can provide meaningful data for size matching.     

Intrafamilial lung xenografts from fox to dog

The technical feasibility and rejection characteristics of intrafamilial fox-to-dog xenografts were studied. The results indicate that (1) both lungs of a smaller donor can be successfully transplanted into a single hemithorax of a larger recipient, (2) fox-to-dog lung xenografts are capable of providing total pulmonary function at tolerable right ventricular pressures, and (3) the rejection process of unmodified intrafamilial lung xenografts, was similar to and not more vigorous or more rapid than that of canine lung allografts in untreated recipients.     

Adaptation Over a Wide Range of Donor Graft Lung Size Discrepancies in Living‐Donor Lobar Lung Transplantation

Living‐donor lobar lung transplantation (LDLLT), unlike deceased donor lung transplantation, often involves a wide range of size discrepancies between donors and recipients. The aim of this study was to evaluate the function of donor lung grafts in the recipient thorax in 14 cases of bilateral LDLLT involving 28 successfully transplanted lower‐lobe grafts. Pulmonary function tests and three‐dimensional computed tomography (3D‐CT) volumetry were performed perioperatively. According to 3D‐CT size matching, donor graft volumes ranged from 40% to 161% of the hemilateral thoracic volumes of the recipients. Graft forced vital capacity (FVC) values increased over time, reaching 102 ± 39% of preoperatively estimated values at 12 months postoperatively. Graft volumes also increased over time, reaching 120 ± 38% of the original values at 12 months postoperatively. Undersized donor grafts expanded more after LDLLT than oversized donor grafts, producing greater FVC values than those estimated preoperatively, whereas oversized donor grafts became inflated to their original size and maintained FVC values that approached the preoperative estimates. Thus, donor grafts were found to overinflate or underinflate to the extent that they could preserve their native function in the new recipient's environment.     

Outcomes of extended donor lung recipients after lung transplantation

BACKGROUND: Lung transplantation is currently limited by the number of suitable donor organs. Many lung-transplant programs use lungs that do not meet the formal criteria for acceptability; however, the immediate and long-term consequences of this approach remain unclear. METHODS: We performed a retrospective cohort study of all patients who underwent lung transplantation at the Columbia University Medical Center from July 2001 to July 2003. We assessed the outcomes of recipients of extended donor lungs compared with those of recipients of optimal donor lungs after adjusting for confounding variables. RESULTS: Fifty-one patients underwent lung transplantation, of which 27 (53%) received extended donor lungs. Recipients of extended donor lungs had fewer intensive care unit-free days at 30 days (P=0.002) and a longer time to hospital discharge (P=0.007) than did recipients of optimal donor lungs. Extended donor recipients also had lower forced expiratory volume in 1 second % predicted at 1 year than did optimal donor recipients (P=0.03). There were no differences in the 30-day or longer-term survival of extended and optimal donor lung recipients. CONCLUSIONS: Recipients of extended donor lungs have a longer intensive care unit course, a prolonged hospital stay, and lower pulmonary function at 1 year than recipients of optimal lungs. Despite these differences, survival is similar between the two groups. The criteria for the optimal lung donor should be re-evaluated considering the current shortage of acceptable organs. Although some outcomes may differ with the use of extended donor lungs, the clinical impact of these differences should be assessed in future prospective multicenter studies.     

Donor-recipient gender mismatch in lung transplantation: impact on obliterative bronchiolitis and survival.

BACKGROUND: Because of the shortage of donor lungs, liberalization of donor selection criteria in terms of age, gas exchange, and smoking history has been proposed. METHODS: We evaluated a single-institution population of lung transplant recipients (n = 98) for donor-recipient gender matching. We measured overall survival, time to acute allograft rejection, and time to development of obliterative bronchiolitis (OB). RESULTS: We found significant improvement in overall survival for gender-mismatched donor and recipient pairs (p = 0.078) and a significantly shorter OB-free period for male donor and female recipient pairs (p = 0.017). CONCLUSION: These findings suggest that donor organ allocation based on gender may affect long-term survival and other outcomes after lung transplantation.     

