Extracorporeal Membrane Oxygenation and the Kidney

Acute kidney injury in patients before and after extracorporeal membrane oxygenation (ECMO) - Retrospective longitudinal analysis of the hospital outcomes

PURPOSE

Acute Kidney Injury (AKI) occurs in up to 85% of patients managed by ECMO support. Limited data are available comparing the outcomes among patients who develop AKI before and after ECMO initiation.

METHODS

A retrospective longitudinal observational study was performed on all adult patients placed on ECMO from January 2000 to December 2015 at our institution. Longitudinal multivariate logistic regressional analysis was performed to identify the variables that are associated with the outcome measures (post-ECMO AKI and in-hospital mortality).

RESULTS

A total of 329 patients were included in our analysis in which AKI occurred in 176 (53%) and 137 (42%) patients before and after ECMO, respectively. In the multivariate analysis, increasing age, pre-existing chronic kidney disease (CKD), increasing bilirubin, decreasing fibrinogen, and use of LVAD had significant association with post-ECMO AKI. In-hospital mortality was seen in 128 out of 176 (73%) patients in the pre-ECMO AKI group and 32 out of 137 (42%) in the post-ECMO AKI group. In the multivariate analysis, age, interstitial lung disease, pre-ECMO AKI, and post-ECMO RRT requirement were independently associated with mortality.

CONCLUSION

AKI before ECMO initiation and the need for RRT post-ECMO are independently associated with poor patient survival.

Fluid Responsiveness Is Associated with Successful Weaning after Liver Transplant Surgery

A positive fluid balance may evolve to fluid overload and associate with organ dysfunctions, weaning difficulties, and increased mortality in ICU patients. We explored whether individualized fluid management, assessing fluid responsiveness via a passive leg-raising maneuver (PLR) before a spontaneous breathing trial (SBT), is associated with less extubation failure in ventilated patients with a high fluid balance admitted to the ICU after liver transplantation (LT). We recruited 15 LT patients in 2023. Their postoperative fluid balance was +4476 {3697, 5722} mL. PLR maneuvers were conducted upon ICU admission (T1) and pre SBT (T2). Cardiac index (CI) changes were recorded before and after each SBT (T3). Seven patients were fluid-responsive at T1, and twelve were responsive at T2. No significant differences occurred in hemodynamic, respiratory, and perfusion parameters between the fluid-responsive and fluid-unresponsive patients at any time. Fluid-responsive patients at T1 and T2 increased their CI during SBT from 3.1 {2.8, 3.7} to 3.7 {3.4, 4.1} mL/min/m2 (p = 0.045). All fluid-responsive patients at T2 were extubated after the SBTs and consolidated extubation. Two out of three of the fluid-unresponsive patients experienced weaning difficulties. We concluded that fluid-responsive patients post LT may start weaning earlier and achieve successful extubation despite a high postoperative fluid balance. This highlights the profound impact of personalized assessments of cardiovascular state on critical surgical patients.

Assessing medication use patterns by clinical outcomes severity among inpatients with COVID-19: A retrospective drug utilization study

PURPOSE

This study assessed medication patterns for inpatients at a central hospital in Portugal and explored their relationships with clinical outcomes in COVID-19 cases.

METHODS

A retrospective study analyzed inpatient medication data, coded using the Anatomical Therapeutic Chemical classification system, from electronic patient records. It investigated the association between medications and clinical severity outcomes such as ICU admissions, respiratory/circulatory support needs, and hospital discharge status, including mortality (identified by ICD-10-CM/PCS codes). Multivariate analyses incorporating demographic data and comorbidities were used to adjust for potential confounders and understand the impact of medication patterns on disease progression and outcomes.

RESULTS

The analysis of 2688 hospitalized COVID-19 patients (55.3% male, average age 62.8 years) revealed a significant correlation between medication types and intensity and disease severity. Cases requiring ICU admission or ECMO support often involved blood and blood-forming organ drugs. Increased use of nervous system and genitourinary hormones was observed in nonsurvivors. Corticosteroids, like dexamethasone, were common in critically ill patients, while tocilizumab was used in ECMO cases. Medications for the alimentary tract, metabolism, and cardiovascular system, although widely prescribed, were linked to more severe cases. Invasive mechanical ventilation correlated with higher usage of systemic anti-infectives and musculoskeletal medications. Trends in co-prescribing blood-forming drugs with those for acid-related disorders, analgesics, and antibacterials were associated with intensive interventions and worse outcomes.

CONCLUSIONS

The study highlights complex medication regimens in managing severe COVID-19, underscoring specific drug patterns associated with critical health outcomes. Further research is needed to explore these patterns.

Concurrent use of continuous kidney replacement therapy during extracorporeal membrane oxygenation: what pediatric nephrologists need to know-PCRRT-ICONIC practice points

Extracorporeal membrane oxygenation (ECMO) provides temporary cardiorespiratory support for neonatal, pediatric, and adult patients when traditional management has failed. This lifesaving therapy has intrinsic risks, including the development of a robust inflammatory response, acute kidney injury (AKI), fluid overload (FO), and blood loss via consumption and coagulopathy. Continuous kidney replacement therapy (CKRT) has been proposed to reduce these side effects by mitigating the host inflammatory response and controlling FO, improving outcomes in patients requiring ECMO. The Pediatric Continuous Renal Replacement Therapy (PCRRT) Workgroup and the International Collaboration of Nephrologists and Intensivists for Critical Care Children (ICONIC) met to highlight current practice standards for ECMO use within the pediatric population. This review discusses ECMO modalities, the pathophysiology of inflammation during an ECMO run, its adverse effects, various anticoagulation strategies, and the technical aspects and outcomes of implementing CKRT during ECMO in neonatal and pediatric populations. Consensus practice points and guidelines are summarized. ECMO should be utilized in patients with severe acute respiratory failure despite the use of conventional treatment modalities. The Extracorporeal Life Support Organization (ELSO) offers guidelines for ECMO initiation and management while maintaining a clinical registry of over 195,000 patients to assess outcomes and complications. Monitoring and preventing fluid overload during ECMO and CKRT are imperative to reduce mortality risk. Clinical evidence, resources, and experience of the nephrologist and healthcare team should guide the selection of ECMO circuit.

Outcomes of ECMO support with polypropylene membrane during pandemic times: a retrospective cohort study

BACKGROUND

The SARS-CoV-2 pandemic resulted in shortages of supplies, which limited the use of extracorporeal membrane oxygenation (ECMO) support. As a contingency strategy, polypropylene (PP) oxygenation membranes were used. This study describes the clinical outcomes in patients on ECMO with PP compared to poly-methylpentene (PMP) oxygenation membranes.

METHODS

Retrospective cohort of patients in ECMO support admitted between 2020 and 2021.

RESULTS

A total of 152 patients with ECMO support were included, 71.05% were men with an average age of 42 (SD 9.91) years. Veno-venous configuration was performed in 75.6% of cases. The PP oxygenation membranes required more changes 22 (63.1%), than the PMP Sorin® 24 (32,8%) and Euroset® 15 (31,9%) (p.0.022). The main indication for membrane change was low oxygen transfer for PP at 56.2%, Sorin® at 50%, and Euroset® at 14.8%. Renal replacement therapy was the most frequent complication with PP membrane in 22 patients (68.7%) Sorin® 25 patients (34.2%), and Euroset® 15 patients (31.9%) (p 0.001) without statistically significant differences in mortality.

CONCLUSION

PP oxygenation membranes was a useful and feasible strategy. It allowed a greater disponibility of ECMO support for critically ill in a situation of great adversity during the SARS-CoV-2 pandemic.

Acute Kidney Injury in Patients Undergoing Extracorporeal Membrane Oxygenation: A Retrospective Cohort Study

Aims and background

Extracorporeal membrane oxygenation (ECMO) is a mode of extracorporeal therapy to support oxygenation of patients with severe cardiac or respiratory failure. Studies have shown that acute kidney injury (AKI) can worsen the outcome in these patients. This study aims to assess the incidence and outcome of AKI in patients on ECMO support.

Materials and methods

This retrospective study included 64 patients who underwent ECMO for more than 24 hours. Patients who died within 48 hours of initiation of ECMO and patients with end-stage renal disease (ESRD) on maintenance hemodialysis were excluded. Acute kidney injury was diagnosed and categorized according to the Kidney Disease Improving Global Outcomes (KDIGO) criteria.

