Plasma concentrations of inflammatory cytokines rise rapidly during ECMO-related SIRS due to the release of preformed stores in the intestine

Imaging Adult ECMO

Adult extracorporal membrane oxygenation utilization in the ICU has rapidly increased. Newer technology and cannulation strategies and the complex hemodynamics make imaging interpretation challenging. There is also a high rate of complications. This review details the common indications, cannulation strategies, relevant hemodynamics and complications which impact imaging interpretation. Recommendations for modifying computed tomography protocols and techniques to obtain diagnostic images and some of the imaging pitfalls are also discussed.

Effects of Ultralow-Tidal-Volume Ventilation under Veno-Venous Extracorporeal Membrane Oxygenation in a Porcine Model with Ventilator-Induced Lung Injury

Low-tidal-volume ventilation decreases mortality in acute respiratory distress syndrome (ARDS) patients. This study investigated the effects of ultralow tidal ventilation under veno-venous extracorporeal membrane oxygenator (ECMO) support in pigs with ARDS. Eight pigs were intubated and inoculated with methicillin-resistant Staphylococcus aureus through bronchoscopy. Ultralow tidal ventilation (3 mL/kg) under extracorporeal membrane oxygenator (ECMO) support was applied to one group and high tidal ventilation (15 mL/kg) was applied to another group to maintain comparable oxygenation for 12 h without ECMO support. Each group had similar arterial blood gas values and hemodynamic variables at baseline and during the experiment. The high-tidal-volume ventilation group showed a gradual decline in arterial oxygen levels, and repeated ANOVA showed significant differences in oxygenation change over time in the ultralow tidal ventilation group. Inflammatory cytokine levels in the bronchoalveolar lavage fluid and lung ultrasound scores were similar between two groups. Histologic analysis showed that both groups developed pneumonia after 12 h; however, the ultralow tidal ventilation group had a lower lung injury score assessed by the pathologist. We developed the first ultralow-tidal-volume ventilation porcine model under veno-venous ECMO support. The ultralow-tidal-volume ventilation strategy can mitigate mechanical ventilator-associated lung injury.

Coagulopathy Characterized by Rotational Thromboelastometry in a Porcine Pediatric ECMO Model

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is used to support patients with reversible cardiopulmonary insufficiency. Although it is a lifesaving technology, bleeding, inflammation, and thrombosis are well-described complications of ECMO. Adult porcine models of ECMO have been used to recapitulate the physiology and hemostatic consequences of ECMO cannulation in adults. However, these models lack the unique physiology and persistence of fetal forms of coagulation factors and fibrinogen as in human infants. We aimed to describe physiologic and coagulation parameters of piglets cannulated and supported with VA-ECMO. Four healthy piglets (5.7-6.4 kg) were cannulated via jugular vein and carotid artery by cutdown and supported for a maximum of 20 hours. Heparin was used with a goal activated clotting time of 180-220 seconds. Arterial blood gas (ABG) was performed hourly, and blood was transfused from an adult donor to maintain hematocrit (Hct) > 24%. Rotational thromboelastometry (ROTEM) was performed at seven time points. All animals achieved adequate flow with a patent circuit throughout the run (pre- and post-oxygenator pressure gradient <10 mmHg). There was slow but significant hemorrhage at cannulation, arterial line, and bladder catheter sites. All animals required the maximum blood transfusion volume available. All animals became anemic after exhaustion of blood for transfusion. ABG showed progressively declining Hct and adequate oxygenation. ROTEM demonstrated decreasing fibrin-only ROTEM (FIBTEM) clot firmness. Histology was overall unremarkable. Pediatric swine are an important model for the study of pediatric ECMO. We have demonstrated the feasibility of such a model while providing descriptions of physiologic, hematologic, and coagulation parameters throughout. Weak whole-blood clot firmness by ROTEM suggested defects in fibrinogen, and there was a clinical bleeding tendency in all animals studied. This model serves as an important means to study the complex derangements in hemostasis during ECMO.

Sedative and Analgesic Pharmacokinetics During Pediatric ECMO

Sedatives and analgesics are often administered to critically ill children supported by extracorporeal membrane oxygenation (ECMO) to facilitate comfort and to decrease risks of life-threatening complications. Optimization of sedative and analgesic dosing is necessary to achieve desired therapeutic benefits and must consider interactions between the circuit and patient that may affect drug metabolism, clearance, and impact on target organs. This paper reviews existing in vitro and pediatric in vivo literature concerning the effects of the ECMO circuit on sedative and analgesic disposition and offers dosing guidance for the management of critically ill children receiving these drugs.

Incidence of healthcare-associated infections in patients with fever during the first 48 hours after decannulation from veno-venous extracorporeal membrane oxygenation

INTRODUCTION

Fevers following decannulation from veno-venous extracorporeal membrane oxygenation often trigger an infectious workup; however, the yield of this workup is unknown. We investigated the incidence of post-veno-venous extracorporeal membrane oxygenation decannulation fever as well as the incidence and nature of healthcare-associated infections in this population within 48 hours of decannulation.

METHODS

All patients treated with veno-venous extracorporeal membrane oxygenation for acute respiratory failure who survived to decannulation between August 2014 and November 2018 were retrospectively reviewed. Trauma patients and bridge to lung transplant patients were excluded. The highest temperature and maximum white blood cell count in the 24 hours preceding and the 48 hours following decannulation were obtained. All culture data obtained in the 48 hours following decannulation were reviewed. Healthcare-associated infections included blood stream infections, ventilator-associated pneumonia, and urinary tract infections.

RESULTS

A total of 143 patients survived to decannulation from veno-venous extracorporeal membrane oxygenation and were included in the study. In total, 73 patients (51%) were febrile in the 48 hours following decannulation. Among this cohort, seven healthcare-associated infections were found, including five urinary tract infections, one blood stream infection, and one ventilator-associated pneumonia. In the afebrile cohort (70 patients), four healthcare-associated infections were found, including one catheter-associated urinary tract infection, two blood stream infections, and one ventilator-associated pneumonia. In all decannulated patients, the majority of healthcare-associated infections were urinary tract infections (55%). No central line-associated blood stream infections were identified in either cohort. When comparing febrile to non-febrile cohorts, there was a significant difference between pre- and post-decannulation highest temperature (p < 0.001) but not maximum white blood cell count (p = 0.66 and p = 0.714) between the two groups. Among all positive culture data, the most commonly isolated organism was Klebsiella pneumoniae (41.7%) followed by Escherichia coli (33%). Median hospital length of stay and time on extracorporeal membrane oxygenation were shorter in the afebrile group compared to the febrile group; however, this did not reach a statistical difference.

CONCLUSION

Fever is common in the 48 hours following decannulation from veno-venous extracorporeal membrane oxygenation. Differentiating infection from non-infectious fever in the post-decannulation veno-venous extracorporeal membrane oxygenation population remains challenging. In our febrile post-decannulation cohort, the incidence of healthcare-associated infections was low. The majority were diagnosed with a urinary tract infection. We believe obtaining cultures in febrile patients in the immediate decannulation period from veno-venous extracorporeal membrane oxygenation has utility, and even in the absence of other clinical suspicion, should be considered. However, based on our data, a urinalysis and urine culture may be sufficient as an initial work up to identify the source of infection.

Extracorporeal membrane oxygenation for near fatal asthma with sudden cardiac arrest

INTRODUCTION

Near fatal asthma is a life-threatening disorder that requires mechanical ventilation. Near fatal asthma and COPD with sudden cardiac arrest can worsen the outcomes. Previous studies demonstrated that ECMO is a live-saving measure for near fatal asthma that does not respond to traditional treatment.

CASE STUDY

A patient with near fatal asthma (NFA) and COPD presented with high airway resistance, life-threatening acidemia and severe hypoxemia that failed to respond to conventional therapy. His hospital course was complicated by sudden cardiac arrest when preparing to initiate V-V mode extracorporeal membrane oxygenation (ECMO). The mode immediately changed from V-V to V-A, then to V-AV and finally to V-V mode in order to improve cardiac function and promote recovery of lung function.

RESULTS

On the sixth day, ECMO was removed and on the ninth day, he was extubated and transferred to the ward. Finally, the patient was discharged home on the nineteenth day after admission to be followed up in the pulmonary clinic.

CONCLUSIONS

The early application of ECMO and mode changing plausibly resulted in dramatic improvement in gas exchange and restoration of cardiac function. This case illustrates the critical role of ECMO mode changing as salvage therapy in NFA and COPD with sudden cardiac arrest.

