Effects of continuous renal replacement therapy on renal inflammatory cytokines during extracorporeal membrane oxygenation in a porcine model

Inflammatory Progression in Patients Undergoing Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is identified as a novel therapeutic strategy that offers short-term support to the metabolism of the heart and lungs in humans. Recently, the clinical centers, which provide ECMO has increased rapidly worldwide. The indications for the use of ECMO in daily clinical practice were broadened dynamically. However, even with the widespread adoption of ECMO, it still remains significant morbidity and mortality, and the underlying mechanisms are still not elucidated. Notably, one of the vital complications during ECMO was proposed as the inflammatory progression within the extracorporeal circulation. via the development of inflammatory response, patients with ECMO may further suffer from systemic inflammatory response syndrome (SIRS), posing serious risks to human health. Recently, growing evidence confirmed that through exposure of blood into the ECMO circuit could lead to the stimulation of the immune system which also facilitated the inflammatory response and systemic impaired. In the current review, the pathological development of inflammatory progression in patients with ECMO is well-listed. Furthermore, the relationship between immune-related activation and the development of inflammation is also summarized, which may further help us to decide the therapeutic strategies in daily clinical practice.

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.

Clinical Characteristics of 10 Pregnant and Postpartum Women With Extracorporeal Membrane Oxygenation: A Retrospective Study

Background: The aim of study was to summarize the clinical characteristics and experience of extracorporeal membrane oxygenation (ECMO) in pregnant and postpartum patients. Methods and Results: We retrospectively reviewed 131 consecutive ECMO patients at our center from May 2015 to May 2021. A total of 10 Chinese patients were pregnant or postpartum at the time of ECMO initiation. Patients ranged in age from 25 to 36 years (median age 30.5 years). The ECMO duration ranged from 3 to 31 days (median duration 8 days). There was a stabilizing trend of acid-base balance and decreasing lactic acid over the 3 days following ECMO initiation. Seven (70%) patients survived at least 48 h after weaning from ECMO. Four (40%) patients survived until discharge, and four (40%) fetuses survived until discharge. Conclusion: ECMO provides a suitable temporary cardiopulmonary support for pregnant and postpartum patients. ECMO shows a favorable effect on short-term stability in critical obstetric patients.

Analysis of the dynamic relationship between immune profiles and the clinical features of patients with COVID-19

Background

The novel coronavirus disease (COVID-19) has been declared a global pandemic, with the cumulative number of confirmed cases and deaths exceeding 150 million and 3 million, respectively. Here, we examined the dynamic changes in the immune and clinical features of patients with COVID-19.

Methods

Clinical data of 98 patients with confirmed COVID-19 diagnosis were acquired from electronic medical records and curated. The data were analyzed based on the stage of the admission, deterioration, and convalescence, which included age, sex, severity, disease stages, biochemical indicators, immune cells, inflammatory cytokines, and immunoglobulins. Additionally, temporal changes in the immune response in patients undergoing continuous renal replacement therapy (CRRT) were also examined.

Results

Compared to mild stage patients, severe stage patients with COVID-19 exhibited a significant reduction in lymphocyte [23.10 (17.58-33.55) vs. 4.80 (2.95-6.50), P<0.001], monocyte [8.65 (7.28-10.00) vs. 3.45 (2.53-4.58), P<0.001], and NK cell levels [244.00 (150.50-335.00) vs. 59.00 (40.00-101.00), P<0.001] but showed elevated levels of neutrophils [64.90 (56.30-73.70) vs. 90.95 (87.60-93.68), P<0.001], inflammatory cytokines [Interleukin-10, 3.05 (1.37-3.86) vs. 5.94 (3.84-8.35), P=0.001; and tumor necrosis factor-α, 11.50 (6.55-26.45) vs. 12.96 (12.22-36.80), P=0.029], which improved during convalescence. Besides, the number of immune cells-T lymphocytes, B lymphocytes, helper T cells, suppressor T cells, NK cells, and monocytes, except neutrophils-slowly increased in critically ill patients receiving CRRT from 0 to 3 weeks.

