To decline or not to decline: Consequences of decision-making regarding lung offers from donors with hepatitis C

OBJECTIVE

Lung transplants from donors with hepatitis C (HCV D+) have excellent outcomes, but these organs continue to be declined. We evaluated whether (1) being listed to consider and (2) accepting versus declining HCV D+ offers provided a survival benefit to lung transplant candidates.

METHODS

Using the Scientific Registry of Transplant Recipients, we identified all adult (≥18 years) lung transplant candidates 2016-2021 and compared waitlist mortality between those willing versus not willing to consider HCV D+ offers using competing risk regression. We identified all candidates offered an HCV D+ lung that was later accepted and followed them from offer decision until death or end-of-study. We estimated adjusted mortality risk of accepting versus declining an HCV D+ lung offer using propensity-weighted Cox regression.

RESULTS

From 2016 to 2021, we identified 21,007 lung transplant candidates, 33.8% of whom were willing to consider HCV D+ offers. Candidates willing to consider HCV D+ offers had a 17% lower risk of waitlist mortality (subhazard ratio, 0.83; 95% confidence interval, 0.75-0.91, P < .001). Over the same period, 665 HCV D+ lung offers were accepted after being declined a total of 2562 times. HCV D+ offer acceptance versus decline was associated with a 20% lower risk of mortality (adjusted hazard ratio, 0.80; 95% confidence interval, 0.66-0.96, P = .02).

CONCLUSIONS

Considering HCV D+ lung offers was associated with a 17% lower risk of waitlist mortality, whereas accepting versus declining an HCV D+ lung offer was associated with a 20% lower risk of mortality. Centers and candidates should consider accepting suitable HCV D+ lung offers to optimize outcomes.

Impact of Extracorporeal Membrane Oxygenation Bridging Duration on Lung Transplant Outcomes

BACKGROUND

We sought to characterize the association between venovenous extracorporeal membrane oxygenation (VV-ECMO) bridging duration and outcomes in patients listed for lung transplantation.

METHODS

A retrospective observational study was conducted using the Organ Procurement and Transplantation Network (OPTN) database to identify adults (≥18 years old) who were listed for lung transplantation between 2016-2020 and who were bridged with VV-ECMO. Patients were then stratified into groups, determined by risk inflection points, depending on the amount of time spent on pre-transplant ECMO: Group 1 (≤5 days), Group 2 (6-10 days), Group 3 (11-20 days), and Group 4 (>20 days). Waitlist survival between groups was analyzed using Fine-Gray competing risk models. Post-transplant survival was compared using Cox regression.

RESULTS

Of 566 eligible VV-ECMO bridge-to-lung-transplant patients (median age=54, 49% male), 174 (31%), 124 (22%), 130 (23%), and 138 (24%) were categorized as Groups 1, 2, 3, and 4, respectively. Overall, median duration of VV-ECMO was 10 days (range=1-211) and 178 patients (31%) died on the waitlist. In the Fine-Gray model, compared to Group 1, patients bridged with longer ECMO durations in Groups 2 (SHR=2.95, 95%CI: 1.63-5.35), 3 (SHR=3.96, 95%CI: 2.36-6.63), and 4 (SHR=4.33, 95%CI: 2.59-7.22, all p<0.001), were more likely to die on the waitlist. Of 388 patients receiving a transplant, pre-transplant ECMO duration was not associated with one-year survival in Cox regression.

CONCLUSIONS

Prolonged ECMO bridging duration was associated with worse waitlist mortality but did not impact post-lung transplant survival. Prioritization of very early transplantation may improve waitlist outcomes in this population.

Bigger pies, bigger slices: Increased hospitalization costs for lung transplantation recipients in the non-donation service area allocation era

OBJECTIVE

On November 24, 2017, lung transplant allocation switched from donation service area to a 250-nautical mile radius policy to improve equity in access to lung transplantation. Given the growing consideration of healthcare costs, we evaluated changes in hospitalization costs after this policy change.

METHODS

Lung transplant hospitalizations were identified within the National Inpatient Sample from 2005 to 2020. Recipients were categorized as donation service area era (August 2015 to October 2017) or non-donation service area era (December 2017 to February 2020). Median total hospitalization costs (inflation adjusted) were compared by era nationally and regionally. Multivariable generalized linear regression was performed to determine if the removal of the donation service area was associated with total hospitalization costs. The model was adjusted for recipient demographics, Charlson Comorbidity Index, hospitalization region, transplant type (single, double), and use of extracorporeal membrane oxygenation, ex vivo lung perfusion, and mechanical ventilation.

RESULTS

We analyzed 12,985 lung transplant recipients (median age of 61 years, 66% were male): 7070 in the donation service area era and 5915 in the non-donation service area era. Demographics were not different between recipients in both eras. Non-donation service area era recipients had greater extracorporeal membrane oxygenation use, mechanical ventilation (<24 hours), and longer length of stay than donation service area era recipients. Median total hospitalization costs for non-donation service area versus donation service area era recipients increased by $24,198 ($157,964 vs $182,162, percentage change = 15.32%, P < .001). Median costs increased in East North Central ($42,281) and Mountain ($35,521) regions (both P < .01). After adjustment, median costs for non-donation service area versus donation service area era recipients still increased ($19,168, 95% CI, 145-38,191, P = .048).

CONCLUSIONS

Hospitalization costs for lung transplant hospitalizations have increased from 2015 to 2020. The transition from donation service area-based allocation to the non-donation service area system may have contributed to this increase after 2017 by increasing access to transplant for sicker recipients.

Impact of recipient age on mortality among Cytomegalovirus (CMV)-seronegative lung transplant recipients with CMV-seropositive donors

BACKGROUND

Cytomegalovirus (CMV)-seronegative lung transplant recipients (LTRs) with seropositive donors (CMV D+/R-) have the highest mortality of all CMV serostatuses. Due to immunosenescence and other factors, we hypothesized CMV D+/R- status might disproportionately impact older LTRs. Thus, we investigated whether recipient age modified the relationship between donor CMV status and mortality among CMV-seronegative LTRs.

METHODS

Adult, CMV-seronegative first-time lung-only recipients were identified through the Scientific Registry of Transplant Recipients between May 2005 and December 2019. We used adjusted multivariable Cox regression to assess the relationship of donor CMV status and death. Interaction between recipient age and donor CMV was assessed via likelihood ratio testing of nested Cox models and by the relative excess risk due to interaction (RERI) and attributable proportion (AP) of joint effects.

RESULTS

We identified 11,136 CMV-seronegative LTRs. The median age was 59 years; 65.2% were male, with leading transplant indication of idiopathic pulmonary fibrosis (35.6%); and 60.8% were CMV D+/R-. In multivariable modeling, CMV D+/R- status was associated with 27% increased hazard of death (adjusted hazard ratio: 1.27, 95% confidence interval: 1.21-1.34) compared to CMV D-/R-. Recipient age ≥60 years significantly modified the relationship between donor CMV-seropositive status and mortality on the additive scale, including RERI 0.24 and AP 11.4% (p = 0.001), that is, the interaction increased hazard of death by 0.24 and explained 11.4% of mortality in older CMV D+ recipients.

CONCLUSIONS

Among CMV-seronegative LTRs, donor CMV-seropositive status confers higher risk of posttransplant mortality, which is amplified in older recipients. Future studies should define optimal strategies for CMV prevention and management in older D+/R- LTRs.

Debunking the July Effect in lung transplantation recipients

Objective

The "July Effect" is a theory that the influx of trainees from July to September negatively impacts patient outcomes. We aimed to study this theoretical phenomenon in lung transplant recipients given the highly technical nature of thoracic procedures.

Methods

Adult lung transplant hospitalizations were identified within the National Inpatient Sample (2005-2020). Recipients were categorized as academic Q1 (July to September) or Q2-Q4 (October to June). In-hospital mortality, operator-driven complications (pneumothorax, dehiscence including wound dehiscence, bronchial anastomosis, and others, and vocal cord/diaphragm paralysis, all 3 treated as a composite outcome), length of stay, and inflation-adjusted hospitalization charges were compared between both groups. Multivariable logistic regression was performed to assess the association between academic quarter and in-hospital mortality and operator-driven complications. The models were adjusted for recipient demographics and transplant characteristics. Subgroup analysis was performed between academic and nonacademic hospitals.

Results

Of 30,788 lung transplants, 7838 occurred in Q1 and 22,950 occurred in Q2-Q4. Recipient demographic and clinical characteristics were similar between groups. Dehiscence (n = 922, 4% vs n = 236, 3%), post-transplant cardiac arrest (n = 532, 2% vs n = 113, 1%), and pulmonary embolism (n = 712, 3% vs n = 164, 2%) were more common in Q2-Q4 versus Q1 recipients (all P < .05). Other operator-driven complications, in-hospital mortality, and resource use were similar between groups (P > .05). These inferences remained unchanged in adjusted analyses and on subgroup analyses of academic versus nonacademic hospitals.

Conclusions

The "July Effect" is not evident in US lung transplantation recipient outcomes during the transplant hospitalization. This suggests that current institutional monitoring systems for trainees across multiple specialties, including surgery, anesthesia, critical care, nursing, and others, are robust.

