Early changes in coagulation profiles and lactate levels in patients with septic shock undergoing extracorporeal membrane oxygenation

Infection in ECMO patients: Changes in epidemiology, diagnosis and prevention

Patients with prolonged duration of extracorporeal membrane oxygenation support (ECMO) are a vulnerable population for sepsis, particularly ventilator-associated pneumonia and bloodstream infections. Rates differ between venous-arterial and venous-venous ECMO patients and according to the cannulation technique used. The presence of particular organisms depends on local epidemiology, antibiotic exposure, and the duration of the intervention; patients undergoing ECMO for more than three weeks present a high risk of persistent candidemia. Recognizing predisposing factors, and establishing the best preventive interventions and therapeutic choices are critical to optimizing the management of these complications. Infection control practices, including shortening the period of the indwelling devices, and reducing antibiotic exposure, must be followed meticulously. Innovations in oxygenator membranes require an updated approach. Hand hygiene and avoiding breaking the circuit-oxygenator sterility are cornerstones. ECMO management would benefit from clearer definitions, optimization of infection control strategies, and updated infectious clinical practice guidelines.

Extracorporeal membrane oxygenation in adult patients with sepsis and septic shock: Why, how, when, and for whom

Sepsis and septic shock remain the leading causes of death in intensive care units. Some patients with sepsis fail to respond to routine treatment and rapidly progress to refractory respiratory and circulatory failure, necessitating extracorporeal membrane oxygenation (ECMO). However, the role of ECMO in adult patients with sepsis has not been fully established. According to existing studies, ECMO may be a viable salvage therapy in carefully selected adult patients with sepsis. The choice of venovenous, venoarterial, or hybrid ECMO modes is primarily determined by the patient's oxygenation and hemodynamics (distributive shock with preserved cardiac output, septic cardiomyopathy (left, right, or biventricular heart failure), or right ventricular failure caused by acute respiratory distress syndrome). Veno-venous ECMO can be used in patients with sepsis and severe acute respiratory distress syndrome when conventional mechanical ventilation fails, and early application of veno-arterial ECMO in patients with sepsis-induced refractory cardiogenic shock may be critical in improving their chances of survival. When ECMO is indicated, the choice of an appropriate mode and determination of the optimal timing of initiation and weaning are critical, particularly in an experienced ECMO center. Furthermore, some special issues, such as ECMO flow, anticoagulation, and antibiotic therapy, should be noted during the management of ECMO support.

Prognostic Impact of the International Society on Thrombosis and Hemostasis Disseminated Intravascular Coagulation Score in Sepsis: A Systematic Review

The International Society on Thrombosis and Haemostasis (ISTH) diagnostic criteria for disseminated intravascular coagulation (DIC) are widely used for DIC diagnosis. However, the prognostic value of the score may vary between different patient populations and settings. This systematic review investigated the association between the ISTH DIC score and mortality in sepsis patients. A literature search was conducted in PubMed and Embase. Inclusion criteria were studies including adult and pediatric patients hospitalized with sepsis, using any sepsis definition, and investigating the association between mortality and the ISTH DIC score. The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. In total, 42 studies were included. A positive association between the ISTH DIC score and mortality was consistently reported, with odds ratios of death in DIC versus non-DIC patients ranging from 1.125 (95% confidence interval [CI]: 0.838-1.511) to 21.008 (95% CI: 1.408-313.405) in adults and from 1.378 (95% CI: 1.004-1.893) to 2.99 (95% CI: 0.54-16.6) in pediatric populations. However, the DIC score only had a low-moderate positive predictive value for mortality, as area under receiver-operator characteristics ranged from 0.602 (95% CI: 0.575-0.630) to 0.815 (95% CI: 0.676-0.954) in adults. Of note, only few studies adjusted for potential confounders such as age, gender, and comorbidity. The ISTH DIC score is consistently associated with sepsis-related mortality but is not a strong positive predictor for mortality. Nevertheless, the score may still have a prognostic value and its use in sepsis is encouraged.

Prognostic models for mortality risk in patients requiring ECMO

PURPOSE

To provide an overview and evaluate the performance of mortality prediction models for patients requiring extracorporeal membrane oxygenation (ECMO) support for refractory cardiocirculatory or respiratory failure.

METHODS

A systematic literature search was undertaken to identify studies developing and/or validating multivariable prediction models for all-cause mortality in adults requiring or receiving veno-arterial (V-A) or veno-venous (V-V) ECMO. Estimates of model performance (observed versus expected (O:E) ratio and c-statistic) were summarized using random effects models and sources of heterogeneity were explored by means of meta-regression. Risk of bias was assessed using the Prediction model Risk Of BiAS Tool (PROBAST).