Results

Of the 64 patients studied, 38 patients (59.38%) developed AKI and 17 patients (44.73%) among them developed AKI within 24 hours of initiation of ECMO. Age, Acute Physiology and Chronic Health Evaluation (APACHE-II) score, hypertension, use of nephrotoxic agents, inotropic support, and poor cardiac function were the risk factors associated with the development of AKI. Diabetes mellitus, type of ECMO used, and duration of ECMO were not found to be risk factors for AKI. Renal replacement therapy was initiated in 31 patients (81.58%). The overall mortality in the whole group was 67.19%, while it was 81.58% among the patients with AKI.

Conclusion

Acute kidney injury was found to be an independent risk factor for mortality in patients on ECMO. Early identification of the risk factors for AKI and management may help to improve the survival rate.

Clinical significance

The occurrence of AKI among patients on ECMO support increases the risk of mortality significantly. Hence, measures to prevent AKI, as well as early detection and appropriate management of AKI, would improve patient outcomes.

How to cite this article

Surjit A, Prasannan B, Abraham J, Balagopal A, Unni VA. Acute Kidney Injury in Patients Undergoing Extracorporeal Membrane Oxygenation: A Retrospective Cohort Study. Indian J Crit Care Med 2024;28(1):26-29.

Acute Kidney Injury and ECMO: Two Sides of the Same Coin

How to cite this article: Gupta S, Tomar DS. Acute Kidney Injury and ECMO: Two Sides of the Same Coin. Indian J Crit Care Med 2024;28(1):3-4.

Acute kidney injury during extracorporeal life support in cardiogenic shock: Does flow matter?

BACKGROUND

This study examines the role of extracorporeal life support flow in the development of acute kidney injury in cardiogenic shock.

METHODS

We performed a retrospective analysis of 465 patients placed on extracorporeal life support at our institution between January 2015 and December 2020 for cardiogenic shock. Flow index was calculated by dividing mean flow by body surface. Stages of acute kidney injury were determined according to Kidney Disease: Improving Global Outcomes (KDIGO) organization guidelines.

RESULTS

There were 179 (38.5%) patients who developed acute kidney injury, 63.1% of which were classified as Stage 3--the only subgroup associated with 1-year mortality (hazard ratio = 2.03, p < .001). Risk of kidney injury increased up to a flow index of 1.6 L/min/m2, and kidney injury was more common among patients with flow index greater than 1.6 L/min/m2 (p = .034). Those with kidney injury had higher baseline lactate levels (4.4 vs 3.1, p = .04), and Stage 3 was associated wit higher baseline creatinine (p < .001).

CONCLUSIONS

In our cohort, kidney injury was common and Stage 3 kidney injury was associated with worse outcomes compared to other stages. Low flow was not associated with increased risk of kidney injury. Elevated baseline lactate and creatinine among patients with acute kidney injury suggest underlying illness severity, rather than flow, may influence kidney injury risk.

Urinary Collectrin as Promising Biomarker for Acute Kidney Injury in Patients Undergoing Cardiac Surgery

BACKGROUND

Early detection of acute kidney injury (AKI) is crucial for timely intervention and improved patient outcomes after cardiac surgery. This study aimed to evaluate the potential of urinary collectrin as a novel biomarker for AKI in this patient population.

METHODS

In this prospective, observational cohort study, 63 patients undergoing elective cardiac surgery with cardiopulmonary bypass (CPB) were studied at the Medical University of Vienna between 2016 and 2018. We collected urine samples prospectively at four perioperative time points, and urinary collectrin was measured using an enzyme-linked immunosorbent assay. Patients were divided into two groups, AKI and non-AKI, defined by Kidney Disease: Improving Global Outcomes Guidelines, and differences between groups were analyzed.

RESULTS

Postoperative AKI was found in 19 (30%) patients. Urine sample analysis revealed an inverse correlation between urinary collectrin and creatinine and AKI stages, as well as significant changes in collectrin levels during the perioperative course. Baseline collectrin levels were 5050 ± 3294 pg/mL, decreased after the start of CPB, reached their nadir at the end of surgery, and began to recover slightly on postoperative day (POD) 1. The most effective timepoint for distinguishing between AKI and non-AKI patients based on collectrin levels was POD 1, with collectrin levels of 2190 ± 3728 pg/mL in AKI patients and 3768 ± 3435 pg/mL in non-AKI patients (p = 0.01).

CONCLUSIONS

Urinary collectrin shows promise as a novel biomarker for the early detection of AKI in patients undergoing cardiac surgery on CPB. Its dynamic changes throughout the perioperative period, especially on POD 1, provide valuable insights for timely diagnosis and intervention. Further research and validation studies are needed to confirm its clinical usefulness and potential impact on patient outcomes.

Assessing Kidney Transplantation Using ECMO-Supported Donors Within a KDPI-Based Allocation System

Background

Organ donors supported by extracorporeal membrane oxygenation (ECMO) have historically been considered high-risk and are judiciously utilized. This study examines transplant outcomes using renal allografts from donors supported on ECMO for nondonation purposes.

Methods

Retrospective review of the Gift of Life (Pennsylvania, New Jersey, Delaware) organ procurement organization database, cross-referenced to the Organ Procurement and Transplantation Network database, assessed kidney transplants using donors supported on venoarterial (VA) and venovenous (VV) ECMO for nondonation purposes. Transplants using VA- and VV-ECMO donors were compared with Kidney Donor Profile Index (KDPI)-stratified non-ECMO donors. Regression modeling of the entire ECMO and non-ECMO populations assessed ECMO as predictive of graft survival. Additional regression of the ECMO population alone assessed for donor features associated with graft survival.

Results

Seventy-eight ECMO donors yielded 128 kidney transplants (VA: 80, VV: 48). Comparing outcomes using these donors to kidney transplants using organs from KDPI-stratified non-ECMO donors, VA- and VV-ECMO donor grafts conferred similar rates of delayed graft function and posttransplant renal function to KDPI-matched non-ECMO counterparts. VA-ECMO kidneys demonstrated superior graft survival compared with the lowest-quality (KDPI 86%-100%) non-ECMO kidneys and similar graft survival to KDPI <85% non-ECMO kidneys. VV-ECMO showed inferior graft survival to all but the lowest-quality (KDPI 86%-100%) non-ECMO kidneys. VV-ECMO, but not VA-ECMO, was associated with increased risk of graft loss on multivariable regression (hazard ratios-VA: 1.02, VV: 2.18). Higher KDPI, advanced age, increased body mass index, hypertension, and diabetes were identified as high-risk features of ECMO donors.

Conclusions

Kidney transplantation using appropriately selected ECMO donors can safely expand the donor pool. Ongoing studies are necessary to determine best practice patterns using kidneys from these donors.

Advances in pulmonary management and weaning from ECLS

ECMO for neonatal and pediatric respiratory failure provides gas exchange to allow lung recovery from reversible pulmonary ailments. This is a comprehensive discussion on the various strategies and advances utilized by pediatric ECLS specialists today. ECMO patients require continual monitoring, serial gasses and radiographs, near-infrared spectroscopy (NIRS - to monitor oxygen delivery to regional tissue beds), and more quality ECLS directed care. As the foundation to lung recovery, good EMCO closely monitors ECLS flow rates, sweep gasses, and membrane lung function. Mixed venous oxygen saturation (Sv02) greater than 65% indicates good oxygen delivery and sweep gas adjustments maintain PaCO2 of 40-45 mm Hg. Lung recovery ventilatory settings do not fully rest the lungs but maintain normal or nontoxic pressure and oxygen levels. Neonatal recovery settings are PIP (cm H20) of 15-20, PEEP of 5-10, ventilator rate of 12-20 and an inspiratory time of 0.5-1 s, and FiO2 of 0.3-0.5. Pediatric recovery settings are PIP (cm H20) < 25, PEEP of 5-15, ventilator rate of 10-20 and an inspiratory time of 0.8-1 s, and FiO2 of <0.5. Some studies demonstrate a higher recovery PEEP level decreases duration of ECMO, but do not demonstrate a mortality difference. Multiple adjunctive therapies such as surfactant, routine pulmonary clearance and respiratory physiotherapy, iNO, prone positioning, bronchoscopy, POCUS, CT imaging, and extubation or "awake ECLS" can significantly affect pulmonary recovery. Patience is necessary as lung recovery may take weeks or even months on the nontoxic settings. On these settings, dynamic recovery will be revealed by improvement in tidal volume, minute ventilation and radiographic pulmonary aeration, prompting discussion about weaning. When this pulmonary compliance recovery becomes evident, decreasing ECLS flow while also decreasing circuit FiO2 and/or sweep gas are common components to ECMO weaning strategies.