Outcomes of Lung Transplant Candidates Aged ≥70 Years During the Lung Allocation Score Era

BACKGROUND

With the increasing age of lung transplant candidates, we studied waitlist and posttransplantation outcomes of candidates ≥70 years during the Lung Allocation Score era.

METHODS

Adult lung transplant candidates from 2005 to 2020 in the United Network for Organ Sharing database were included and stratified on the basis of age at listing into 18 to 59 years old, 60 to 69 years old, and ≥70 years old. Baseline characteristics, waitlist outcomes, and posttransplantation outcomes were assessed.

RESULTS

A total of 37,623 candidates were included (52.3% aged 18-59 years, 40.6% aged 60-69 years, 7.1% aged ≥70 years). Candidates ≥70 years were more likely than younger candidates to receive a transplant (81.9% vs 72.7% [aged 60-69 years] vs 61.6% [aged 18-59 years]) and less likely to die or to deteriorate on the waitlist within 1 year (9.1% vs 10.1% [aged 60-69 years] vs 12.2% [aged 18-59 years]; P < .001). Donors for older recipients were more likely to be extended criteria (75.7% vs 70.1% [aged 60-69 years] vs 65.7% [aged 18-59 years]; P < .001). Recipients ≥70 years were found to have lower rates of acute rejection (6.7% vs 7.4% [aged 60-69 years] vs 9.2% [aged 18-59 years]; P < .001) and prolonged intubation (21.7% vs 27.4% [aged 60-69 years] vs 34.5% [aged 18-59 years]; P < .001). Recipients aged ≥70 years had increased 1-year (adjusted hazard ratio [aHR], 1.19 [95% CI, 1.06-1.33]; P < .001), 3-year (aHR, 1.28 [95% CI, 1.18-1.39]; P < .001), and 5-year mortality (aHR, 1.29 [95% CI, 1.21-1.38]; P < .001) compared with recipients aged 60 to 69 years.

CONCLUSIONS

Candidates ≥70 years had favorable waitlist and perioperative outcomes despite increased use of extended criteria donors. Careful selection of candidates and postoperative surveillance may improve posttransplantation survival in this population.

Cell-Free DNA Maps Tissue Injury and Correlates with Disease Severity in Lung Transplant Candidates

Rationale: Plasma cell-free DNA levels correlate with disease severity in many conditions. Pretransplant cell-free DNA may risk stratify lung transplant candidates for post-transplant complications. Objectives: To evaluate if pretransplant cell-free DNA levels and tissue sources identify patients at high risk of primary graft dysfunction and other pre- and post-transplant outcomes. Methods: This multicenter, prospective cohort study recruited 186 lung transplant candidates. Pretransplant plasma samples were collected to measure cell-free DNA. Bisulfite sequencing was performed to identify the tissue sources of cell-free DNA. Multivariable regression models determined the association between cell-free DNA levels and the primary outcome of primary graft dysfunction and other transplant outcomes, including Lung Allocation Score, chronic lung allograft dysfunction, and death. Measurements and Main Results: Transplant candidates had twofold greater cell-free DNA levels than healthy control patients (median [interquartile range], 23.7 ng/ml [15.1-35.6] vs. 12.9 ng/ml [9.9-18.4]; P < 0.0001), primarily originating from inflammatory innate immune cells. Cell-free DNA levels and tissue sources differed by native lung disease category and correlated with the Lung Allocation Score (P < 0.001). High pretransplant cell-free DNA increased the risk of primary graft dysfunction (odds ratio, 1.60; 95% confidence interval [CI], 1.09-2.46; P = 0.0220), and death (hazard ratio, 1.43; 95% CI, 1.07-1.92; P = 0.0171) but not chronic lung allograft dysfunction (hazard ratio, 1.37; 95% CI, 0.97-1.94; P = 0.0767). Conclusions: Lung transplant candidates demonstrate a heightened degree of tissue injury with elevated cell-free DNA, primarily originating from innate immune cells. Pretransplant plasma cell-free DNA levels predict post-transplant complications.

Outcomes of Recipients Aged 65 Years and Older Bridged to Lung Transplant With Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplant (BTT) has been used for critically ill candidates with excellent outcomes, but data on this strategy in older recipients remain limited. We compared outcomes of no BTT, mechanical ventilation (MV)-only BTT, and ECMO BTT in recipients of greater than or equal to 65 years. Lung-only recipients of greater than or equal to 65 years in the United Network for Organ Sharing database between 2008 and 2022 were included and stratified by bridging strategy. Of the 9,936 transplants included, 226 (2.3%) were MV-only BTT and 159 (1.6%) were ECMO BTT. Extracorporeal membrane oxygenation BTT recipients were more likely to have restrictive disease pathology, had higher median lung allocation score, and spent fewer days on the waitlist (all p < 0.001). Compared to no-BTT recipients, ECMO BTT recipients were more likely to be intubated or on ECMO at 72 hours posttransplant and had longer hospital lengths of stay (all p < 0.001). Extracorporeal membrane oxygenation BTT recipients had increased risk of 3 years mortality compared to both no-BTT (adjusted hazard ratio [aHR] = 1.48 [95% confidence interval {CI}: 1.14-1.91], p = 0.003) and MV-only recipients (aHR = 1.50 [95% CI: 1.08-2.07], p = 0.02). Overall, we found that ECMO BTT in older recipients is associated with inferior posttransplant outcomes compared to MV-only or no BTT, but over half of recipients remained alive at 3 years posttransplant.

Age and associated outcomes among patients receiving venovenous extracorporeal membrane oxygenation for acute respiratory failure: analysis of the Extracorporeal Life Support Organization registry

PURPOSE

Venovenous extracorporeal membrane oxygenation (VV-ECMO) can be used to support patients with refractory acute respiratory failure, though guidance on patient selection is lacking. While age is commonly utilized as a factor in establishing the potential VV-ECMO candidacy of these patients, little is known regarding its association with outcome. We studied the association between increasing patient age and outcomes among patients with acute respiratory failure receiving VV-ECMO.

METHODS

In this registry-based cohort study, we used individual patient data from 144 centres. We included adult patients (≥ 18 years of age) receiving VV-ECMO from 2017 to 2022. The primary outcome was hospital mortality. Secondary outcomes included a composite of complications following initiation of VV-ECMO. We conducted Bayesian analyses to estimate the association between chronological age and outcomes.

RESULTS

We included 27,811 patients receiving VV-ECMO. Of these, 11,533 (41.5%) died in hospital. For the analysis conducted using weakly informed priors, and as compared to the reference category of age 18-29, the age brackets of 30-39 (odds ratio [OR] 1.17, 95% credible interval [CrI] 1.06-1.31), 40-49 (OR 1.65, 95% CrI 1.49-1.82), 50-59 (OR 2.39, 95% CrI 2.16-2.61), 60-69 (OR 3.29, 95% CrI 2.97-3.67), 70-79 (OR 4.57, 95% CrI 3.90-5.37), and ≥ 80 (OR 8.08, 95% CrI 4.85-13.74) were independently associated with increasing hospital mortality. Similar results were found between increasing age and post-ECMO complications.

CONCLUSIONS

Among patients receiving VV-ECMO for acute respiratory failure, increasing age is significantly associated with poorer outcomes, and this association emerges as early as 30 years of age.

Racial Disparities in Waiting List Outcomes of Patients Listed for Lung Transplantation

BACKGROUND

The Lung Allocation Score, implemented in 2005, prioritized lung transplant candidates by medical urgency rather than waiting list time and was expected to improve racial disparities in transplant allocation. We evaluated whether racial disparities in lung transplant persisted after 2005.

METHODS

We identified all wait-listed adult lung transplant candidates in the United States from 2005 through 2021 using the Scientific Registry of Transplant Recipients. We evaluated the association between race and receipt of a transplant by using a multivariable competing risk regression model adjusted for demographics, socioeconomic status, Lung Allocation Score, clinical measures, and time. We evaluated interactions between race and age, sex, socioeconomic status, and Lung Allocation Score.

RESULTS

We identified 33,158 candidates on the lung transplant waiting list between 2005 and 2021: 27,074 White (82%), 3350 African American (10%), and 2734 Hispanic (8%). White candidates were older, had higher education levels, and had lower Lung Allocation Scores (P < .001). After multivariable adjustment, African American and Hispanic candidates were less likely to receive lung transplants than White candidates (African American: adjusted subhazard ratio, 0.86; 95% CI, 0.82-0.91; Hispanic: adjusted subhazard ratio, 0.82; 95% CI, 0.78-0.87). Lung transplant was significantly less common among Hispanic candidates aged >65 years (P = .003) and non-White candidates from higher-poverty communities (African-American: P = .013; Hispanic: P =.0036).

CONCLUSIONS

Despite implementation of the Lung Allocation Score, racial disparities persisted for wait-listed African American and Hispanic lung transplant candidates and differed by age and poverty status. Targeted interventions are needed to ensure equitable access to this life-saving intervention.

Uptake and 1-year outcomes of lung transplantation for COVID-19

OBJECTIVE

End-stage lung disease from severe COVID-19 infection is an increasingly common indication for lung transplantation (LT), but there are limited data on outcomes. We evaluated 1-year COVID-19 LT outcomes.

