Review of Extracorporeal Membrane Oxygenation and Dialysis-Based Liver Support Devices for the Use of Nephrologists

Bridge to simultaneous heart-kidney transplantation via extracorporeal life support: National outcomes in the new heart allocation policy era

BACKGROUND

Since United Network for Organ Sharing (UNOS) revised their heart allocation policy in 2018, usage of veno-arterial extracorporeal life support (VA-ECLS) has dramatically increased as a bridge to transplant. This study investigated outcomes of VA-ECLS patients bridged to simultaneous heart-kidney transplant (SHK) in the new policy era.

METHODS

This study included 774 adult patients from the UNOS database who received SHK between 10/18/18 and 12/31/21 and compared patients bridged to transplant on VA-ECLS (n = 50) with those not bridged (n = 724).

RESULTS

At baseline, SHK recipients bridged from VA-ECLS were younger (50.5 vs 58.0 years, p = 0.007), had higher estimated glomerular filtration rate (eGFR) at time of transplant (47.6 vs 30.1, p < 0.001), and spent fewer days on the waitlist (7.0 vs 33.5 days, p < 0.001). In the perioperative period, VA-ECLS was associated with higher rates of temporary dialysis (56.0% vs 28.0%, p < 0.001) but similar 2-year cumulative incidence of chronic dialysis (7.5% vs 5.4%, p = 0.800) and renal allograft failure (12.0% vs 8.1%, p = 0.500) compared to non-ECLS cohort. However, VA-ECLS patients had decreased survival to discharge (76.0% vs 92.7%, p < 0.001) and 2-year post-transplant survival (71.7% vs 83.0%, p = 0.004), as well as greater 2-year cumulative incidence of cardiac allograft failure (10.0% vs 2.7%, p = 0.002). Multivariable analyses found VA-ECLS at time of transplant to be independently associated with 2-year post-transplant mortality (HR [95% CI]: 3.40 [1.66-6.96], p = 0.001) and cardiac allograft failure (sub-distribution hazard ratio [SHR] [95% CI]: 8.51 [2.77-26.09], p < 0.001).

CONCLUSION

Under the new allocation policy, patients bridged to SHK from VA-ECLS displayed greater early mortality and cardiac allograft failure but similar renal outcomes compared to non-ECLS counterparts.

Decreased survival of simultaneous heart-kidney transplant recipients in the new heart allocation era

BACKGROUND

In 2018, the United Network for Organ Sharing (UNOS) modified their heart allocation policy to reduce waitlist mortality. The rates of simultaneous heart-kidney transplant (SHKT) have dramatically increased in recent years, despite increased rates of posttransplant renal failure in the new policy era. This study sought to investigate the impact of the new allocation system on waitlist and posttransplant outcomes of simultaneous heart-kidney transplantation.

METHODS

Adult patients listed for SHKT between 2012 and 2021 were included. Patients were cross-validated across both Thoracic and Kidney UNOS databases to confirm accurate listing and transplant data. Patients were stratified according to listing era. The Fine and Gray model was used to assess waitlist outcomes and posttransplant renal graft function. Kaplan-Meier analysis and Cox regression were used to compare posttransplant survival.

RESULTS

A total of 2,588 patients were included, of whom 1,406 (54.1%) were listed between 2012 and 2018 (era 1) and 1,182 (45.9%) between 2019 and 2021 (era 2). Era 2 was associated with increased likelihood of transplant (adjusted Sub-hazard ratios (aSHR): 1.52; p < 0.01) and decreased waitlist mortality (aSHR: 0.63; p < 0.01). Posttransplant survival at 2 years was decreased in era 2 (78.8% vs 86.9%; p < 0.01). Undersized hearts (hazard ratio [HR]: 2.02; p < 0.01), use of extracorporeal membrane oxygenation (HR: 2.67; p < 0.1), and transplants performed following the policy change (HR: 1.45; p = 0.03) were associated with increased mortality. Actuarial survival (combined waitlist and posttransplant) was significantly lower in the modern era (71.6% vs 62.2%; p = 0.02).

CONCLUSIONS

The allocation policy change has improved waitlist outcomes in patients listed for SHKT but potentially at the cost of worsened posttransplant outcomes.