Independent risk factors of acute kidney injury among patients receiving extracorporeal membrane oxygenation

OBJECTIVE

Acute kidney injury (AKI) is one of the most frequent complications in patients treated with extracorporeal membrane oxygenation (ECMO) support. The aim of this study was to investigate the risk factors of AKI in patients undergoing ECMO support.

METHODS

We performed a retrospective cohort study which included 84 patients treated with ECMO support at intensive care unit in the People's Hospital of Guangxi Zhuang Autonomous Region from June 2019 to December 2020. AKI was defined as per the standard definition proposed by the Kidney Disease Improving Global Outcome (KDIGO). Independent risk factors for AKI were evaluated through multivariable logistic regression analysis with stepwise backward approach.

RESULTS

Among the 84 adult patients, 53.6% presented AKI within 48 h after initiation of ECMO support. Three independent risk factors of AKI were identified. The final logistic regression model included: left ventricular ejection fraction (LVEF) before ECMO initiation (OR, 0.80; 95% CI, 0.70-0.90), sequential organ failure assessment (SOFA) score before ECMO initiation (OR, 1.41; 95% CI, 1.16-1.71), and serum lactate at 24 h after ECMO initiation (OR, 1.27; 95% CI, 1.09-1.47). The area under receiver operating characteristics of the model was 0.879.

CONCLUSION

Severity of underlying disease, cardiac dysfunction before ECMO initiation and the blood lactate level at 24 h after ECMO initiation were independent risk factors of AKI in patients who received ECMO support.

Effect of flow change on brain injury during an experimental model of differential hypoxaemia in cardiogenic shock supported by extracorporeal membrane oxygenation

Differential hypoxaemia (DH) is common in patients supported by femoral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) and can cause cerebral hypoxaemia. To date, no models have studied the direct impact of flow on cerebral damage. We investigated the impact of V-A ECMO flow on brain injury in an ovine model of DH. After inducing severe cardiorespiratory failure and providing ECMO support, we randomised six sheep into two groups: low flow (LF) in which ECMO was set at 2.5 L min-1 ensuring that the brain was entirely perfused by the native heart and lungs, and high flow (HF) in which ECMO was set at 4.5 L min-1 ensuring that the brain was at least partially perfused by ECMO. We used invasive (oxygenation tension-PbTO2, and cerebral microdialysis) and non-invasive (near infrared spectroscopy-NIRS) neuromonitoring, and euthanised animals after five hours for histological analysis. Cerebral oxygenation was significantly improved in the HF group as shown by higher PbTO2 levels (+ 215% vs - 58%, p = 0.043) and NIRS (67 ± 5% vs 49 ± 4%, p = 0.003). The HF group showed significantly less severe brain injury than the LF group in terms of neuronal shrinkage, congestion and perivascular oedema (p < 0.0001). Cerebral microdialysis values in the LF group all reached the pathological thresholds, even though no statistical difference was found between the two groups. Differential hypoxaemia can lead to cerebral damage after only a few hours and mandates a thorough neuromonitoring of patients. An increase in ECMO flow was an effective strategy to reduce such damages.

The impact of preservation and recovery of renal function on survival after veno-arterial extracorporeal life support: A retrospective cohort study

BACKGROUND

Veno-arterial extracorporeal life support (V-A ECLS) has become a cornerstone in the management of critical cardiogenic shock, but it can also precipitate organ injury, e.g., acute kidney injury (AKI). Available studies highlight the effect of non-cardiac organ injury on patient outcomes. Only very little is known about the impact of non-cardiac organ recovery on patient survival. AKI occurs frequently during cardiogenic shock and carries a poor prognosis. We have developed descriptive models to hypothesize on the role of AKI severity versus that of recovery of renal function for patient survival.

METHODS

Retrospective, observational study including 175 patients who were successfully decannulated from V-A ECLS. We assessed AKI severity using the "Kidney Disease: Improving Global Outcomes" (KDIGO) criteria. We defined recovered or preserved renal function (RPRF) prior to decannulation from V-A ECLS as 0 (AKI with no improvement) or 1 (no AKI or AKI with improvement). We classified patient outcomes as alive or dead at hospital discharge.

RESULTS

78% (n = 138) of all patients survived hospital discharge of which 38% (n = 67) never developed AKI. After adjusting for shock severity and non-renal organ injury, RPRF emerged as an independent predictor of survival in both the overall cohort [OR (95% CI) - 4.11 (1.72-9.79)] and the AKI-only sub-cohort [OR (95% CI) - 5.18 (1.8-14.92)]. Neither maximum KDIGO stage nor KDIGO stage at the end of V-A ECLS was independently associated with survival.

CONCLUSIONS

Our model identifies RPRF, but not AKI severity, as an independent predictor of hospital survival in patients undergoing V-A ECLS for cardiogenic shock. We hypothesize that recovered or preserved non-cardiac organ function during V-A ECLS is crucial for patient survival.

Influence of confirmed viral infection on adult acute fulminant myocarditis supported with extracorporeal membrane oxygenation

BACKGROUND

The impact of etiologies of acute fulminant myocarditis (AFM), which requires extracorporeal membrane oxygenation (ECMO), on clinical outcomes remains unknown. This study aimed to investigate the risk factors for ECMO weaning and mortality among patients with AFM due to viral etiologies in a tertiary referral medical center.

METHODS

We included 33 adults with AFM who received ECMO and were admitted between January 2002 and January 2021. General demographics, laboratory data, echocardiography findings, and long-term outcomes were analyzed for confirmed viral etiology and unconfirmed etiology groups.

RESULTS

The overall hospital survival rate was 54.5%. The age, sex, severity of the hemodynamic condition, and cardiac rhythm were similar between the two groups. Multivariate Cox regression analysis revealed that a confirmed viral etiology (HR 4.201, 95% CI 1.061-16.666), peri-ECMO renal replacement therapy (RRT) (HR 9.804, 1.140-83.333) and a high positive end-expiratory pressure (PEEP) in the ventilator settings at 24 h after ECMO (HR 1.479, 1.020-2.143) were significant prognostic factors for in-hospital mortality. Peri-ECMO RRT was also a significant negative prognostic factor for successful ECMO weaning (OR 0.061, 0.006-0.600) in the multivariate logistic model.

CONCLUSIONS

Among AFM patients receiving ECMO support, RRT use was associated with a decreased chance of survival to ECMO weaning. Multiple organ dysfunction and a high PEEP were also predictive of a lower chance of hospital survival. Those with a confirmed diagnosis of viral myocarditis may require more medical attention due to the higher risk of hospital mortality than those without a definite diagnosis.

Effect of a standardized fluid management algorithm on acute kidney injury and mortality in pediatric patients on extracorporeal support

Acute kidney injury (AKI), fluid overload (FO), and mortality are common in pediatric patients supported by extracorporeal membrane oxygenation (ECMO). The aim of this study is to evaluate if using a fluid management algorithm reduced AKI and mortality in children supported by ECMO. We performed a retrospective study of pediatric patients aged birth to 25 years requiring ECMO at a quaternary level children's hospital from 2007 to 2019 In October 2017, a fluid management algorithm was implemented for protocolized fluid removal after deriving a daily fluid goal using a combination of diuretics and ultrafiltration. Daily algorithm compliance was defined as ≥ 12 h on the algorithm each day. The primary and secondary outcomes were AKI and mortality, respectively, and were assessed in the entire cohort and the sub-analysis of children from the era in which the algorithm was implemented. Two hundred and ninety-nine (median age 5.3 months; IQR: 0.2, 62.3; 45% male) children required ECMO (venoarterial in 85%). The fluid algorithm was applied in 74 patients. The overall AKI rate during ECMO was 38% (26% severe-stage 2/3). Both AKI incidence and mortality were significantly lower in patients managed on the algorithm (p = 0.02 and p = 0.05). After adjusting for confounders, utilization of the algorithm was associated with lower odds of AKI (aOR: 0.40, 95%CI: 0.21, 0.76; p = 0.005) but was not associated with a reduction in mortality. In the sub-analysis, algorithm compliance of 80-100% was associated with a 54% reduction in mortality (ref: < 60% compliant; aOR:0.46, 95%CI:0.22-1.00; p = 0.05).  Conclusion: Among the entire cohort, the use of a fluid management algorithm reduced the odds of AKI. Better compliance on the algorithm was associated with lower mortality. Multicenter studies that implement systematic fluid removal may represent an opportunity for improving ECMO-related outcomes. What is Known: • Acute kidney injury and fluid overload are associated with morbidity and mortality in children supported by extracorporeal membrane oxygenation. What is New: • A systematic and protocolized approach to fluid removal in children supported by extracorporeal membrane oxygenation reduces acute kidney injury incidence. • Greater adherence to a protocolized fluid removal algorithm is associated with a reduction in mortality.