RESULTS

Among 4905 articles screened, 96 studies described a total of 58 models and 225 external validations. Out of all 58 models which were specifically developed for ECMO patients, 14 (24%) were ever externally validated. Discriminatory ability of frequently validated models developed for ECMO patients (i.e., SAVE and RESP score) was moderate on average (pooled c-statistics between 0.66 and 0.70), and comparable to general intensive care population-based models (pooled c-statistics varying between 0.66 and 0.69 for the Simplified Acute Physiology Score II (SAPS II), Acute Physiology and Chronic Health Evaluation II (APACHE II) score and Sequential Organ Failure Assessment (SOFA) score). Nearly all models tended to underestimate mortality with a pooled O:E > 1. There was a wide variability in reported performance measures of external validations, reflecting a large between-study heterogeneity. Only 1 of the 58 models met the generally accepted Prediction model Risk Of BiAS Tool criteria of good quality. Importantly, all predicted outcomes were conditional on the fact that ECMO support had already been initiated, thereby reducing their applicability for patient selection in clinical practice.

CONCLUSIONS

A large number of mortality prediction models have been developed for ECMO patients, yet only a minority has been externally validated. Furthermore, we observed only moderate predictive performance, large heterogeneity between-study populations and model performance, and poor methodological quality overall. Most importantly, current models are unsuitable to provide decision support for selecting individuals in whom initiation of ECMO would be most beneficial, as all models were developed in ECMO patients only and the decision to start ECMO had, therefore, already been made.

Causes of platelet loss during extracorporeal life support

BACKGROUND

Most pediatric patients show a decline in platelet counts while on extracorporeal life support (ECLS) and require multiple platelet transfusions. To better understand platelet loss during ECLS, this study estimated platelet loss rates due to diagnostic phlebotomy, platelet activation, bleeding and other causes.

METHODS

We collected data on 91 patients (1d-20y, 50 M, 41F). Platelet losses were estimated based on changes in platelet count, patient+circuit blood volume, and transfused platelet volumes. Platelet extracellular vesicles were measured by flow cytometry.

RESULTS

Median platelet loss was 2.8 × 10⁹ /L/hr, more than twice the normal rate of platelet removal and equivalent to a 67 000/μl decrease in platelet count per day. While platelet loss was correlated with platelet transfusion (r²  = 0.51), transfusion underestimated platelet loss in patients with large decreases in platelet count and over-estimated platelet loss in neonates where the circuit volume > patient blood volume. Patients with disseminated intravascular coagulation before or significant bleeding during ECLS have double the rate of platelet loss. Platelet activation accounted for ~32% of total platelet loss, bleeding ~36% and phlebotomy 4%, with the remaining one-third due to other causes. Annexin-negative platelet extracellular vesicle release, a measure of platelet damage, was increased 9-fold during ECLS.

CONCLUSION

Our study is the first to quantitate total, phlebotomy and activation related platelet loss during ECLS. Platelet activation accounts for ~32% of total platelet loss, while bleeding doubles the platelet loss rate. The etiology of the remaining platelet loss is unknown.

Venoarterial extracorporeal membrane oxygenation as mechanical circulatory support in adult septic shock: a systematic review and meta-analysis with individual participant data meta-regression analysis

BACKGROUND

While recommended by international societal guidelines in the paediatric population, the use of venoarterial extracorporeal membrane oxygenation (VA ECMO) as mechanical circulatory support for refractory septic shock in adults is controversial. We aimed to characterise the outcomes of adults with septic shock requiring VA ECMO, and identify factors associated with survival.

METHODS

We searched Pubmed, Embase, Scopus and Cochrane databases from inception until 1st June 2021, and included all relevant publications reporting on > 5 adult patients requiring VA ECMO for septic shock. Study quality and certainty in evidence were assessed using the appropriate Joanna Briggs Institute checklist, and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach, respectively. The primary outcome was survival to hospital discharge, and secondary outcomes included intensive care unit length of stay, duration of ECMO support, complications while on ECMO, and sources of sepsis. Random-effects meta-analysis (DerSimonian and Laird) were conducted.

DATA SYNTHESIS

We included 14 observational studies with 468 patients in the meta-analysis. Pooled survival was 36.4% (95% confidence interval [CI]: 23.6%-50.1%). Survival among patients with left ventricular ejection fraction (LVEF) < 20% (62.0%, 95%-CI: 51.6%-72.0%) was significantly higher than those with LVEF > 35% (32.1%, 95%-CI: 8.69%-60.7%, p = 0.05). Survival reported in studies from Asia (19.5%, 95%-CI: 13.0%-26.8%) was notably lower than those from Europe (61.0%, 95%-CI: 48.4%-73.0%) and North America (45.5%, 95%-CI: 16.7%-75.8%). GRADE assessment indicated high certainty of evidence for pooled survival.