Conclusions

Our results indicate that the surveillance of immune cells may contribute to monitoring COVID-19 disease progression, and CRRT is a potential therapeutic strategy to regulate the immune balance in critically ill patients.

Acute Kidney Injury in Pediatric Patients on Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-analysis

Background: Acute kidney injury (AKI) is a well-established complication of extra-corporal membrane oxygenation (ECMO) in the adult population. The data in the pediatric and neonatal population is still limited. Moreover, the mortality risk of AKI among pediatric patients requiring ECMO remains unclear. Thus, this meta-analysis aims to assess the incidence of AKI, AKI requiring renal replacement therapy and AKI associated mortality in pediatric/neonatal patients requiring ECMO. Methods: A literature search was performed utilizing MEDLINE, EMBASE, and the Cochrane Database from inception through June 2019. We included studies that evaluated the incidence of AKI, severe AKI requiring renal replacement therapy (RRT) and the risk of mortality among pediatric patients on ECMO with AKI. Random-effects meta-analysis was used to calculate the pooled incidence of AKI and the odds ratios (OR) for mortality. Results: 13 studies with 3523 pediatric patients on ECMO were identified. Pooled incidence of AKI and AKI requiring RRT were 61.9% (95% confidence interval (CI): 39.0-80.4%) and 40.9% (95%CI: 31.2-51.4%), respectively. A meta-analysis limited to studies with standard AKI definitions showed a pooled estimated AKI incidence of 69.2% (95%CI: 59.7-77.3%). Compared with patients without AKI, those with AKI and AKI requiring RRT while on ECMO were associated with increased hospital mortality ORs of 1.70 (95% CI, 1.38-2.10) and 3.64 (95% CI: 2.02-6.55), respectively. Conclusions: The estimated incidence of AKI and severe AKI requiring RRT in pediatric patients receiving ECMO are high at 61.9% and 40.9%, respectively. AKI among pediatric patients on ECMO is significantly associated with reduced patient survival.

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.

Blood purification treatment initiated at the time of sepsis diagnosis effectively attenuates serum HMGB1 upregulation and improves patient prognosis

The aim of the present study was to investigate the increase in serum and urine levels of high mobility group box protein 1 (HMGB1) during sepsis and the effect of blood purification treatments on HMGB1 levels and patient prognosis. A total of 40 intensive care patients with sepsis were randomly assigned to different groups (n=10 per group): A control group (sepsis group), a continuous renal replacement treatment (CRRT) group, a hemoperfusion (HP) group and an HP+CRRT group. The blood purification treatments using HP and/or CRRT were performed immediately after the diagnosis of sepsis. HMGB1 levels were measured using ELISA, and Acute Physiology and Chronic Health Evaluation (APACHE) II scores and 30-day survival rates were evaluated. Relative to a healthy control group (n=10), HMGB1 levels were observed to be significantly upregulated during sepsis (P<0.05). Following the initiation of sepsis, serum HMGB1 continued to increase in the sepsis group and was significantly elevated at 24 h (P<0.05), whereas urine HMGB1 levels decreased significantly at 12 and 24 h (P<0.05). Serum HMGB1 levels were significantly positively correlated with APACHE II scores (r=0.7284, P<0.01) and significantly negatively correlated with urine HMGB1 levels (r=−0.5103, P=0.026). Serum HMGB1 levels were significantly reduced in the HP and HP+CRRT groups by 12 and 24 h following the initiation of treatment (both P<0.05). Changes in the urine HMGB1 level differed in each group. Relative to the sepsis group, the APACHE II scores of all blood purification groups were significantly reduced (P<0.05) and the 30-day survival rate of the HP+CRRT group was significantly increased (P=0.0107). The results of the present study indicate that blood purification initiated at the point of diagnosis in patients with sepsis may attenuate serum HMGB1 upregulation, promote urinary excretion of HMGB1 and improve the prognosis of sepsis.