Immunity and Stress Responses Are Induced During Ex Situ Heart Perfusion

BACKGROUND

Ex situ heart perfusion (ESHP) preserves the donated heart in a perfused, beating condition preventing cold storage-related ischemia and provides a platform to evaluate myocardial viability during preservation. However, myocardial function declines gradually during ESHP. Extracorporeal circulation systems are associated with the induction of systemic inflammatory and stress responses. Our aim was to evaluate the incidence of inflammation and induction of endoplasmic reticulum stress responses during an extended period of ESHP.

METHODS

Cardiac function, myocardial tissue injury, markers of inflammation, oxidative stress, and endoplasmic reticulum stress were assessed in healthy pig hearts, perfused for 12 hours either in nonworking mode (non-WM=7) or working mode (WM, n=6).

RESULTS

Cardiac function declined during ESHP but was significantly better preserved in the hearts perfused in WM (median 11-hour cardiac index/1-hour cardiac index: WM=27% versus non-WM=9.5%, P=0.022). Myocardial markers of endoplasmic reticulum stress were expressed higher in ESHP hearts compared with in vivo samples. The proinflammatory cytokines and oxidized low-density lipoprotein significantly increased in the perfusate throughout the perfusion in both perfusion groups. The left ventricular expression of the cytokines and malondialdehyde was induced in non-WM, whereas it was not different between WM and in vivo.

CONCLUSIONS

Myocardial function declines during ESHP regardless of perfusion mode. However, ESHP in WM may lead to superior preservation of myocardial function and viability. Both inflammation and endoplasmic reticulum stress responses are significantly induced during ESHP and may contribute to the myocardial functional decline, representing a potential therapeutic target to improve the clinical donor heart preservation.

Pulmonary complications associated with veno-arterial extra-corporeal membrane oxygenation: a comprehensive review

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a life-saving technology that provides transient respiratory and circulatory support for patients with profound cardiogenic shock or refractory cardiac arrest. Among its potential complications, VA-ECMO may adversely affect lung function through various pathophysiological mechanisms. The interaction of blood components with the biomaterials of the extracorporeal membrane elicits a systemic inflammatory response which may increase pulmonary vascular permeability and promote the sequestration of polymorphonuclear neutrophils within the lung parenchyma. Also, VA-ECMO increases the afterload of the left ventricle (LV) through reverse flow within the thoracic aorta, resulting in increased LV filling pressure and pulmonary congestion. Furthermore, VA-ECMO may result in long-standing pulmonary hypoxia, due to partial shunting of the pulmonary circulation and to reduced pulsatile blood flow within the bronchial circulation. Ultimately, these different abnormalities may result in a state of persisting lung inflammation and fibrotic changes with concomitant functional impairment, which may compromise weaning from VA-ECMO and could possibly result in long-term lung dysfunction. This review presents the mechanisms of lung damage and dysfunction under VA-ECMO and discusses potential strategies to prevent and treat such alterations.

Combined Use of CytoSorb and ECMO in Patients with Severe Pneumogenic Sepsis

BACKGROUND

High morbidity and mortality are frequently reported in intensive care patients suffering from severe sepsis with systemic inflammation. With the development of severe respiratory failure, extracorporeal membrane oxygenation (ECMO) is often required. In this study, cytokine adsorption therapy in combination with ECMO is applied in patients with acute respiratory distress syndrome (ARDS) due to severe pneumogenic sepsis. The efficacy of this therapy is evaluated compared with a historical cohort without hemoadsorption therapy.

METHODS

Between January and May 2018, combined high-flow venovenous ECMO and CytoSorb therapy (CytoSorb filter connected to ECMO circuit) was applied in patients (n = 13) with pneumogenic sepsis and ARDS. These patients were prospectively included (CytoSorb group). Data from patients (n = 7) with pneumogenic sepsis and ECMO therapy were retrospectively analyzed (control group).

RESULTS

All patients survived in the CytoSorb group, where the 30-day mortality rate reached 57% in the control group. After CytoSorb therapy, we instantly observed a significant reduction in procalcitonin (PCT) and C-reactive protein (CRP) levels compared with the control group. Within 48 hours, the initial high doses of catecholamine could be weaned off only in the CytoSorb group.

CONCLUSIONS

Our results indicate that CytoSorb in combination with ECMO is an effective therapy to prevent escalation of sepsis with rapid weaning off high-dose catecholamine infusions and quick reduction in PCT and CRP levels. Optimal timing of immunomodulatory therapy and impact on ECMO-related inflammation still need to be furtherly investigated.

Biomarkers of Inflammation and Lung Recovery in Extracorporeal Membrane Oxygenation Patients With Persistent Pulmonary Hypertension of the Newborn: A Feasibility Study

OBJECTIVES

Extracorporeal membrane oxygenation is a treatment for Persistent Pulmonary Hypertension of the Newborn with high mortality.

HYPOTHESIS

the extracorporeal membrane oxygenation circuit results in inflammatory responses that mitigate against successful weaning.

DESIGN

Single-center prospective observational feasibility study.

SETTING

PICU.

PATIENTS

Twenty-four neonates requiring extracorporeal membrane oxygenation support for Persistent Pulmonary Hypertension of the Newborn.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The reference outcome was death or more than 7 days of extracorporeal membrane oxygenation support. Other outcomes included serial measures of plasma-free hemoglobin and markers of its metabolism, leucocyte, platelet and endothelial activation, and biomarkers of inflammation. Of 24 participants recruited between February 2016 and June 2017, 10 died or required prolonged extracorporeal membrane oxygenation support. These patients were sicker at baseline with higher levels of plasma-free hemoglobin within 12 hours of cannulation (geometric mean ratio, 1.92; 95% CIs, 1.00-3.67; p = 0.050) but not thereafter, versus those requiring less than 7 days extracorporeal membrane oxygenation. Serum haptoglobin concentrations were significantly elevated in both groups. Patients who died or required prolonged extracorporeal membrane oxygenation support demonstrated elevated levels of platelet-leucocyte aggregation, but decreased concentrations of mediators of the inflammatory response: interleukin-8, C-reactive protein, and tumor necrosis factor α.

CONCLUSIONS

Clinical status at baseline and not levels of plasma-free hemoglobin or the systemic inflammatory response may determine the requirement for prolonged extracorporeal membrane oxygenation support in neonates.

The impact of interleukin serum levels on the prognosis of patients undergoing venoarterial extracorporeal membrane oxygenation

Extracorporeal life support is increasingly used in the treatment of patients presenting with cardiogenic shock or in need of cardiopulmonary resuscitation. Identifying therapeutic targets and factors associated with the prognosis are highly desirable. The present study analyzed the impact of interleukin 6 and 8 on the outcome of patients undergoing venoarterial extracorporeal membrane oxygenation (VA ECMO). Interleukin 6 and 8 serum levels of 329 patients were analyzed prior to, on days 1 and 5 of VA ECMO therapy. Interleukin 6 and 8 serum levels of surviving and nonsurviving patients were compared. At time points with significant differences, receiver operating characteristics and cutoff levels were analyzed to determine the prognostic value of interleukin serum levels. Survival analysis was performed to compare patients above and below cutoff levels. Interleukin 6 serum levels were significantly elevated in nonsurviving patients prior to VA ECMO initiation. Interleukin 6 and 8 serum levels in nonsurviving patients were significantly elevated on day 1 of VA ECMO. Receiver operating characteristics analysis revealed significant prognostic impact of interleukin 6 and 8 on day 1 of VA ECMO (AUC 0.70 and 0.72). Survival analysis comparing patients above and below the cutoff showed a 1-year survival of 32.6% for IL6 and 20.8% for IL8 above, as well as 66.9% for IL6 and 61.9% for IL8 below the cutoff (P < .05). Interleukin 6 and 8 serum levels demonstrated prognostic value early in VA ECMO therapy. The technical applicability of interleukin reduction raises interest in interleukins 6 and 8 as therapeutic targets.