CONCLUSIONS

When treated with VA ECMO, the majority of patients with septic shock and severe sepsis-induced myocardial depression survive. However, VA ECMO has poor outcomes in adults with septic shock without severe left ventricular depression. VA ECMO may be a viable treatment option in carefully selected adult patients with refractory septic shock.

Different characteristics of bloodstream infection during venoarterial and venovenous extracorporeal membrane oxygenation in adult patients

Currently, there is scarcity of data on whether differences exist in clinical characteristics and outcomes of bloodstream infection (BSI) between venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) and whether they differ between Candida BSI and bacteremia in adult ECMO patients. We retrospectively reviewed data of patients who required ECMO for > 48 h and had BSIs while receiving ECMO between January 2015 and June 2020. Cases with a positive blood culture result within 24 h of ECMO implantation were excluded. We identified 94 (from 64 of 194 patients) and 38 (from 17 of 56 patients) BSI episodes under VA and VV ECMO, respectively. Fifty nine BSIs of VA ECMO (59/94, 62.8%) occurred in the first 2 weeks after ECMO implantation, whereas 24 BSIs of VV ECMO (24/38, 63.2%) occurred after 3 weeks of ECMO implantation. Gram-negative bacteremia (39/59, 66.1%) and gram-positive bacteremia (10/24, 41.7%) were the most commonly identified BSI types in the first 2 weeks after VA ECMO implantation and after 3 weeks of VV implantation, respectively. Timing of Candida BSI was early (6/11, 54.5% during the first 2 weeks) in VA ECMO and late (6/9, 66.7% after 3 weeks of initiation) in VV ECMO. Compared with bacteremia, Candida BSI showed no differences in clinical characteristics and outcomes during VA and VV ECMO, except the significant association with prior exposure to carbapenem in VA ECMO (vs. gram-negative bacteremia [P = 0.006], vs. gram-positive bacteremia [P = 0.03]). Our results suggest that ECMO modes may affect BSI clinical features and timing. In particular, Candida BSI occurrence during the early course of VA ECMO is not uncommon, especially in patients with prior carbapenem exposure; however, it usually occurs during the prolonged course of VV ECMO. Consequently, routine blood culture surveillance and empiric antifungal therapy might be warranted in targeted populations of adult ECMO patients, regardless of levels of inflammatory markers and severity scores.

Risk factors for in-hospital mortality and acute kidney injury in neonatal-pediatric patients receiving extracorporeal membrane oxygenation

BACKGROUND

Acute kidney injury (AKI) is the most frequent complication in critically ill neonatal and pediatric patients receiving extracorporeal membrane oxygenation (ECMO) support. This study analyzed risk factors for in-hospital mortality and the incidence of AKI in neonatal and pediatric patients received ECMO support.

METHODS

We reviewed the medical records of 105 neonatal and 171 pediatric patients who received ECMO support at the intensive care unit (ICU) of a tertiary care university hospital between January 2008 and December 2015. Demographic, clinical, and laboratory data were retrospectively collected as survival and AKI predictors, utilizing the Kidney Disease Improving Global Outcome (KDIGO) consensus definition for AKI.

RESULTS

In the 105 neonatal and 171 pediatric patients, the overall in-hospital mortality rate were 58% and 55% respectively. The incidence of AKI at post-ECMO 24 h were 64.8% and 61.4%. A greater KDIGO_24-h severity was associated with a higher in-hospital mortality rate (chi-square test; p < 0.01) and decreased survival rate (log-rank tests, p < 0.01). In univariate logistic regression analysis of in-hospital mortality, the CVP level at post ECOMO 24-h increased odds ratio (OR) (OR = 1.27 [1.10-1.46], p = 0.001) of in-hospital mortality in neonatal group; as for pediatric group, elevated lactate (OR = 1.12 [1.03-1.20], p = 0.005) and PT (OR = 1.86 [1.17-2.96], p = 0.009) increased OR of in-hospital mortality. And the KDIGO_24h stage 3 had the strongest association with in-hospital mortality in both neonatal (p = 0.005) and pediatric (p = 0.001) groups. In multivariate OR of neonatal and pediatric groups were 4.38 [1.46-13.16] (p = 0.009) and 3.76 [1.70-8.33] (p = 0.001), respectively.