METHODS

We identified all adult US LT recipients January 2020 to October 2022 in the Scientific Registry for Transplant Recipients, using diagnosis codes to identify recipients transplanted for COVID-19. We used multivariable regression to compare in-hospital acute rejection, prolonged ventilator support, tracheostomy, dialysis, and 1-year mortality between COVID-19 and non-COVID-19 recipients, adjusting for donor, recipient, and transplant characteristics.

RESULTS

LT for COVID-19 increased from 0.8% to 10.7% of total LT volume during 2020 to 2021. The number of centers performing LT for COVID-19 increased from 12 to 50. Recipients transplanted for COVID-19 were younger; were more likely to be male and Hispanic; were more likely to be on a ventilator, extracorporeal membrane oxygenation support, and dialysis pre-LT; were more likely to receive bilateral LT; and had higher lung allocation score and shorter waitlist time than other recipients (all P values < .001). COVID-19 LT had higher risk of prolonged ventilator support (adjusted odds ratio, 2.28; P < .001), tracheostomy (adjusted odds ratio 5.3; P < .001), and longer length of stay (median, 27 vs 19 days; P < .001). Risk of in-hospital acute rejection (adjusted odds ratio, 0.99; P = .95) and 1-year mortality (adjusted hazard ratio, 0.73; P = .12) were similar for COVID-19 LTs and LTs for other indications, even accounting for center-level differences.

CONCLUSIONS

COVID-19 LT is associated with higher risk of immediate postoperative complications but similar risk of 1-year mortality despite more severe pre-LT illness. These encouraging results support the ongoing use of LT for COVID-19-related lung disease.

The effect of allograft ischemic time on outcomes following bilateral, single, and reoperative lung transplantation

OBJECTIVE

To determine whether allograft ischemic times affect outcomes following bilateral, single, and redo lung transplantation.

METHODS

A nationwide cohort of lung transplant recipients from 2005 through 2020 was examined using the Organ Procurement and Transplantation Network registry. The effects of standard (<6 hours) and extended (≥6 hours) ischemic times on outcomes following primary bilateral (n = 19,624), primary single (n = 688), redo bilateral (n = 8461), and redo single (n = 449) lung transplantation were analyzed. A priori subgroup analysis was performed in the primary and redo bilateral-lung transplant cohorts by further stratifying the extended ischemic time group into mild (≥6 and <8 hours), moderate (≥8 and <10 hours), and long (≥10 hours) subgroups. Primary outcomes included 30-day mortality, 1-year mortality, intubation at 72 hours' posttransplant, extracorporeal membrane oxygenation (ECMO) support at 72 hours' posttransplant, and a composite variable of intubation or ECMO at 72 hours' posttransplant. Secondary outcomes included acute rejection, postoperative dialysis, and hospital length of stay.

RESULTS

Recipients of allografts with ischemic times ≥6 hours experienced increased 30-day and 1-year mortality following primary bilateral-lung transplantation, but increased mortality was not observed following primary single, redo bilateral, or redo single-lung transplants. Extended ischemic times correlated with prolonged intubation or increased postoperative ECMO support in the primary bilateral, primary single, and redo bilateral-lung transplant cohorts but did not affect these outcomes following redo single-lung transplantation.

CONCLUSIONS

Since prolonged allograft ischemia correlates with worse transplant outcomes, the decision to use donor lungs with extended ischemic times must consider the specific benefits and risks associated with individual recipient factors and institutional expertise.

Racial disparities among patients on venovenous extracorporeal membrane oxygenation in the pre-Coronavirus Disease 2019 and Coronavirus Disease 2019 eras: A retrospective registry review

Objectives

Although many studies have addressed such disparities caused by COVID-19, to our knowledge, no study has focused on the association of race on outcomes for patients with COVID-19 requiring venovenous extracorporeal membrane oxygenation support. The goal of this study was to assess association of race on death and duration on venovenous extracorporeal membrane oxygenation in both the pre-COVID-19 and COVID-19 eras.

Methods

We retrospectively reviewed the Extracorporeal Life Support Organization registry and included adults (≥18 years) who required venovenous extracorporeal membrane oxygenation between January 2019 and April 2021. We performed descriptive statistics and multivariable logistic regression. Our primary outcomes were death and extracorporeal membrane oxygenation duration.

Results

A total of 7477 patients were included after excluding 340 patients (4.3%) who were missing race data. In the COVID-19 era, 1474 of 2777 COVID-19-positive patients (53.1%) died. Our regression model suggested somewhat of a protective effect on death for Black and multiple race patients. Additionally, a diagnosis of COVID-19 and patients in the COVID-19 era in general, irrespective of COVID-19 diagnosis, had higher odds of death. Hispanic patients had the longest average venovenous extracorporeal membrane oxygenation run times.

Conclusions

Our study using data from the international Extracorporeal Life Support Organization Registry provides updated data on patients supported with venovenous extracorporeal membrane oxygenation in the pre-COVID-19 and COVID-19 eras between 2019 and 2021 with a focus on race. Patients in the COVID-19 era group also had higher mortality compared with those in the pre-COVID-19 era even after being adjusted for COVID-19 diagnosis. Black and multiple races appeared somewhat protective in terms of death. Hispanic race was associated with longer venovenous extracorporeal membrane oxygenation duration.

Extracorporeal membrane oxygenation as a bridge to lung transplantation: Practice patterns and patient outcomes

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly relied on to bridge patients with respiratory failure to lung transplantation despite limited evidence for its use in this setting. This study evaluated longitudinal trends in practice patterns, patient characteristics, and outcomes in patients bridged with ECMO to lung transplant.

METHODS

A retrospective review of all adult isolated lung transplant patients in the United Network for Organ Sharing database between 2000 and 2019 was performed. Patients were classified as "ECMO" if supported with ECMO at the time of listing or transplantation and "non-ECMO" otherwise. Linear regression was used to evaluate trends in patient demographics during the study period. Trends in mortality were evaluated using Cox proportional hazards modeling, with time period as the primary covariate (2000-2004, 2005-2009, 2010-2014, or 2015-2019) and age, time on the waitlist, and underlying diagnosis as covariates.

RESULTS

The number of patients included were 40,866, of whom 1,387 (3.4%) were classified as ECMO and 39,479 (96.6%) as no ECMO. Average age and initial Lung Allocation Score increased significantly during the study period in both cohorts, but occurred at a slower rate in the ECMO population. The hazard of death was significantly lower in more recent years (2015-2019) for both the ECMO and non-ECMO cohorts (aHR (adjusted hazards ratio) 0.59, 95% confidence interval (CI) 0.37-0.96 and aHR 0.74, 95% CI 0.70-0.79) when compared to the early years (2000-2004) of the study period.

CONCLUSIONS

Post-transplantation survival for patients bridged to transplantation with ECMO demonstrates ongoing improvement despite cannulation of progressively older and sicker patients.

Incidence, risk factors, and outcomes of postoperative stroke in combined heart-lung transplantation: A retrospective cohort study of the UNOS registry

Stroke is a well-characterized complication of isolated heart and lung transplantation, but has not been described in combined heart-lung transplantation (HLTx). We retrospectively reviewed national U.S. data to describe the incidence, risk factors, and impact of postoperative stroke in HLTx recipients. Of 871 heart-lung recipients between 1994-2022, 35 (4.0%) experienced stroke, and the incidence increased over time, trending toward significance (p-trend = .07). After adjustment, extracorporeal membrane oxygenation (ECMO) (Adjusted odds ratio [aOR] = 2.63, 95%CI = [1.13-6.11]) and pre-transplant implantable defibrillator (aOR = 2.86, 95%CI = [1.20-6.81]) were independent risk factors for stroke. Postoperative stroke is common and is increasing in an era where organ allocation is driven by mechanical circulatory support (MCS) bridging.

National utilization, trends, and lung transplant outcomes of static versus portable ex vivo lung perfusion platforms

BACKGROUND

This study compared utilization and outcomes of the 2 widely utilized ex vivo lung perfusion (EVLP) platforms in the United States: a static platform and a portable platform.

METHODS

Adult (age 18 years or older) bilateral lung-only transplants utilizing EVLP between February 28, 2018, and December 31, 2022, in the United Network for Organ Sharing database were included. Predischarge acute rejection, intubation at 72 hours posttransplant, extracorporeal membrane oxygenation at 72 hours posttransplant, primary graft dysfunction grade 3 at 72 hours posttransplant, 30-day mortality, and 1-year mortality were evaluated using multivariable regressions.

RESULTS

Overall, 607 (6.3%) lung transplants during the study period used EVLP (51.2% static, 48.8% portable). Static EVLP was primarily utilized in the eastern United States, whereas portable EVLP was primarily utilized in the western United States. Static EVLP donors were more likely to be donation after circulatory death (33.4% vs 26.0%; P = .005), have a >20 pack-year smoking history (13.5% vs 6.5%; P = .005), and be extended criteria donors (92.3% vs 85.0%; P = .013), whereas portable EVLP donors were more likely to be older than age 55 years (14.2% vs 8.0%; P = .02). Transplants utilizing the static and portable platforms had similar risk of acute rejection, intubation at 72 hours, extracorporeal membrane oxygenation at 72 hours, primary graft dysfunction grade 3 at 72 hours, and posttransplant mortality at 30 days and 1 year (all P values > .05).