Extracorporeal Membrane Oxygenation in Transport Part 2: Complications and Troubleshooting

Factors taken for granted while the extracorporeal membrane oxygenation (ECMO) patient is maintained in a hospital setting can become critical when planning for transport. These issues include but are not limited to positioning of patients on a small transport stretcher, positioning of cannulas and equipment, ensuring adequate power sources and supply, inefficient temperature control, and a much higher risk of decannulation. It is paramount to be comfortable with the management strategies required to handle common complications of ECMO with limited resources in a relatively austere environment. Coagulopathy and bleeding are the most common complications occurring in up to 50% of ECMO patients. Loss of flow and hypotension from loss of volume or profound vasodilation after ECMO initiation need to be managed accordingly. Oxygenator malfunction can occur, and clinicians must be able to recognize the indicators of this complication promptly. Loss of pulsatility, low end-tidal carbon dioxide (ETCO₂), and differential hypoxia are common complications in venoarterial ECMO. In addition, an air embolism is life-threatening on venoarterial ECMO but may be better tolerated in the setting of venovenous ECMO. Recirculation in venovenous ECMO leads to circulation of poorly oxygenated blood and must be recognized and addressed. Lastly, pump failure, circuit rupture, and decannulation are devastating complications. Over the last decade, the use of extracorporeal membrane oxygenation (ECMO) has accelerated rapidly,^1-3 providing support for patients in severe respiratory or cardiac failure. With ongoing clinical experience and improvements in technology, the indications for ECMO are increasing.⁴ Many areas are developing centralized ECMO centers to serve their surrounding communities.^5-7 To use a centralized ECMO referral model, patients need access to effective, safe critical care transport, but transporting a patient on ECMO carries a significant risk of adverse events.^8-13 The purpose of this review is to highlight some of the most common adverse events in ECMO transports and provide management suggestions. Note that these recommendations are not a substitution for close collaboration with medical control, and all adverse events should be promptly reported per organizational protocols.

Platelets trigger perivascular mast cell degranulation to cause inflammatory responses and tissue injury

Platelet responses have been associated with end-organ injury and mortality following complex insults such as cardiac surgery, but how platelets contribute to these pathologies remains unclear. Our studies originated from the observation of microvascular platelet retention in a rat cardiac surgery model. Ensuing work supported the proximity of platelet aggregates with perivascular mast cells (MCs) and demonstrated that platelet activation triggered systemic MC activation. We then identified platelet activating factor (PAF) as the platelet-derived mediator stimulating MCs and, using chimeric animals with platelets defective in PAF generation or MCs lacking PAF receptor, defined the role of this platelet-MC interaction for vascular leakage, shock, and tissue inflammation. In application of these findings, we demonstrated that inhibition of platelet activation in modeled cardiac surgery blunted MC-dependent inflammation and tissue injury. Together, our work identifies a previously undefined mechanism of inflammatory augmentation, in which platelets trigger local and systemic responses through activation of perivascular MCs.

[99mTc]-labelled interleukin-8 as a diagnostic tool compared to [18F]FDG and CT in an experimental porcine osteomyelitis model

Osteomyelitis (OM) is an important cause of morbidity and sometimes mortality in children and adults. Long-term complications can be reduced when treatment is initiated in an early phase. The diagnostic gold standard is microbial examination of a biopsy and current non-invasive imaging methods are not always optimal. [¹¹¹In]-leukocyte scintigraphy is recommended for peripheral OM, but is time-consuming and not recommended in children. [¹⁸F]FDG PET/CT is recommended for vertebral OM in adults, but has the disadvantage of false positive findings and a relatively high radiation exposure; the latter is a problem in children. [^99mTc]-based tracers are consequently preferred in children. We, therefore, aimed to find a [^99mTc]-marked tracer with high specificity and sensitivity for early detection of OM. Suppurating inflammatory lesions like OM caused by Staphylococcus aureus (S. aureus) will attract large numbers of neutrophils and macrophages. A preliminary study has shown that [^99m Tc]-labelled IL8 may be a possible candidate for imaging of peripheral OM. We investigated [^99mTc]IL8 scintigraphy in a juvenile pig model of peripheral OM and compared it with [¹⁸F]FDG PET/CT. The pigs were experimentally inoculated with S. aureus to induce OM and scanned one week later. We also examined leukocyte count, serum CRP and IL8, as well as performed histopathological and microbiological investigations. [ ^99m Tc]IL8 was easily and relatively quickly prepared and was shown to be suitable for visualization of OM lesions in peripheral bones detecting 70% compared to a 100% sensitivity of [¹⁸F]FDG PET/CT. [ ^99m Tc]IL8 is a promising candidate for detection of OM in peripheral bones in children.

Mesenchymal stem cells may ameliorate inflammation in an ex vivo model of extracorporeal membrane oxygenation

INTRODUCTION

Mesenchymal stem cells exhibit immunomodulatory properties which are currently being investigated as a novel treatment option for Acute Respiratory Distress Syndrome. However, the feasibility and efficacy of mesenchymal stem cell therapy in the setting of extracorporeal membrane oxygenation is poorly understood. This study aimed to characterise markers of innate immune activation in response to mesenchymal stem cells during an ex vivo simulation of extracorporeal membrane oxygenation.

METHODS

Ex vivo extracorporeal membrane oxygenation simulations (n = 10) were conducted using a commercial extracorporeal circuit with a CO₂-enhanced fresh gas supply and donor human whole blood. Heparinised circuits (n = 4) were injected with 40 × 10⁶-induced pluripotent stem cell-derived human mesenchymal stem cells, while the remainder (n = 6) acted as controls. Simulations were maintained, under physiological conditions, for 240 minutes. Circuits were sampled at 15, 30, 60, 120 and 240 minutes and assessed for levels of interleukin-1β, interleukin-6, interleukin-8, interleukin-10, tumour necrosis factor-α, transforming growth factor-β1, myeloperoxidase and α-Defensin-1. In addition, haemoglobin, platelet and leukocyte counts were performed.

RESULTS

There was a trend towards reduced levels of pro-inflammatory cytokines in mesenchymal stem cell-treated circuits and a significant increase in transforming growth factor-β1. Blood cells and markers of neutrophil activation were reduced in mesenchymal stem cell circuits during the length of the simulation. As previously reported, the addition of mesenchymal stem cells resulted in a reduction of flow and increased trans-oxygenator pressures in comparison to controls.

CONCLUSIONS

The addition of mesenchymal stem cells during extracorporeal membrane oxygenation may cause an increase in transforming growth factor-β1. This is despite their ability to adhere to the membrane oxygenator. Further studies are required to confirm these findings.

Effect of ex vivo extracorporeal membrane oxygenation flow dynamics on immune response

BACKGROUND

Extracorporeal membrane oxygenation is a life-saving support for heart and/or lung failure patients. Despite technological advancement, abnormal physiology persists and has been associated with subsequent adverse events. These include thrombosis, bleeding, systemic inflammatory response syndrome and infection. However, the underlying mechanisms are yet to be elucidated. We aimed to investigate whether the different flow dynamics of extracorporeal membrane oxygenation would alter immune responses, specifically the overall inflammatory response, leukocyte numbers and activation/adhesion surface antigen expression.

METHODS

An ex vivo model was used with human whole blood circulating at 37°C for 6 hours at high (4 L/minute) or low (1.5 L/minute) flow dynamics, with serial blood samples taken for analysis.

RESULTS

During high flow, production of interleukin-1β (p < 0.0001), interleukin-6 (p = 0.0075), tumour necrosis factor-α (p = 0.0013), myeloperoxidase (p < 0.0001) and neutrophil elastase (p < 0.0001) were significantly elevated over time compared to low flow, in particular at 6 hours. While the remaining assessments exhibited minute changes between flow dynamics, a consistent trend of modulation in leukocyte subset numbers and phenotype was observed at 6 hours.

CONCLUSION

We conclude that prolonged circulation at high flow triggers a prominent pro-inflammatory cytokine response and activates neutrophil granule release, but further research is needed to better characterize the effect of flow during extracorporeal membrane oxygenation.

The Functional Immune Response of Patients on Extracorporeal Life Support

Extracorporeal life support (ECLS) is a widely used lifesaving technology. Whether ECLS results in immune dysregulation is unclear. This study's aim was to examine whether ECLS affected innate immune response. All patients placed on ECLS were eligible. Blood was obtained before, during, and after ECLS. Function of the innate immune system was measured by ex vivo lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) and plasma cytokine levels (interleukin [IL]-6, IL-8, IL-10, and TNF-α). Immunoparalysis was defined as ex vivo TNF-α levels less than 200 pg/ml. Nineteen patients were enrolled with twelve <18 years old. Median ECLS duration was 10 days (range: 3-108); nine patients died. After stratifying the cohort by the presence of immunoparalysis before ECLS, those immunoparalyzed showed increased response to LPS on days 1 and 3 (p = 0.016). Those without pre-ECLS immunoparalysis showed a transient decrease in response on day 3 (p = 0.008). Plasma IL-10 levels were elevated in those with pre-ECLS immunoparalysis and dropped significantly by day 1 (p = 0.031). The number treated with steroids was similar in the two groups. In conclusion, patients with immunoparalysis before ECLS showed a gradual increase in immune function during ECLS, whereas those without immunoparalysis had a transient decrease in responsiveness on day 3.

