Extracorporeal organ support (ECOS) in critical illness and acute kidney injury: from native to artificial organ crosstalk

Extracorporeal organ support for critically ill patients: Overcoming the past, achieving the maximum at present, and redefining the future

Extracorporeal organ support (ECOS) has made remarkable progress over the last few years. Renal replacement therapy, introduced a few decades ago, was the first available application of ECOS. The subsequent evolution of ECOS enabled the enhanced support to many other organs, including the heart [veno-arterial extracorporeal membrane oxygenation (ECMO), slow continuous ultrafiltration], the lungs (veno-venous ECMO, extracorporeal carbon dioxide removal), and the liver (blood purification techniques for the detoxification of liver toxins). Moreover, additional indications of these methods, including the suppression of excessive inflammatory response occurring in severe disorders such as sepsis, coronavirus disease 2019, pancreatitis, and trauma (blood purification techniques for the removal of exotoxins, endotoxins, or cytokines), have arisen. Multiple organ support therapy is crucial since a vast majority of critically ill patients present not with a single but with multiple organ failure (MOF), whereas, traditional therapeutic approaches (mechanical ventilation for acute respiratory failure, antibiotics for sepsis, and inotropes for cardiac dysfunction) have reached the maximum efficacy and cannot be improved further. However, several issues remain to be clarified, such as the complexity and cost of ECOS systems, standardization of indications, therapeutic protocols and initiation time, choice of the patients who will benefit most from these interventions, while evidence from randomized controlled trials supporting their use is still limited. Nevertheless, these methods are currently a part of routine clinical practice in intensive care units. This editorial presents the past, present, and future considerations, as well as perspectives regarding these therapies. Our better understanding of these methods, the pathophysiology of MOF, the crosstalk between native organs resulting in MOF, and the crosstalk between native organs and artificial organ support systems when applied sequentially or simultaneously, will lead to the multiplication of their effects and the minimization of complications arising from their use.

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.

Heparin dosing in patients with Impella-supported cardiogenic shock

BACKGROUND

Impella™ is increasingly used in cardiogenic shock. However, thromboembolic and bleeding events are frequent during percutaneous mechanical circulatory support (pMCS).

OBJECTIVE

Therefore, we aimed to explore the optimal anticoagulation regime for pMCS to prevent thromboembolism and bleedings.

METHODS

This hypothesis-generating multi-center cohort study investigated 170 patients with left-Impella™ support. We (A) compared bleeding/thrombotic events in two centers with therapeutic range (TR-aPTT) activated partial thromboplastin time (60-80s) and (B) compared events of these centers with one center with intermediate range aPTT (40-60s).

RESULTS

After matching, there were no differences in patients' characteristics. In centers aiming at TR-aPTT, major bleeding was numerically lower with aPTT <60s within 48 h of left-Impella™ support, versus patients that achieved the aimed aPTT of ≥60s [aPTT ≥60s: 22 (37.3%) vs. aPTT<60s 14 (23.7%); Hazard ratio [HR], 0.62 (95%) CI, 0.28-1.38; p = 0.234]. Major cardiovascular and cerebrovascular adverse events (MACCE) did not differ between groups. In comparison of centers, TR-aPTT strategy showed higher major bleeding rates [TR: 8 (47.1%) vs. intermediate range: 1 (5.9%); HR, 0.06 (95%) CI, 0.01-0.45; p = 0.006]. MACCE were lower in the intermediate range aPTT group as well [TR 12 (70.6%) vs. intermediate range 5 (29.4%) HR, 0.32 (95%) CI, 0.11-0.92; p = 0.034].

CONCLUSION

This pilot analysis showed that lowering UFH-targets in left-Impella™ supported CS patients seems to be a safe and promising strategy for reducing major bleedings without increasing MACCE. This needs to be validated in larger, randomized clinical trials.

Kidney Increase Natriuresis but Not Glomerular Filtration Under Veno-venous ECMO, a Retrospective Study

PURPOSE

Acute kidney injury is a frequent complication of acute respiratory distress syndrome (ARDS). We aim to study the evolution of kidney function in patients presenting severe ARDS and requiring veno-venous extracorporeal membrane oxygenation (VV ECMO).

METHODS

We conducted a multicenter retrospective study, including adult patients requiring VV ECMO for ARDS. The primary outcome was the evolution of the serum creatinine level after VV ECMO initiation. Secondary outcomes were change in urine output, and urine biochemical parameters after VV ECMO initiation.

RESULTS

One hundred and two patients were included. VV ECMO was initiated after a median of 6 days of mechanical ventilation, mainly for ARDS caused by COVID-19 (73%). Serum creatinine level did not significantly differ after VV ECMO initiation (P = .20). VV ECMO was associated with a significant increase in daily urine output (+6.6 mL/kg/day, [3.8;9.3] P < .001), even after adjustment for potential confounding factors; with an increase in natriuresis. The increase in urine output under VV ECMO was associated with a reduced risk of receiving kidney replacement therapy (OR 0.4 [0.2;0.8], P = .026).

CONCLUSIONS

VV ECMO initiation in severe ARDS is associated with an increase in daily urine output and natriuresis, without change in glomerular filtration rate.

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.

Current knowledge gaps in extracorporeal respiratory support

Extracorporeal life support (ECLS) for acute respiratory failure encompasses veno-venous extracorporeal membrane oxygenation (V-V ECMO) and extracorporeal carbon dioxide removal (ECCO2R). V-V ECMO is primarily used to treat severe acute respiratory distress syndrome (ARDS), characterized by life-threatening hypoxemia or ventilatory insufficiency with conventional protective settings. It employs an artificial lung with high blood flows, and allows improvement in gas exchange, correction of hypoxemia, and reduction of the workload on the native lung. On the other hand, ECCO2R focuses on carbon dioxide removal and ventilatory load reduction ("ultra-protective ventilation") in moderate ARDS, or in avoiding pump failure in acute exacerbated chronic obstructive pulmonary disease. Clinical indications for V-V ECLS are tailored to individual patients, as there are no absolute contraindications. However, determining the ideal timing for initiating extracorporeal respiratory support remains uncertain. Current ECLS equipment faces issues like size and durability. Innovations include intravascular lung assist devices (ILADs) and pumpless devices, though they come with their own challenges. Efficient gas exchange relies on modern oxygenators using hollow fiber designs, but research is exploring microfluidic technology to improve oxygenator size, thrombogenicity, and blood flow capacity. Coagulation management during V-V ECLS is crucial due to common bleeding and thrombosis complications; indeed, anticoagulation strategies and monitoring systems require improvement, while surface coatings and new materials show promise. Moreover, pharmacokinetics during ECLS significantly impact antibiotic therapy, necessitating therapeutic drug monitoring for precise dosing. Managing native lung ventilation during V-V ECMO remains complex, requiring a careful balance between benefits and potential risks for spontaneously breathing patients. Moreover, weaning from V-V ECMO is recognized as an area of relevant uncertainty, requiring further research. In the last decade, the concept of Extracorporeal Organ Support (ECOS) for patients with multiple organ dysfunction has emerged, combining ECLS with other organ support therapies to provide a more holistic approach for critically ill patients. In this review, we aim at providing an in-depth overview of V-V ECMO and ECCO2R, addressing various aspects of their use, challenges, and potential future directions in research and development.

