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

ECLS-associated infections in adults: what we know and what we don't yet know

Extracorporeal life support (ECLS) is increasingly used in the management of patients with severe cardiopulmonary disease. Infections are frequently the etiologies underlying the respiratory, and occasionally cardiac, failure that necessitates ECLS. Just as importantly, infections are among the most commonly reported adverse events during ECLS. Infections in this setting may be the sequelae of prolonged critical illness or of underlying immune dysregulation; they may be hospital-acquired infections, and they may or may not be attributable to the presence of ECLS itself, the latter being an aspect that can be difficult to determine. Current registry data and evidence from the literature offer some insights, but also leave open many questions regarding the nature and significance of infections reported both before and during ECLS, including the question of any causal link between ECLS and the development of infections. An ongoing lack of consistency in the identification, diagnosis, management, and prevention of infections during ECLS is limiting our ability to interpret literature data and thus highlighting the need for more rigorous investigation and standardization of definitions. This review aims to characterize the current understanding of infections associated with the use of ECLS, taking into account data from the updated Extracorporeal Life Support Organization Registry, which provides important context for understanding the epidemiology and outcomes of these patients.

Acute kidney injury

Acute kidney injury (AKI) is defined by a rapid increase in serum creatinine, decrease in urine output, or both. AKI occurs in approximately 10-15% of patients admitted to hospital, while its incidence in intensive care has been reported in more than 50% of patients. Kidney dysfunction or damage can occur over a longer period or follow AKI in a continuum with acute and chronic kidney disease. Biomarkers of kidney injury or stress are new tools for risk assessment and could possibly guide therapy. AKI is not a single disease but rather a loose collection of syndromes as diverse as sepsis, cardiorenal syndrome, and urinary tract obstruction. The approach to a patient with AKI depends on the clinical context and can also vary by resource availability. Although the effectiveness of several widely applied treatments is still controversial, evidence for several interventions, especially when used together, has increased over the past decade.

Renal hemodynamics by return cannular position of extracorporeal membrane oxygenation in swine

Background

Whether arterial return cannula position affects the kidney during Veno-Arterial extracorporeal membrane oxygenation (ECMO) is unclear. Therefore, we compared hemodynamic parameters and acute kidney injury (AKI) biomarkers between ascending aorta return (aECMO) and femoral artery return ECMO (fECMO) in swine to evaluate the effect of cannula position on the kidney.

Methods

A total of twelve swines were allocated randomly into two groups. ECMO was maintained for 6h. Hemodynamic parameters including mean arterial pressure (MAP), renal arterial flow rate (AF), energy equivalent pressure (EEP), and surplus hemodynamic energy (SHE) were measured at the left renal artery. For evaluation of kidney injury, samples were obtained for blood urea nitrogen, creatinine, cystatin C, and neutrophil gelatinase-associated lipocalin (before ECMO, and 1, 3, and 6 h after initiating ECMO).

Results

Before the start of ECMO, hemodynamic parameters were not different between the two groups. With regard to the rate of change before and after ECMO, the fECMO group showed a significantly higher increase in MAP, AF, and EEP and a greater decrease in SHE than the aECMO group (P<0.001). In inter-group analysis, no significant difference in time-dependent trends were observed for biochemical laboratory levels.

Conclusions

fECMO support was associated with a higher energy profile at the renal artery than that with aECMO, whereas pulsatility was decreased.

The golden hour of polymyxin B hemoperfusion in endotoxic shock: The basis for sequential extracorporeal therapy in sepsis

Endotoxin is recognized as a major trigger of the immune response leading to pro- and anti-inflammatory cytokine release, activation of the coagulation cascade, vasoplegic shock, and multiple organ dysfunction syndrome. A beneficial effect could be achieved through extracorporeal adsorption of circulating endotoxins in the blood as adjunctive treatment for unresponsive endotoxic shock. However, the precise clinical indication for its initiation is widely debated in the literature. Similar to the source control, microbiological cultures and antibiotics administration, endotoxin activity assay evaluation at regular intervals, and the targeted use of PMX-B hemoperfusion could be lifesaving and adequate within the golden hour for the diagnosis and treatment of endotoxic shock.

Extracorporeal Life Support for Adults With Respiratory Failure and Related Indications: A Review

IMPORTANCE

The substantial growth over the last decade in the use of extracorporeal life support for adults with acute respiratory failure reveals an enthusiasm for the technology not always consistent with the evidence. However, recent high-quality data, primarily in patients with acute respiratory distress syndrome, have made extracorporeal life support more widely accepted in clinical practice.