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.

Impact of Extracorporeal Membrane Oxygenation in an Infant Treated with Vancomycin: A Case Report

Vancomycin is a glycopeptide antibiotic used for prophylaxis and treatment of infections caused by methicillin-resistant Staphylococcus aureus. Although major organ sizes and functions mature during infancy, pharmacokinetic studies, especially those focused on infants, are limited. Changes in extracorporeal membrane oxygenation-related drug disposition largely contribute to changes in pharmacokinetics. Here, pharmacokinetic profiles of vancomycin in an infant receiving extracorporeal membrane oxygenation therapy are presented. A two-month-old Japanese infant with moderately decreased renal function was started on 12.0 mg/kg vancomycin every 8 h from day X for prophylaxis of pneumonia during extracorporeal membrane oxygenation therapy. As the trough concentration of vancomycin observed on day X+3 was 27.1 μg/mL, vancomycin was then discontinued. The trough concentration decreased to 18.6 μg/mL 24 h after discontinuation, and 9.0 mg/kg vancomycin every 12 h was restarted from day X+5. On day X+6, the trough concentration increased to 36.1 μg/mL, and vancomycin therapy was again discontinued. On day X+7, the trough concentration decreased to 22.4 μg/mL. The pharmacokinetic profiles of vancomycin based on first-order conditional estimation in this infant were as follows: plasma clearance = 0.053 L/kg/hour, distribution volume = 2.19 L/kg, and half-life = 29.5 h. This research reported the prolonged half-life of vancomycin during extracorporeal membrane oxygenation in infants with moderately decreased renal function.

Continuous renal replacement therapy and extracorporeal membrane oxygenation: implications in the COVID-19 era

The novel severe acute respiratory syndrome coronavirus 2, SARS-CoV-2 (coronavirus Disease 19 (COVID-19)) was identified as the causative agent of viral pneumonias in Wuhan, China in December 2019, and has emerged as a pandemic causing acute respiratory distress syndrome (ARDS) and multiple organ dysfunction. Interim guidance by the World Health Organization states that extracorporeal membrane oxygenation (ECMO) should be considered as a rescue therapy in COVID-19-related ARDS. International registries tracking ECMO in COVID-19 patients reveal a 21%-70% incidence of acute renal injury requiring renal replacement therapy (RRT) during ECMO support. The indications for initiating RRT in patients on ECMO are similar to those for patients not requiring ECMO. RRT can be administered during ECMO via a temporary dialysis catheter, placement of a circuit in-line hemofilter, or direct connection of continuous RRT in-line with the ECMO circuit. Here we review methods for RRT during ECMO, RRT initiation and timing during ECMO, anticoagulation strategies, and novel cytokine filtration approaches to minimize COVID-19's pathophysiological impact.

Patient-Specific Computational Modeling of Different Cannulation Strategies for Extracorporeal Membrane Oxygenation

Institution of extracorporeal membrane oxygenation (ECMO) results in unique blood flow characteristics to the end-organ vascular beds. We studied the interplay between cardiac-driven and extracorporeal membrane oxygenation (ECMO)-driven flow to vascular beds in different ECMO configurations using a patient-specific computational fluid dynamics (CFD) analysis. A computational ECMO model (femoral artery cannulation [FAC]) was constructed using patient-specific imaging and hemodynamic data. Following model calibration, we augmented the 3D geometrical model to represent alternative ECMO configurations (ascending aorta cannulation [AAC] and subclavian artery cannulation [SAC]). We performed CFD analyses, including a novel virtual color-dye analysis to compare global and regional blood flow and pressure characteristics as well as contributions of cardiac and ECMO-derived flow to the various vascular beds. Flow waveforms at all the aortic branch vessels were pulsatile, despite low cardiac output and predominant nonpulsatile ECMO-driven hemodynamics. Virtual color-dye analysis revealed differential contribution of cardiac and ECMO-derived flow to the end-organ vascular beds in the FAC model, while this was more evenly distributed in the AAC and SAC models. While global hemodynamics were relatively similar between various ECMO configurations, several distinct hemodynamic indices, in particular wall shear stress and oscillatory shear patterns, as well as differential contribution of ECMO-derived flow to various vascular beds, showed remarkable differences. The clinical impact of this study highlighting the relevance of CFD modeling in assessment of complex hemodynamics in ECMO warrants further evaluation.

Safety and Effectiveness of Veno-Venous Extracorporeal Membrane Oxygenation Combined with Continuous Renal Replacement Therapy

Patients receiving extracorporeal membrane oxygenation (ECMO) often suffer from acute kidney injury (AKI), requiring continuous renal replacement therapy (CRRT). In our clinical practice, we connected the inlet line of a CRRT machine to the postoxygenator Luer port and the outlet line to the inlet Luer port of the oxygenator. In this case series, we analyzed the interaction between the two machines. Between December 31, 2017, and December 31, 2019, we enrolled 15 patients from the ICU of the San Matteo Hospital, Pavia, Italy. All of them suffered from severe acute respiratory distress syndrome and AKI stage 3. We analyzed 570 hours of CRRT combined with venovenous ECMO and collected 261,751 CRRT data. No discontinuation of CRRT occurred before 48 hours. Most of the alarms occurred within 24 hours of the connection: 22/10,831 (0.2%) showed an outranged inlet pressure, 11/10831 (0.11%) showed an outranged transmembrane pressure, 14/10,831 (0.13%) showed an outranged inlet pressure, and 138/10,831 (1.27%) an outranged effluent pressure. The rate per minute set for the ECMO circuit was correlated with the inlet (β = 5.38; CI, 95% 1.42-9.35; p = 0.008), transmembrane (β = 4.6; CI, 95% 1.97-7.24; p = 0.001), effluent (β = 3.02; CI, 95% 1.15-4.90; p = 0.002), and outlet pressures (β = 597; CI, 95% 2.31-9.63; p = 0.001) of the CRRT circuit. We reported that our configuration could be safe and effective, however well-designed studies would be beneficial for determining the potential risks and benefits.

Risk factors for bloodstream infection (BSI) in patients with severe acute respiratory distress syndrome (ARDS) supported by veno-venous extracorporeal membrane oxygenation (VV-ECMO)

Background

There were relatively few studies about the incidence and risk factors for bloodstream infection (BSI) in patients with severe acute respiratory distress syndrome (ARDS) supported by veno–venous extracorporeal membrane oxygenation (VV–ECMO).

Methods

Patients who were diagnosed with severe ARDS and received VV–ECMO treatment in the medical intensive care unit of China–Japan Friendship Hospital from August 2013 to March 2019 were retrospectively studied. The pathogens isolated from blood culture (BC) were identified and analyzed for drug sensitivity. The risk factors for BSI were analyzed by logistic regression.

Results

A total of 105 patients were included in this single–center retrospective cohort study. Among them, 23 patients (22%) had BSIs. 19 cases were identified as primary BSI; while the other 4 cases were as secondary BSI. A total of 23 pathogenic strains were isolated from BCs, including gram–negative (G^–) bacilli in 21 (91%) cases, gram–positive (G⁺) cocci in 1 case, fungus in 1 case, and multidrug–resistant (MDR) organisms in 8 cases. Compared with patients without BSI, patients with BSI had a higher Murray score (odds ratio = 6.29, P = 0.01) and more blood transfusion (odds ratio = 1.27, P = 0.03) during ECMO.