COVID-19 and Kidney: The Importance of Follow-Up and Long-Term Screening

Renal involvement and kidney injury are common in COVID-19 patients, and the symptoms are more severe if the patient already has renal impairment. Renal involvement in COVID-19 is multifactorial, and the renal tubule is mainly affected, along with podocyte injury during SARS-CoV-2 infection. Inflammation, complement activation, hypercoagulation, and crosstalk between the kidney and lungs, brain, and heart are contributory factors. Kidney injury during the acute phase, termed acute kidney injury (AKI), may proceed to chronic kidney disease if the patient is discharged with renal impairment. Both AKI and chronic kidney disease (CKD) increase mortality in COVID-19 patients. Further, COVID-19 infection in patients suffering from CKD is more severe and increases the mortality rate. Thus, it is important to address both categories of patients, either developing AKI or CKD after COVID-19 or previously having CKD, with proper management and treatment. This review discusses the pathophysiology involved in AKI and CKD in COVID-19 infection, followed by management and treatment of AKI and CKD. This is followed by a discussion of the importance of screening and treatment of CKD patients infected with COVID-19 and future perspectives to improve treatment in such patients.

Impact of renal complications on outcome in adult patients with acute fulminant myocarditis receiving venoarterial extracorporeal membrane oxygenation: an analysis of nationwide CSECLS database in China

BACKGROUND

Limited data are available on renal complications in patients with acute fulminant myocarditis (AFM) receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) support in China. To evaluate the impact of renal complications on outcomes in adult patients with AFM supported with VA-ECMO.

METHODS

Data were extracted from Chinese Society of ExtraCorporeal Life Support (CSECLS) Registry database. Adult patients who were diagnosed with AFM receiving VA-ECMO support in the database were included. The primary outcome was 30-day mortality in patients with AFM supported with VA-ECMO. Logistic regression model was used to examine the impact of renal complications on 30-day mortality by adjusting confounders.

RESULTS

A total of 202 patients were included. The median age was 38 years (IQR 29-48) and males (n = 103) represented 51.0% of the total accounted patients. The median ECMO duration was 142.9 h (IQR 112.1-188.8 h). 178 (88.1%) patients weaned from ECMO and 156 (71.9%) patients survived. 94(46.5%) patients developed renal complications while on ECMO course. Patients with renal complications had higher 30-day mortality (40.7% (37 of 94) vs 8.3% (9 of 108), P < 0.001) compared with those without. The development of renal complications was related to a 3.12-fold increase risk of 30-day mortality (adjusted OR 3.120, 95%CI 1.002-6.577, P = 0.049). Increasing age (adjusted OR1.025, 95% CI 1.008-1.298, P = 0.040) and higher SOFA score (adjusted OR 1.162, 95%CI 1.012-1.334, P = 0.034) were independent risk factors of renal complications.

CONCLUSIONS

Our findings demonstrated that patients with AFM receiving VA-ECMO at high risk of developing renal complications. Advancing age and higher SOFA score was associated with increased risk of developing renal complications. The onset of renal complications was significantly associated with 30-day mortality.

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.

Sepsis-associated acute kidney injury: consensus report of the 28th Acute Disease Quality Initiative workgroup

Sepsis-associated acute kidney injury (SA-AKI) is common in critically ill patients and is strongly associated with adverse outcomes, including an increased risk of chronic kidney disease, cardiovascular events and death. The pathophysiology of SA-AKI remains elusive, although microcirculatory dysfunction, cellular metabolic reprogramming and dysregulated inflammatory responses have been implicated in preclinical studies. SA-AKI is best defined as the occurrence of AKI within 7 days of sepsis onset (diagnosed according to Kidney Disease Improving Global Outcome criteria and Sepsis 3 criteria, respectively). Improving outcomes in SA-AKI is challenging, as patients can present with either clinical or subclinical AKI. Early identification of patients at risk of AKI, or at risk of progressing to severe and/or persistent AKI, is crucial to the timely initiation of adequate supportive measures, including limiting further insults to the kidney. Accordingly, the discovery of biomarkers associated with AKI that can aid in early diagnosis is an area of intensive investigation. Additionally, high-quality evidence on best-practice care of patients with AKI, sepsis and SA-AKI has continued to accrue. Although specific therapeutic options are limited, several clinical trials have evaluated the use of care bundles and extracorporeal techniques as potential therapeutic approaches. Here we provide graded recommendations for managing SA-AKI and highlight priorities for future research.

Antimicrobial Exposure in Critically Ill Patients with Sepsis-Associated Multi-Organ Dysfunction Requiring Extracorporeal Organ Support: A Narrative Review

Sepsis is a leading cause of disability and mortality worldwide. The pathophysiology of sepsis relies on the maladaptive host response to pathogens that fosters unbalanced organ crosstalk and induces multi-organ dysfunction, whose severity was directly associated with mortality. In septic patients, etiologic interventions aiming to reduce the pathogen load via appropriate antimicrobial therapy and the effective control of the source infection were demonstrated to improve clinical outcomes. Nonetheless, extracorporeal organ support represents a complementary intervention that may play a role in mitigating life-threatening complications caused by sepsis-associated multi-organ dysfunction. In this setting, an increasing amount of research raised concerns about the risk of suboptimal antimicrobial exposure in critically ill patients with sepsis, which may be worsened by the concomitant delivery of extracorporeal organ support. Accordingly, several strategies have been implemented to overcome this issue. In this narrative review, we discussed the pharmacokinetic features of antimicrobials and mechanisms that may favor drug removal during renal replacement therapy, coupled plasma filtration and absorption, therapeutic plasma exchange, hemoperfusion, extracorporeal CO₂ removal and extracorporeal membrane oxygenation. We also provided an overview of evidence-based strategies that may help the physician to safely prescribe effective antimicrobial doses in critically ill patients with sepsis-associated multi-organ dysfunction who receive extracorporeal organ support.

Rationale for sequential extracorporeal therapy (SET) in sepsis

Sepsis and septic shock remain drivers for morbidity and mortality in critical illness. The clinical picture of patients presenting with these syndromes evolves rapidly and may be characterised by: (a) microbial host invasion, (b) establishment of an infection focus, (c) opsonisation of bacterial products (e.g. lipopolysaccharide), (d) recognition of pathogens resulting in an immune response, (e) cellular and humoral effects of circulating pathogen and pathogen products, (f) immunodysregulation and endocrine effects of cytokines, (g) endothelial and organ damage, and (h) organ crosstalk and multiple organ dysfunction. Each step may be a potential target for a specific therapeutic approach. At various stages, extracorporeal therapies may target circulating molecules for removal. In sequence, we could consider: (a) pathogen removal from the circulation with affinity binders and cartridges (specific), (b) circulating endotoxin removal by haemoperfusion with polymyxin B adsorbers (specific), (c) cytokine removal by haemoperfusion with sorbent cartridges or adsorbing membranes (non-specific), (d) extracorporeal organ support with different techniques for respiratory and cardiac support (CO₂ removal or extracorporeal membrane oxygenation), and renal support (haemofiltration, haemodialysis, or ultrafiltration). The sequence of events and the use of different techniques at different points for specific targets will likely require trials with endpoints other than mortality. Instead, the primary objectives should be to achieve the desired action by using extracorporeal therapy at a specific point.