ECMO and Right Ventricular Failure: Review of the Literature

Right ventricular (RV) failure is the inability of the RV to maintain sufficient cardiac output in the setting of adequate preload, due to either intrinsic injury to the RV or increased afterload. Medical treatment of RV failure should include optimizing preload, augmenting contractility with vasopressors and inotropes, and considering inhaled pulmonary vasodilators. However, when medical therapies are insufficient, mechanical circulatory support (MCS) is needed to maintain systemic and RV perfusion. The data on MCS for isolated RV failure are limited, but extracorporeal membrane oxygenation (ECMO) appears to be the most efficient and effective modality. For patients with isolated RV failure from acute hypoxemic respiratory failure, veno-venous (VV) ECMO is an appropriate initial configuration, even if the patient is in shock. With primary RV injury or RV failure with concomitant left ventricle (LV) failure, however, venoarterial (VA) ECMO is indicated. Both modalities provide indirect support to the RV by reducing preload, reducing RV wall tension, and delivering oxygenated blood to the coronary circulation. Peripheral cannulation is required in VV-ECMO and is most commonly used in VA-ECMO, allowing for rapid cannulation even in emergencies. Changes in pulsatility on an arterial catheter waveform can indicate changes in clinical status including changes in myocardial function, inadequate preload, worsening RV failure, and excessive VA-ECMO support leading to an elevated LV afterload. Myocardial function may be improved by titration of inotropes or vasodilators, utilization of an Impella or an intra-aortic balloon counterpulsation support devices, or by changes in VA-ECMO support.

A Pilot Study Identifying Brain-Targeting Adaptive Immunity in Pediatric Extracorporeal Membrane Oxygenation Patients With Acquired Brain Injury

Supplemental Digital Content is available in the text.

Objectives:

Extracorporeal membrane oxygenation provides short-term cardiopulmonary life support, but is associated with peripheral innate inflammation, disruptions in cerebral autoregulation, and acquired brain injury. We tested the hypothesis that extracorporeal membrane oxygenation also induces CNS-directed adaptive immune responses which may exacerbate extracorporeal membrane oxygenation-associated brain injury.

Design:

A single center prospective observational study.

Setting:

Pediatric and cardiac ICUs at a single tertiary care, academic center.

Patients:

Twenty pediatric extracorporeal membrane oxygenation patients (0–14 yr; 13 females, 7 males) and five nonextracorporeal membrane oxygenation Pediatric Logistic Organ Dysfunction score matched patients

Interventions:

None.

Measurements and Main Results:

Venous blood samples were collected from the extracorporeal membrane oxygenation circuit at day 1 (10–23 hr), day 3, and day 7 of extracorporeal membrane oxygenation. Flow cytometry quantified circulating innate and adaptive immune cells, and CNS-directed autoreactivity was detected using an in vitro recall response assay. Disruption of cerebral autoregulation was determined using continuous bedside near-infrared spectroscopy and acquired brain injury confirmed by MRI. Extracorporeal membrane oxygenation patients with acquired brain injury (n = 9) presented with a 10-fold increase in interleukin-8 over extracorporeal membrane oxygenation patients without brain injury (p < 0.01). Furthermore, brain injury within extracorporeal membrane oxygenation patients potentiated an inflammatory phenotype in adaptive immune cells and selective autoreactivity to brain peptides in circulating B cell and cytotoxic T cell populations. Correlation analysis revealed a significant relationship between adaptive immune responses of extracorporeal membrane oxygenation patients with acquired brain injury and loss of cerebral autoregulation.

Conclusions:

We show that pediatric extracorporeal membrane oxygenation patients with acquired brain injury exhibit an induction of pro-inflammatory cell signaling, a robust activation of adaptive immune cells, and CNS-targeting adaptive immune responses. As these patients experience developmental delays for years after extracorporeal membrane oxygenation, it is critical to identify and characterize adaptive immune cell mechanisms that target the developing CNS.

Insult to Injury: Development of Alveolar Hemorrhage after Initiation of Extracorporeal Membrane Oxygenation

Background

Extracorporeal membrane oxygenation (ECMO) is associated with complications that are separate from the underlying diagnoses that require its use. One of the foremost complications of ECMO is a high incidence of bleeding, including alveolar hemorrhage (AH), which is believed to be due to both prophylactic anticoagulation and critical illness-induced systemic coagulopathy. However, akin to systemic inflammatory response syndrome after cardiopulmonary bypass, ECMO causes widespread systemic inflammation and acute lung injury, which likely further predisposes patients to AH. The burden of clinically significant AH among patients on ECMO for advanced lung disease remains unknown.

Patients and methods

Charts of patients with advanced lung disease who required ECMO at a single institution were reviewed. The clinical course and variables of patients who developed AH and those who did not were compared.

Results

This report describes five patients who developed AH after initiation of venovenous ECMO for refractory hypoxemia. Clinical and laboratory variables did not predict the development or the prognosis of AH. Two of these patients with refractory hypoxemia and AH were treated with pulse-dose corticosteroids, with a dramatic response in one case.

Conclusion

The acute decompensation of the patients and response to corticosteroids suggest AH was mediated by a systemic inflammatory process, as opposed to coagulopathy alone. Judicious use of steroids may be considered among select patients who develop AH without symptoms of systemic coagulopathy after initiation of ECMO.

How to cite this article

Williams S, Batra K, Mohanka M, Bollineni S, Kaza V, Torres F, et al. Insult to Injury: Development of Alveolar Hemorrhage after Initiation of Extracorporeal Membrane Oxygenation. Indian J Crit Care Med 2020;24(12):1201-1205.

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.

Drug Disposition and Pharmacotherapy in Neonatal ECMO: From Fragmented Data to Integrated Knowledge

Extracorporeal membrane oxygenation (ECMO) is a lifesaving support technology for potentially reversible neonatal cardiac and/or respiratory failure. As the survival and the overall outcome of patients rely on the treatment and reversal of the underlying disease, effective and preferentially evidence-based pharmacotherapy is crucial to target recovery. Currently limited data exist to support the clinicians in their every-day intensive care prescribing practice with the contemporary ECMO technology. Indeed, drug dosing to optimize pharmacotherapy during neonatal ECMO is a major challenge. The impact of the maturational changes of the organ function on both pharmacokinetics (PK) and pharmacodynamics (PD) has been widely established over the last decades. Next to the developmental pharmacology, additional non-maturational factors have been recognized as key-determinants of PK/PD variability. The dynamically changing state of critical illness during the ECMO course impairs the achievement of optimal drug exposure, as a result of single or multi-organ failure, capillary leak, altered protein binding, and sometimes a hyperdynamic state, with a variable effect on both the volume of distribution (Vd) and the clearance (Cl) of drugs. Extracorporeal membrane oxygenation introduces further PK/PD perturbation due to drug sequestration and hemodilution, thus increasing the Vd and clearance (sequestration). Drug disposition depends on the characteristics of the compounds (hydrophilic vs. lipophilic, protein binding), patients (age, comorbidities, surgery, co-medications, genetic variations), and circuits (roller vs. centrifugal-based systems; silicone vs. hollow-fiber oxygenators; renal replacement therapy). Based on the potential combination of the above-mentioned drug PK/PD determinants, an integrated approach in clinical drug prescription is pivotal to limit the risks of over- and under-dosing. The understanding of the dose-exposure-response relationship in critically-ill neonates on ECMO will enable the optimization of dosing strategies to ensure safety and efficacy for the individual patient. Next to in vitro and clinical PK data collection, physiologically-based pharmacokinetic modeling (PBPK) are emerging as alternative approaches to provide bedside dosing guidance. This article provides an overview of the available evidence in the field of neonatal pharmacology during ECMO. We will identify the main determinants of altered PK and PD, elaborate on evidence-based recommendations on pharmacotherapy and highlight areas for further research.

Complications of veno-arterial extracorporeal membrane oxygenation for refractory cardiogenic shock or cardiac arrest

Background:

The frequency of using veno-arterial extracorporeal membrane oxygenation increased, especially in patients with refractory cardiogenic shock or cardiac arrest. However, data of complications of veno-arterial extracorporeal membrane oxygenation are lacking. This study sought to investigate the incidence of veno-arterial extracorporeal membrane oxygenation complications for acute myocardial infarction patients with refractory cardiogenic shock or cardiac arrest and its relationship with patient survival.