Fluid Management in Veno-Arterial Extracorporeal Membrane Oxygenation Therapy-Analysis of an Experimental Pig Model

(1) Background: Fluid resuscitation is a necessary part of therapeutic measures to maintain sufficient hemodynamics in extracorporeal membrane oxygenation (ECMO) circulation. In a post-hoc analysis, we aimed to investigate the impact of increased volume therapy in veno-arterial ECMO circulation on renal function and organ edema in a large animal model. (2) Methods: ECMO therapy was performed in 12 female pigs (Deutsche Landrasse × Pietrain) for 10 h with subsequent euthanasia. Applicable volume, in regard to the necessary maintenance of hemodynamics, was divided into moderate and extensive volume therapy (MVT/EVT) due to the double quantity of calculated physiologic urine output for the planned study period. Respiratory and hemodynamic data were measured continuously. Additionally, renal function and organ edema were assessed by blood and tissue samples. (3) Results: Four pigs received MVT, and eight pigs received EVT. After 10 h of ECMO circulation, no major differences were seen between the groups in regard to hemodynamic and respiratory data. The relative change in creatinine after 10 h of ECMO support was significantly higher in EVT (1.3 ± 0.3 MVT vs. 1.8 ± 0.5 EVT; p = 0.033). No major differences were evident for lung, heart, liver, and kidney samples in regard to organ edema in comparison of EVT and MVT. Bowel tissue showed a higher percentage of edema in EVT compared to MVT (77 ± 2% MVT vs. 80 ± 3% EVT; p = 0.049). (4) Conclusions: The presented data suggest potential deterioration of renal function and intestinal mucosa function by an increase in tissue edema due to volume overload in ECMO therapy.

Predictors of acute kidney injury in patients after extracorporeal cardiopulmonary resuscitation

OBJECTIVES

Extracorporeal cardiopulmonary resuscitation (eCPR) is increasingly used due to its beneficial outcomes and results compared with conventional CPR. Data after eCPR for acute kidney injury (AKI) are lacking. We sought to investigate factors predicting AKI in patients who underwent eCPR.

METHODS

From January 2016 until December 2020, patients who underwent eCPR at our institution were retrospectively analyzed and divided into two groups: patients who developed AKI (n = 60) and patients who did not develop AKI (n = 35) and analyzed for outcome parameters.

RESULTS

Overall, 63% of patients suffered AKI after eCPR and 45% of patients who developed AKI needed subsequent dialysis. Patients who developed AKI showed higher values of creatinine (1.1 mg/dL vs 1.5 mg/dL, p ⩽ 0.01), urea (34 mg/dL vs 42 mg/dL, p = 0.04), CK (creatine kinase) (923 U/L vs 1707 U/L, p = 0.07) on admission, and CK after 24 hours of ECMO support (1705 U/L vs 4430 U/L, p = 0.01). ECMO explantation was significantly more often performed in patients who suffered AKI (24% vs 48%, p = 0.01). In-hospital mortality (86% vs 70%; p = 0.07) did not differ significantly.

CONCLUSION

Patients after eCPR are at high risk for AKI, comparable to those after conventional CPR. Baseline urea levels predict the development of AKI during the hospital stay.

Higher Rates of Dialysis and Subsequent Mortality in the New Allocation Era for Heart Transplants

BACKGROUND

In 2018, a United Network for Organ Sharing (UNOS) policy change increased prioritization of patients bridged with temporary mechanical circulatory support devices, such as venoarterial ECMO, for cardiac transplantation. Considering increased waitlist acuity, we sought to characterize whether this was associated with an increased risk for development of postoperative acute renal failure requiring dialysis (AKI-D) and risk of death after transplantation.

METHODS

Dialysis-naive adults receiving single-organ heart transplant between November 2009 and February 2020 were stratified by receipt of AKI-D. Era 1 and era 2 were defined by the periods of UNOS allocation before and after policy change, respectively. Multivariable logistic regression was performed to determine risk factors for AKI-D. Rates of AKI-D were compared by propensity score-matched cohorts. Survival was compared by Kaplan-Meier analysis.

RESULTS

A total of 20 698 patients were included. Venoarterial ECMO use significantly increased in era 2 (5.6% vs 0.58%; P < .01). Overall prevalence of AKI-D was greater in era 2 (13.5% vs 10.2%; P < .01). Use of preoperative ECMO, intra-aortic balloon pump, and ventilators and longer ischemia times were identified as independent risk factors for development of AKI-D. Five- and 10-year survival rates were significantly decreased for patients with AKI-D. There was no short-term survival difference of patients with AKI-D between era 2 and the more contemporary era 1.

CONCLUSIONS

Patients in whom AKI-D develops after transplantation have significantly worse short- and long-term outcomes. Preoperative use of ECMO, preoperative ventilator support, and longer ischemia times are risk factors for development of AKI-D, and their prevalence has increased since the allocation policy change.