Conclusions

The incidence of BSI in patients with severe ARDS supported by VV–ECMO was 22%. G^– bacilli was the main pathogen, and most of them were MDR–G^– bacilli (MDR–GNB). Higher Murray score and more blood transfusion may be the independent risk factors for BSI.

Different Acute Kidney Injury Patterns after Renal Ischemia Reperfusion Injury and Extracorporeal Membrane Oxygenation in Mice

The use of extracorporeal membrane oxygenation (ECMO) is associated with acute kidney injury (AKI) in thoracic organ transplantation. However, multiple other factors contribute to AKI development after these procedures such as renal ischemia-reperfusion injury (IRI) due to hypo-perfusion of the kidney during surgery. In this study, we aimed to explore the kidney injury patterns in mouse models of ECMO and renal IRI. Kidneys of C57BL/6 mice were examined after moderate (35 min) and severe (45 min) unilateral transient renal pedicle clamping and 2 h of veno-venous ECMO. Renal injury markers, neutrophil infiltration, tubular transport function, pro-inflammatory cytokines, and renal heme oxygenase-1 (HO-1) expression were determined by immunofluorescence and qPCR. Both procedures caused AKI, but with different injury patterns. Severe neutrophil infiltration of the kidney was evident after renal IRI, but not following ECMO. Tubular transport function was severely impaired after renal IRI, but preserved in the ECMO group. Both procedures caused upregulation of pro-inflammatory cytokines in the renal tissue, but with different time kinetics. After ECMO, but not IRI, HO-1 was strongly induced in tubular cells indicating contact with hemolysis-derived proteins. After IRI, HO-1 was expressed on infiltrating myeloid cells in the tubulo-interstitial space. In conclusion, renal IRI and ECMO both caused AKI, but kidney damage after renal IRI was more pronounced including severe neutrophil infiltration and tubular transport impairment. Enhanced HO-1 expression in tubular cells after ECMO encourages limitation of hemolysis as a therapeutic approach to reduce ECMO-associated AKI.

Outcomes after heart transplantation in patients who have undergone a bridge-to-bridge strategy

Objectives

We compared posttransplant outcomes between patients bridged from temporary mechanical circulatory support to durable left ventricular assist device before transplant (bridge-to-bridge [BTB] strategy) and patients bridged from temporary mechanical circulatory support directly to transplant (bridge-to-transplant [BTT] strategy).

Methods

We identified adult heart transplant recipients in the Organ Procurement and Transplantation Network database between 2005 and 2020 who were supported with extracorporeal membrane oxygenation, intra-aortic balloon pump, or temporary ventricular assist device as a BTB or BTT strategy. Kaplan-Meier survival analysis and Cox regressions were used to assess 1-year, 5-year, and 10-year survival. Posttransplant length of stay and complications were compared as secondary outcomes.

Results

In total, 201 extracorporeal membrane oxygenation (61 BTB, 140 BTT), 1385 intra-aortic balloon pump (460 BTB, 925 BTT), and 234 temporary ventricular assist device (75 BTB, 159 BTT) patients were identified. For patients supported with extracorporeal membrane oxygenation, intra-aortic balloon pump, or temporary ventricular assist device, there were no differences in survival between BTB and BTT at 1 and 5 years posttransplant, as well as 10 years posttransplant even after adjusting for baseline characteristics. The extracorporeal membrane oxygenation BTB group had greater rates of acute rejection (32.8% vs 13.6%; P = .002) and lower rates of dialysis (1.6% vs 21.4%; P < .001). For intra-aortic balloon pump and temporary ventricular assist device patients, there were no differences in posttransplant length of stay, acute rejection, airway compromise, stroke, dialysis, or pacemaker insertion between BTB and BTT recipients.

Conclusions

BTB patients have similar short- and midterm posttransplant survival as BTT patients. Future studies should continue to investigate the tradeoff between prolonged temporary mechanical circulatory support versus transitioning to durable mechanical circulatory support.

Extracorporeal organ support and the kidney

The concept of extracorporeal organ support (ECOS) encompasses kidney, respiratory, cardiac and hepatic support. In an era of increasing incidence and survival of patients with single or multiple organ failure, knowledge on both multiorgan crosstalk and the physiopathological consequences of extracorporeal organ support have become increasingly important. Immerse within the cross-talk of multiple organ failure (MOF), Acute kidney injury (AKI) may be a part of the clinical presentation in patients undergoing ECOS, either as a concurrent clinical issue since the very start of ECOS or as a de novo event at any point in the clinical course. At any point during the clinical course of a patient with single or multiple organ failure undergoing ECOS, renal function may improve or deteriorate, as a result of the interaction of multiple factors, including multiorgan crosstalk and physiological consequences of ECOS. Common physiopathological ways in which ECOS may influence renal function includes: 1) multiorgan crosstalk (preexisting or de-novo 2)Hemodynamic changes and 3) ECOS-associated coagulation abnormalities and 3) Also, cytokine profile switch, neurohumoral changes and toxins clearance may contribute to the expected physiological changes related to ECOS. The main objective of this review is to summarize the described mechanisms influencing the renal function during the course of ECOS, including renal replacement therapy, extracorporeal membrane oxygenation/carbon dioxide removal and albumin dialysis.

Cellular recovery after prolonged warm ischaemia of the whole body

After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death^1,2. Yet with targeted interventions, these processes can be mitigated or reversed, even minutes or hours post mortem, as also reported in the isolated porcine brain using BrainEx technology³. To date, translating single-organ interventions to intact, whole-body applications remains hampered by circulatory and multisystem physiological challenges. Here we describe OrganEx, an adaptation of the BrainEx extracorporeal pulsatile-perfusion system and cytoprotective perfusate for porcine whole-body settings. After 1 h of warm ischaemia, OrganEx application preserved tissue integrity, decreased cell death and restored selected molecular and cellular processes across multiple vital organs. Commensurately, single-nucleus transcriptomic analysis revealed organ- and cell-type-specific gene expression patterns that are reflective of specific molecular and cellular repair processes. Our analysis comprises a comprehensive resource of cell-type-specific changes during defined ischaemic intervals and perfusion interventions spanning multiple organs, and it reveals an underappreciated potential for cellular recovery after prolonged whole-body warm ischaemia in a large mammal.

Trends, Advantages and Disadvantages in Combined Extracorporeal Lung and Kidney Support From a Technical Point of View

Extracorporeal membrane oxygenation (ECMO) provides pulmonary and/or cardiac support for critically ill patients. Due to their diseases, they are at high risk of developing acute kidney injury. In that case, continuous renal replacement therapy (CRRT) is applied to provide renal support and fluid management. The ECMO and CRRT circuits can be combined by an integrated or parallel approach. So far, all methods used for combined extracorporeal lung and kidney support present serious drawbacks. This includes not only high risks of circuit related complications such as bleeding, thrombus formation, and hemolysis, but also increase in technical workload and health care costs. In this sense, the development of a novel optimized artificial lung device with integrated renal support could offer important treatment benefits. Therefore, we conducted a review to provide technical background on existing techniques for extracorporeal lung and kidney support and give insight on important aspects to be addressed in the development of this novel highly integrated artificial lung device.

Monitoring during extracorporeal membrane oxygenation

PURPOSE OF REVIEW

Extracorporeal membrane oxygenation (ECMO) offers advanced mechanical support to patients with severe acute respiratory and/or cardiac failure. Ensuring an adequate therapeutic approach as well as prevention of ECMO-associated complications, by means of timely liberation, forms an essential part of standard ECMO care and is only achievable through continuous monitoring and evaluation. This review focus on the cardiorespiratory monitoring tools that can be used to assess and titrate adequacy of ECMO therapy; as well as methods to assess readiness to wean and/or discontinue ECMO support.

RECENT FINDINGS

Surrogates of tissue perfusion and near infrared spectroscopy are not standards of care but may provide useful information in select patients. Echocardiography allows to determine cannulas position, evaluate cardiac structures, and function, and diagnose complications. Respiratory monitoring is mandatory to achieve lung protective ventilation and identify early lung recovery, surrogate measurements of respiratory effort and ECMO derived parameters are invaluable in optimally managing ECMO patients.

SUMMARY

Novel applications of existing monitoring modalities alongside evolving technological advances enable the advanced monitoring required for safe delivery of ECMO. Liberation trials are necessary to minimize time sensitive ECMO related complications; however, these have yet to be standardized.