NEUROLOGIC IMPAIRMENT IN PATIENTS WITH EXTRACORPOREAL CARDIOPULMONARY RESUSCITATION SUPPORT: CLINICAL FEATURES AND LONG-TERM OUTCOMES

ABSTRACT

Introduction: The present study aimed to explore the clinical features and long-term outcomes associated with neurologic impairment in patients with cardiac arrest (CA) who received extracorporeal cardiopulmonary resuscitation (ECPR). Methods: A total of 37 adult CA patients who underwent venoarterial extracorporeal membrane oxygenation and were admitted to our department between January 2015 and February 2022 were divided according to neurologic impairment. Baseline and CPR- and ECMO-related characteristics were compared between the two groups. Long-term neurologic outcomes were collected via telephone follow-ups. Results: Twenty-four (64.9%) ECPR-supported patients developed neurologic impairments. The two groups differed significantly in median age (P = 0.026), proportion of intra-aortic balloon pump (IABP) support (P = 0.011), proportion of continuous renal replacement therapy (P = 0.025), and median serum creatinine (Cr) level (P = 0.012) pre-ECMO. The 28-day mortality (P = 0.001), hospital mortality (P = 0.003), median duration from CA to restoration of spontaneous circulation (P = 0.029), proportion of patients with nonpulsatile perfusion (NP) >12 hours (P = 0.040), and median ECMO duration (P = 0.047) were higher in the neurologic impairment group. In contrast, the group without neurologic impairment exhibited a longer median intensive care unit length of stay (P = 0.047), longer median hospital LOS (P = 0.031), and more successful ECMO weaning (P = 0.049). Moreover, NP >12 hours combined with IABP support (odds ratio [OR], 14.769; 95% confidence interval [CI], 1.417~153.889; P = 0.024) and serum Cr level (OR, 1.028; 95% CI, 1.001~1.056; P = 0.043) were independent risk factors for neurologic impairment. Furthermore, neurologic impairment was associated with significantly worse 90-day survival (hazards ratio, 4.218; 95% CI, 1.745~10.2; P = 0.0014). Conclusions: The incidence of neurologic impairment was higher in patients who received ECPR and was closely related to 28-day mortality and discharge survival. NP >12 hours combined with IABP support and serum Cr levels were independent risk factors for neurologic impairments in ECPR-supported patients. Neurologic impairment significantly adversely affected the long-term outcomes of ECPR-supported patients after discharge.

Complications Associated With Venovenous Extracorporeal Membrane Oxygenation-What Can Go Wrong?

OBJECTIVES

Despite increasing use and promising outcomes, venovenous extracorporeal membrane oxygenation (V-V ECMO) introduces the risk of a number of complications across the spectrum of ECMO care. This narrative review describes the variety of short- and long-term complications that can occur during treatment with ECMO and how patient selection and management decisions may influence the risk of these complications.

DATA SOURCES

English language articles were identified in PubMed using phrases related to V-V ECMO, acute respiratory distress syndrome, severe respiratory failure, and complications.

STUDY SELECTION

Original research, review articles, commentaries, and published guidelines from the Extracorporeal Life support Organization were considered.

DATA EXTRACTION

Data from relevant literature were identified, reviewed, and integrated into a concise narrative review.

DATA SYNTHESIS

Selecting patients for V-V ECMO exposes the patient to a number of complications. Adequate knowledge of these risks is needed to weigh them against the anticipated benefit of treatment. Timing of ECMO initiation and transfer to centers capable of providing ECMO affect patient outcomes. Choosing a configuration that insufficiently addresses the patient's physiologic deficit leads to consequences of inadequate physiologic support. Suboptimal mechanical ventilator management during ECMO may lead to worsening lung injury, delayed lung recovery, or ventilator-associated pneumonia. Premature decannulation from ECMO as lungs recover can lead to clinical worsening, and delayed decannulation can prolong exposure to complications unnecessarily. Short-term complications include bleeding, thrombosis, and hemolysis, renal and neurologic injury, concomitant infections, and technical and mechanical problems. Long-term complications reflect the physical, functional, and neurologic sequelae of critical illness. ECMO can introduce ethical and emotional challenges, particularly when bridging strategies fail.

CONCLUSIONS

V-V ECMO is associated with a number of complications. ECMO selection, timing of initiation, and management decisions impact the presence and severity of these potential harms.

COVID-19 and hepatorenal syndrome

Coronavirus disease 2019 (COVID-19) is a highly infectious disease which emerged into a global pandemic. Although it primarily causes respiratory symptoms for affected patients, COVID-19 was shown to have multi-organ manifestations. Elevated liver enzymes appear to be commonly observed during the course of COVID-19, and there have been numerous reports of liver injury secondary to COVID-19 infection. It has been established that patients with pre-existing chronic liver disease (CLD) are more likely to have poorer outcomes following COVID-19 infection compared to those without CLD. Co-morbidities such as diabetes, hypertension, obesity, cardiovascular and chronic kidney disease frequently co-exist in individuals living with CLD, and a substantial population may also live with some degree of frailty. The mechanisms of how COVID-19 induces liver injury have been postulated. Hepatorenal syndrome (HRS) is the occurrence of kidney dysfunction in patients with severe CLD/fulminant liver failure in the absence of another identifiable cause, and is usually a marker of severe decompensated liver disease. Select reports of HRS following acute COVID-19 infection have been presented, although the risk factors and pathophysiological mechanisms leading to HRS in COVID-19 infection or following COVID-19 treatment remain largely unestablished due to the relative lack and novelty of published data. Evidence discussing the management of HRS in high-dependency care and intensive care contexts is only emerging. In this article, we provide an overview on the speculative pathophysiological mechanisms of COVID-19 induced HRS and propose strategies for clinical diagnosis and management to optimize outcomes in this scenario.

The patient safety in extracorporeal blood purification treatments of critical patients

Today, health systems are complex due to both the technological development in diagnostic and therapeutic procedures and the complexity of the patients that are increasingly older with several comorbidities. In any care setting, latent, organizational, and systematic errors can occur causing critical incident harmful for patients. Management of patients with acute kidney injury (AKI) requires a multidisciplinary approach for the diagnostic-therapeutic-rehabilitative path that can also require an extracorporeal blood purification treatment (EBPT). The complexity of these patients and EBPT require a clinical risk analysis and the introduction of protocols, procedures, operating instructions, and checklists to reduce clinical risk through promotion of the safety culture for all care providers. Caregivers must acquire a series of tools to evaluate the clinical risk in their reality to prevent incidents and customize patient safety in a proactive and reactive way. Established procedures that are made more needed by the COVID-19 pandemic can help to better manage patients in critical care area with intrinsic higher clinical risk. This review analyzes the communication and organizational aspects that need to be taken into consideration in the management of EBPT in a critical care setting by providing tools that can be used to reduce the clinical risk. This review is mostly addressed to all the caregivers involved in the EBPT in Critical Care Nephrology and in the Intensive Care Units.