OBSERVATIONS

Clinical trials of extracorporeal life support for acute respiratory failure in adults in the 1970s and 1990s failed to demonstrate benefit, reducing use of the intervention for decades and relegating it to a small number of centers. Nonetheless, technological improvements in extracorporeal support made it safer to use. Interest in extracorporeal life support increased with the confluence of 2 events in 2009: (1) the publication of a randomized clinical trial of extracorporeal life support for acute respiratory failure and (2) the use of extracorporeal life support in patients with severe acute respiratory distress syndrome during the influenza A(H1N1) pandemic. In 2018, a randomized clinical trial in patients with very severe acute respiratory distress syndrome demonstrated a seemingly large decrease in mortality from 46% to 35%, but this difference was not statistically significant. However, a Bayesian post hoc analysis of this trial and a subsequent meta-analysis together suggested that extracorporeal life support was beneficial for patients with very severe acute respiratory distress syndrome. As the evidence supporting the use of extracorporeal life support increases, its indications are expanding to being a bridge to lung transplantation and the management of patients with pulmonary vascular disease who have right-sided heart failure. Extracorporeal life support is now an acceptable form of organ support in clinical practice.

CONCLUSIONS AND RELEVANCE

The role of extracorporeal life support in the management of adults with acute respiratory failure is being redefined by advances in technology and increasing evidence of its effectiveness. Future developments in the field will result from technological advances, an increased understanding of the physiology and biology of extracorporeal support, and increased knowledge of how it might benefit the treatment of a variety of clinical conditions.

Acute Kidney Injury in Critically Ill Children: A Retrospective Analysis of Risk Factors

INTRODUCTION

Children admitted to paediatric intensive care unit (PICU) are at risk of acute kidney injury (AKI). However, few paediatric studies have focused on the identification of factors potentially associated with the development of this condition. The aim of our study was to assess the incidence rate of AKI, identify risk factors, and evaluate clinical outcome in a large sample of critically ill children.

METHODS

This retrospective observational study was conducted including patients admitted to our PICU from January 2014 to December 2016. AKI was defined according to Kidney Disease: Improving Global Outcome criteria.

RESULTS

A total of 222 PICU patients out of 811 (27%) had AKI (stage I 39%, stage II 24%, stage III 37%). The most common PICU admission diagnoses in AKI cases were heart disease (38.6%), respiratory failure (16.8%) and postsurgical non-cardiac patients (11%). Hypoxic-ischaemic was the most frequent cause of AKI. Significant risk factors for AKI following multivariate analysis were age >2 months (OR 2.43; 95% CI 1.03-7.87; p = 0.05), serum creatinine at admission >44 µmol/L (OR 2.23; 95% CI 1.26-3.94; p = 0.006), presence of comorbidities (OR 1.84; 95% CI 1.03-3.30; p = 0.04), use of inotropes (OR 2.56; 95% CI 1.23-5.35; p= 0.012) and diuretics (OR 2.78; 95% CI 1.49-5.19; p = 0.001), exposure to nephrotoxic drugs (OR 1.66; 95% CI 1.01-2.91; p= 0.04), multiple organ dysfunction syndrome (OR 2.68; 95% CI 1.43-5.01; p = 0.002), and coagulopathy (OR 1.89; 95% CI 1.05-3.38, p = 0.03). AKI was associated with a significant longer PICU stay (median LOS of 8 days, interquartile range [IQR] 3-16, versus 4 days, IQR 2-8, in non-AKI patients; p < 0.001). The mortality rate resulted tenfold higher in AKI than non-AKI patients (12.6 vs. 1.2%; p < 0.001).

CONCLUSIONS

The incidence of AKI in critically ill children is high, with an associated increased length of stay and risk of mortality. In the PICU setting, risk factors of AKI are multiple and mainly associated with illness severity.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Acute kidney injury in trauma patients admitted to the ICU: a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis of acute kidney injury (AKI) in trauma patients admitted to the intensive care unit (ICU).

METHODS

We conducted a systematic literature search of studies on AKI according to RIFLE, AKIN, or KDIGO criteria in trauma patients admitted to the ICU (PROSPERO CRD42017060420). We searched PubMed, Cochrane Database of Systematic Reviews, UpToDate, and NICE through 3 December 2018. Data were collected on incidence of AKI, risk factors, renal replacement therapy (RRT), renal recovery, length of stay (LOS), and mortality. Pooled analyses with random effects models yielded mean differences, OR, and RR, with 95% CI.

RESULTS

Twenty-four observational studies comprising 25,182 patients were included. Study quality (Newcastle-Ottawa scale) was moderate. Study heterogeneity was substantial. Incidence of post-traumatic AKI in the ICU was 24% (20-29), of which 13% (10-16) mild, 5% (3-7) moderate, and 4% (3-6) severe AKI. Risk factors for AKI were African American descent, high age, chronic hypertension, diabetes mellitus, high Injury Severity Score, abdominal injury, shock, low Glasgow Coma Scale (GCS) score, high APACHE II score, and sepsis. AKI patients had 6.0 (4.0-7.9) days longer ICU LOS and increased risk of death [RR 3.4 (2.1-5.7)] compared to non-AKI patients. In patients with AKI, RRT was used in 10% (6-15). Renal recovery occurred in 96% (78-100) of patients.

CONCLUSIONS

AKI occurred in 24% of trauma patients admitted to the ICU, with an RRT use among these of 10%. Presence of AKI was associated with increased LOS and mortality, but renal recovery in AKI survivors was good.