The inflammatory response to extracorporeal membrane oxygenation (ECMO): a review of the pathophysiology

Extracorporeal membrane oxygenation (ECMO) is a technology capable of providing short-term mechanical support to the heart, lungs or both. Over the last decade, the number of centres offering ECMO has grown rapidly. At the same time, the indications for its use have also been broadened. In part, this trend has been supported by advances in circuit design and in cannulation techniques. Despite the widespread adoption of extracorporeal life support techniques, the use of ECMO remains associated with significant morbidity and mortality. A complication witnessed during ECMO is the inflammatory response to extracorporeal circulation. This reaction shares similarities with the systemic inflammatory response syndrome (SIRS) and has been well-documented in relation to cardiopulmonary bypass. The exposure of a patient’s blood to the non-endothelialised surface of the ECMO circuit results in the widespread activation of the innate immune system; if unchecked this may result in inflammation and organ injury. Here, we review the pathophysiology of the inflammatory response to ECMO, highlighting the complex interactions between arms of the innate immune response, the endothelium and coagulation. An understanding of the processes involved may guide the design of therapies and strategies aimed at ameliorating inflammation during ECMO. Likewise, an appreciation of the potentially deleterious inflammatory effects of ECMO may assist those weighing the risks and benefits of therapy.

Severe ARDS caused by adenovirus: early initiation of ECMO plus continuous renal replacement therapy

The reported survival rates of patients with acute respiratory distress syndrome (ARDS) caused by human adenovirus (HAdV) pneumonia are poor. The results do not differ much in immunocompetent patients supported by extracorporeal membrane oxygenation (ECMO). We report two immunocompetent patients with severe ARDS complicating HAdV pneumonia who were treated successfully and survived to discharge. Compared with previous cases, our cases might have benefited from several factors. First, the time interval between mechanical ventilator support and ECMO implantation was shorter. Second, we implemented conservative fluid management as recommended by the ARDS network using continuous renal replacement therapy (CRRT). Third, we administered an antiviral agent as early as possible. A clinical trial of early ECMO with CRRT and the administration of cidofovir in patients with severe ARDS complicating HAdV pneumonia are needed to confirm our results.

The influence of extracorporeal membrane oxygenation therapy on intestinal mucosal barrier in a porcine model for post-traumatic acute respiratory distress syndrome

Background

It is unclear at present whether extracorporeal membrane oxygenation (ECMO) therapy can improve intestinal mucous barrier function through increased perfusion. The present study establishes an animal model for post-traumatic acute respiratory distress syndrome (ARDS) and evaluates the effect of v-vECMO treatment on the intestinal mucosal barrier.

Method

Pulmonary contusion combined with ischemia-reperfusion injury was induced in 30 piglets. The animals were randomly divided into control, model, and ECMO groups. Serum I-FABP, d-lactate, and endotoxin were measured over a 24-h period. The jejunum and colon were collected post-mortem and evaluated histopathologically. The tissue was also examined using electron microscopy, and intestinal tight junction proteins (ZO-1 and occludin) were measured after 24 h of ECMO therapy. Mortality rate and cause of death were also recorded.

Results

The serum markers evaluating the intestinal mucosal barrier deteriorated in the model group compared to the control group (p < 0.05). At 2 h, serum I-FABP, d-lactate, and endotoxin were significantly increased in the ECMO group compared to the model group (p < 0.05). At 12 h, I-FABP and d-lactate in the ECMO group dropped to model group levels. Serum d-lactate was slightly lower in the ECMO group (p > 0.05) and serum I-FABP was significantly lower than in the model group (p < 0.05) at 24 h. Similarly, serum endotoxin was slightly lower in the ECMO group than in the model group (p > 0.05) at 24 h. After 24 h of ECMO therapy, the occludin and ZO-1 protein concentrations in jejunum and colon mucosa increased moderately compared to that in the model group (p < 0.05). Morphologic structure of the jejunum and colon did not improved significantly after ECMO therapy. Finally, we observed that ECMO therapy moderately decreased mortality (25% vs. 50%).