Initial Experiences of Extracorporeal Membrane Oxygenation for Trauma Patients at a Single Regional Trauma Center in South Korea

Purpose For severe lung injuries or acute respiratory distress syndrome that occurs during critical care due to trauma, extracorporeal membrane oxygenation (ECMO) may be used as a salvage treatment. This study aimed to describe the experiences at a single center with the use of ECMO in trauma patients. Methods We enrolled a total of 25 trauma patients who were treated with ECMO between January 2015 and December 2019 at a regional trauma center. We analyzed and compared patients’ characteristics between survivors and non-survivors through a medical chart review. We also compared the characteristics of patients between direct and indirect lung injury groups. Results The mean age of the 25 patients was 45.9±19.5 years, and 19 patients (76.0%) were male. The mean Injury Severity Score was 26.1±10.1. Ten patients (40.0%) had an Abbreviated Injury Scale (AIS) 3 score of 4, and six patients (24.0%) had an AIS 3 score of 5. There were 19 cases (76.6%) of direct lung injury. The mortality rate was 60.0% (n=15). Sixteen patients (64.0%) received a loading dose of heparin for the initiation of ECMO. There was no significant difference in heparin use between the survivors and non-survivors (70% in survivors vs. 60% in non-survivors, p=0.691). When comparing the direct and indirect lung injury groups, there were no significant differences in variables other than age and ECMO onset time. Conclusions If more evidence is gathered, risk factors and indications will be identified and we expect that more trauma patients will receive appropriate treatment with ECMO.

Acute Kidney Injury During Extracorporeal Membrane Oxygenation: VA ECMO Versus VV ECMO

PURPOSE

Acute kidney injury (AKI) has been reported to be one of the most common complications in patients receiving extracorporeal membrane oxygenation (ECMO), yet variations in AKI between different types of ECMO remain unclear. This meta-analysis systematically compares AKI/severe AKI in adult patients requiring different types of ECMO.

METHODS

Two authors independently performed a literature search using PubMed, Web of Science, and Embase, encompassing publications up until April 20, 2020 (inclusive). The number of AKI patients, including patients who required/did not require renal replacement therapy (RRT), and deceased patients with AKI/severe AKI, who received different types of ECMO were collated and analyzed using STATA.

RESULTS

The results indicated that there were no significant differences in the risk of AKI/severe AKI among different types of ECMO. However, the presence of AKI and severe AKI during veno-arterial (VA) ECMO was more strongly associated with mortality.

CONCLUSIONS

Although mortality rates related to AKI/severe AKI during VV ECMO are high, the occurrence of AKI/severe AKI during VA ECMO should be given greater attention, as these instances are considered strong indicators of patient deterioration and even death. Additional studies are needed to corroborate these findings.

Continuous renal replacement therapy and extended indications

Extracorporeal blood purification (EBP) techniques provide support for critically ill patients with single or multiple organ dysfunction. Continuous renal replacement therapy (CRRT) is the modality of choice for kidney support for those patients and orchestrates the interactions between the different artificial organ support systems. Intensive care teams should be familiar with the concept of sequential extracorporeal therapy and plan on how to incorporate new treatment modalities into their daily practices. Importantly, scientific evidence should guide the decision-making process at the bedside and provide robust arguments to justify the costs of implementing new EBP treatments. In this narrative review, we explore the extended indications for CRRT as an adjunctive treatment to provide support for the heart, lung, liver, and immune system. We detail practicalities on how to run the treatments and how to tackle the most frequent complications regarding each of the therapies, whether applied alone or integrated. The physicochemical processes and technologies involved at the molecular level encompassing the interactions between the molecules, membranes, and resins are spotlighted. A clinical case will illustrate the timing for the initiation, maintenance, and discontinuation of EBP techniques.

Analysis of survival after initiation of continuous renal replacement therapy in patients with extracorporeal membrane oxygenation

Background

No study has specifically investigated the duration of continuous renal replacement therapy (CRRT) in patients who experienced acute kidney injury during extracorporeal membrane oxygenation (ECMO) support. However, there are concerns that prolonged CRRT may be futile.

Methods

We conducted a retrospective population-based cohort study using Taiwan National Health Insurance Research Database data collected between January 1, 2007 and December 31, 2013. Patients who received ECMO and CRRT during the study period were included. We divided patients into three groups based on the duration of CRRT received: ≤ 3 days, 4–6 days, and ≥ 7 days. The outcomes were all-cause mortality, end-stage renal disease, ventilator dependency, and readmission rate.

Results

There were 247, 134 and 187 patients who survived the hospitalization in the CRRT for ≤3 days, 4–6 days and > 7 days respectively. Survival after discharge did not differ significantly between CRRT for 4–6 days vs. ≤ 3 days (adjusted hazard ratio [aHR] 1.16, 95% confidence interval [CI] 0.85–1.57), between CRRT for > 7 days vs. ≤ 3 days (aHR 1.001, 95% CI 0.73–1.38) and between CRRT for > 7 days vs. 4–6 days (aHR 0.87, 95% CI 0.62–1.22). The patients who received CRRT for ≥7 days had a higher risk of ESRD than did those who received CRRT for ≤3 days (adjusted hazard ratio [aHR] 3.46, 95% confidence interval [CI] 1.47–8.14) and for 4–6 days (aHR 3.10, 95% CI 1.03–9.29). The incidence of ventilator dependence was higher in the patients with CRRT ≥7 days than in those with ≤3 days (aHR 2.45, 95% CI 1.32–4.54). The CRRT ≥7 days group also exhibited a higher readmission rate than did the 4–6 days and ≤ 3 days groups (aHR 1.43, 95% CI 1.04–1.96 and aHR 1.67, 95% CI 1.13–2.47, respectively).