CONCLUSIONS

The static and portable platforms had significant differences in donor characteristics and geographic distributions of utilization. Despite this, posttransplant survival was similar between the 2 EVLP platforms.

Current status and future potential of ex vivo lung perfusion in clinical lung transplantation

Lung transplantation is accepted as a well-established and effective treatment for patients with end-stage lung disease. While the number of candidates added to the waitlist continues to rise, the number of transplants performed remains limited by the number of suitable organ donors. Ex vivo lung perfusion (EVLP) emerged as a method of addressing the organ shortage by allowing the evaluation and potential reconditioning of marginal donor lungs or minimizing risks of prolonged ischemic time due to logistical challenges. The currently available FDA-approved EVLP systems have demonstrated excellent outcomes in clinical trials, and retrospective studies have demonstrated similar post-transplant survival between recipients who received marginal donor lungs perfused using EVLP and recipients who received standard criteria lungs stored using conventional methods. Despite this, widespread utilization has plateaued in the last few years, likely due to the significant costs associated with initiating EVLP programs. Centralized, dedicated EVLP perfusion centers are currently being investigated as a potential method of further expanding utilization of this technology. In the preclinical setting, potential applications of EVLP that are currently being studied include prolongation of organ preservation, reconditioning of unsuitable lungs, and further enhancement of already suitable lungs. As adoption of EVLP technology becomes more widespread, we may begin to see future implementation of these potential applications into the clinical setting.

Race-Specific Interpretation of Spirometry: Impact on the Lung Allocation Score

Rationale: Interpretation of spirometry using race-specific reference equations may contribute to health disparities via underestimation of the degree of lung function impairment in Black patients. The use of race-specific equations may differentially affect patients with severe respiratory disease via the use of percentage predicted forced vital capacity (FVCpp) when included in the lung allocation score (LAS), the primary determinant of priority for lung transplantation. Objectives: To determine the impact of a race-specific versus a race-neutral approach to spirometry interpretation on the LAS among adults listed for lung transplantation in the United States. Methods: We developed a cohort from the United Network for Organ Sharing database including all White and Black adults listed for lung transplantation between January 7, 2009, and February 18, 2015. The LAS at listing was calculated for each patient under race-specific and race-neutral approaches, using the FVCpp generated from the Global Lung Function Initiative equation corresponding to each patient's race (race-specific) or from the Global Lung Function Initiative "other" (race-neutral) equation. Differences in LAS between approaches were compared by race, with positive values indicating a higher LAS under the race-neutral approach. Results: In this cohort of 8,982 patients, 90.3% were White and 9.7% were Black. The mean FVCpp was 4.4% higher versus 3.8% lower among White versus Black patients (P < 0.001) under a race-neutral compared with a race-specific approach. Compared with White patients, Black patients had a higher mean LAS under both a race-specific (41.9 vs. 43.9; P < 0.001) and a race-neutral (41.3 vs. 44.3; P < 0.001) approach. However, the mean difference in LAS under a race-neutral approach was -0.6 versus +0.6 for White versus Black patients (P < 0.001). Differences in LAS under a race-neutral approach were most pronounced for those in group B (pulmonary vascular disease) (-0.71 vs. +0.70; P < 0.001) and group D (restrictive lung disease) (-0.78 vs. +0.68; P < 0.001). Conclusions: A race-specific approach to spirometry interpretation has potential to adversely affect the care of Black patients with advanced respiratory disease. Compared with a race-neutral approach, a race-specific approach resulted in lower LASs for Black patients and higher LASs for White patients, which may have contributed to racially biased allocation of lung transplantation. The future use of race-specific equations must be carefully considered.

National Trends, Risk Factors, and Outcomes of Acute In-Hospital Stroke Following Lung Transplantation in the United States: Analysis of the United Network for Organ Sharing Registry

BACKGROUND

Lung transplantation (LTx) is the definitive treatment for end-stage lung failure. However, there have been no large, long-term studies on the impact of acute in-hospital stroke in this population.

RESEARCH QUESTION

What are the trends, risk factors, and outcomes of acute stroke in patients undergoing LTx in the United States?

STUDY DESIGN AND METHODS

We identified adult first-time isolated LTx recipients from the United Network for Organ Sharing database, which comprehensively captures every transplant in the United States, between May 2005 and December 2020. Stroke was defined as occurring at any time after LTx but prior to discharge. Multivariable logistic regression with stepwise feature elimination was used to identify risk factors for stroke. Freedom from death in patients with a stroke vs those without a stroke was evaluated with Kaplan-Meier analysis. Cox proportional hazards analysis was used to identify predictors of death at 24 months.

RESULTS

Of 28,564 patients (median age, 60 years; 60% male), 653 (2.3%) experienced an acute in-hospital stroke after LTx. Median follow-up was 1.2 (stroke) and 3.0 (non-stroke) years. Annual incidence of stroke increased (1.5% in 2005 to 2.4% in 2020; P for trend = .007), as did lung allocation score and utilization of post-LTx extracorporeal membrane oxygenation (P = .01 and P < .001, respectively). Compared with those without stroke, patients with stroke had lower survival at 1 month (84% vs 98%), 12 months (61% vs 88%), and 24 months (52% vs 80%) (log-rank test, P < .001 for all). In Cox analysis, acute stroke conferred a high hazard of mortality (hazard ratio, 3.01; 95% CI, 2.67-3.41). Post-LTx extracorporeal membrane oxygenation was the strongest risk factor for stroke (adjusted OR, 2.98; 95% CI, 2.19-4.06).

INTERPRETATION

Acute in-hospital stroke post-LTx has been increasing over time and is associated with markedly worse short- and long-term survival. As increasingly sicker patients undergo LTx as well as experience stroke, further research on stroke characteristics, prevention, and management strategies is warranted.

Lower Oxygen Tension and Intracranial Hemorrhage in Veno-venous Extracorporeal Membrane Oxygenation

INTRODUCTION AND METHODS

We examined the relationship between 24-h pre- and post-cannulation arterial oxygen tension (PaO2) and arterial carbon dioxide tension (PaCO2) and subsequent acute brain injury (ABI) in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) with granular arterial blood gas (ABG) data and institutional standardized neuromonitoring.

RESULTS

Eighty-nine patients underwent VV-ECMO (median age = 50, 63% male). Twenty (22%) patients experienced ABI; intracranial hemorrhage (ICH) was the most common diagnosis (n = 14, 16%). Lower post-cannulation PaO2 levels were significantly associated with ICH (66 vs. 81 mmHg, p = 0.007) and a post-cannulation PaO2 level < 70 mmHg was more frequent in these patients (71% vs. 33%, p = 0.007). PaCO2 parameters were not associated with ABI. By multivariable logistic regression, hypoxemia post-cannulation increased the odds of ICH (OR = 5.06, 95% CI:1.41-18.17; p = 0.01).

CONCLUSION

In summary, lower oxygen tension in the 24-h post-cannulation was associated with ICH development. The precise roles of peri-cannulation ABG changes deserve further investigation, as they may influence the management of VV-ECMO patients.

Trends in use and three-year outcomes of hepatitis C virus-viremic donor lung transplants for hepatitis C virus-seronegative recipients

OBJECTIVE

The feasibility and 6-month outcome safety of lung transplants (LTs) from hepatitis C virus (HCV)-viremic donors for HCV-seronegative recipients (R-) were established in 2019, but longer-term safety and uptake of this practice nationally remain unknown.

METHODS

We identified HCV-seronegative LT recipients (R-) 2015-2020 using the Scientific Registry of Transplant Recipients. We classified donors as seronegative (D-) or viremic (D+). We used χ2 testing, rank-sum testing, and Cox regression to compare posttransplant outcomes between HCV D+/R- and D-/R- LT recipients.

RESULTS

HCV D+/R- LT increased from 2 to 97/year; centers performing HCV D+/R- LT increased from 1 to 25. HCV D+/R- versus HCV D-/R- LT recipients had more obstructive disease (35.7% vs 23.3%, P < .001), lower lung allocation score (36.5 vs 41.1, P < .001), and longer waitlist time (P = .002). HCV D+/R- LT had similar risk of acute rejection (adjusted odds ratio [aOR], 0.87; P = .58), extracorporeal membranous oxygenation (aOR, 1.94; P = .10), and tracheostomy (aOR, 0.42; P = .16); similar median hospital stay (P = .07); and lower risk of ventilator > 48 hours (aOR, 0.68; P = .006). Adjusting for donor, recipient, and transplant characteristics, risk of all-cause graft failure and mortality were similar at 30 days, 1 year, and 3 years for HCV D+/R- versus HCV D-/R- LT (all P > .1), as well as for high- (≥20/year) versus low-volume LT centers and high- (≥5/year) versus low-volume HCV D+/R- LT centers (all P > .5).

CONCLUSIONS

HCV D+/R- and HCV D-/R- LT have similar outcomes at 3 years posttransplant. These results underscore the safety of HCV D+/R- LT and the potential benefit of expanding this practice further.