Methods:

This study included 151 consecutive patients who underwent veno-arterial extracorporeal membrane oxygenation between 2006 and 2018 at a single referral center. We divided the patients into those who survived for 30 days after veno-arterial extracorporeal membrane oxygenation ( n = 57, 38%; group 1) and those who died within 30 days after veno-arterial extracorporeal membrane oxygenation support ( n = 94, 62%; group 2). The major adverse clinical events associated with veno-arterial extracorporeal membrane oxygenation were defined as first occurrence of infection, major bleeding, and stroke.

Results:

Adverse clinical events associated with veno-arterial extracorporeal membrane oxygenation occurred in 34 (59.6%) and 56 (59.6%) patients in groups 1 and 2, respectively. Group 2 had more patients who underwent new renal replacement therapy (21.1% vs 37.2%, p = 0.037). After multivariable analysis, cardiac arrest was independently associated with 30-day mortality (odds ratio = 3.6; 95% confidence interval = 1.7–7.63; p = 0.001). After excluding patients who died within 48 h after undergoing veno-arterial extracorporeal membrane oxygenation, new renal replacement therapy (odds ratio = 4.47; 95% confidence interval = 1.58–12.61; p = 0.005) and major adverse clinical events (odds ratio = 2.66; 95% confidence interval = 1.01–7.03; p = 0.049) were independently associated with 30-day mortality.

Conclusion:

Although veno-arterial extracorporeal membrane oxygenation can improve the survival, it is associated with morbidity. Therefore, risk–benefit analysis for veno-arterial extracorporeal membrane oxygenation and prevention of complications are important to improve prognosis.

Early continuous renal replacement therapy during infant extracorporeal life support is associated with decreased lung opacification

Lung opacification on chest radiography (CXR) is common during extracorporeal life support (ECLS), often resulting from pulmonary edema or inflammation. Concurrent use of continuous renal replacement therapy (CRRT) during ECLS is associated with improved fluid balance and cytokine filtration; through modification of these pathologic states, CRRT may modulate lung opacification observed on CXRs. We hypothesize that early CRRT use during infant ECLS decreases lung opacification on CXR. We conducted a retrospective cohort study comparing CXRs from infants receiving ECLS and early CRRT (n = 7) to matched infants who received ECLS alone (n = 7). The CXR obtained prior to ECLS, all CXRs obtained within the first 72 h of ECLS, and daily CXRs for the remainder of the ECLS course were analyzed. The outcome measure was the degree of opacification, determined by independent assessment of two, blinded pediatric radiologists using a modified Edwards et al.'s lung opacification scoring system (from Score 0: no opacification to Score 5: complete opacification). 220 CXRs were assessed (cases: 93, controls: 127). Inter-rater reliability was established (Cohen's weighted к = 0.74; p < 0.0001, good agreement). At baseline, the mean opacification score difference between cases and controls was 1 point (cases: 1.8, controls 2.8; p = 0.049). Using mixed modeling analysis for repeated measures accounting for differences at baseline, the average overall opacification score was 1.2 points lower in cases than controls (cases: 2.1, controls: 3.3; p < 0.0001). The overall distribution of scores was lower in cases than controls. Early CRRT utilization during infant ECLS was associated with decreased lung opacification on CXR.

Extracorporeal life support and systemic inflammation

Extracorporeal life support (ECLS) encompasses a wide range of extracorporeal modalities that offer short- and intermediate-term mechanical support to the failing heart or lung. Apart from the daily use of cardiopulmonary bypass (CPB) in the operating room, there has been a resurgence of interest and utilization of veno-arterial and veno-venous extracorporeal membrane oxygenation (VA- and VV-ECMO, respectively) and extracorporeal carbon dioxide removal (ECCO₂R) in recent years. This might be attributed to the advancement in technology, nonetheless the morbidity and mortality associated with the clinical application of this technology is still significant. The initiation of ECLS triggers a systemic inflammatory response, which involves the activation of the coagulation cascade, complement systems, endothelial cells, leukocytes, and platelets, thus potentially contributing to morbidity and mortality. This is due to the release of cytokines and other biomarkers of inflammation, which have been associated with multiorgan dysfunction. On the other hand, ECLS can be utilized as a therapy to halt the inflammatory response associated with critical illness and ICU therapeutic intervention, such as facilitating ultra-protective mechanical ventilation. In addition to addressing the impact on outcome of the relationship between inflammation and ECLS, two different but complementary pathophysiological perspectives will be developed in this review: ECLS as the cause of inflammation and ECLS as the treatment of inflammation. This framework may be useful in guiding the development of novel therapeutic strategies to improve the outcome of critical illness.

ECMO attenuates inflammation response and increases ATPase activity in brain of swine model with cardiac arrest compared with CCPR

Extracorporeal membrane oxygenation (ECMO) could increase survival rate and neurological outcomes of cardiac arrest (CA) patients compared with conventional cardiopulmonary resuscitation (CCPR). Currently, the underlying mechanisms how ECMO improves neurological outcomes of CA patients compared with CCPR have not been revealed. A pig model of CA was established by ventricular fibrillation induction and then underwent CCPR or ECMO. Survival and hemodynamics during the 6 h after return of spontaneous circulation (ROSC) were compared. The levels of inflammatory cytokines and Ca²⁺-ATPase and NA⁺-K⁺-ATPase activities were detected. Brain tissues histology and ultra-microstructure in CCPR and ECMO groups were also examined. Results suggested that ECMO significantly improved the survival of pigs compared with CCPR. Heart rate (HR) decreased while cardiac output (CO) increased along with the time after ROSC in both ECMO and CCPR groups. At each time point, HR in ECMO groups was lower than that in CCPR group while CO and mean arterial pressure in ECMO group was higher than CCPR group. In ECMO group, lower levels of IL-1, IL-1β, IL-6, TNFα, and TGFβ, especially IL-1, IL-6, TNFα, and TGFβ, were found compared that in CCPR group while no difference of IL-10 between the two groups was observed. Similar with the results from enzyme-linked immunosorbent assay, decreased expressions of IL-6 and TGFβ were also identified by Western blotting. And Ca²⁺-ATPase and NA⁺-K⁺-ATPase activities were increased by ECMO compared with CCPR. Hematoxylin and eosin staining and ultra-microstructure examination also revealed an improved inflammation situation in ECMO group compared with CCPR group.

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.

Splenic development and injury in premature lambs supported by the artificial placenta

INTRODUCTION

The purpose of this study is to evaluate splenic effects during artificial placenta (AP) support.

METHODS

AP lambs (118-121 d, n = 14) were delivered and placed on the AP support for a goal of 10-14 days. Cannulation used right jugular drainage and umbilical vein reinfusion. Early (ETC; 115-120 d; n = 7) and late (LTC; 125-131 d; n = 7) tissue controls were delivered and immediately sacrificed. Spleens were formalin fixed, H&E stained, and graded for injury, response to inflammation, and extramedullary hematopoiesis (EMH). CD68 and CD163 stains were used to assess for macrophage activation and density. Clinical variables were correlated with splenic scores. Groups were compared using Fisher's Exact Test and descriptive statistics. p < 0.05 indicated significance.

RESULTS

Mean survival for AP lambs was 12 ± 5 d. There was no necrosis found in any of the groups. Vascular congestion and sinusoidal histiocytosis did not significantly differ between AP and control groups (p = 0.72; p = 0.311). There were significantly more pigmented macrophages (p = 0.008), CD163 (p = <0.001), and CD68 (p = <0.001) stained cells in the AP group. ETC and LTC demonstrated more EMH than AP spleens (p = <0.001).

CONCLUSIONS

During AP support, spleens appear to develop normally and exhibit an appropriate inflammatory response. After initiation of AP support, EMH transitions away from the spleen.

STUDY TYPE

Research Paper/Therapeutic Potential.

LEVEL OF EVIDENCE

N/A.

The post-cardiac arrest syndrome: A case for lung-brain coupling and opportunities for neuroprotection

Systemic inflammation and multi-organ failure represent hallmarks of the post-cardiac arrest syndrome (PCAS) and predict severe neurological injury and often fatal outcomes. Current interventions for cardiac arrest focus on the reversal of precipitating cardiac pathologies and the implementation of supportive measures with the goal of limiting damage to at-risk tissue. Despite the widespread use of targeted temperature management, there remain no proven approaches to manage reperfusion injury in the period following the return of spontaneous circulation. Recent evidence has implicated the lung as a moderator of systemic inflammation following remote somatic injury in part through effects on innate immune priming. In this review, we explore concepts related to lung-dependent innate immune priming and its potential role in PCAS. Specifically, we propose and investigate the conceptual model of lung-brain coupling drawing from the broader literature connecting tissue damage and acute lung injury with cerebral reperfusion injury. Subsequently, we consider the role that interventions designed to short-circuit lung-dependent immune priming might play in improving patient outcomes following cardiac arrest and possibly other acute neurological injuries.