Multidisciplinary basic and clinical research of acute kidney injury with COVID-19: Pathophysiology, mechanisms, incidence, management and kidney transplantation

Acute kidney injury (AKI) linked to coronavirus disease 2019 (COVID-19) has been identified in the course of the disease. AKI can be mild or severe and that is dependent on the presence of comorbidities and the severity of COVID-19. Among patients who had been hospitalized with COVID-19, some were admitted to intensive care unit. The etiology of AKI associated with COVID-19 is multifactorial. Prevention of severe AKI is the prime task in patients with COVID-19 that necessitates a battery of measurements and precautions in management. Patients with AKI who have needed dialysis are in an increased risk to develop chronic kidney disease (CKD) or a progression of their existing CKD. Kidney transplantation patients with COVID-19 are in need of special management to adjust the doses of immunosuppression drugs and corticosteroids to guard against graft rejection but not to suppress the immune system to place the patient at risk of developing a COVID-19 infection. Immunosuppression drugs and corticosteroids for patients who have had a kidney transplant has to be adjusted based on laboratory results and is individualized aiming at the protection of the transplanted from rejection.

Veno-Venous Extracorporeal Membrane Oxygenation in Minipigs as a Robust Tool to Model Acute Kidney Injury: Technical Notes and Characteristics

Objective

Veno-venous extracorporeal membrane oxygenation (vv-ECMO) can save lives in severe respiratory distress, but this innovative approach has serious side-effects and is accompanied by higher rates of iatrogenic morbidity. Our aims were, first, to establish a large animal model of vv-ECMO to study the pathomechanism of complications within a clinically relevant time frame and, second, to investigate renal reactions to increase the likelihood of identifying novel targets and to improve clinical outcomes of vv-ECMO-induced acute kidney injury (AKI).

Methods

Anesthetized Vietnamese miniature pigs were used. After cannulation of the right jugular and femoral veins, vv-ECMO was started and maintained for 24 hrs. In Group 1 (n = 6) ECMO was followed by a further 6-hr post-ECMO period, while (n = 6) cannulation was performed without ECMO in the control group, with observation maintained for 30 h. Systemic hemodynamics, blood gas values and hour diuresis were monitored. Renal artery flow (RAF) was measured in the post-ECMO period with an ultrasonic flowmeter. At the end of the experiments, renal tissue samples were taken for histology to measure myeloperoxidase (MPO) and xanthine oxidoreductase (XOR) activity and to examine mitochondrial function with high-resolution respirometry (HRR, Oroboros, Austria). Plasma and urine samples were collected every 6 hrs to determine neutrophil gelatinase-associated lipocalin (NGAL) concentrations.

Results

During the post-ECMO period, RAF dropped (96.3 ± 21 vs. 223.6 ± 32 ml/min) and, similarly, hour diuresis was significantly lower as compared to the control group (3.25 ± 0.4 ml/h/kg vs. 4.83 ± 0.6 ml/h/kg). Renal histology demonstrated significant structural damage characteristic of ischemic injury in the tubular system. In the vv-ECMO group NGAL levels, rose significantly in both urine (4.24 ± 0.25 vs. 2.57 ± 0.26 ng/ml) and plasma samples (4.67 ± 0.1 vs. 3.22 ± 0.2 ng/ml), while tissue XOR (5.88 ± 0.8 vs. 2.57 ± 0.2 pmol/min/mg protein) and MPO (11.93 ± 2.5 vs. 4.34 ± 0.6 mU/mg protein) activity was elevated. HRR showed renal mitochondrial dysfunction, including a significant drop in complex-I-dependent oxidative capacity (174.93 ± 12.7 vs. 249 ± 30.07 pmol/s/ml).

Conclusion

Significantly decreased renal function with signs of structural damage and impaired mitochondrial function developed in the vv-ECMO group. The vv-ECMO-induced acute renal impairment in this 30-hr research protocol provides a good basis to study the pathomechanism, biomarker combinations or possible therapeutic possibilities for AKI.

Impact of Pretransplant Renal Replacement Therapy on Clinical Outcome After Isolated Heart Transplantation

End stage renal disease (ESRD) is a contraindication to isolated heart transplantation (HT). However, heart candidates with cardiogenic shock may experience acute kidney injury and require renal replacement therapy (RRT) and isolated HT as a life-saving operation. The outcomes, including survival and renal function, are rarely reported. We enrolled 569 patients undergoing isolated HT from 1989 to 2018. Among them, 66 patients required RRT before HT (34 transient and 32 persistent). The survival was worse in patients with RRT than those without (65.2% vs 84.7%; 27.3% vs 51.1% at 1- and 10-year, p < 0.001 and p = 0.012, respectively). Multivariate Cox analysis identified pre-transplant hyperbilirubinemia (Hazard ratio (HR) 2.534, 95% confidence interval (CI) 1.098–5.853, p = 0.029), post-transplant RRT (HR 5.551, 95%CI 1.280–24.068, p = 0.022) and post-transplant early bloodstream infection (HR 3.014, 95%CI 1.270–7.152, p = 0.012) as independent risk factors of 1-year mortality. The majority of operative survivors (98%) displayed renal recovery after HT. Although patients with persistent or transient RRT before HT had a similar long-term survival, patients with persistent RRT developed a high incidence (49.2%) of dialysis-dependent ESRD at 10 years. In transplant candidates with pretransplant RRT, hyperbilirubinemia should be carefully re-evaluated for the eligibility of HT whereas prevention and management of bloodstream infection after HT improve survival.

The role of the ADVanced Organ Support (ADVOS) system in critically ill patients with multiple organ failure

Background

Multi‐organ failure characterized by acute kidney injury, liver dysfunction, and respiratory failure is a complex condition associated with high mortality, for which multiple individual support devices may be simultaneously required. This review aims to appraise the current evidence for the ADVanced Organ Support (ADVOS) system, a novel device integrating liver, lung, and kidney support with blood detoxification.

Methods

We performed a literature review of the PubMed database to identify human and animal studies evaluating the ADVOS system.

Results

In porcine models of acute liver injury and small clinical studies in humans, ADVOS significantly enhanced the elimination of water‐soluble and protein‐bound toxins and metabolites, including creatinine, ammonia, blood urea nitrogen, and lactate. Cardiovascular parameters (mean arterial pressure, cerebral perfusion pressure, and cardiac index) and renal function were improved. ADVOS clears carbon dioxide (CO₂) effectively with rapid correction of pH abnormalities, achieving normalization of CO₂, and bicarbonate levels. In patients with COVID‐19 infection, ADVOS enables rapid correction of acid–base disturbance and respiratory acidosis. ADVOS therapy reduces mortality in multi‐organ failure and has been shown to be safe with minimal adverse events.

Conclusions

From the small observational studies analyzed, ADVOS demonstrates excellent detoxification of water‐soluble and protein‐bound substances. In particular, ADVOS permits the correction of metabolic and respiratory acidosis through the fluid‐based direct removal of acid and CO₂. ADVOS is associated with significant improvements in hemodynamic and biochemical parameters, a trend toward improved survival in multi‐organ failure, and is well‐tolerated. Larger randomized trials are now necessary to further validate these encouraging results.

A Minimally Invasive and Highly Effective Extracorporeal CO2 Removal Device Combined With a Continuous Renal Replacement Therapy

OBJECTIVES

Extracorporeal carbon dioxide removal is used to treat patients suffering from acute respiratory failure. However, the procedure is hampered by the high blood flow required to achieve a significant CO2 clearance. We aimed to develop an ultralow blood flow device to effectively remove CO2 combined with continuous renal replacement therapy (CRRT).

DESIGN

Preclinical, proof-of-concept study.