Management of Anticoagulation Therapy in ECMO-Associated Ischemic Stroke and Intracranial Hemorrhage

OBJECTIVE

Despite the common occurrence of extracorporeal membrane oxygenation (ECMO)-associated acute ischemic stroke (AIS) and intracranial hemorrhage (ICH), there are little data to guide optimal anticoagulation management. We sought to describe antithrombotic therapy management after stroke and outcomes.

METHODS

A retrospective analysis was conducted of venoarterial (VA) and venovenous (VV) ECMO patients treated at a tertiary care center from June 2016 to February 2021. Patients with image-confirmed diagnosis of AIS or ICH while receiving ECMO were included for study with data collected regarding anticoagulation management and clinical outcomes.

RESULTS

Overall, 216 patients (153 VA-ECMO, 63 VV-ECMO) were included in this study. Of the 153 patients on VA-ECMO, 13 (8.4%) had AIS and 6 (3.9%) had ICH. Of the 63 patients on VV-ECMO, none had AIS and 5 (7.9%) had ICH. One patient (9%) received anticoagulation reversal after ICH. Anticoagulation was discontinued and later resumed in all 5 ICH survivors (median cessation time, 30 h) and 1 of 2 (50%) AIS survivors (median cessation time, 96 h). While off anticoagulation, 2 of 11 patients (18%) had thromboembolic events and none had new AIS. Upon resumption, there were no cases of hemorrhagic transformation of AIS or ICH expansion. There was no difference in in-hospital mortality between patients with ICH and those without in both the VA-ECMO and VV-ECMO cohorts nor between VA-ECMO patients with AIS and those without.

CONCLUSIONS

Early cessation and judicious resumption of anticoagulation appeared feasible in the cohort of patients with ECMO-associated AIS and ICH.

Trends and three-year outcomes of hepatitis C virus-viremic donor heart transplant for hepatitis C virus-seronegative recipients

Objective

Heart transplants (HTs) from hepatitis C virus (HCV)-viremic donors to HCV-seronegative recipients (HCV D+/R-) have good 6-month outcomes, but practice uptake and long-term outcomes overall and among candidates on mechanical circulatory support (MCS) have yet to be established.

Methods

Using the Scientific Registry of Transplant Recipients, we identified US adult HCV-seronegative HT recipients (R-) from 2015 to 2021. We classified donors as HCV-seronegative (D-) or HCV-viremic (D+). We used multivariable regression to compare post-HT extracorporeal membranous oxygenation, dialysis, pacemaker, acute rejection, and risk of post-HT mortality between HCV D+/R- and HCV D-/R-. Models were adjusted for donor, recipient, and transplant characteristics and center HT volume. We performed subgroup analyses of recipients bridged with MCS.

Results

From 2015 to 2021, the number of HCV D+/R- HT increased from 1 to 181 and the number of centers performing HCV D+/R- HT increased from 1 to 60. Compared with HCV D-/R- recipients, HCV D+/R- versus D-/R- recipients overall and among patients bridged with MCS had similar odds of post-HT extracorporeal membranous oxygenation, dialysis, pacemaker, and acute rejection; and mortality risk at 30 days, 1 year, and 3 years (all P > .05). High center HT volume but not HCV D+/R- volume (<5 vs >5 in any year) was associated with lower mortality for HCV D+/R- HT.

Conclusions

HCV D+/R- and D-/R- HT have similar outcomes at 3 years' posttransplant. These results underscore the opportunity provided by HCV D+/R- HT, including among the growing population bridged with MCS, and the potential benefit of further expanding use of HCV+ allografts.

Lung Transplantation in Patients With COVID-19-The Early National Experience

Lung transplant (LT) has become a viable option for COVID-19 patients suffering from end-stage Acute Respiratory Distress Syndrome (ARDS). This analysis sought to describe the early national experience of COVID-19 patients who received LT and compare transplant characteristics and short-term outcomes of COVID-19 and non-COVID-19 ARDS LT recipients. We queried the Organ Procurement and Transplantation database for adults (≥18 years old) receiving LT from January 2009 to March 31, 2022 with diagnoses of COVID-19 or ARDS. We identified 353 COVID-19 and 64 non-COVID-19 ARDS LT recipients. COVID-19 recipients were older (median age: 51, interquartile range [40-57] years vs 41 [26-52]; P < 0.001), more predominantly male (78% (n = 274) vs 55% (n = 35), P < 0.001), and had higher body mass indices (median 27.2 interquartile range [24.5-30.9] vs 25.4 [22.1-28.6]; P < 0.01) than non-COVID-19 ARDS recipients. COVID-19 LT recipients were less frequently reliant on extra-corporeal membrane oxygenation at 72 hours after transplant (26% (n = 80) vs 31% (n = 15), P < 0.001), and were less frequently dependent on dialysis post-transplant than non-COVID-19 ARDS LT recipients (14% (n = 43) vs 23% (n = 14); P = 0.01). Survival at 90 days post-transplant was comparable for the non-COVID ARDS (90%, n = 54) and COVID-19 (94%, n = 202) LT recipients with available follow-up (P = 0.17). LT appears to be a viable therapy for COVID-19 patients with end-stage lung disease. COVID-19 LT and non-COVID-19 ARDS LT recipients have comparable 90 days post-transplant survival.

Ambient Air Pollution and Adverse Waitlist Events Among Lung Transplant Candidates

BACKGROUND

Air pollution is associated with cardiopulmonary disease and death in the general population. Fine particulate matter (PM2.5) is particularly harmful due to its ability to penetrate into areas of gas exchange within the lungs. Persons with advanced lung disease are believed to be particularly susceptible to PM2.5 exposure, but only a few studies have examined the effect of exposure on this population. Here we investigate the association between PM2.5 exposure and adverse waitlist events among lung transplant (LT) candidates.

METHODS

US registry data were used to identify LT candidates listed between January 1, 2010 and December 31, 2016. Annual PM2.5 concentration at year of listing was estimated for each candidate's ZIP Code using National Aeronautics and Space Administration's (NASA) Socioeconomic Data and Applications Center Global Annual PM2.5 Grids. We estimated crude and adjusted hazard ratios for adverse waitlist events, defined as death or removal, using Cox proportional hazards regression.

RESULTS

Of the 15 075 included candidates, median age at listing was 60, 43.8% were female individuals, and 81.7% were non-Hispanic White. Median ZIP Code PM2.5 concentration was 9.06 µg/m3. When compared with those living in ZIP Codes with lower PM2.5 exposure (PM2.5 <10.53 µg/m3), candidates in ZIP Codes in the highest quartile of PM2.5 exposure (≥10.53 µg/m3) had 1.14-fold (95% confidence interval, 1.04-1.25) risk of adverse waitlist events. The result remained significant after adjusting for demographics, education, insurance, smoking, lung allocation score, body mass index, and blood type (hazard ratio, 1.17; 95% confidence interval, 1.07-1.29).

CONCLUSIONS

Elevated ambient PM2.5 concentration was associated with adverse waitlist events among LT candidates. These findings highlight the impact of air pollution on clinical outcomes in this critically ill population.

Assessing the SAfety and FEasibility of bedside portable low-field brain Magnetic Resonance Imaging in patients on ECMO (SAFE-MRI ECMO study): study protocol and first case series experience

Background

To assess the safety and feasibility of imaging of the brain with a point-of-care (POC) magnetic resonance imaging (MRI) system in patients on extracorporeal membrane oxygenation (ECMO). Early detection of acute brain injury (ABI) is critical in improving survival for patients with ECMO support.

Methods

Patients from a single tertiary academic ECMO center who underwent head CT (HCT), followed by POC brain MRI examinations within 24 h following HCT while on ECMO. Primary outcomes were safety and feasibility, defined as completion of MRI examination without serious adverse events (SAEs). Secondary outcome was the quality of MR images in assessing ABIs.

Results

We report 3 consecutive adult patients (median age 47 years; 67% male) with veno-arterial (n = 1) and veno-venous ECMO (n = 2) (VA- and VV-ECMO) support. All patients were imaged successfully without SAEs. Times to complete POC brain MRI examinations were 34, 40, and 43 min. Two patients had ECMO suction events, resolved with fluid and repositioning. Two patients were found to have an unsuspected acute stroke, well visualized with MRI.

Conclusions

Adult patients with VA- or VV-ECMO support can be safely imaged with low-field POC brain MRI in the intensive care unit, allowing for the assessment of presence and timing of ABI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03990-6.

Neuromonitoring detects brain injury in patients receiving extracorporeal membrane oxygenation support

OBJECTIVE

There is limited evidence on standardized protocols for optimal neurological monitoring methods in patients receiving extracorporeal membrane oxygenation (ECMO). We previously introduced protocolized noninvasive multimodal neuromonitoring using serial neurological examinations, electroencephalography, transcranial Doppler ultrasound, and somatosensory evoked potentials. The purpose of this study was to examine if standardized neuromonitoring is associated with detection of acute brain injury (ABI) and improved patient outcomes.