CONCLUSIONS

AKI was a significant risk factor for in-hospital mortality in the neonatal and pediatric patients who received ECMO support. A greater KDIGO24-h severity was associated with higher mortality rates and decreased survival rate in both neonatal and pediatric groups. Of note, KDIGO24h can be an easy and early tool for the prognosis of AKI in the neonatal and pediatric patients.

Subdural extravasation of crystalloids and blood products through a scalp peripheral intravenous catheter into the subdural space of a neonate on veno-arterial extracorporeal membrane oxygenation

We describe a rare and devastating complication of a malpositioned scalp peripheral intravenous catheter (PIV) that resulted in subdural extravasation of infused fluids and midline shift in a critically ill neonate who required extracorporeal membrane oxygenation (ECMO). Recognition of increased intracranial pressure was hindered by the hemodynamic changes of being on ECMO and only identified by routine surveillance ultrasonography. Awareness of this complication may lead providers to seek alternate sites for vascular access in such patients, and encourage closer monitoring for this complication when an alternate site is unavailable.

Disseminated Intravascular Coagulation Score Is Related to Short-term Mortality in Patients Undergoing Venoarterial Extracorporeal Membrane Oxygenation After Cardiac Surgery

Disseminated intravascular coagulation (DIC) score is associated with short-term mortality in various conditions but has not been studied in postcardiotomy cardiogenic shock (PCS) patients supported with venoarterial extracorporeal membrane oxygenation (VA-ECMO). The objective of this study was to evaluate the relationship between DIC score at day 1 from VA-ECMO initiation and short-term mortality. We included all PCS patients supported with VA-ECMO at the Beijing Anzhen Hospital between January 2015 and December 2018. Multivariable logistic regression analysis was performed to assess the relationship between DIC score at day 1 and in-hospital mortality, and adjust for potential confounding variables. Of 222 PCS patients treated with VA-ECMO, 145 (65%) patients were weaned from VA-ECMO, and median (IQR) ECMO support duration was five (3-6) days. In-hospital mortality was 53%. The median (IQR) DIC score at day 1 was five (4-6). Patients with DIC score ≥5 at day 1 (overt DIC) had higher in-hospital mortality as compared with patients with DIC score <5 (64% vs. 22%; P < 0.001). After adjusting for age, sex, ECMO indication, and peak serum lactate, a one-point rise in DIC score [OR, 2.20; 95% confidence intervals (CI), 1.64-2.95] or DIC score ≥5 at day 1 (OR, 4.98; 95% CI, 2.42-10.24) was associated with an increased risk of in-hospital mortality. The area under the receiver operating characteristic curve for DIC score at day 1 was 0.76 (95% CI, 0.69-0.82). Our study suggests that DIC score at day 1 is associated with short-term mortality in patients undergoing VA-ECMO after cardiac surgery, independent of age, sex, disease characteristics, and severity of illness.

Clinical and pathophysiologic aspects of ECMO-associated hemorrhagic complications

Extracorporeal membrane oxygenation (ECMO) is increasingly used to treat severe cases of acute respiratory or cardiac failure. Hemorrhagic complications represent one of the most common complications during ECMO, and can be life threatening. The purpose of this study was to elucidate pathophysiological mechanisms of ECMO-associated hemorrhagic complications and their impact on standard and viscoelastic coagulation tests. The study cohort included 27 patients treated with VV-ECMO or VA-ECMO. Hemostasis was evaluated using standard coagulation tests and viscoelastic parameters investigated with rotational thromboelastometry. Anticoagulation and hemorrhagic complications were analyzed for up to seven days depending on ECMO duration. Hemorrhagic complications developed in 16 (59%) patients. There were 102 discrete hemorrhagic episodes among 116 24-hour-intervals, of which 27% were considered to be clinically significant. The highest number of ECMO-associated hemorrhages occurred on the 2^nd and 3^rd day of treatment. Respiratory tract bleeding was the most common hemorrhagic complication, occurring in 62% of the 24-hour intervals. All 24-hours-intervals were divided into two groups: “with bleeding” and “without bleeding”. The probability of hemorrhage was significantly associated with abnormalities of four parameters: increased international normalized ratio (INR, sensitivity 71%, specificity 94%), increased prothrombin time (PT, sensitivity 90%, specificity 72%), decreased intrinsic pathway maximal clot firmness (MCFin, sensitivity 76%, specificity 89%), and increased extrinsic pathway clot formation time (CFTex, sensitivity 77%, specificity 87%). In conclusions, early ECMO-associated hemorrhagic complications are related to one traditional and two novel viscoelastic coagulation abnormalities: PT/INR elevation, reduced maximum clot firmness due to intrinsic pathway dysfunction (MCFin), and prolonged clot formation time due to extrinsic pathway dysfunction (CFTex). When managing hemostasis during ECMO, derangements in PT/INR, MCFin and CFT_ex should be focused on.