Rationale of Hemoadsorption during Extracorporeal Membrane Oxygenation Support

Extracorporeal membrane oxygenation (ECMO) and extracorporeal life support are increasingly used for treating various forms of shock, lung failure, protected interventions and life support including resuscitation. Most patients on ECMO are affected by a systemic inflammatory response caused by the underlying disease as well as the ECMO support itself, which contributes to vasoplegia, multi-organ failure, deterioration and death. Unfortunately, effective strategies for control of inflammation and related organ failure and shock on ECMO are lacking. Recently, a new polystyrene-based device for hemoadsorption, which aims to reduce excessive levels of inflammatory molecules such as interleukins, cytokines as well as damage- and pathogen-associated molecular patterns, has become available. Here we summarize the rationale, available data and technical aspects of polystyrene-based hemoadsorption during ECMO support, and give recommendations based on existing experience.

Study Protocol for a Pilot, Open-Label, Prospective, and Observational Study to Evaluate the Pharmacokinetics of Drugs Administered to Patients during Extracorporeal Circulation; Potential of In Vivo Cytochrome P450 Phenotyping to Optimise Pharmacotherapy

Pharmacokinetic alterations of medications administered during surgeries involving cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) have been reported. The impact of CPB on the cytochrome P450 (CYP) enzymes’ activity is the key factor. The metabolic rates of caffeine, dextromethorphan, midazolam, omeprazole, and Losartan to the CYP-specific metabolites are validated measures of in vivo CYP 1A2, 2D6, 3A4, 2C19, and 2C9 activities, respectively. The study aim is to assess the activities of major CYPs in patients on extracorporeal circulation (EC). This is a pilot, prospective, open-label, observational study in patients undergoing surgery using EC and patients undergoing laparoscopic cholecystectomy as a control group. CYP activities will be measured on the day, and 1–2 days pre-surgery/3–4 days post-surgery (cardiac surgery and Laparoscopic cholecystectomy) and 1–2 days after starting ECMO, 1–2 weeks after starting ECMO, and 1–2 days after discontinuation from ECMO. Aforementioned CYP substrates will be administered to the patient and blood samples will be collected at 0, 1, 2, 4, and 6 h post-dose. Major CYP enzymes’ activities will be compared in each participant on the day, and before/after surgery. The CYP activities will be compared in three study groups to investigate the impact of CYPs on EC.

Intraoperative vasoplegic syndrome in patients with fulminant myocarditis on ventricular assist device placement

PURPOSE

Fulminant myocarditis is uncommon, but life-threatening, and some patients need mechanical circulatory support. This study was performed to evaluate how different types of mechanical circulatory support-biventricular assist device (BiVAD) or left ventricular assist device (LVAD) placement-affect intraoperative hemodynamic status.

METHODS

From January 2013 to September 2016, the patients who underwent BiVAD or LVAD placement for fulminant myocarditis were analyzed. The mean arterial pressure (MAP), mean pulmonary arterial pressure, central venous pressure (CVP), vasoactive score, and inotropic score were recorded at five time points: after the induction of anesthesia; at weaning, 30 min after weaning, and 60 min after weaning from cardiopulmonary bypass (CPB); and at the end of surgery. The vasoactive and inotropic scores were calculated as follows: vasoactive score = norepinephrine (µg/kg/min) × 100 + milrinone (µg/kg/min) × 10 + olprinone (µg/kg/min) × 25: inotropic score = dopamine (µg/kg/min) × 1 + dobutamine (µg/kg/min) × 1 + epinephrine (µg/kg/min) × 100.

RESULTS

We enrolled 16 patients of fulminant myocarditis. Ten of them underwent BiVAD placement, and the other underwent LVAD placement. After weaning from CPB, the BiVAD group had a significantly lower MAP but no difference in CVP. The vasoactive score was significantly higher in the BiVAD group at weaning of CPB (p = 0.015), 30 min after weaning (p = 0.004), 60 min after weaning (p = 0.005), and at the end of surgery (p < 0.016).

CONCLUSION

Patients with BiVAD placement required more vasoactive support to maintain optimal hemodynamic status compared with those with LVAD placement. This result indicates that BiVAD placement was more associated with vasoplegic syndrome.

Phosphodiesterase-4 inhibition reduces ECLS-induced vascular permeability and improves microcirculation in a rodent model of extracorporeal resuscitation

Extracorporeal circulation can be accompanied by increased vascular permeability leading to pathological fluid balance and organ dysfunction. The second messenger cAMP is involved in capillary permeability and maintains endothelial integrity. The aim of the present study was to evaluate the effect of phosphodiesterase-4 (PDE4) inhibition with rolipram on extracorporeal circulation-induced capillary leakage, microcirculatory dysfunction, and organ injury in rodents. Rats were randomly allocated to the following groups: sham ( n = 5), venoarterial extracorporeal circulation [extracorporeal life support (ECLS), n = 7], ECLS + rolipram ( n = 7), extracorporeal resuscitation (ECPR; n = 7), and ECPR + rolipram ( n = 7). In the groups that underwent ECPR, ECLS-based cardiopulmonary resuscitation (ECPR) was performed after the induction of hypoxic cardiac arrest. Upon return of spontaneous circulation, rolipram was administered intravenously. The mesenteric microcirculation was studied using intravital microscopy, and organ specimens were harvested upon completion of the study. ECLS and ECPR induced a proinflammatory response (cytokines IL-1β, IL-6, and TNF-α). Although PDE4 expression was upregulated in vascular tissue, PDE4 inhibition abrogated impaired microcirculation and capillary leak (albumin extravasation of the sham group: 1 ± 0.03-fold, ECLS group: 1.2 ± 0.05-fold, ECLS + rolipram group: 0.99 ± 0.04-fold, ECPR group: 1.6 ± 0.04-fold, and ECPR + rolipram group: 1.06 ± 0.02-fold from the sham group, P < 0.05). PDE4 inhibition led to stabilization of vascular cAMP levels but did not affect cytokine levels. Capillary leak was reduced, as demonstrated by the decrease of the systemic biomarkers soluble vascular-endothelial cadherin and activated complement 3. Histological analysis revealed reduced injury to the lungs and kidneys after PDE4 inhibition, with a significant decrease in systemic renal damage markers. Our findings demonstrate that extracorporeal circulation causes an inflammatory reaction associated with decreased vascular cAMP levels, increased vascular permeability, and impaired microcirculation. PDE4 inhibition proved to be capable of reducing these side effects in ECLS and ECPR, leading to reduced microcirculatory, renal, and pulmonary injury. NEW & NOTEWORTHY Various complications are common after extracorporeal circulation. Among these, endothelial injury may cause impaired microcirculation and capillary leak. Here, we report that phosphodiesterase-4 inhibition targeting endothelial cAMP is capable of reducing microvascular complications in a rodent model of extracorporeal resuscitation. Microcirculation and vascular permeability are influenced without targeting extracorporeal circulation-induced inflammation. Thus, pulmonary and renal organ protection may be conferred.

Overcoming barriers to optimal drug dosing during ECMO in critically ill adult patients

INTRODUCTION

One major challenge to achieving optimal patient outcome in extracorporeal membrane oxygenation (ECMO) is the development of effective dosing strategies in this critically ill patient population. Suboptimal drug dosing impacts on patient outcome as patients on ECMO often require reversal of the underlying pathology with effective pharmacotherapy in order to be liberated of the life-support device. Areas covered: This article provides a concise review of the effective use of antibiotics, analgesics, and sedative by characterizing the specific changes in PK secondary to the introduction of the ECMO support. We also discuss the barriers to achieving optimal pharmacotherapy in patients on ECMO and also the current and potential research that can be undertaken to address these clinical challenges. Expert opinion: Decreased bioavailability due to sequestration of drugs in the ECMO circuit and ECMO induced PK alterations are both significant barriers to optimal drug dosing. Evidence-based drug choices may minimize sequestration in the circuit and would enable safety and efficacy to be maintained. More work to characterize ECMO related pharmacodynamic alterations such as effects of ECMO on hepatic cytochrome system are still needed. Novel techniques to increase target site concentrations should also be explored.