METHODS

A retrospective analysis of ECMO patients who received neurocritical care consultation was performed and outcomes were reviewed. The cohort was stratified according to those who did not receive standardized neuromonitoring (era 1: 2016-2017) and those who received standardized neuromonitoring (era 2: 2017-2020). Multivariable logistic regression was used to evaluate the association between standardized neuromonitoring and ABI.

RESULTS

A total of 215 patients (mean age, 54 years; 60% male) underwent ECMO (71% venoarterial-ECMO) in our institution, 70 in era 1 and 145 in era 2. The proportion of patients diagnosed with ABI were 23% in era 1 and 33% in era 2 (P = .12). In multivariable logistic regression, standardized neuromonitoring (odds ratio, 2.24; 95% CI, 1.12-4.48; P = .02) and pre-ECMO cardiac arrest (odds ratio, 2.17; 95% CI, 1.14-4.14; P = .02) were independently associated with ABI. There was a greater proportion of patients with good neurological outcomes when discharged alive in era 2 (54% vs 30%; P = .04).

CONCLUSIONS

Standardized neuromonitoring was associated with increased ABIs in ECMO patients. Although neuromonitoring does not prevent ABI from occurring, it might prevent worsening with timely interventions (eg, anticoagulation management, optimizing oxygen delivery and blood pressure), leading to improved neurological outcomes at discharge.

Neurological Complications in COVID-19 Patients With ECMO Support: A Systematic Review and Meta-Analysis

Background

Patients with Coronavirus disease 2019 (COVID-19)-related acute respiratory disease (ARDS) increasingly receive extracorporeal membrane oxygenation (ECMO) support. While ECMO has been shown to increase risk of stroke, few studies have examined this association in COVID-19 patients.

Objective

We conducted a systematic review to characterise neurological events during ECMO support in COVID-19 patients.

Design

Systematic review of cohort and large case series of COVID-19 patients who received ECMO support.

Data Sources

Studies retrieved from PubMed, EMBASE, Cochrane, Cochrane COVID-19 Study Register, Web of Science, Scopus, Clinicaltrials.gov, and medRχiv from inception to November 11, 2020.

Eligibility Criteria

Inclusion criteria were a) Adult population (>18 year old); b) Positive PCR test for SARS-CoV-2 with active COVID-19 disease; c) ECMO therapy due to COVID-19 ARDS; and d) Neurological events and outcome described while on ECMO support. We excluded articles when no details of neurologic events were available.

Results

1,322 patients from 12 case series and retrospective cohort studies were included in our study. The median age was 49.2, and 75% (n=985) of the patients were male. Diabetes mellitus and dyslipidaemia were the most common comorbidities (24% and 20%, respectively). Most (95%, n=1,241) patients were on venovenous ECMO with a median P:F ratio at the time of ECMO cannulation of 69.1. The prevalence of intracranial haemorrhage (ICH), ischaemic stroke, and hypoxic ischaemic brain injury (HIBI) was 5.9% (n=78), 1.1% (n=15), and 0.3% (n=4), respectively. The overall mortality of the 1,296 ECMO patients in the 10 studies that reported death was 36% (n=477), and the mortality of the subset of patients who had a neurological event was 92%.

Conclusions

Neurological injury is a concern for COVID-19 patients who receive ECMO. Further research is required to explore how neuromonitoring protocols can inform tailored anticoagulation management and improve survival in COVID-19 patients with ECMO support.

ISHLT consensus document on lung transplantation in patients with connective tissue disease: Part II: Cardiac, surgical, perioperative, operative, and post-operative challenges and management statements

Patients with connective tissue disease (CTD) present unique surgical, perioperative, operative, and postoperative challenges related to the often underlying severe pulmonary hypertension and right ventricular dysfunction. The International Society for Heart and Lung Transplantation-supported consensus document on lung transplantation in patients with CTD standardization addresses the surgical challenges and relevant cardiac involvement in the perioperative, operative, and postoperative management in patients with CTD.

SARS-CoV-2 messenger RNA vaccine antibody response and reactogenicity in heart and lung transplant recipients

Background

While several studies have observed that solid organ transplant recipients experience diminished antibody responses to SARS-CoV-2 mRNA vaccination, data specific to heart and lung transplant (HT/LT) recipients remains sparse.

Methods

US adult HT and LT recipients completed their vaccine series between January 7 and April 10, 2021. Reactogencity and SARS-CoV-2 anti-spike antibody were assessed after a priming dose (D1) and booster dose (D2). Modified Poisson regression with robust variance estimator was used to evaluate associations between participant characteristics and antibody development.

Results

Of 134 heart recipients, there were 38% non-responders (D1-/D2-), 48% booster responders (D1-/D2+), and 14% priming dose responders (D1+/D2+). Of 103 lung recipients, 64% were non-responders, 27% were booster responders, and 9% were priming dose responders. Lung recipients were less likely to develop antibodies (p < .001). Priming dose antibody response was associated with younger recipient age (p = .04), transplant-to-vaccination time ≥6 years (p < .01), and lack of anti-metabolite maintenance immunosuppression (p < .001). Pain at injection site was the most commonly reported reaction (85% after D1, 76% after D2). Serious reactions were rare, the most common being fatigue (2% after D1 and 3% after D2). No serious adverse events were reported.

Conclusions

HT and LT recipients experienced diminished antibody response following vaccination; reactogenicity was comparable to that of the general population. LT recipients may exhibit a more impaired antibody response than HT recipients. While current recommendations are to vaccinate eligible candidates and recipients, further studies characterizing the cell-mediated immune response and clinical efficacy of these vaccines in this population are needed.

Palliative care in lung transplantation

The role of palliative care in lung transplantation has grown exponentially in the past two decades. From assisting with evaluating and optimizing candidates for transplant, to playing a crucial role in patients requiring extracorporeal cardiopulmonary life support (ECLS) as a bridge to lung transplant, perioperatively, or even during their first year post-transplant, palliative care has been shown to be an effective if underutilized tool in the armamentarium used to care for lung transplant patients. For patients being considered for primary transplantation and for lung transplant recipients, palliative care can decrease symptom burden and help to lessen the psychological distress experienced by patients and family members. For older patients listed for transplant, palliative care can help address cognitive impairment, depression, and frailty. Patients listed for lung re-transplant also benefit from palliative care involvement to address frequent symptom exacerbations, hospitalizations, and higher morbidity and mortality. Even for organ donors and their families, palliative care can facilitate communication and provide support to the family. While palliative care use in lung transplantation may be gradually increasing, further work is necessary to optimally integrate palliative care into lung transplantation. Barriers to lung transplant patients receiving palliative care are multifactorial and include physician, patient, and institutional factors. The potential role of palliative care in every aspect of lung transplantation has made a knowledge of palliative care principles crucial for the lung transplant practitioner. In this review, we will clearly delineate the potential benefit of palliative care for the perioperative lung transplant patient and make an argument for its increased use in this patient population.

Lung Volume Reduction Surgery Before Lung Transplantation: A Propensity-Matched Analysis

BACKGROUND

Lung volume reduction surgery (LVRS) is treatment option for chronic obstructive pulmonary disease, the second most common indication for lung transplantation (LTx) in the United States. Lung volume reduction surgery before LTx is controversial. Single-institution studies report contradicting results, and the impact of undergoing LVRS before LTx on outcomes after LTx is unclear.

METHODS

We reviewed the United Network for Organ Sharing database for all adults (aged more than 18 years) who underwent first-time LTx for chronic obstructive pulmonary disease in the lung allocation score era. We used patient demographic and clinical characteristics and lung allocation score to propensity match patients who did and patients who did not undergo LVRS before LTx. The primary exposure was prior LVRS. The primary outcome was graft failure after LTx. Unadjusted Kaplan-Meier and adjusted Cox proportional hazards models were used to assess outcomes.

RESULTS

A total of 4905 patients with chronic obstructive pulmonary disease underwent LTx between May 2005 and March 2017. Of them, 107 patients (2.2%) underwent LVRS before LTx. Propensity matching generated 212 matches (106 LVRS+LTx, and 106 LTx only). Median survival was significantly longer in the LTx only cohort (6.5 vs 3.4 years, P = .034). Lung volume reduction surgery before lung transplantation was associated with significantly increased risk of graft failure after lung transplant (hazard ratio 1.72; 95% confidence interval, 1.13 to 2.60; P = .01).

CONCLUSIONS

In this national, propensity-matched analysis of LVRS before LTx, we show that LVRS is associated with a significantly increased risk of graft failure. Patients who undergo LVRS and remain in need of LTx should be carefully assessed and followed postoperatively.

Better Understanding the Disparity Associated With Black Race in Heart Transplant Outcomes: A National Registry Analysis

BACKGROUND

Black heart transplant recipients have higher risk of mortality than White recipients. Better understanding of this disparity, including subgroups most affected and timing of the highest risk, is necessary to improve care of Black recipients. We hypothesize that this disparity may be most pronounced among young recipients, as barriers to care like socioeconomic factors may be particularly salient in a younger population and lead to higher early risk of mortality.

METHODS

We studied 22 997 adult heart transplant recipients using the Scientific Registry of Transplant Recipients data from January 2005 to 2017 using Cox regression models adjusted for recipient, donor, and transplant characteristics.