Comparative outcome of double lung transplantation using conventional donor lungs and non-acceptable donor lungs reconditioned ex vivo

A method to evaluate and recondition lungs ex vivo has been tested on donor lungs that have been rejected for transplantation. In the present paper, we compare early postoperative course between the six patients who received reconditioned lungs and the patients who received conventional donor lungs during the same period of time. During 2006 and 2007, a total of 21 patients underwent double sequential lung transplantation at the University Hospital of Lund. Six of those patients received reconditioned lungs. The other 15 patients received conventional donor lungs for transplantation without reconditioning ex vivo. The results are presented as median and interquartile range. Time in intensive care unit (days) between recipients of reconditioned lungs [13 (5-24) days], and recipients of conventional donor lungs [7 (5-12) days], P=0.44. Total hospital stay after transplantation (days) between recipients of reconditioned lungs [52 (47-60) days] and recipients of conventional donor lungs [44 (37-48) days], P=0.9. Ex vivo lung evaluation and reconditioning might not prolong early postoperative course in double lung transplantation. However, given the small number of patients, there might be a failure to detect a difference between the two groups.     

Retransplantation following isolated lung transplantation.

The results of retransplantation for early allograft failure are discouraging. Fortunately, with recent technical advances and improved postoperative immunosuppression, airway complications have been significantly reduced. It is now unusual to see patients with airway complications following lung transplantation. This group of patients is not likely to represent a large population in need of retransplantation in the future. However, rejection-mediated OB remains a persistent problem seen in all transplant centers. The group of patients who deteriorate despite augmented immunosuppression will put increasing pressure on transplant programs to provide the only known solution for survival: retransplantation. In the Toronto experience, only 1 patient survived early retransplantation. Three of the 5 recipients retransplanted late in their course have survived and 2 are presently alive and well. Yet this is in sharp contrast to the current 80% 1-year survival for initial transplant recipients. As the demand for donor lungs increases with the growing need for first-time procedures, the use of donor lungs for retransplantation becomes a significant problem. The decision whether to allocate a donor lung (and commit significant hospital resources) to a retransplant recipient or to a first-time recipient is difficult. A patient with early graft failure has a dismal prognosis and a decision not to retransplant may be straightforward. However, the decision to retransplant a patient who has developed OB late following their initial transplant is much more difficult. It is still our responsibility to manage this limited resource and provide donor lungs to those who have the optimal chance of survival.     

大白鼠无心跳供体肺移植的实验研究

目的　探讨不同热缺血时间对无心跳供体肺的组织结构和功能的影响及无心跳供体肺应用于肺移植的可能性。　方法　取 6 0只健康大白鼠 ,随机分成有心跳组、无心跳 缺血 30min组、无心跳 缺血 6 0min组 ,每组 10对 ,分别为供体和受体。有心跳组供体在处死的同时灌注 4℃低钾右旋糖苷液 ,无心跳 缺血 30min组、无心跳 缺血 6 0min组供体处死后维持辅助呼吸 ,分别放置室温中30和 6 0min ,再灌注低钾右旋糖苷液 ,供肺置于 4℃低钾右旋糖苷液中 4h。受体鼠行左侧开胸术和原位左肺移植术。术后维持辅助呼吸 1h ,经右侧进胸 ,阻断右肺门。　结果　无心跳 缺血 30min组存活时间均超过 30min ,肺顺应性为 0 .16 4 0± 0 0 0 4 9,动脉血氧分压 (85± 4 )mmHg ,动脉血二氧化碳分压 (41 9± 1 9)mmHg ,腺苷核苷酸总量 (75 8± 30 )mol/ g蛋白 ,超微结构改变为轻度的淤血和肺实质水肿 ,与有心跳组相比 ,差异均无显著意义 (P >0 0 5 )。无心跳 缺血 6 0min组有 4只 10min后心跳停止 ,3只 2 0min后心跳停止 ,与另两组相比 ,所测各项指标的差异有显著意义 (P <0 0 5 )。　结论　采用无心跳供体是增加供肺来源的一种安全而有效的方法 ,热缺血 30min大白鼠无心跳供体肺适于肺移植。     

Experimental study on size matching in a canine living-donor lobar lung transplant model.