Factors affecting the clinical outcomes in pediatric post-cardiotomy patients requiring perioperative peritoneal dialysis

OBJECTIVE

Fluid overload is associated with increased mortality and morbidity in pediatric cardiac surgery. In the pediatric age group, peritoneal dialysis might improve postoperative outcome with avoiding fluid overload and electrolyte imbalance. It preserves hemodynamic status with the advantage of passive drainage. In this study, we are reporting our results of peritoneal dialysis after cardiac surgery.

METHODS

In this retrospective study, we evaluated the patients who underwent pediatric cardiac surgery in our hospital between December 2010 and January 2020. Patients who required peritoneal dialysis during hospitalization period were included in the study. Patients' clinical status and outcomes were evaluated.

RESULTS

Peritoneal dialysis was performed to 89 patients during the study period. The age varies from the newborn to 4 years old. The indication of peritoneal dialysis was prophylactic in 68.5% (n=61) and for the treatment in 31.5% (n=28). There were 31 mortalities. The risk factors for the mortality were preoperative lower age, longer cardiopulmonary bypass time, lengthened intubation, lengthened inotropic support, and requirement of extracorporeal membrane oxygenation (p<0.0001).

CONCLUSION

Earlier initiation of peritoneal dialysis in pediatric cardiac surgery helps maintain hemodynamic instability by avoiding fluid overload, considering the difficulty in the treatment of electrolyte imbalance and diuresis.

Determinants of Major Adverse Kidney Events in Extracorporeal Membrane Oxygenation Survivors

OBJECTIVES:

DESIGN:

SETTING:

PATIENTS:

INTERVENTIONS:

MEASURES AND MAIN RESULTS:

CONCLUSIONS:

Pediatric Extracorporeal Membrane Oxygenation Anticoagulation Protocol Associated with a Decrease in Complications

Extracorporeal membrane oxygenation (ECMO) in pediatrics has rapidly progressed in recent years; however, there continues to be considerable variation in anticoagulation practices. In 2016, we implemented a standardized anticoagulation protocol in effort to reduce clotting and bleeding complications. A single-center retrospective analysis of pediatric patients requiring ECMO between 2014 and 2018 was performed. One hundred one ECMO cases in 94 pediatric patients met eligibility criteria (preprotocol = 64 cases; postprotocol = 37 cases). Demographics, ECMO parameters, complications, laboratories, and blood product requirements were analyzed for differences between the two groups. There was a significant decrease in the incidence of hematologic (p < 0.022), neurologic (p < 0.001), and renal complications (p < 0.001) in the postprotocol era. Incidence of bleeding, cardiac/pulmonary complications, and circuit changes were similar between the groups. The postprotocol group required fewer transfusions of red blood cells and cryoprecipitate. Additionally, platelet counts and fibrinogen levels were maintained higher in the postprotocol era. In conclusion, implementation of a standardized anticoagulation protocol was associated with improved anticoagulation parameters and a decrease in hematologic and neurologic complications, coagulopathy, renal injury, and blood product administration. We attribute these findings to transitioning to anti-Xa as a measure of heparinization and maintaining higher platelet counts.

Nephrology Considerations in the Management of Durable and Temporary Mechanical Circulatory Support

Durable and temporary mechanical circulatory support (MCS) use is growing for a range of cardiovascular indications. Kidney dysfunction is common in people evaluated for or receiving durable or temporary MCS and portends worse outcomes. This kidney dysfunction can be due to preexisting kidney chronic kidney disease (CKD), acute kidney injury (AKI) related to acute cardiovascular disease necessitating MCS, AKI due to cardiac procedures, and acute and chronic MCS effects and complications. Durable MCS, with implantable continuous flow pumps, is used for long-term support in advanced heart failure refractory to guideline-directed medical and device therapy, either permanently or as a bridge to heart transplantation. Temporary MCS-encompassing in this review intra-aortic balloon pumps (IABP), axial flow pumps, centrifugal flow pumps, and venoarterial ECMO-is used for diverse situations: high-risk percutaneous coronary interventions (PCI), acute decompensated heart failure, cardiogenic shock, and resuscitation after cardiac arrest. The wide adoption of MCS makes it imperative to improve understanding of the effects of MCS on kidney health/function and of kidney health/function on MCS outcomes. The complex structure and functions of the kidney, and the complex health states of individuals receiving MCS, makes investigations in this area challenging, and current knowledge is limited. Fortunately, the increasing nephrology toolbox of noninvasive kidney health/function assessments may enable development and testing of individualized management strategies and therapeutics in the future. We review technology, epidemiology, pathophysiology, clinical considerations, and future directions in MCS and nephrology.

Renal Recovery in Critically Ill Adult Patients Treated with Veno-Venous Or Veno-Arterial Extra Corporeal Membrane Oxygenation: a Retrospective Cohort Analysis

Introduction

Patients on extracorporeal membrane oxygenator (ECMO) therapy are critically ill and often develop acute kidney injury (AKI) during hospitalisation. Little is known about the association of exposure to and the effect of the type of ECMO and extent of renal recovery after AKI development.

Aim of the study

In patients who developed AKI, renal recovery was characterised as complete, partial or dialysis-dependent at the time of hospital discharge in both the Veno-Arterial (VA) and Veno-Venous (VV) ECMO treatment groups.

Material and methods

The study consisted of a single-centre retrospective cohort that includes all adult patients (n=125) who received ECMO treatment at a tertiary academic medical centre between 2015 to 2019. Data on demographics, type of ECMO circuit, comorbidities, exposure to nephrotoxic factors and receipt of renal replacement therapy (RRT) were collected as a part of the analysis. Acute Kidney Injury Network (AKIN) criteria were used for the diagnosis and classification of AKI. Group differences were assessed using Fisher’s exact tests for categorical data and independent t-tests for continuous outcomes.

Results

Sixty-four patients received VA ECMO, and 58 received VV ECMO. AKI developed in 58(91%) in the VA ECMO group and 51 (88%) in the VV ECMO group (p=0.77). RRT was prescribed in significantly higher numbers in the VV group 38 (75%) compared to the VA group 27 (47%) (p=0.0035). At the time of discharge, AKI recovery rate in the VA group consisted of 15 (26%) complete recovery and 5 (9%) partial recovery; 1 (2%) remained dialysis-dependent. In the VV group, 22 (43%) had complete recovery (p=0.07), 3(6%) had partial recovery (p=0.72), and 1 (2%) was dialysis-dependent (p>0.99). In-hospital mortality was 64% in the VA group and 49% in the VV group (p=0.13).

Conclusions

Renal outcomes in critically ill patients who develop AKI are not associated with the type of ECMO used. This serves as preliminary data for future studies in the area.

Residual Lesion Diagnostics in Pediatric Postcardiotomy Extracorporeal Membrane Oxygenation and Its Outcomes

BACKGROUND

To assess the impact of diagnostic procedures in identifying residual lesions during extracorporeal membrane oxygenation (ECMO) on survival after pediatric cardiac surgery.

METHODS

Between January 2012 and December 2017, 74 patients required postcardiotomy ECMO. Patients were retrospectively divided into 2 groups: Group I underwent only echocardiography ([echo only] 46 patients, 62.2%) and group II (echo+) underwent additional diagnostic tests (ie, computed tomography [CT] or cardiac catheterization; 28 patients, 37.8%). Propensity score matching was used to balance the 2 groups by baseline characteristics.

RESULTS

Two equal groups (28 patients in each group) were formed by propensity score matching. Fourteen (50%) patients in the echo-only group and 20 (71%) patients in the echo+ group were successfully weaned from ECMO (P = .17). Four (14.3%) patients survived in the echo-only group and 15 (53.5%) patients survived in the echo+ group (P = .004). Patients in the echo+ group had a lower chance of dying compared to the echo-only group (odds ratio, 0.14.6; 95% CI, 0.039-0.52; P = .003). The residual lesions, which may have served as a mortality factor, were found by autopsy in 8 (40%) patients in the echo-only group, while none were found in the echo+ group (P = .014).

CONCLUSIONS

The autopsies of patients who died despite postcardiotomy ECMO support showed that in 40% of cases that had been investigated by echo only, residual lesions that had not been detected by echocardiography were present. The cardiac catheterization and CT during ECMO are effective and safe for identifying residual lesions. Early detection and repair of residual lesions may increase the survival rate of pediatric cardiac patients on ECMO.