Conclusions

Our study found similar long-term survival but increased ESRD and ventilator dependency among ECMO patients who underwent CRRT for ≥7 days. These results offer reason to be concerned that this aggressive life support may maintain patient survival but do so at the cost of long-term disabilities and a lower quality of life.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1516-6) contains supplementary material, which is available to authorized users.

Incidence and Impact of Acute Kidney Injury in Patients Receiving Extracorporeal Membrane Oxygenation: A Meta-Analysis

BACKGROUND

Although acute kidney injury (AKI) is a frequent complication in patients receiving extracorporeal membrane oxygenation (ECMO), the incidence and impact of AKI on mortality among patients on ECMO remain unclear. We conducted this systematic review to summarize the incidence and impact of AKI on mortality risk among adult patients on ECMO.

METHODS

A literature search was performed using EMBASE, Ovid MEDLINE, and Cochrane Databases from inception until March 2019 to identify studies assessing the incidence of AKI (using a standard AKI definition), severe AKI requiring renal replacement therapy (RRT), and the impact of AKI among adult patients on ECMO. Effect estimates from the individual studies were obtained and combined utilizing random-effects, generic inverse variance method of DerSimonian-Laird. The protocol for this systematic review is registered with PROSPERO (no. CRD42018103527).

RESULTS

41 cohort studies with a total of 10,282 adult patients receiving ECMO were enrolled. Overall, the pooled estimated incidence of AKI and severe AKI requiring RRT were 62.8% (95%CI: 52.1%-72.4%) and 44.9% (95%CI: 40.8%-49.0%), respectively. Meta-regression showed that the year of study did not significantly affect the incidence of AKI (p = 0.67) or AKI requiring RRT (p = 0.83). The pooled odds ratio (OR) of hospital mortality among patients receiving ECMO with AKI on RRT was 3.73 (95% CI, 2.87-4.85). When the analysis was limited to studies with confounder-adjusted analysis, increased hospital mortality remained significant among patients receiving ECMO with AKI requiring RRT with pooled OR of 3.32 (95% CI, 2.21-4.99). There was no publication bias as evaluated by the funnel plot and Egger's regression asymmetry test with p = 0.62 and p = 0.17 for the incidence of AKI and severe AKI requiring RRT, respectively.

CONCLUSION

Among patients receiving ECMO, the incidence rates of AKI and severe AKI requiring RRT are high, which has not changed over time. Patients who develop AKI requiring RRT while on ECMO carry 3.7-fold higher hospital mortality.

Long-term outcomes after extracorporeal membrane oxygenation in patients with dialysis-requiring acute kidney injury: A cohort study

Background

Acute kidney injury (AKI) is a common complication of extracorporeal membrane oxygenation (ECMO) treatment. The aim of this study was to elucidate the long-term outcomes of adult patients with AKI who receive ECMO.

Materials and methods

The study analyzed encrypted datasets from Taiwan’s National Health Insurance Research Database. The data of 3251 patients who received first-time ECMO treatment between January 1, 2003, and December 31, 2013, were analyzed. Characteristics and outcomes were compared between patients who required dialysis for AKI (D-AKI) and those who did not in order to evaluate the impact of D-AKI on long-term mortality and major adverse kidney events.

Results

Of the 3251 patients, 54.1% had D-AKI. Compared with the patients without D-AKI, those with D-AKI had higher rates of all-cause mortality (52.3% vs. 33.3%; adjusted hazard ratio [aHR] 1.82, 95% confidence interval [CI] 1.53–2.17), chronic kidney disease (13.7% vs. 8.1%; adjusted subdistribution HR [aSHR] 1.66, 95% CI 1.16–2.38), and end-stage renal disease (5.2% vs. 0.5%; aSHR 14.28, 95% CI 4.67–43.62). The long-term mortality of patients who survived more than 90 days after discharge was 22.0% (153/695), 32.3% (91/282), and 50.0% (10/20) in the patients without D-AKI, with recovery D-AKI, and with nonrecovery D-AKI who required long-term dialysis, respectively, demonstrating a significant trend (Pfor trend <0.001).

Conclusion

AKI is associated with an increased risk of long-term mortality and major adverse kidney events in adult patients who receive ECMO.