OBJECTIVE: In an effort to address the donor-shortage issue, living-donor lobar lung transplants have been performed with satisfactory results. The use of small grafts is potentially problematic because it could cause high pulmonary artery pressure, resulting in lung edema. The purpose of this study was to evaluate the effect of small grafts on early pulmonary function and to identify the predictor for acceptable size discrepancy. METHODS: Seventeen pairs of mongrel dogs with various donor-recipient sizes were used. Body weight, height, chest circumference, and lung weight were measured as size parameters. Right middle, lower, and cardiac lobes were implanted as a right lung of the recipient and the left lower lobe was implanted as a left lung without use of cardiopulmonary bypass. Pulmonary function of the recipient was measured for 6 hours after reperfusion. RESULTS: A significant negative correlation was found between donor/recipient body-weight ratio and mean pulmonary artery pressure at 1 hour (r = -0.594, P =.025). A significant correlation was found between donor/recipient body-weight ratio and PaO(2) at 6 hours (r = 0.704; P =.007). There was no significant correlation between the other 3 size parameters and postoperative pulmonary function. All 8 recipients with a donor/recipient body-weight ratio of 1.2 or greater survived the 6-hour assessment period, and their PaO(2) exceeded 500 mm Hg at 6 hours. CONCLUSIONS: Donor/recipient weight ratio is an important predictor of early pulmonary function in a canine living-donor lobar lung transplant model.     

Influence of gender donor-recipient combinations on survival after human lung transplantation

BackgroundIn the current practice of lung transplantation, donor and recipient genders are neither directly considered nor matched. However, some data have suggested a possible effect of gender combinations on survival following lung transplantation.MethodsA total of 249 adult lung transplant recipients at a single center between February 1988 and December 2008, were analyzed retrospectively for donor-recipient gender matching. We compared the mortality by calculating one-term survival rates after transplantation using the Kaplan-Meier method with comparisons using the log-rank (Mantel-Cox) test. Statistical significance of the mean effects of size matching was assessed by paired Student t tests and Wilcoxon signed rank tests.ResultsKaplan-Meier survival analysis shown that male compared to female recipients did not have an effect on outcomes after lung transplantation at 5 years (P = .5379), 10 years (P = .107), 15 years (P = .0841), 20 years (P = .0711). No effect of gender on lung transplantation outcomes was observed with donor-recipient gender mismatches at 5 years (P = .1804), 10 years (P = .1457), 15 years (P = .0731), or 20 years (P = .0629). Similarly, no differences were observed for each gender combination. The degree of size matching was defined as the ratio of donor-to-recipient predicted total lung capacity. The ratios were similar for the donor-recipient gender match and significantly different for the donor-recipient gender mismatch.ConclusionsThese analyses suggested that gender was not a significant independent risk factor affecting survival after lung transplantation. Size mismatch caused by gender mismatch did not increase mortality.     

Critical care and ventilatory management of deceased organ donors impact lung use and recipient graft survival

Current risk-adjusted models for donor lung use and lung graft survival do not include donor critical care data. We sought to identify modifiable donor physiologic and mechanical ventilation parameters that predict donor lung use and lung graft survival. This is a prospective observational study of donors after brain death (DBDs) managed by 19 Organ Procurement Organizations from 2016 to 2019. Demographics, mechanical ventilation parameters, and critical care data were recorded at standardized time points during donor management. The lungs were transplanted from 1811 (30%) of 6052 DBDs. Achieving ≥7 critical care endpoints was a positive predictor of donor lung use. After controlling for recipient factors, donor blood pH positively predicted lung graft survival (OR 1.48 per 0.1 unit increase in pH) and the administration of dopamine during donor management negatively predicted lung graft survival (OR 0.19). Tidal volumes ≤8 ml/kg predicted body weight (OR 0.65), and higher positive end-expiratory pressures (OR 0.91 per cm H₂O) predicted decreased donor lung use without affecting lung graft survival. A randomized clinical trial is needed to inform optimal ventilator management strategies in DBDs.