Prognostic Risk Analyses for Postcardiotomy Extracorporeal Membrane Oxygenation in Children: A Review of Early and Intermediate Outcomes

We evaluated the morbidity and mortality of children requiring postcardiotomy extracorporeal membrane oxygenation (ECMO) to determine independent factors affecting early and intermediate outcomes. Between January 2002 and December 2015, 79 instances of ECMO after cardiac surgery in 73 children were retrospectively reviewed. Follow-up was completed in December 2016. Predictive risk analyses were employed concerning weaning of ECMO, hospital discharge, and mortality after discharge. Age and weight were 14.9 ± 25.6 months and 7.0 ± 5.3 kg, respectively. Median support time was 8.3 ± 4.4 days. Sixty-seven (85%) were successfully weaned off ECMO and 48 (61%) survived to hospital discharge. Multi-variate logistic regression analysis identified the first day to obtain negative fluid balance after initiation of support (adjusted odds ratio = 0.42), high serum lactate levels (0.97), and high total bilirubin (0.84) during support as significant independent factors associated with successful separation from ECMO. The first day of negative fluid balance (0.65) after successful decannulation was an independent risk factor for survival to hospital discharge. After hospital discharge, actuarial 1-year, 5-year, and 10-year survival rates were 94%, 78%, and 78%, respectively. Low weight increased the risk of death after hospital discharge by a multi-variate Cox hazard model. High serum lactate, high serum bilirubin, and unable to obtain early negative fluid balance during support impacted mortality of decannulation. Obtaining a late negative fluid balance in post-ECMO were independent risk factors for death after successful weaning. Low weight affected intermediate outcomes.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

An Analysis of Risk Factors for Hemolysis in Children on Extracorporeal Membrane Oxygenation

OBJECTIVES

Hemolysis is a known complication of pediatric extracorporeal membrane oxygenation associated with renal failure and mortality. We sought to identify predictors of hemolysis in pediatric extracorporeal membrane oxygenation patients and determine its influence on outcomes.

DESIGN

Retrospective, single-center study.

SETTING

Urban, quaternary care center pediatric and neonatal ICU.

PATIENTS

Ninety-six patients requiring extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily measurements of plasma-free hemoglobin were obtained while patients were on extracorporeal membrane oxygenation. Patients with a prior extracorporeal membrane oxygenation run, on extracorporeal membrane oxygenation for less than 24 hours, or without complete medical records were excluded from the study. Ninety-six patients met inclusion criteria, of which, 25 patients (26%) had plasma-free hemoglobin greater than 30 mg/dL. Of those patients, 15 of 25(60%) had plasma-free hemoglobin greater than 50 mg/dL, and 21 of 25(84%) occurred during the first 7 days on extracorporeal membrane oxygenation. Compared with patients without hemolysis, those with hemolysis were younger (0.2 mo [0.06-3.2 mo] vs 8.2 mo [0.6-86 mo]; p < 0.001), had a higher pericannulation international normalized ratio (3.9 [3.5-5.5] vs 2.6 [1.8-3.7]; p = 0.003), lower pericannulation platelet count (33 × 10/μL [22-42 × 10/μL] vs 61 × 10/μL [38-86 × 10/μL]; p < 0.001), and had a less negative inlet pressure (-3.5 mm Hg [-14 to 11.5 mm Hg] vs -19 mm Hg [-47 to 0 mm Hg]; p = 0.01). A greater proportion of patients with hemolysis had a heparin assay less than 0.2 mg/dL (50% vs 17%; p = 0.001) and had fluid removal via slow continuous ultrafiltration (32% vs 6%; p < 0.001). Patients with hemolysis had increased risk of in-hospital mortality (odds ratio 10.0; 95% CI 3.4-32; p < 0.001). On multivariable analysis, continuous ultrafiltration (odds ratio, 8.0; 95% CI, 1.9-42; p = 0.007) and pericannulation international normalized ratio greater than 3.5 (odds ratio, 7.2; 95% CI, 2.3-26; p = 0.001) were significantly associated with hemolysis.

CONCLUSIONS

Hemolysis is a common complication of pediatric extracorporeal membrane oxygenation. We found that patients with hemolysis (plasma-free hemoglobin > 30 mg/dL) had a 10-fold increase in in-hospital mortality. In our study cohort, hemolysis was associated with continuous ultrafiltration use, but not continuous renal replacement therapy. Additionally, our results suggest that the degree of coagulopathy (international normalized ratio > 3.5) at the time of cannulation influences hemolysis. Additional prospective studies are necessary to define further strategies to prevent hemolysis and improve outcomes in pediatric extracorporeal membrane oxygenation patients.

Extracellular histones indicate the prognosis in patients undergoing extracorporeal membrane oxygenation therapy

Introduction:

Extracellular histones have been recently identified as damage-associated molecular-pattern (DAMP) molecules involved with the pathogenesis of various inflammatory diseases. This study intended to investigate whether extracellular histones can indicate the prognosis in critically ill patients supported by extracorporeal membrane oxygenation (ECMO) therapy.

Methods:

A total of 56 patients undergoing ECMO were analysed retrospectively. Median concentrations of extracellular histones in patients before ECMO were assessed and used to divide the patients into two groups (Group 1 <48 µg/ml and Group 2 ⩾48 µg/ml). Mortality rate, Sequential Organ Failure Assessment (SOFA) scores and systemic inflammation were compared between the groups.

Results:

There were relatively higher concentrations of extracellular histones in Group 2 patients (57.78 µg/ml [48.4, 71.3]) than in Group 1 patients (36.76 µg/ml [28.5, 39.3], p<0.0001). The hospital mortality rate was 55.4% for the entire study subjects, with significantly worsened mortality in Group 2 in contrast to Group 1 (58.8% vs. 50%, p=0.031). Moreover, Group 2 patients had significantly higher SOFA scores and more pronounced systemic inflammation than Group 1 patients prior to ECMO initialization.

Conclusions:

Extracellular histones are known contributors to cell damage and organ injury. Our study showed that extracellular histones have a predictive value in the assessment of outcome of patients undergoing ECMO therapy and may be helpful for risk stratification in clinical settings.

Pediatric extracorporeal membrane oxygenation (ECMO): a guide for radiologists

Extracorporeal membrane oxygenation (ECMO) is a life-saving treatment for pediatric patients with respiratory and/or cardiac failure. The ECMO circuit oxygenates and sometimes pumps the blood, effectively replacing lung and/or heart function temporarily. ECMO patients are clinically very complex not only because of their underlying, life-threatening pathology, but also because of the many physiological parameters that must be monitored and adjusted to maintain adequate tissue perfusion and oxygenation. Drainage and reinfusion cannulae connecting the patient to the ECMO circuit are visible on radiograph. These cannulae have different functions, different configurations, different radiographic appearances, and different positions that should be familiar to the interpreting pediatric radiologist. The primary complications of ECMO include hemorrhage, thrombosis and ischemia, as well as equipment failure and cannula malpositioning, all of which may be detected on imaging. In this pictorial essay, we discuss the basics of ECMO function and clinical management, ECMO cannula features and configurations, and the many complications of ECMO from an imaging perspective. Our goal is to educate pediatric radiologists about ECMO imaging, equipping them to properly interpret these studies and to become a useful consultant in ECMO patient care.

Physiologically Based Pharmacokinetic Approach to Determine Dosing on Extracorporeal Life Support: Fluconazole in Children on ECMO

Extracorporeal life support (e.g., dialysis, extracorporeal membrane oxygenation (ECMO)) can affect drug disposition, placing patients at risk for therapeutic failure. In this population, dose selection to achieve safe and effective drug exposure is difficult. We developed a novel and flexible approach that uses physiologically based pharmacokinetic (PBPK) modeling to translate results from ECMO ex vivo experiments into bedside dosing recommendations. To determine fluconazole dosing in children on ECMO, we developed a PBPK model, which was validated using fluconazole pharmacokinetic (PK) data in adults and critically ill infants. Next, an ECMO compartment was added to the PBPK model and parameterized using data from a previously published ex vivo study. Simulations using the final ECMO PBPK model reasonably characterized observed PK data in infants on ECMO, and the model was used to derive dosing in children on ECMO across the pediatric age spectrum. This approach can be generalized to other forms of extracorporeal life support (ECLS), such as dialysis.

Beneficial effects of levosimendan on survival in patients undergoing extracorporeal membrane oxygenation after cardiovascular surgery

BACKGROUND

The impact of levosimendan treatment on clinical outcome in patients undergoing extracorporeal membrane oxygenation (ECMO) support after cardiovascular surgery is unknown. We hypothesized that the beneficial effects of levosimendan might improve survival when adequate end-organ perfusion is ensured by concomitant ECMO therapy. We therefore studied the impact of levosimendan treatment on survival and failure of ECMO weaning in patients after cardiovascular surgery.