SETTING

An extracorporeal circuit where 200 mL/min of blood flowed through a hemofilter connected to a closed-loop dialysate circuit. An ion-exchange resin acidified the dialysate upstream, a membrane lung to increase Pco2 and promote CO2 removal.

PATIENTS

Six, 38.7 ± 2.0-kg female pigs.

INTERVENTIONS

Different levels of acidification were tested (from 0 to 5 mEq/min). Two l/hr of postdilution CRRT were performed continuously. The respiratory rate was modified at each step to maintain arterial Pco2 at 50 mm Hg.

MEASUREMENTS AND MAIN RESULTS

Increasing acidification enhanced CO2 removal efficiency of the membrane lung from 30 ± 5 (0 mEq/min) up to 145 ± 8 mL/min (5 mEq/min), with a 483% increase, representing the 73% ± 7% of the total body CO2 production. Minute ventilation decreased accordingly from 6.5 ± 0.7 to 1.7 ± 0.5 L/min. No major side effects occurred, except for transient tachycardia episodes. As expected from the alveolar gas equation, the natural lung Pao2 dropped at increasing acidification steps, given the high dissociation between the oxygenation and CO2 removal capability of the device, thus Pao2 decreased.

CONCLUSIONS

This new extracorporeal ion-exchange resin-based multiple-organ support device proved extremely high efficiency in CO2 removal and continuous renal support in a preclinical setting. Further studies are required before clinical implementation.

Continuous Renal Replacement Therapy in the Critically Ill Patient: From Garage Technology to Artificial Intelligence

The history of continuous renal replacement therapy (CRRT) is marked by technological advances linked to improvements in the knowledge of the mechanisms and kinetics of extracorporeal removal of solutes, and the pathophysiology of acute kidney injury (AKI) and other critical illnesses. In the present article, we review the main steps in the history of CRRT, from the discovery of continuous arteriovenous hemofiltration to its evolution into the current treatments and its early use in the treatment of AKI, to the novel sequential extracorporeal therapy. Beyond the technological advances, we describe the development of new medical specialties and a shared nomenclature to support clinicians and researchers in the broad and still evolving field of CRRT.

A Unique Presentation of Acute Kidney Injury With COVID-19

Although the respiratory system is the primary target of COVID-19 pneumonia, it can also notably affect the other systemic organs such as renal and cardiac. The incidence and prevalence of SARS CoV-2 associated acute renal failure are emerging day by day. While the pathogenesis is not clearly understood, it is considered multifactorial. Initially, the COVID-19-associated renal dysfunction was limited to acute tubular injury. However, over time a wide spectrum of clinical manifestations has been reported. Therefore, prompt investigation and early initiation of supportive treatment can potentially reduce the mortality and morbidity associated with this systemic disease. In this case report, we present a unique presentation of a COVID-19 with acute kidney injury where the patient was admitted to the intensive care unit with clinical features of acute renal failure with concomitant diagnosis of COVID-19, unlike other reported cases where patients were admitted to the intensive unit with respiratory distress and subsequently developed renal failure.

Timing of renal-replacement therapy in intensive care unit-related acute kidney injury

PURPOSE OF REVIEW

The optimal timing of renal-replacement therapy (RRT) initiation for the management of acute kidney injury (AKI) in the intensive care unit (ICU) is frequently controversial. An earlier-strategy has biological rationale, even in the absence of urgent indications; however, a delayed-strategy may prevent selected patients from receiving RRT and avoid complications related to RRT.

RECENT FINDINGS

Previous studies assessing the optimal timing of RRT initiation found conflicting results, contributing to variation in clinical practice. The recent multinational trial, standard vs. accelerated initiation of renal replacement therapy in acute kidney injury (STARRT-AKI) found no survival benefit and a higher risk of RRT dependence with an accelerated compared to a standard RRT initiation strategy in critically ill patients with severe AKI. Nearly 40% of patients allocated to the standard-strategy group did not receive RRT. The Artificial Kidney Initiation in Kidney Injury-2 (AKIKI-2) trial further assessed delayed compared to more-delayed strategies for RRT initiation. The more-delayed strategy did not confer an increase in RRT-free days and was associated with a higher risk of death.

SUMMARY

Early preemptive initiation of RRT in critically ill patients with AKI does not confer clear clinical benefits. However, protracted delays in RRT initiation may be harmful.

Central, peripheral ECMO or CPB? Comparsion between circulatory support methods used during lung transplantation

BACKGROUND

Chronic obstructive pulmonary disease, cystic fibrosis and usual interstitial pneumonia are three most common indications for lung transplantation (LuTx) in Poland. As a result of irreversible destruction of pulmonary parenchyma and extended respiratory insufficiency that appear afterwards, it is crucial to estimate the reserve of gas exchange in each lung before and during surgery. Altering conditions of gas exchange require adaptation in circulatory system as well. In some of the cases the use of extracorporeal life support appears to be necessary to undergo the transplantation successfully. Cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation (ECMO) used during operation allow to replace the function of heart and lung, but they are also related to complications in the form of acute kidney failure, bleeding, heart arrhythmias or thromboembolic complications.

METHODS

We reviewed 77 LuTx from 2009 to 2020 performed at the Department of Thoracic Surgery and Transplantation. 40/77 (51%) patients required intraoperative extracorporeal assistance: 8 required CBP and 32 required ECMO. In the ECMO group 14/32 (44%) patients had peripheral cannulation and 18/32 (56%) had central one. We have calculated the survival rates and reviewed postoperative complications after lung transplantations. Cumulative Kaplan-Meier survival curves were calculated. Differences between the groups were evaluated by the Chi- square analysis for discontinuous variables and t-test for continuous variables.

RESULTS

The use of intraoperative central extracorporeal membrane oxygenator was associated with increased survival rates comparing to patients without external support (30-days, 1-year, 3-years, 5-years rates: 78%, 66%, 66%, 66% vs 83%, 65%, 59%, 44% respectively). Furthermore, survival was enhanced comparing to peripheral ECMO or cardiopulmonary bypass as well (50%, 41%, 41%, 33%; 75%, 50%, 50%, 38% respectively). Acute kidney injury and thromboembolic complications occurred statistically more often in case of patients that underwent lung transplantation with support devices (p = 0.005, p = 0.02 respectively). Frequency of other complications was comparable among groups.

CONCLUSIONS

The use of central extracorporeal membrane oxygenation should be favorized over peripheral cannulation or cardiopulmonary bypass. CPB should be no longer used during LuTx. Trial registration Not applicable.

An innovative ovine model of severe cardiopulmonary failure supported by veno-arterial extracorporeal membrane oxygenation

Refractory cardiogenic shock (CS) often requires veno-arterial extracorporeal membrane oxygenation (VA-ECMO) to sustain end-organ perfusion. Current animal models result in heterogenous cardiac injury and frequent episodes of refractory ventricular fibrillation. Thus, we aimed to develop an innovative, clinically relevant, and titratable model of severe cardiopulmonary failure. Six sheep (60 ± 6 kg) were anaesthetized and mechanically ventilated. VA-ECMO was commenced and CS was induced through intramyocardial injections of ethanol. Then, hypoxemic/hypercapnic pulmonary failure was achieved, through substantial decrease in ventilatory support. Echocardiography was used to compute left ventricular fractional area change (LVFAC) and cardiac Troponin I (cTnI) was quantified. After 5 h, the animals were euthanised and the heart was retrieved for histological evaluations. Ethanol (58 ± 23 mL) successfully induced CS in all animals. cTnI levels increased near 5000-fold. CS was confirmed by a drop in systolic blood pressure to 67 ± 14 mmHg, while lactate increased to 4.7 ± 0.9 mmol/L and LVFAC decreased to 16 ± 7%. Myocardial samples corroborated extensive cellular necrosis and inflammatory infiltrates. In conclusion, we present an innovative ovine model of severe cardiopulmonary failure in animals on VA-ECMO. This model could be essential to further characterize CS and develop future treatments.