Risk Factors for Acute Kidney Injury Requiring Renal Replacement Therapy after Orthotopic Heart Transplantation in Patients with Preserved Renal Function

Acute kidney injury (AKI), requiring renal replacement therapy (RRT). is a serious complication after orthotopic heart transplantation (HTX). In patients with preexisting impaired renal function, postoperative AKI is unsurprising. However, even in patients with preserved renal function, AKI requiring RRT is frequent. Therefore, this study aimed to identify risk factors associated with postoperative AKI requiring RRT after HTX in this sub-cohort. This retrospective cohort study included patients ≥ 18 years of age with preserved renal function (defined as preoperative glomerular filtration rate ≥ 60 mL/min) who underwent HTX between 2010 and 2021. In total, 107 patients were included in the analysis (mean age 52 ± 12 years, 78.5% male, 45.8% AKI requiring RRT). Based on univariate logistic regression, use of extracorporeal membrane oxygenation, postoperative infection, levosimendan therapy, duration of norepinephrine (NE) therapy and maximum daily increase in tacrolimus plasma levels were chosen to be included into multivariate analysis. Duration of NE therapy and maximum daily increase in tacrolimus plasma levels remained as independent significant risk factors (NE: OR 1.01, 95%CI: 1.00–1.02, p = 0.005; increase in tacrolimus plasma level: OR 1.18, 95%CI: 1.01–1.37, p = 0.036). In conclusion, this study identified long NE therapy and maximum daily increase in tacrolimus plasma levels as risk factors for AKI requiring RRT in HTX patients with preserved renal function.

Acute kidney injury in ECMO patients

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2021. Other selected articles can be found online at  https://www.biomedcentral.com/collections/annualupdate2021 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from  https://link.springer.com/bookseries/8901 .

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.

Liberation From Venoarterial Extracorporeal Membrane Oxygenation: A Review

Venoarterial extracorporeal membrane oxygenation may be used for circulatory support in cardiogenic shock as a bridge to recovery, a bridge to a ventricular assist device (VAD), or a bridge to transplant. While the determination of potential exit strategies is essential before cannulation, the final determination of a patient's options may change, in part, through their in-hospital clinical course. We propose that liberation from venoarterial extracorporeal membrane oxygenation should be conceptualized as a process of discovery in the assessment of a patient's underlying clinical status and a key driver of further clinical decision-making. A trial of liberation from support should be considered when the goals of the weaning trial are well-defined and, ideally, in the absence of potentially confounding clinical factors. In this review, we will discuss readiness to wean criteria from venoarterial extracorporeal membrane oxygenation, as well as specific clinical, biochemical, and echocardiographic parameters that may prove useful in determining weaning timing and revealing the patient's underlying hemodynamic status and prognosis. The role of various cannula configurations, support devices, and pharmacological adjuncts will also be discussed. Finally, we highlight current gaps in evidence and suggest areas of future research.

Outcome of extracorporeal membrane oxygenation support in patients with liver cirrhosis: a nationwide population-based cohort study

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) is used for life support in patients with liver cirrhosis (LC). However, there have been no studies evaluating the outcome of ECMO support in patients with LC.

METHODS

Using Taiwan's National Health Insurance (NHI) database, we retrospectively evaluated patients with LC who received veno-venous or veno-arterial ECMO between 1 January 2000 and 31 December 2013. The outcomes included ECMO-related complications, in-hospital mortality, all-cause mortality and long-term outcomes in patients with and without LC.

RESULTS

A total of 7003 patients who received ECMO, of whom 233 (3.3%) had LC, were eligible for analysis. The LC patients who received ECMO support had a significantly higher risk of in-hospital mortality than the non-LC group (76.4% vs 60.7%; odds ratio 1.97; 95% confidence interval 1.44-2.70). The LC group also had a higher risk of complications, including de novo dialysis and massive blood transfusion with >10 units of red blood cells. Patients ≥65 years of age, patients with respiratory disease, patients with hypoalbuminaemia and liver transplant patients had higher in-hospital and 1-year mortality. The mortality rates for patients with 2 or more risk factors were 90.3% and 95.8%, respectively. LC was associated with a higher incidence of all-cause mortality and liver-related outcomes during follow-up.

CONCLUSIONS

Our findings raise questions regarding the utility of ECMO for LC patients, especially when >2 risk factors have been identified. ECMO support for LC patients should be used with caution and with careful patient selection.

Myocardial Injury Promotes Matrix Metalloproteinase-9 Activity in the Renal Cortex in Preclinical Models of Acute Myocardial Infarction

New mechanistic insight into how the kidney responds to cardiac injury during acute myocardial infarction (AMI) is required. We hypothesized that AMI promotes inflammation and matrix metalloproteinase-9 (MMP9) activity in the kidney and studied the effect of initiating an Impella CP or veno-arterial extracorporeal membrane oxygenation (VA-ECMO) before coronary reperfusion during AMI. Adult male swine were subjected to coronary occlusion and either reperfusion (ischemia-reperfusion; IR) or support with either Impella or VA-ECMO before reperfusion. IR and ECMO increased while Impella reduced levels of MMP-9 in the myocardial infarct zone, circulation, and renal cortex. Compared to IR, Impella reduced myocardial infarct size and urinary KIM-1 levels, but VA-ECMO did not. IR and VA-ECMO increased pro-fibrogenic signaling via transforming growth factor-beta and endoglin in the renal cortex, but Impella did not. These findings identify that AMI increases inflammatory activity in the kidney, which may be attenuated by Impella support.

Continuous renal replacement therapy in patients treated with extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a life‐saving therapy utilized for patients with severe life‐threatening cardiorespiratory failure. Patients treated with ECMO are among the most severely ill encountered in critical care and are at high‐risk of developing multiple organ dysfunction, including acute kidney injury (AKI) and fluid overload. Continuous renal replacement therapy (CRRT) is increasingly utilized inpatients on ECMO to manage AKI and treat fluid overload. The indications for renal replacement therapy for patients on ECMO are similar to those of other critically ill populations; however, there is wide practice variation in how renal supportive therapies are utilized during ECMO. For patients requiring both CRRT and ECMO, CRRT may be connected directly to the ECMO circuit, or CRRT and ECMO may be performed independently. This review will summarize current knowledge of the epidemiology of AKI, indications and timing of CRRT, delivery of CRRT, and the outcomes of patients requiring CRRT with ECMO.

Risk Factors of Acute Kidney Injury in ECMO Patients: A Systematic Review and Meta-Analysis

PURPOSE

Acute kidney injury (AKI) is one of the most common complications in patients receiving extracorporeal membrane oxygenation (ECMO), but there is no systematic analysis regarding its risk factors. This meta-analysis aims to determine the risk factors of AKI in adult patients with ECMO treatment.

METHODS

Two authors independently carried out a systemic literature search using PubMed, Web of Science, and Embase until April 20, 2020 (inclusive) to enroll 12 studies reporting the necessary clinical characteristics. The Gender (male), age, APACHE II score, SOFA score, cancer, diabetes mellitus (DM), intra-aortic balloon pump (IABP), postcardiotomy, and ECMO supporting duration were pooled for further analysis by STATA.

RESULTS

Adult patients receiving ECMO who develop AKI and severe AKI incidents are usually older or have a higher APACHE II scores; in addition, severe AKI is related to higher SOFA scores, DM, and longer duration of ECMO support.

CONCLUSIONS

Patients with these clinical characteristics should be paid more attention during ECMO. There remains a need for additional studies to validate these conclusions and to detect additional AKI risk factors for ECMO patients.

Concurrent Use of Renal Replacement Therapy during Extracorporeal Membrane Oxygenation Support: A Systematic Review and Meta-Analysis

Patients supported with extracorporeal membrane oxygenation (ECMO) often receive renal replacement therapy (RRT). We conducted this systematic review and meta-analysis (between January 2000 and September 2020) to assess outcomes in patients who received RRT on ECMO. Random-effects meta-analyses were performed using R 3.6.1 and certainty of evidence was rated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The primary outcome was pooled mortality. The duration of ECMO support and ICU/hospital lengths of stay were also investigated. Meta-regression analyses identified factors associated with mortality. A total of 5896 adult patients (from 24 observational studies and 1 randomised controlled trial) were included in this review. Overall pooled mortality due to concurrent use of RRT while on ECMO from observational studies was 63.0% (95% CI: 56.0–69.6%). In patients receiving RRT, mortality decreased by 20% in the last five years; the mean duration of ECMO support and ICU and hospital lengths of stay were 9.33 days (95% CI: 7.74–10.92), 15.76 days (95% CI: 12.83–18.69) and 28.47 days (95% CI: 22.13–34.81), respectively, with an 81% increased risk of death (RR: 1.81, 95% CI: 1.56–2.08, p < 0.001). RRT on ECMO was associated with higher mortality rates and a longer ICU/hospital stay compared to those without RRT. Future research should focus on minimizing renal dysfunction in ECMO patients and define the optimal timing of RRT initiation.

