Increased Donor Organ Size and Age is Associated with Reduced Survival in Female Lung Transplant Recipients

BACKGROUND

Organ selection in lung transplantation (LTx) is still controversial. We here analyze the impact of mismatches in size, age, and gender on early and long-term outcome after LTx.

METHODS

Retrospective analysis of donor and recipient characteristics of patients who underwent double LTx between March 2003 and December 2021. Statistical analysis was performed using SPSS and GraphPad software.

RESULTS

Two hundred three patients were included (94 women and 109 men). In the whole cohort, oversizing donor organs 10% to 20% compared to the recipients' predicted total lung capacity led to a decreased incidence of severe Primary Graft Dysfunction grades 2 and 3 (2/3; 15% vs 41%, P = .03), and further oversizing > 20% was associated with reduced long-term survival (hazard ratio, 2.33, P = .011). Analyzing donor and recipient age, we found that increased donor age correlated with reduced long-term survival (P = .013). In this cohort, female recipients received older organs (median 57 vs 46 years, P = .0003) and had a higher incidence of > 20% oversizing (13% vs 4%, P = .019) of donor lungs, which resulted in a significantly reduced long-term survival (P = .02) compared with male recipients. Median Lung Allocation Scores were similar in both groups.

CONCLUSION

Mismatch of donor age and size can be important for organ function and survival in LTx recipients. Particularly female recipients seem to have a higher risk for unfavorable long-term outcome when transplanting organs of increased size and age. Multicenter studies are warranted to further address this question.

TRIAL REGISTRATION NUMBER

(DKRS): 00033312.

Critical Care of the Lung Transplant Patient

Lung transplantation is a therapeutic option for end-stage lung disease that improves survival and quality of life. Prelung transplant admission to the intensive care unit (ICU) for bridge to transplant with mechanical ventilation and extracorporeal membrane oxygenation (ECMO) is common. Primary graft dysfunction is an important immediate complication of lung transplantation with short- and long-term morbidity and mortality. Later transplant-related causes of respiratory failure necessitating ICU admission include acute cellular rejection, atypical infections, and chronic lung allograft dysfunction. Lung transplantation for COVID-19-related ARDS is increasingly common..

Lobar lung transplantation from deceased donors: A systematic review

AIM

To systematically review reports on deceased-donor-lobar lung transplantation (ddLLTx) and uniformly describe size matching using the donor-to-recipient predicted-total lung-capacity (pTLC) ratio.

METHODS

We set out to systematically review reports on ddLLTx and uniformly describe size matching using the donor-to-recipient pTLC ratio and to summarize reported one-year survival data of ddLLTx and conventional-LTx. We searched in PubMed, CINAHL via EBSCO, Cochrane Database of Systematic Reviews via Wiley (CDSR), Database of Abstracts of Reviews of Effects via Wiley (DARE), Cochrane Central Register of Controlled Trials via Wiley (CENTRAL), Scopus (which includes EMBASE abstracts), and Web of Science for original reports on ddLLTx.

RESULTS

Nine observational cohort studies reporting on 301 ddLLTx met our inclusion criteria for systematic review of size matching, and eight for describing one-year-survival. The ddLLTx-group was often characterized by high acuity; however there was heterogeneity in transplant indications and pre-operative characteristics between studies. Data to calculate the pTLC ratio was available for 242 ddLLTx (80%). The mean pTLCratio before lobar resection was 1.25 ± 0.3 and the transplanted pTLCratio after lobar resection was 0.76 ± 0.2. One-year survival in the ddLLTx-group ranged from 50%-100%, compared to 72%-88% in the conventional-LTx group. In the largest study ddLLTx (n = 138) was associated with a lower one-year-survival compared to conventional-LTx (n = 539) (65.1% vs 84.1%, P < 0.001).

CONCLUSION

Further investigations of optimal donor-to-recipient size matching parameters for ddLLTx could improve outcomes of this important surgical option.