The multivariable prognostic models for severe complications after heart valve surgery

Background

To provide multivariable prognostic models for severe complications prediction after heart valve surgery, including low cardiac output syndrome (LCOS), acute kidney injury requiring hemodialysis (AKI-rH) and multiple organ dysfunction syndrome (MODS).

Methods

We developed multivariate logistic regression models to predict severe complications after heart valve surgery using 930 patients collected retrospectively from the first affiliated hospital of Sun Yat-Sen University from January 2014 to December 2015. The validation was conducted using a retrospective dataset of 713 patients from the same hospital from January 2016 to March 2017. We considered two kinds of prognostic models: the PRF models which were built by using the preoperative risk factors only, and the PIRF models which were built by using both of the preoperative and intraoperative risk factors. The least absolute shrinkage selector operator was used for developing the models. We assessed and compared the discriminative abilities for both of the PRF and PIRF models via the receiver operating characteristic (ROC) curve.

Results

Compared with the PRF models, the PIRF modes selected additional intraoperative factors, such as auxiliary cardiopulmonary bypass time and combined tricuspid valve replacement. Area under the ROC curves (AUCs) of PRF models for predicting LCOS, AKI-rH and MODS are 0.565 (0.466, 0.664), 0.688 (0.62, 0.757) and 0.657 (0.563, 0.751), respectively. As a comparison, the AUCs of the PIRF models for predicting LOCS, AKI-rH and MODS are 0.821 (0.747, 0.896), 0.78 (0.717, 0.843) and 0.774 (0.7, 0.847), respectively.

Conclusions

Adding the intraoperative factors can increase the predictive power of the prognostic models for severe complications prediction after heart valve surgery.

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.

Extracorporeal carbon dioxide Removal (ECCO2 R) with the Advanced Organ Support (ADVOS) system in critically ill COVID-19 patients

Disturbed oxygenation is foremost the leading clinical presentation in COVID‐19 patients. However, a small proportion also develop carbon dioxide removal problems. The Advanced Organ Support (ADVOS) therapy (ADVITOS GmbH, Munich, Germany) uses a less invasive approach by combining extracorporeal CO₂‐removal and multiple organ support for the liver and the kidneys in a single hemodialysis device. The aim of our study is to evaluate the ADVOS system as treatment option in‐COVID‐19 patients with multi‐organ failure and carbon dioxide removal problems. COVID‐19 patients suffering from severe respiratory insufficiency, receiving at least two treatments with the ADVOS multi system (ADVITOS GmbH, Munich, Germany), were eligible for study inclusion. Briefly, these included patients with acute kidney injury (AKI) according to KDIGO guidelines, and moderate or severe ARDS according to the Berlin definition, who were on invasive mechanical ventilation for more than 72 hours. In total, nine COVID‐19 patients (137 ADVOS treatment sessions with a median of 10 treatments per patient) with moderate to severe ARDS and carbon dioxide removal problems were analyzed. During the ADVOS treatments, a rapid correction of acid‐base balance and a continuous CO₂ removal could be observed. We observed a median continuous CO₂ removal of 49.2 mL/min (IQR: 26.9‐72.3 mL/min) with some treatments achieving up to 160 mL/min. The CO₂ removal significantly correlated with blood flow (Pearson 0.421; P < .001), PaCO₂ (0.341, P < .001) and HCO3‐ levels (0.568, P < .001) at the start of the treatment. The continuous treatment led to a significant reduction in PaCO₂ from baseline to the last ADVOS treatment. In conclusion, it was feasible to remove CO₂ using the ADVOS system in our cohort of COVID‐19 patients with acute respiratory distress syndrome and multiorgan failure. This efficient removal of CO₂ was achieved at blood flows up to 300 mL/min using a conventional hemodialysis catheter and without a membrane lung or a gas phase.

Acute kidney injury after lung transplantation: a narrative review

Acute kidney injury (AKI) is a commonly recognized complication after lung transplantation (LT) and is related to increased mortality and morbidity. With the improvement of survival after LT and the increasing number of lung transplant recipients, the detrimental impact of current management on renal function has become increasingly apparent. Multifarious risk factors in the perioperative setting contribute to the development of AKI, including the preoperative status and complications of the recipient, complex perioperative problems especially hemodynamic fluctuation, and exposure to nephrotoxic agents, mainly calcineurin inhibitors (CNIs) and antimicrobial drugs. Identification and minimization of the effects of these risk factors can relieve AKI severity and incidence in high-risk patients. Close monitoring of urine output and serum creatinine (sCr) levels and of specific biomarkers may promote early recognition of AKI and rapid nephrology intervention to improve outcomes. This review summarizes advances in the epidemiology, diagnostic criteria, biological markers of AKI, and further recommends appropriate treatment strategies for the long-term management of AKI related manifestations in lung transplant recipients. Future work will need to focus on developing more accurate measures of renal function and identifying patients before the occurrence of early renal damage. Combining renal protection strategies with the use of new biomarkers to develop early kidney risk identification and protection protocols is a promising idea that requires further investigation.

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.

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.

Registry on extracorporeal multiple organ support with the advanced organ support (ADVOS) system: 2-year interim analysis

The objective of this registry is to collect data on real-life treatment conditions for patients for whom multiple organ dialysis with Advanced Organ Support (ADVOS) albumin hemodialysis is indicated.This registry was performed under routine conditions and without any study-specific intervention, diagnostic procedures, or assessments. Data on clinical laboratory tests, health status, liver function, vital signs, and examinations were collected (DRKS-ID: DRKS00017068). Mortality rates 28 and 90 days after the first ADVOS treatment, adverse events and ADVOS treatment parameters, including treatment abortions, were documented.This analysis was performed 2 years after the first patient was included on January 18, 2017. As of February 20, 2019, 4 clinical sites in Germany participated and enrolled 118 patients with a median age of 60 (IQR: 45, 69) of whom 70 were male (59.3%). Patients had a median SOFA Score of 14 (IQR: 11, 16) and a predicted mortality of 80%. The median number of failing organs was 3 (IQR: 2, 4).Four hundred twenty nine ADVOS treatments sessions were performed with a median duration of 17 hours (IQR: 6, 23). A 5.8% of the ADVOS sessions (25 of 429) were aborted due to device related errors, while 14.5% (62 of 429) were stopped for other reasons. Seventy nine adverse events were documented, 13 of them device related (all clotting, and all recovered without sequels).A significant reduction in serum creatinine (1.5 vs 1.2 mg/dl), blood urea nitrogen (24 vs 17 mg/dl) and bilirubin (6.9 vs 6.5 mg/dl) was observed following the first ADVOS treatment session. Blood pH, bicarbonate (HCO3-) and base excess returned to the physiological range, while partial pressure of carbon dioxide (pCO2) remained unchanged. At the time of the analysis, 28- and 90-day mortality were 60% and 65%, respectively, compared to an expected ICU-mortality rate of 80%. SOFA score was an independent predictor for outcome in a multivariable logistic regression analysis.The reported data show a high quality and completion of all participating centers. Data interpretation must be cautious due to the small number of patients, and the nature of the registry, without a control group. However, the data presented here show an improvement of expected mortality rates. Minor clotting events similar to other dialysis therapies occurred during the treatments.