Early Fluid Accumulation and Intensive Care Unit Mortality in Children Receiving Extracorporeal Membrane Oxygenation

Purpose of this study was to evaluate the impact of early fluid accumulation and renal dysfunction on mortality in children receiving extracorporeal membrane oxygenation (ECMO). Retrospective cohort study of neonatal and pediatric patients who received ECMO between January 2010 and December 2012 in a tertiary level multidisciplinary pediatric intensive care unit (ICU). Ninety-six patients were included, and forty-six (48%) of them received continuous renal replacement therapy (CRRT) during ECMO. Overall mortality was 38.5%. Proportion of patients with acute kidney injury (AKI) at ICU admission was 33% and increased to 47% at ECMO initiation. High-risk diagnoses, extracorporeal cardiopulmonary resuscitation (ECPR), and venoarterial (VA)-ECMO were more common among nonsurvivors. Nonsurvivors had significantly higher proportion of AKI at ICU admission (OR: 2.59, p = 0.04) and fluid accumulation on ECMO day 1 (9% vs. 1%, p = 0.05) compared with survivors. Multivariable logistic regression analysis (adjusted for a propensity score based on nonrenal factors associated with increased mortality) demonstrated that fluid accumulation on ECMO day 1 is significantly associated with increased ICU mortality (OR: 1.07, p = 0.04). Fluid accumulation within the first 24 hours after ECMO cannulation is significantly associated with increased ICU mortality in neonatal and pediatric patients. Prospective studies evaluating the impact of conservative fluid management and CRRT during the initial phase of ECMO may help further define this relationship.

How To Prescribe And Troubleshoot Continuous Renal Replacement Therapy: A Case-Based Review

Continuous RRT (CRRT) is the preferred dialysis modality for solute management, acid-base stability, and volume control in patients who are critically ill with AKI in the intensive care unit (ICU). CRRT offers multiple advantages over conventional hemodialysis in the critically ill population, such as greater hemodynamic stability, better fluid management, greater solute control, lower bleeding risk, and a more continuous (physiologic) approach of kidney support. Despite its frequent use, several aspects of CRRT delivery are still not fully standardized, or do not have solid evidence-based foundations. In this study, we provide a case-based review and recommendations of common scenarios and interventions encountered during the provision of CRRT to patients who are critically ill. Specific focus is on initial prescription, CRRT dosing, and adjustments related to severe hyponatremia management, concomitant extracorporeal membrane oxygenation support, dialysis catheter placement, use of regional citrate anticoagulation, and antibiotic dosing. This case-driven simulation is made as the clinical status of the patient evolves, and is on the basis of step-wise decisions made during the care of this patient, according to the specific patient's needs and the logistics available at the corresponding institution.

Continuous Renal Replacement Therapy in Venovenous Extracorporeal Membrane Oxygenation: A Retrospective Study on Regional Citrate Anticoagulation

Systemic infusion of unfractionated heparin (UFH) is the standard anticoagulation technique for continuous renal replacement therapy (CRRT) during extracorporeal membrane oxygenation (ECMO), but often fails to avoid CRRT circuit clotting. The aim of this study was to assess, in patients undergoing CRRT during venovenous ECMO (vv-ECMO), the efficacy and safety of adding regional citrate anticoagulation (RCA) for CRRT circuit anticoagulation (RCA + UFH group) compared with the sole systemic heparin anticoagulation (UFH group). We performed a retrospective chart review (2009-2018) of patients treated with CRRT during ECMO. We evaluated filter life span, rate of CRRT circuit clotting, and coagulation parameters. The incidence of citrate anticoagulation-related complications was recorded. Forty-eight consecutive adult patients underwent CRRT during vv-ECMO in the study period. The incidence of CRRT circuit clotting was lower in the RCA + UFH group (11% vs. 38% in the UFH group, p < 0.001). Log-rank survival analysis demonstrated longer circuit lifetime for RCA + UFH group. No complication ascribable to citrate anticoagulation was recorded. Regional citrate anticoagulation resulted a feasible, safe, and effective technique as additional anticoagulation for CRRT circuits during ECMO. Compared with systemic heparinization only, this technique allowed to reduce the rate of CRRT circuit clotting.

Severe Acute Kidney Injury in Cardiovascular Surgery: Thrombotic Microangiopathy as a Differential Diagnosis to Ischemia Reperfusion Injury. A Retrospective Study

BACKGROUND

Acute kidney injury (AKI) after cardiovascular surgery (CVS) infers high morbidity and mortality and may be caused by thrombotic microangiopathy (TMA). This study aimed to assess incidence, risk factors, kidney function, and mortality of patients with a postoperative TMA as possible cause of severe AKI following cardiovascular surgery.

METHODS

We analyzed retrospectively all patients admitted to the ICU after a cardiovascular procedure between 01/2018 and 03/2019 with severe AKI and need for renal replacement therapy (RRT). TMA was defined as post-surgery-AKI including need for RRT, hemolytic anemia, and thrombocytopenia. TMA patients were compared to patients with AKI requiring RRT without TMA.

RESULTS

Out of 893 patients, 69 (7.7%) needed RRT within one week after surgery due to severe AKI. Among those, 15 (21.7%) fulfilled TMA criteria. Aortic surgery suggested an increased risk for TMA (9/15 (60.0%) vs. 7/54 (31.5%), OR 3.26, CI 1.0013-10.64). Ten TMA patients required plasmapheresis and/or eculizumab, and five recovered spontaneously. Preoperative kidney function was significantly better in TMA patients than in controls (eGFR 92 vs. 60.5 mL/min, p = 0.004). However, postoperative TMA resulted in a more pronounced GFR loss (ΔeGFR -54 vs. -17 mL/min, p = 0.062). There were no deaths in the TMA group.

CONCLUSION

Our findings suggest TMA as an important differential diagnosis of severe AKI following cardiovascular surgery, which may be triggered by aortic surgery. Therefore, early diagnosis and timely treatment of TMA could reduce kidney damage and improve mortality of AKI following cardiovascular surgery, which should be further investigated.

Post-operative renal failure management in mechanical circulatory support patients

Acute kidney injury (AKI) occurs commonly in patients requiring mechanical circulatory support (MCS) after cardiothoracic surgery. The prognostic implications of AKI in this patient group relate closely to the pathophysiology and risk factors associated with the underlying disease; pre-operative, intra-operative, and post-operative variables; hemodynamic factors; and type of support device used. General approaches to AKI management, including prevention strategies, medical management, and hemodynamic support, are also applicable in patients requiring MCS. Approaches to renal replacement therapy vary depend on patient factors, device-specific factors, and local preferences and experience. In this invited narrative review, we discuss the pathophysiology, risk factors, and prognostic implications of AKI in post-operative adult patients following institution of MCS. Management strategies for AKI are presented with a focus on those supported with either extracorporeal membrane oxygenation or a ventricular assist device.

The science of safety: complications associated with the use of mechanical circulatory support in cardiogenic shock and best practices to maximize safety

Acute mechanical circulatory support (MCS) devices are widely used in cardiogenic shock (CS) despite a lack of high-quality clinical evidence to guide their use. Multiple devices exist across a spectrum from modest to complete support, and each is associated with unique risks. In this review, we summarize existing data on complications associated with the three most widely used acute MCS platforms: the intra-aortic balloon pump (IABP), Impella systems, and veno-arterial extracorporeal membrane oxygenation (VA-ECMO). We review evidence from available randomized trials and highlight challenges comparing complication rates from case series and comparative observational studies where a lack of granular data precludes appropriate matching of patients by CS severity. We further offer a series of best practices to help shock practitioners minimize the risk of MCS-associated complications and ensure the best possible outcomes for patients.