Donor to recipient sizing in thoracic organ transplantation

Donor-to-recipient organ size matching is a critical aspect of thoracic transplantation. In the United States potential recipients for lung transplant and heart transplant are listed with limitations on donor height and weight ranges, respectively. Height is used as a surrogate for lung size and weight is used as a surrogate for heart size. While these measures are important predictors of organ size, they are crude surrogates that fail to incorporate the influence of sex on organ size. Independent of other measures, a man’s thoracic organs are approximately 20% larger than a woman’s. Lung size can be better estimated using the predicted total lung capacity, which is derived from regression equations correcting for height, sex and age. Similarly, heart size can be better estimated using the predicted heart mass, which adjusts for sex, age, height, and weight. These refined organ sizing measures perform better than current sizing practice for the prediction of outcomes after transplantation, and largely explain the outcome differences observed after sex-mismatch transplantation. An undersized allograft is associated with worse outcomes. In this review we examine current data pertaining to size-matching in thoracic transplantation. We advocate for a change in the thoracic allocation mechanism from a height-or-weight-based strategy to a size-matching process that utilizes refined estimates of organ size. We believe that a size-matching approach based on refined estimates of organ size would optimize outcomes in thoracic transplantation without restricting or precluding patients from thoracic transplantation.

MECHANICAL VENTILATION FOR THE LUNG TRANSPLANT RECIPIENT

Mechanical ventilation (MV) is an important aspect in the intraoperative and early postoperative management of lung transplant (LTx)-recipients. There are no randomized-controlled trials of LTx-recipient MV strategies; however there are LTx center experiences and international survey studies reported. The main early complication of LTx is primary graft dysfunction (PGD), which is similar to the adult respiratory distress syndrome (ARDS). We aim to summarize information pertinent to LTx-MV, as well as PGD, ARDS, and intraoperative MV and to synthesize these available data into recommendations. Based on the available evidence, we recommend lung-protective MV with low-tidal-volumes (≤6 mL/kg predicted body weight [PBW]) and positive end-expiratory pressure for the LTx-recipient. In our opinion, the MV strategy should be based on donor characteristics (donor PBW as a parameter of actual allograft size), rather than based on recipient characteristics; however this donor-characteristics-based protective MV is based on indirect evidence and requires validation in prospective clinical studies.

Lung size mismatch and primary graft dysfunction after bilateral lung transplantation

BACKGROUND

Donor-to-recipient lung size matching at lung transplantation (LTx) can be estimated by the predicted total lung capacity (pTLC) ratio (donor pTLC/recipient pTLC). We aimed to determine whether the pTLC ratio is associated with the risk of primary graft dysfunction (PGD) after bilateral LTx (BLT).

METHODS

We calculated the pTLC ratio for 812 adult BLTs from the Lung Transplant Outcomes Group between March 2002 to December 2010. Patients were stratified by pTLC ratio >1.0 ("oversized") and pTLC ratio ≤1.0 ("undersized"). PGD was defined as any ISHLT Grade 3 PGD (PGD3) within 72 hours of reperfusion. We analyzed the association between risk factors and PGD using multivariable conditional logistic regression. As transplant diagnoses can influence the size-matching decisions and also modulate the risk for PGD, we performed pre-specified analyses by assessing the impact of lung size mismatch within diagnostic categories.

RESULTS

In univariate analyses oversizing was associated with a 39% lower odds of PGD3 (OR 0.61, 95% CI, 0.45-0.85, p = 0.003). In a multivariate model accounting for center-effects and known PGD risks, oversizing remained independently associated with a decreased odds of PGD3 (OR 0.58, 95% CI 0.38 to 0.88, p = 0.01). The risk-adjusted point estimate was similar for the non-COPD diagnosis groups (OR 0.52, 95% CI 0.32 to 0.86, p = 0.01); however, there was no detected association within the COPD group (OR 0.72, 95% CI 0.29 to 1.78, p = 0.5).

CONCLUSION

Oversized allografts are associated with a decreased risk of PGD3 after BLT; this effect appears most apparent in non-COPD patients.