The dynamic association between COVID-19 and chronic disorders: An updated insight into prevalence, mechanisms and therapeutic modalities

The devastating pandemic of coronavirus disease 2019 (COVID-19) has caused thousands of deaths and left millions of restless patients suffering from its complications. Increasing data indicate that the disease presents in a severe form in patients with pre-existing chronic conditions like cardiovascular diseases, diabetes, respiratory system diseases, and renal diseases. This denotes that these patients are more susceptible to COVID-19 and have higher mortality rates compared to patients with no comorbid conditions. Several factors can explain the heightened susceptibility and fatal presentation of COVID-19 in these patients, for example, the enhanced expression of the angiotensin-converting enzyme-2 (ACE2) in specific organs, cytokine storm, and drug interactions contribute to the increased morbidity and mortality. Adding to the findings that individuals with pre-existing conditions may be more susceptible to COVID-19, it has also been shown that COVID-19 can induce chronic diseases in previously healthy patients. Therefore, understanding the interlinked relationship between COVID-19 and chronic diseases helps in optimizing the management of susceptible patients. This review comprehensively described the molecular mechanisms that contribute to worse COVID-19 prognosis in patients with pre-existing comorbidities such as diabetes, cardiovascular diseases, respiratory diseases, gastrointestinal and renal diseases, blood disorders, autoimmune diseases, and finally, obesity. It also focused on how COVID-19 could, in some cases, lead to chronic conditions as a result of long-term multi-organ damage. Lastly, this work carefully discussed the tailored management plans for each specific patient population, aiming to achieve the best therapeutic outcome with minimum complications.

SARS-CoV-2 and Viral Sepsis: Immune Dysfunction and Implications in Kidney Failure

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of coronavirus disease 2019 (COVID-19), first emerged in Wuhan, China. The clinical manifestations of patients infected with COVID-19 include fever, cough, and dyspnea, up to acute respiratory distress syndrome (ARDS) and acute cardiac injury. Thus, a lot of severe patients had to be admitted to intensive care units (ICU). The pathogenic mechanisms of SARS-CoV-2 infection are mediated by the binding of SARS-CoV-2 spikes to the human angiotensin-converting enzyme 2 (ACE-2) receptor. The overexpression of human ACE-2 is associated with the disease severity in SARS-CoV-2 infection, demonstrating that viral entry into cells is a pivotal step. Although the lung is the organ that is most commonly affected by SARS-CoV-2 infection, acute kidney injury (AKI), heart dysfunction and abdominal pain are the most commonly reported co-morbidities of COVID-19. The occurrence of AKI in COVID-19 patients might be explained by several mechanisms that include viral cytopathic effects in renal cells and the host hyperinflammatory response. In addition, kidney dysfunction could exacerbate the inflammatory response started in the lungs and might cause further renal impairment and multi-organ failure. Mounting recent evidence supports the involvement of cardiovascular complications and endothelial dysfunction in COVID-19 syndrome, in addition to respiratory disease. To date, there is no vaccine, and no specific antiviral medicine has been shown to be effective in preventing or treating COVID-19. The removal of pro-inflammatory cytokines and the shutdown of the cytokine storm could ameliorate the clinical outcome in severe COVID-19 cases. Therefore, several interventions that inhibit viral replication and the systemic inflammatory response could modulate the severity of the renal dysfunction and increase the probability of a favorable outcome.

Controversies in acute kidney injury: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Conference

In 2012, Kidney Disease: Improving Global Outcomes (KDIGO) published a guideline on the classification and management of acute kidney injury (AKI). The guideline was derived from evidence available through February 2011. Since then, new evidence has emerged that has important implications for clinical practice in diagnosing and managing AKI. In April of 2019, KDIGO held a controversies conference entitled Acute Kidney Injury with the following goals: determine best practices and areas of uncertainty in treating AKI; review key relevant literature published since the 2012 KDIGO AKI guideline; address ongoing controversial issues; identify new topics or issues to be revisited for the next iteration of the KDIGO AKI guideline; and outline research needed to improve AKI management. Here, we present the findings of this conference and describe key areas that future guidelines may address.

Temporary circulatory support for cardiogenic shock

Cardiogenic shock can occur due to acute ischaemic or non-ischaemic cardiac events, or from progression of long-standing underlying heart disease. When addressing the cause of underlying disease, the management of cardiogenic shock consists of vasopressors and inotropes; however, these agents can increase myocardial oxygen consumption, impair tissue perfusion, and are frequently ineffective. An alternative approach is to temporarily augment cardiac output using mechanical devices. The use of these devices-known as temporary circulatory support systems-has increased substantially in recent years, despite being expensive, resource intensive, associated with major complications, and lacking high-quality evidence to support their use. This Review summarises the physiological basis underlying the use of temporary circulatory support for cardiogenic shock, reviews the evidence informing indications and contraindications, addresses ethical considerations, and highlights the need for further research.

Management of acute kidney injury in patients with COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) has rapidly evolved into a global pandemic. Most patients with COVID-19 have mild symptoms, but about 5% develop severe symptoms, which can include acute respiratory distress syndrome, septic shock, and multiple organ failure. Kidney involvement is frequent, with clinical presentation ranging from mild proteinuria to progressive acute kidney injury (AKI) necessitating renal replacement therapy (RRT). An understanding of the pathophysiology and mechanisms of kidney damage and AKI in the setting of critical illness and COVID-19 is emerging, although further research is needed to identify patients at risk of AKI and to guide management strategies. As no specific treatment options exist for AKI secondary to COVID-19, intensive care is largely supportive. Current approaches to prevention and management of AKI, and identification of potential indications for use of RRT and sequential extracorporeal therapies, are based mainly on clinical experience, and AKI strategies are adapted empirically to patients with COVID-19. International collaborative and cross-disciplinary research is needed to obtain adequate evidence to support current clinical approaches and to develop new approaches to management.

Acute cardiorenal syndrome in acute heart failure: focus on renal replacement therapy

Almost half of hospitalised patients with acute heart failure develop acute cardiorenal syndrome. Treatment consists of optimisation of fluid status and haemodynamics, targeted therapy for the underlying cardiac disease, optimisation of heart failure treatment and preventive measures such as avoidance of nephrotoxic agents. Renal replacement therapy may be temporarily needed to support kidney function, mostly in case of diuretic resistant fluid overload or severe metabolic derangement. The best timing to initiate renal replacement therapy and the best modality in acute heart failure are still under debate. Several modalities are available such as intermittent and continuous renal replacement therapy as well as hybrid techniques, based on two main principles: haemofiltration and haemodialysis. Although continuous techniques have been associated with less haemodynamic instability and a greater chance of renal recovery, cohort data are conflicting and randomised controlled trials have not shown a difference in recovery or mortality. In the presence of diuretic resistance, isolated ultrafiltration with individualisation of ultrafiltration rates is a valid option for decongestion in acute heart failure patients. Practical tools to optimise the use of renal replacement therapy in acute heart failure-related acute cardiorenal syndrome were discussed.