Venoarterial Extracorporeal Membrane Oxygenation for Severe Neonatal Acute Respiratory Distress Syndrome in a Developing Country

Objective: Extracorporeal membrane oxygenation (ECMO) has supported oxygen delivery and carbon dioxide removal in neonatal severe respiratory failure for more than 4 decades. The definition and diagnosis of neonatal acute respiratory distress syndrome (ARDS) was made according to the criteria first established by a Montreux Conference in 2017. By far, there has been no ECMO efficiency studies in neonatal ARDS. We aimed to compare the outcomes of neonates with severe ARDS supported with and without ECMO. Design: Retrospective pair-matched study. Setting: In the present retrospective pair-matched study, the outcomes of severe ARDS with ECMO support and without ECMO support were analyzed and compared. Propensity score matching was conducted. The study subjects were selected from a China Neonatal ECMO (CNECMO) study. In total, five hospitals were included in the CNECMO study. The patients were matched with demographic and clinical data. The primary endpoint was in-hospital mortality. Secondary outcomes included ventilator-time, ICU stay, hospitalization costs and cranial MRI results. Patients: 145 neonates with severe ARDS (Oxygenation Index, OI ≥16) from 5 hospitals. Interventions: No interventions. Measurements and Main Results: We collected the data of 145 neonates with severe ARDS (Oxygenation Index, OI≥16) from 5 hospitals. Among them, 42 neonates received venoarterial (VA) ECMO support, and the remaining 103 neonates were treated with conventional mechanical ventilation. The mortality of ECMO-supported neonates was not significantly different compared with the ESLO neonatal respiratory-supported from 2012 to 2018 (23.8 vs. 32.5%, p = 0.230). After matching with the propensity score we got 31 pairs. The ECMO-supported neonates had a lower in-hospital mortality (6 of 31, 19.4%) vs. non ECMO-supported patients (18 of 31, 58.1%) (p = 0.002). Hospitalization costs of survivors in ECMO-supported neonates were significantly higher than that of non-ECMO-supported neonates (p < 0.001). There was no difference of ventilator-times (p = 0.206), ICU stay (p = 0.879) and cranial MRI (p = 0.899) between the survivors of ECMO-supported and non-ECMO-supported neonates with ARDS. Conclusions: By far, there has been no ECMO efficiency studies in neonatal ARDS. This study found that ECMO-support have superior outcomes compared with non-ECMO-support in neonates with severe ARDS.

Current Understanding of How Extracorporeal Membrane Oxygenators Activate Haemostasis and Other Blood Components

Extracorporeal membrane oxygenators are used in critical care for the management of severe respiratory and cardiac failure. Activation of the coagulation system is initiated by the exposure of blood to synthetic surfaces and the shear stresses of the circuit, especially from device pumps. Initial fibrinogen deposition and subsequent activation of coagulation factors and complement allow platelets and leucocytes to adhere to oxygenator surfaces and enhance thrombin generation. These changes and others contribute to higher rates of thrombosis seen in these patients. In addition, bleeding rates are also high. Primary haemostasis is impaired by platelet dysfunction and loss of their key adhesive molecules and shear stress causes an acquired von Willebrand defect. In addition, there is also altered fibrinolysis and lastly, administration of systemic anticoagulation is required to maintain circuit patency. Further research is required to fulyl establish the complexities of the haemostatic changes with these devices, and to elucidate the mechanistic changes that are mainly responsible so that plans can be made to reduce their complications and improve management.

Clinical complications during veno-arterial extracorporeal membrane oxigenation in post-cardiotomy and non post-cardiotomy shock: still the achille's heel

Extracorporeal membrane oxygenation (ECMO) is life-saving for potentially reversible heart failure and respiratory injuries not responsive to conventional therapies. Technological innovations have produced over the years significant improvements in ECMO devices (pump, cannula design and oxygenator) and have allowed a better risk/benefit profile. Alongside with recognized advantages in the treatment of very sick patients, ECMO remains an invasive procedure for mechanical circulatory support (MCS) and it is associated with complications that strongly influence the prognosis. Current review was designed to provide a comprehensive outline on ECMO complications, analyzing risk factors and strategies of management, focusing on adult population undergoing veno-arterial ECMO (VA-ECMO) therapy.