METHODS

We enrolled a total of 240 patients undergoing veno-arterial ECMO therapy after cardiovascular surgery at a university-affiliated tertiary care centre into our observational single-centre registry.

RESULTS

During a median follow-up period of 37 months (interquartile range 19-67 months), 65% of patients died. Seventy-five per cent of patients received levosimendan treatment within the first 24 h after initiation of ECMO therapy. Cox regression analysis showed an association between levosimendan treatment and successful ECMO weaning [adjusted hazard ratio (HR) 0.41; 95% confience interval (CI) 0.22-0.80; P=0.008], 30 day mortality (adjusted HR 0.52; 95% CI 0.30-0.89; P=0.016), and long-term mortality (adjusted HR 0.64; 95% CI 0.42-0.98; P=0.04).

CONCLUSIONS

These data suggest an association between levosimendan treatment and improved short- and long-term survival in patients undergoing ECMO support after cardiovascular surgery.

Early Graft Loss after Kidney Transplantation: Endothelial Dysfunction of Renal Microvasculature

Decision process about the acceptance of the deceased donor kidney for transplantation might be challenging. Although histological evaluation of pretransplant donor kidney biopsy provides reliable information regarding cortical necrosis, vascular thrombosis, extensive global glomerulosclerosis, and interstitial fibrosis/tubular atrophy, only electron microscopy enables thorough and reliable insights into microvasculature changes of kidney graft. The aim of the present paper is to briefly present two cases of early kidney graft loss. In one case, the donor was exposed to long-term extracorporeal membrane oxygenation (ECMO); in the other case, the donor experienced Takotsubo cardiomyopathy. In both cases, light microscopy of pretransplant biopsy found no pathology or significant discrepancy in morphology of kidney graft, while electron microscopy revealed severe endothelial dysfunction of renal microvasculature. Our results suggest that severe injury of renal microvasculature with relatively preserved tubular epithelium may be associated with some conditions of deceased kidney donors leading to early kidney graft nonfunction and loss. Further studies are needed to determine prognostic significance of severe ultrastructural microvasculature lesions and to evaluate disease states and conditions that could be associated with severe endothelial dysfunction of kidney graft.

Endothelial Microvesicles and Soluble Markers of Endothelial Injury in Critically Ill Newborns

Neonatal systemic inflammatory response and multiple organ dysfunction syndrome are the main postnatal insults influencing mortality and morbidity. Critically ill newborns with high predicted mortality are supported by extracorporeal membrane oxygenation (ECMO). Biomarkers of inflammatory response and endothelial injury can be used for early diagnosis and treatment of critical neonatal situations. The aim of our study was to explore plasma proteins and endothelial microvesicles as markers of inflammation and endothelial activation in newborns on ECMO and to compare them with healthy neonates. Thirteen newborns on ECMO and 13 healthy newborns were included in the study. Plasma soluble biomarkers were measured using multiplex immunoassay based on Luminex® xMAP multianalyte profiling platform. The total microvesicle count and plasma level of surface antigen-specific microvesicles were determined by flow cytometry. The plasma concentration of cell-derived microvesicles was measured using annexin-V labeling, and the endothelial origin of microvesicles was determined using lineage-specific antigen labeling of endothelial cell/microvesicle markers (endoglin/CD105, PECAM1/CD31, VEGFR2/CD309, and MadCAM1). Inflammatory markers (procalcitonin, IL-1β, IL-6, and IL-22) were increased in the ECMO group (P < 0.01). The assessment of endothelial markers showed higher concentrations of endocan and angiopoietin-2 (P < 0.01) in the ECMO group while VEGF in the ECMO group was significantly lower (P < 0.01). In the ECMO group, the concentration of annexin-V-positive microvesicles (total microvesicles) and endothelial microvesicles expressing mucosal vascular addressin cell adhesion molecule 1 (MadCAM1) was increased (P = 0.05). In summary, we found increased concentrations of soluble inflammatory and endothelial markers in the plasma of critically ill newborns with multiple organ dysfunction. Increased plasma concentrations of microvesicles may reflect the activation or damage of blood cells and vasculature including endothelial cells. The measurement of cell membrane-derived microvesicles may be added to the panel of established inflammatory markers in order to increase the sensitivity and specificity of the diagnostic process in critically ill newborns.

Extracorporeal membrane oxygenation and cytokine adsorption

Extracorporeal membrane oxygenation (ECMO) is an increasingly used technology for mechanical support of respiratory and cardio-circulatory failure. Excessive systemic inflammatory response is observed during sepsis and after cardiopulmonary bypass (CPB) with similar clinical features. The overwhelming inflammatory response is characterized by highly elevated pro- and anti-inflammatory cytokine levels. The excessive cytokine release during the overwhelming inflammatory response may result in multiple organ damage and failure. During ECMO therapy activation of complement and contact systems occur which may be followed by cytokine release. Controlling excessively increased cytokines may be considered as a valuable treatment option. Hemoadsorption therapy may be used to decrease cytokine levels in case of excessive inflammatory response and due to its unspecific adsorptive characteristics also substances like myoglobin, free hemoglobin or bilirubin. Controlling pro-inflammatory response with hemoadsorption may have positive impact on the endothelial glycocalix and also may be advantageous for maintenance of the vascular barrier function which plays a pivotal role in the development of tissue edema and oxygen mismatch. Hemoadsorption therapy seems to offer a promising new option for the treatment of patients with overwhelming inflammatory response leading to faster hemodynamic and metabolic stabilization finally resulting in preserved organ functions.

Vasoactive Inotropic Score as a Predictor of Mortality in Adult Patients With Cardiogenic Shock: Medical Therapy Versus ECMO

INTRODUCTION AND OBJECTIVES

This study investigated whether the vasoactive inotropic score (VIS) is independently predictive of mortality in cardiogenic shock (CS).

METHODS

This study was retrospective, observational study. Patients who were admitted to the cardiac intensive care unit from January 2012 to December 2015 were screened, and 493 CS patients were finally enrolled. To quantify pharmacologic support, the patients were divided into 5 groups based on a quintile of VIS: 1 to 10, 11 to 20, 21 to 38, 39 to 85, and > 85. The primary outcome was in-hospital mortality.

RESULTS

In-hospital mortalities in the 5 VIS groups in increasing order were 8.2%, 14.1%, 21.1%, 32.0%, and 65.7%, respectively (P < .001). Multivariable analysis indicated that VIS ranges of 39 to 85 (aOR, 3.85; 95%CI, 1.60-9.22; P = .003) and over 85 (aOR, 10.83; 95%CI, 4.43-26.43; P < .001) remained significant prognostic predictors for in-hospital mortality. With multiple logistic regression to remove any confounding effects, we found that the localized regression lines regarding the odds of death intersected each other's (medical therapy alone and combined extracorporeal membrane oxygenation group) path at VIS = 130. In contrast to linear correlation between VIS and mortality for patients treated with medical therapy alone, there was little association between a VIS of 130 or more and the probability of in-hospital mortality for patients who were treated with extracorporeal membrane oxygenation.

CONCLUSIONS

A high level of vasoactive inotropic support during the first 48hours was significantly associated with increased in-hospital mortality in adult CS patients.

Effects of pumpless extracorporeal lung assist on hemodynamics, gas exchange and inflammatory cascade response during experimental lung injury

Pumpless extracorporeal lung assist (pECLA) has been reported to efficiently remove the systemic CO₂ production and provide mild to moderate oxygenation, thereby allowing for ventilator settings and modes prioritizing oxygenation and lung protection. However, an adequate bypass flow, the capacity to provide respiratory support and the effect on the inflammatory cascade response and tissue perfusion require further study to be determined. After induction of acute lung injury (ALI) by oleic acid injection, pECLA was implemented in 12 anaesthetized and mechanically ventilated dogs for 48 h. Improved oxygenation [partial oxygen pressure (PaO₂) and oxygen saturation (SaO₂) was measured by arterial blood gas analysis, and increased by 29 and 18%, respectively] and CO₂ elimination (partial CO₂ pressure decreased by 43.35%) were obtained after pECLA implementation. A maximum arterio-venous shunt flow of up to 25% of the foundational CO resulted in stable hemodynamics. The pECLA procedure did not elicit any further increase in the concentration of tumor necrosis factor-α, interleukin (IL)-6, IL-8 and endothelin-1 compared with that in the group subjected to oleic acid injection only. In addition, the pECLA procedure had no effect on lactate levels and urine production. In conclusion, pECLA is an efficient and promising strategy for providing a mild to moderate oxygenation and adequate decarboxylation, while avoiding excessive inflammatory cascade response and tissue hypoperfusion in an experimental ALI model.