Extracorporeal Blood Purification and Organ Support in the Critically Ill Patient during COVID-19 Pandemic: Expert Review and Recommendation

Critically ill COVID-19 patients are generally admitted to the ICU for respiratory insufficiency which can evolve into a multiple-organ dysfunction syndrome requiring extracorporeal organ support. Ongoing advances in technology and science and progress in information technology support the development of integrated multi-organ support platforms for personalized treatment according to the changing needs of the patient. Based on pathophysiological derangements observed in COVID-19 patients, a rationale emerges for sequential extracorporeal therapies designed to remove inflammatory mediators and support different organ systems. In the absence of vaccines or direct therapy for COVID-19, extracorporeal therapies could represent an option to prevent organ failure and improve survival. The enormous demand in care for COVID-19 patients requires an immediate response from the scientific community. Thus, a detailed review of the available technology is provided by experts followed by a series of recommendation based on current experience and opinions, while waiting for generation of robust evidence from trials.

Options in extracorporeal support of multiple organ failure

Multiorgan failure is among the most frequent reasons of death in critically ill patients. Based on extensive and long-term use of renal replacement therapy, extracorporeal organ support became available for other organ failures. Initially, most of these techniques (e.g. extracorporeal membrane oxygenation, extracorporeal CO₂ removal [ECCO2R] and extracorporeal liver support) were used as stand-alone single organ support systems. Considering multiple interactions between native organs (“crosstalk”), combined or integrated extracorporeal organ support (ECOS) devices are intriguing. The concept of multiple organ support therapy (MOST) providing simultaneous and combined support for different failing organs was described more than 15 years ago by Ronco and Bellomo. This concept also implicates overcoming the “compartmentalized” approach provided by different single organ specialized professionals by a multidisciplinary and multiprofessional strategy. The idea of MOST is supported by the failure of several recent studies on single organ support including liver and lung support. Improvement of outcome by ECOS necessarily depends on optimized patient selection, integrated organ support and limitation of its side effects. This implicates challenges for engineers, industry and healthcare professionals. From a technical viewpoint, modular combination of pre-existing technologies such as renal replacement, albumin-dialysis, ECCO2R and potentially cytokine elimination can be considered as a first step. While this allows for stepwise and individual combination of standard organ support facilities, it carries the disadvantage of large extracorporeal blood volume and surfaces as well as additive costs. The more intriguing next step is an integrated platform providing the capacity of multiple organ support within one device. (This article is freely available.)

Distant organ dysfunction in acute kidney injury

Acute kidney injury (AKI) is a common complication in critically ill patients and it is associated with increased morbidity and mortality. Epidemiological and clinical data show that AKI is linked to a wide range of distant organ injuries, with the lungs, heart, liver, and intestines representing the most clinically relevant affected organs. This distant organ injury during AKI predisposes patients to progression to multiple organ dysfunction syndrome and ultimately, death. The strongest direct evidence of distant organ injury occurring in AKI has been obtained from animal models. The identified mechanisms include systemic inflammatory changes, oxidative stress, increases in leucocyte trafficking and the activation of proapoptotic pathways. Understanding the pathways driving AKI-induced distal organ injury are critical for the development and refinement of therapies for the prevention and attenuation of AKI-related morbidity and mortality. The purpose of this review is to summarize both clinical and preclinical studies of AKI and its role in distant organ injury.

Carbon monoxide in intensive care medicine-time to start the therapeutic application?!

Carbon monoxide (CO) is not only known as a toxic gas due to its characteristics as an odorless molecule and its rapid binding to haem-containing molecules, thus inhibiting the respiratory chain in cells resulting in hypoxia. For decades, scientists established evidence about its endogenously production in the breakdown of haem via haem-oxygenase (HO-1) and its physiological effects. Among these, the modulation of various systems inside the body are well described (e.g., anti-inflammatory, anti-oxidative, anti-apoptotic, and anti-proliferative). Carbon monoxide is able to modulate several extra- and intra-cellular signaling molecules leading to differentiated response according to the specific stimulus. With our growing understanding in the way CO exerts its effects, especially in the mitochondria and its intracellular pathways, it is tempting to speculate about a clinical application of this substance. Since HO-1 is not easy to induce, research focused on the application of the gaseous molecule CO by itself or the implementation of carbon monoxide releasing molecules (CO-RM) to deliver the molecule at a time- and dose dependently safe way to any target organ. After years of research in cellular systems and animal models, summing up data about safety issues as well as possible target to treat in various diseases, the first feasibility trials in humans were established. Up-to-date, safety issues have been cleared for low-dose carbon monoxide inhalation (up to 500 ppm), while there is no clinical data regarding the injection or intake of any kind of CO-RM so far. Current models of human research include sepsis, acute lung injury, and acute respiratory distress syndrome as well as acute kidney injury. Carbon monoxide is a most promising candidate in terms of a therapeutic agent to improve outbalanced organ conditions. In this paper, we summarized the current understanding of carbon monoxide’s biology and its possible organ targets to treating the critically ill patients in tomorrow’s ICU.

Acute kidney injury in burn patients admitted to the intensive care unit: a systematic review and meta-analysis

Background

Acute kidney injury (AKI) is a common complication in burn patients admitted to the intensive care unit (ICU) associated with increased morbidity and mortality. Our primary aim was to review incidence, risk factors, and outcomes of AKI in burn patients admitted to the ICU. Secondary aims were to review the use of renal replacement therapy (RRT) and impact on health care costs.

Methods

We conducted a systematic search in PubMed, UpToDate, and NICE through 3 December 2018. All reviews in Cochrane Database of Systematic Reviews except protocols were added to the PubMed search. We searched for studies on AKI according to Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE); Acute Kidney Injury Network (AKIN); and/or Kidney Disease: Improving Global Outcomes (KDIGO) criteria in burn patients admitted to the ICU. We collected data on AKI incidence, risk factors, use of RRT, renal recovery, length of stay (LOS), mortality, and health care costs.

Results

We included 33 observational studies comprising 8200 patients. Overall study quality, scored according to the Newcastle-Ottawa scale, was moderate. Random effect model meta-analysis revealed that the incidence of AKI among burn patients in the ICU was 38 (30–46) %. Patients with AKI were almost evenly distributed in the mild, moderate, and severe AKI subgroups. RRT was used in 12 (8–16) % of all patients. Risk factors for AKI were high age, chronic hypertension, diabetes mellitus, high Total Body Surface Area percent burnt, high Abbreviated Burn Severity Index score, inhalation injury, rhabdomyolysis, surgery, high Acute Physiology and Chronic Health Evaluation II score, high Sequential Organ Failure Assessment score, sepsis, and mechanical ventilation. AKI patients had 8.6 (4.0–13.2) days longer ICU LOS and higher mortality than non-AKI patients, OR 11.3 (7.3–17.4). Few studies reported renal recovery, and no study reported health care costs.

Conclusions

AKI occurred in 38% of burn patients admitted to the ICU, and 12% of all patients received RRT. Presence of AKI was associated with increased LOS and mortality.

Trial registration

PROSPERO (CRD42017060420)