Conclusion

Intestinal mucosal barrier continued to deteriorate in the model group. Although early ECMO therapy aggravates intestinal mucosal injury, the damage gradually improves later during therapy. The results show that ECMO therapy has a protective effect on the intestinal mucosal barrier in the later treatment stage.

Effects of continuous renal replacement therapy on intestinal mucosal barrier function during extracorporeal membrane oxygenation in a porcine model

Backgrounds

Extracorporeal membrane oxygenation (ECMO) has been recommended for treatment of acute, potentially reversible, life-threatening respiratory failure unresponsive to conventional therapy. Intestinal mucosal barrier dysfunction is one of the most critical pathophysiological disorders during ECMO. This study aimed to determine whether combination with CRRT could alleviate damage of intestinal mucosal barrier function during VV ECMO in a porcine model.

Methods

Twenty-four piglets were randomly divided into control(C), sham(S), ECMO(E) and ECMO + CRRT(EC) group. The animals were treated with ECMO or ECMO + CRRT for 24 hours. After the experiments, piglets were sacrificed. Jejunum, ileum and colon were harvested for morphologic examination of mucosal injury and ultrastructural distortion. Histological scoring was assessed according to Chiu’s scoring standard. Blood samples were taken from the animals at -1, 2, 6, 12 and 24 h during experiment. Blood, liver, spleen, kidney and mesenteric lymphnode were collected for bacterial culture. Serum concentrations of diamine oxidase (DAO) and intestinal fatty acid binding protein (I-FABP) were tested as markers to assess intestinal epithelial function and permeability. DAO levels were determined by spectrophotometry and I-FABP levels by enzyme linked immunosorbent assay.

Results

Microscopy findings showed that ECMO-induced intestinal microvillus shedding and edema, morphological distortion of tight junction between intestinal mucous epithelium and loose cell-cell junctions were significantly improved with combination of CRRT. No significance was detected on positive rate of serum bacterial culture. The elevated colonies of bacterial culture in liver and mesenteric lymphnode in E group reduced significantly in EC group (p < 0.05). Compared with E group, EC group showed significantly decreased level of serum DAO and I-FABP (p < 0.05).

Conclusions

CRRT can alleviate the intestinal mucosal dysfunction and bacterial translocation during VV ECMO, which may extenuate the ECMO-associated SIRS and raise the clinical effect and safety.

In-line hemofiltration minimized extracorporeal membrane oxygenation-related inflammation in a porcine model

We evaluated a pattern for connecting a hemofiltration apparatus after the ECMO oxygenator and observed the effects on the levels of inflammatory cytokines. All animals were anesthetized and ventilated, were randomly divided into 3 groups and observed for 24 h: S group (n = 6) received cannulation and heparin infusion; E group (n = 6) received venovenous (VV)-ECMO and heparin infusion; E+H group (n = 6) received hemofiltration with VV-ECMO placed after the oxygenator and heparin infusion. Hemodynamics, gas exchange parameters and plasma cytokine levels were measured simultaneously. After VV-ECMO, oxygenation was maintained in the E and E+H groups. In the E group, the levels of TNF-α, IL-1β, IL-6 and IL-8 increased markedly in the first 2-6 h and then remained stable from 12-24 h. Concentrations of TNF-α, IL-1β, IL-6 and IL-8 in the E+H group were lower than those in the E group. We concluded that the manner of connecting the hemofiltration apparatus after the oxygenator helped maintain adequate oxygenation and was easy to perform. Connecting hemofiltration to ECMO minimized the ECMO-associated effects of pro-inflammatory cytokines.