RESULTS

Among recipients aged 18 to 30 years, Black recipients had 2.05-fold (95% CI, 1.67-2.51) higher risk of mortality compared with non-Black recipients (P<0.001, interaction P<0.001); however, the risk was significant only in the first year post-transplant (first year: adjusted hazard ratio, 2.30 [95% CI, 1.60-3.31], P<0.001; after first year: adjusted hazard ratio, 0.84 [95% CI, 0.54-1.29]; P=0.4). This association was attenuated among recipients aged 31 to 40 and 41 to 60 years, in whom Black recipients had 1.53-fold ([95% CI, 1.25-1.89] P<0.001) and 1.20-fold ([95% CI, 1.09-1.33] P<0.001) higher risk of mortality. Among recipients aged 61 to 80 years, no significant association was seen with Black race (adjusted hazard ratio, 1.12 [95% CI, 0.97-1.29]; P=0.1).

CONCLUSIONS

Young Black recipients have a high risk of mortality in the first year after heart transplant, which has been masked in decades of research looking at disparities in aggregate. To reduce overall racial disparities, clinical research moving forward should focus on targeted interventions for young Black recipients during this period.

Association of severe lymphopenia and disease progression in unresectable locally advanced non-small cell lung cancer treated with definitive chemoradiation and immunotherapy

BACKGROUND

Definitive chemoradiation with consolidative immunotherapy offers the best chance for cure in patients with unresectable, locally advanced non-small cell lung cancer (NSCLC). However, treatment-related lymphopenia (TRL) may negatively impact outcomes.

METHODS

Patients definitively treated with chemoradiation and immunotherapy from 2015 to 2019 at a single tertiary academic center were identified. Severe lymphopenia was defined as <0.5 × 10⁹ cells/L. Progression-free survival (PFS) was calculated by Kaplan Meier methodology. Univariate and multivariate Cox Proportional Hazard modeling was used to correlate clinical variables with disease outcome. Immune-related adverse events (irAEs) were assessed according to CTCAE version 5.0 criteria.

RESULTS

Seventy-eight patients were included in the final cohort. The median age was 66 years (IQR: 58-73), 55 % were males, and 88 % had a KPS of >70. At baseline, 90 % (n = 70/78) of patients had a normal ALC and one patient had severe lymphopenia. After chemoradiation, the median ALC decreased from 1.52 × 10⁹cells/L (IQR: 1.23-1.98) to 0.72 × 10⁹cells/L (IQR: 0.52-0.94) (p < 0.001), 22 % (n = 17/78) of patients had a normal ALC, and 23 % (n = 18/78) of patients developed severe lymphopenia. Patients who initiated consolidative immunotherapy with severe lymphopenia had worse PFS than those who did not (median 217 days [IQR: 120-434] vs. 570 days [IQR: 401-NR], p < 0.001). On multivariate modeling, severe lymphopenia at the time of immunotherapy initiation remained an independent predictor of worse PFS (HR 4.90, p < 0.001).

CONCLUSIONS

This is the first report to associate severe TRL with disease progression in patients with locally advanced NSCLC receiving consolidative immunotherapy. Factors associated with development of lymphopenia and strategies to mitigate lymphopenic effects should be considered.

Acute Brain Injury in Postcardiotomy Shock Treated With Venoarterial Extracorporeal Membrane Oxygenation

OBJECTIVE

Acute brain injury (ABI) is common in venoarterial extracorporeal membrane oxygenation (VA-ECMO). One of the most common indications for use of VA-ECMO is postcardiotomy shock (PCS). The authors aimed to characterize the prevalence of ABI and its association with outcomes in this population.

DESIGN

prospective observational.

SETTING

Single-center tertiary care university hospital.

PARTICIPANTS

Fifty-two consecutive patients treated for PCS with VA-ECMO from November 2017 to March 2020.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The median age of patients was 64 (interquartile range 44-84), 62% were male. Of 52 PCS patients treated with extracorporeal membrane oxygenation, 38% (n = 20) experienced acute brain injury. Ischemic stroke was the most common (n = 13, 25%). Patients with central versus peripheral cannulation experienced more ischemic and hemorrhagic strokes (8% v 38%, p = 0.04). Patients with intracardiac thrombus experienced more brain injury (n = 4, 8% p = 0.02). The in-hospital mortality in patients with brain injury was 90% (n = 18/20) compared to 78% (n = 25/32) in patients without brain injury.

CONCLUSIONS

ABI is common in postcardiotomy VA-ECMO and associated with worse outcome. Patients with central recanalization experienced the majority of acute strokes. Intracardiac thrombus was significantly associated with acute brain injury.

CD3+CD4-CD8- Double-negative αβ T cells attenuate lung ischemia-reperfusion injury

OBJECTIVE

Lung ischemia-reperfusion injury (IRI) is a common complication after lung transplantation, and immune cells have been implicated in modulating outcomes. We hypothesized that a newly described subset of αβ T-cell receptor positive cells; that is, CD4-CD8- (double negative [DN]) T cells, are found in lungs and can protect against lung IRI.

METHODS

Ischemia was induced in C57BL/6 mice by left pulmonary artery and vein occlusion for 30 minutes followed by 180 minutes of reperfusion. These mice were paired with sham hilar dissected surgical controls. In mice undergoing IRI, adoptive transfer of DN T cells or conventional T cells was performed 12 hours before occlusion. Flow cytometry was used to quantify T cells and inflammatory cytokines, and apoptotic signaling pathways were evaluated with immunoblotting. Lung injury was assessed with Evans blue dye extravasation.

RESULTS

DN T cells were significantly higher (5.29% ± 1% vs 2.21% ± 3%; P < .01) in IRI lungs and secreted higher levels of interleukin-10 (30% ± 5% vs 6% ± 1%; P < .01) compared with surgical sham controls. Immunoblotting, hematoxylin and eosin staining and Evans blue dye demonstrated that adoptive transfer of DN T cells significantly decreased interstitial edema (P < .01) and attenuated apoptosis/cleaved caspase-3 expression in the lungs following lung IRI (P < .01).

CONCLUSIONS

DN T cells traffic into lungs during IRI, and have tissue protective functions regulating inflammation and apoptosis. We propose a potential novel immunoregulatory function of DN T cells during lung IRI.

Risk Factors of Ischemic and Hemorrhagic Strokes During Venovenous Extracorporeal Membrane Oxygenation: Analysis of Data From the Extracorporeal Life Support Organization Registry

OBJECTIVES

Stroke is commonly reported in patients receiving venovenous extracorporeal membrane oxygenation, but risk factors are not well described. We sought to determine preextracorporeal membrane oxygenation and on-extracorporeal membrane oxygenation risk factors for both ischemic and hemorrhagic strokes in patients with venovenous extracorporeal membrane oxygenation support.

DESIGN

Retrospective analysis.

SETTING

Data reported to the Extracorporeal Life Support Organization by 366 extracorporeal membrane oxygenation centers from 2013 to 2019.

PATIENTS

Patients older than 18 years supported with a single run of venovenous extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 15,872 venovenous extracorporeal membrane oxygenation patients, 812 (5.1%) had at least one type of acute brain injury, defined as ischemic stroke, hemorrhagic stroke, or brain death. Overall, 215 (1.4%) experienced ischemic stroke and 484 (3.1%) experienced hemorrhagic stroke. Overall inhospital mortality was 36%, but rates were higher in those with ischemic or hemorrhagic stroke (68% and 73%, respectively). In multivariable analysis, preextracorporeal membrane oxygenation pH (adjusted odds ratio = 0.10; 95% CI, 0.03-0.35; p < 0.001), hemolysis (adjusted odds ratio = 2.27; 95% CI, 1.22-4.24; p = 0.010), gastrointestinal hemorrhage (adjusted odds ratio = 2.01; 95% CI 1.12-3.59; p = 0.019), and disseminated intravascular coagulation (adjusted odds ratio = 3.61; 95% CI, 1.51-8.66; p = 0.004) were independently associated with ischemic stroke. Pre-extracorporeal membrane oxygenation pH (adjusted odds ratio = 0.28; 95% CI, 0.12-0.65; p = 0.003), preextracorporeal membrane oxygenation Po2 (adjusted odds ratio = 0.96; 95% CI, 0.93-0.99; p = 0.021), gastrointestinal hemorrhage (adjusted odds ratio = 1.70; 95% CI, 1.15-2.51; p = 0.008), and renal replacement therapy (adjusted odds ratio=1.57; 95% CI, 1.22-2.02; p < 0.001) were independently associated with hemorrhagic stroke.

CONCLUSIONS

Among venovenous extracorporeal membrane oxygenation patients in the Extracorporeal Life Support Organization registry, approximately 5% had acute brain injury. Mortality rates increased two-fold when ischemic or hemorrhagic strokes occurred. Risk factors such as lower pH and hypoxemia during the pericannulation period and markers of coagulation disturbances were associated with acute brain injury. Further research on understanding preextracorporeal membrane oxygenation and on-extracorporeal membrane oxygenation risk factors and the timing of acute brain injury is necessary to develop appropriate prevention and management strategies.

Elevated neutrophil to lymphocyte ratio is associated with poor long-term survival and graft failure after lung transplantation

PURPOSE

We aimed to assess the prognostic value of Neutrophil to Lymphocyte Ratio (NLR) on long-term outcomes and graft dysfunction after lung transplantation.

METHODS

We retrospectively reviewed all patients receiving a lung transplant at our institution from 2011 to 2014. The primary exposure was elevated NLR at the time of transplant, defined by NLR>4. The primary outcomes were graft failure and three-year all-cause mortality. Multivariate logistic regression and Kaplan-Meier survival analysis were used to analyze outcomes.

RESULTS

95 patients were included. 40 patients (42%) had an elevated NLR. Elevated NLR was associated with graft failure (OR: 4.7 [1.2-18.8], p = 0.02), and three-year mortality (OR: 5.4 [1.3-23.2], p = 0.03) on multivariate logistic regression. Patients with elevated NLR demonstrated significantly lower survival on Kaplan-Meier analysis (50% versus 74%, p = 0.02). The c-statistic for our multivariate model was 0.91.

CONCLUSION

Elevated neutrophil to lymphocyte ratio is associated with poor long-term survival and graft failure after lung transplantation.

TCR+CD4-CD8- (double negative) T cells protect from cisplatin-induced renal epithelial cell apoptosis and acute kidney injury

Acute kidney injury (AKI) due to cisplatin is a significant problem that limits its use as an effective chemotherapeutic agent. T cell receptor⁺CD4^-CD8^- double negative (DN) T cells constitute the major T cell population in the human and mouse kidney, express programmed cell death protein (PD)-1, and protect from ischemic AKI. However, the pathophysiological roles of DN T cells in cisplatin-induced AKI is unknown. In this study, wild-type mice were treated with cisplatin (30 mg/kg) or vehicle, and the effects on kidney DN T cell numbers and function were measured. In vitro experiments evaluated effects of kidney DN T cells on cisplatin-induced apoptosis and PD ligand 1 (PD-L1) in renal epithelial cells. Adoptive transfer experiments assessed the therapeutic potential of DN T cells during cisplatin-induced AKI. Our results show that kidney DN T cell population increased at 24 h and declined by 72 h after cisplatin treatment. Cisplatin treatment increased kidney DN T cell proliferation, apoptosis, CD69, and IL-10 expression, whereas CD62L, CD44, IL-17A, interferon-γ, and TNF-α were downregulated. Cisplatin treatment decreased both PD-1 and natural killer 1.1 subsets of kidney DN T cells with a pronounced effect on the PD-1 subset. In vitro kidney DN T cell coculture decreased cisplatin-induced apoptosis in kidney proximal tubular epithelial cells, increased Bcl-2, and decreased cleaved caspase 3 expression. Cisplatin-induced expression of PD ligand 1 was reduced in proximal tubular epithelial cells cocultured with DN T cells. Adoptive transfer of DN T cells attenuated kidney dysfunction and structural damage from cisplatin-induced AKI. These results demonstrate that kidney DN T cells respond rapidly and play a protective role during cisplatin-induced AKI.

Epigenetic therapy inhibits metastases by disrupting premetastatic niches

Cancer recurrence after surgery remains an unresolved clinical problem^1-3. Myeloid cells derived from bone marrow contribute to the formation of the premetastatic microenvironment, which is required for disseminating tumour cells to engraft distant sites^4-6. There are currently no effective interventions that prevent the formation of the premetastatic microenvironment^6,7. Here we show that, after surgical removal of primary lung, breast and oesophageal cancers, low-dose adjuvant epigenetic therapy disrupts the premetastatic microenvironment and inhibits both the formation and growth of lung metastases through its selective effect on myeloid-derived suppressor cells (MDSCs). In mouse models of pulmonary metastases, MDSCs are key factors in the formation of the premetastatic microenvironment after resection of primary tumours. Adjuvant epigenetic therapy that uses low-dose DNA methyltransferase and histone deacetylase inhibitors, 5-azacytidine and entinostat, disrupts the premetastatic niche by inhibiting the trafficking of MDSCs through the downregulation of CCR2 and CXCR2, and by promoting MDSC differentiation into a more-interstitial macrophage-like phenotype. A decreased accumulation of MDSCs in the premetastatic lung produces longer periods of disease-free survival and increased overall survival, compared with chemotherapy. Our data demonstrate that, even after removal of the primary tumour, MDSCs contribute to the development of premetastatic niches and settlement of residual tumour cells. A combination of low-dose adjuvant epigenetic modifiers that disrupts this premetastatic microenvironment and inhibits metastases may permit an adjuvant approach to cancer therapy.

Size Mismatching Increases Mortality After Lung Transplantation in Preadolescent Patients

BACKGROUND

The effect of size mismatch between donor and recipient in pediatric lung transplantation (PLTx) is currently unknown. Previous studies in adults have suggested that oversized allografts are associated with improved outcomes after lung transplantation. We investigated this relationship to quantify its effect on posttransplant outcomes in children.

METHODS

The United Network of Organ Sharing database was queried for preadolescent (age <13 years) patients undergoing PLTx. Donor-to-recipient height, weight, and predictive total lung capacity (pTLC; ages 4 to 13; pTLC = 0.160 x exp[0.021 x height]) ratios were calculated. Exploratory analysis was performed to identify disjoint intervals at which survival was statistically different. Patients were categorized as well-matched, undersized, or oversized. Multivariate Cox proportional hazard regression modeling assessed the adjusted effect of mismatching on mortality. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

The analysis included 540 children. One-year mortality was higher with a height mismatch of 5% or less (hazard ratio [HR], 2.97; p = 0.001) and above 5% (HR, 2.22; p = 0.009). Similarly, 1-year mortality was worse with weight mismatch of 10% or less (HR, 1.99; p = 0.035) and above 10% (HR, 2.04; p = 0.028). On unadjusted analysis, a pTLC ratio of less than 0.9 was associated with worse survival (p = 0.017). This finding persisted after multivariate risk adjustment (HR, 2.93; p = 0.02). Contrary to findings in adults, an oversized allograft (pTLC ratio > 1.1) was not associated with improved survival (HR, 1.95; p = 0.147).

CONCLUSIONS

In preadolescent children undergoing PLTx, size mismatching is associated with increased death. Our findings differ from studies in adults, which demonstrated improved survival associated with oversized allografts. Accordingly, well-matched allografts should be prioritized when assessing donor-recipient pairs for transplantation.

Sarcopenia of the Psoas Muscles Is Associated With Poor Outcomes Following Lung Transplantation

BACKGROUND

Sarcopenia, a known component of frailty, defined by diminished cross-sectional area of the psoas muscles, is associated with poor outcomes after a range of surgical procedures. However, little is known of the relationship between sarcopenia of the psoas muscles (SPM) and long-term survival, decline in pulmonary function, and graft failure after lung transplantation.

METHODS

We reviewed patients who underwent primary lung transplantation at our institution from 2011 to 2014. Cross-sectional areas of the psoas muscles at the L4 vertebral level were measured using preoperative computed tomography. Gender-based cutoff values for sarcopenia were generated and validated. The primary outcomes were 1-, 2-, and 3-year all-cause mortality, forced expiratory volume in 1 second values, and graft function. Adjusted logistic regression and survival analysis was used to analyze outcomes.

RESULTS

Ninety-five patients were included in this study; 39 (41.1%) patients were considered sarcopenic. SPM was significantly associated with short-term and midterm mortality on multivariate analysis (1 year: odds ratio [OR], 8.7, p = 0.017; 2 years: OR, 12.7, p < 0.01; 3 years: OR, 13.4, p < 0.01). Survival analysis showed significantly decreased survival in sarcopenic patients at 3 years (35.9% versus 76.8%; p < 0.01). SPM is also associated with decreased forced expiratory volume in 1 second (coefficient, -17.3; p = 0.03). Adjusted Cox analysis showed an increased hazard for all-cause mortality (hazard ratio, 5.8, p < 0.01) and graft failure (hazard ratio, 14.7, p < 0.01) in sarcopenic patients.

CONCLUSIONS

This study demonstrates a significant association between SPM and death, pulmonary function, and graft failure in patients receiving a lung transplant. Determining SPM preoperatively may be a useful component of frailty assessment and a predictor of survival in this patient population.

Distant Organ Dysfunction in Acute Kidney Injury: A Review

Acute kidney injury (AKI) is common in critically ill patients and is associated with increased morbidity and mortality. Dysfunction of other organs is an important cause of poor outcomes from AKI. Ample clinical and epidemiologic data show that AKI is associated with distant organ dysfunction in lung, heart, brain, and liver. Recent advancements in basic and clinical research have demonstrated physiologic and molecular mechanisms of distant organ interactions in AKI, including leukocyte activation and infiltration, generation of soluble factors such as inflammatory cytokines/chemokines, and endothelial injury. Oxidative stress and production of reactive oxygen species, as well as dysregulation of cell death in distant organs, are also important mechanism of AKI-induced distant organ dysfunction. This review updates recent clinical and experimental findings on organ crosstalk in AKI and highlights potential molecular mechanisms and therapeutic targets to improve clinical outcomes during AKI.