Blood Conservation in Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome

Association of RBC Transfusion Thresholds and Outcomes in Medical Patients With Acute Respiratory Failure Supported With Extracorporeal Membrane Oxygenation: A Single-Center Retrospective Cohort Study

BACKGROUND

The hemoglobin value to trigger RBC transfusion for patients receiving venovenous extracorporeal membrane oxygenation (ECMO) is controversial. Previous guidelines recommended transfusing to a normal hemoglobin level, but recent studies suggest that more RBC transfusions are associated with increased adverse outcomes.

RESEARCH QUESTION

Is implementation of different institutional RBC transfusion thresholds for patients receiving venovenous ECMO associated with changes in RBC use and patient outcomes?

STUDY DESIGN AND METHODS

This single-center retrospective study of patients receiving venovenous ECMO used segmented regression to test associations between implementation of institutional transfusion thresholds and trends in RBC use. Associations with secondary outcomes, including in-hospital survival, also were assessed.

RESULTS

The study included 229 patients: 91 in the no threshold cohort, 48 in the hemoglobin < 8 g/dL cohort, and 90 in the hemoglobin < 7 g/dL cohort. Despite a decrease in number of RBC units transfused per day of ECMO support after implementation of different thresholds (mean ± SD: 0.6 ± 1.0 in the no threshold cohort, 0.3 ± 0.8 in the hemoglobin < 8 g/dL cohort, and 0.3 ± 1.1 in the hemoglobin < 7 g/dL cohort; P < .001), segmented regression showed no association between implementation of transfusion thresholds and changes in trends in number of RBC units per day of ECMO. We observed an increased hazard of death in the no threshold cohort compared with the hemoglobin < 8 g/dL cohort (adjusted hazard ratio [aHR], 2.08; 95% CI, 1.12-3.88) and in the hemoglobin < 7 g/dL cohort compared with the hemoglobin < 8 g/dL cohort (aHR, 1.93; 95% CI, 1.02-3.62). No difference was found in the hazard of death between the no threshold and hemoglobin < 7 g/dL cohorts (aHR, 1.08; 95% CI, 0.69-1.69).

INTERPRETATION

We observed a decrease in number of RBC units per day of ECMO over time, but changes were not associated temporally with implementation of transfusion thresholds. A transfusion threshold of hemoglobin < 8 g/dL was associated with a lower hazard of death, but these findings are limited by study methodology. Further research is needed to investigate optimal RBC transfusion practices for patients supported with venovenous ECMO.

Successful ECMO treatment in patients with cerebral hemorrhage and PROC gene mutation associated with VTE: a case report

In this report, we report a case of a middle-aged male, admitted to the ICU with cerebral hemorrhage resulting from a severe high-altitude fall. The patient encountered significant challenges in oxygenation index correction, attributed to extensive embolism in both the primary and branch pulmonary arteries. Consequently, the patient underwent an immediate initiation of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) therapy, persisting for 20 days. During this treatment period, a mutation in the protein C (PROC) gene was identified. The medical team meticulously navigated the delicate balance between anticoagulation and bleeding risks. Eventually, the patient was successfully weaned off VA-ECMO and subsequently discharged. This report aims to delve into the etiology and therapeutic approaches of this uncommon case, with the intention of offering insightful reference for managing similar clinical scenarios in the future.

Respiratory extracorporeal membrane oxygenation : From rescue therapy to standard tool for treatment of acute respiratory distress syndrome?

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) for patients with acute respiratory distress syndrome (ARDS) has increased substantially. With modern trials supporting its efficacy, ECMO has become an important tool in the management of severe ARDS.

OBJECTIVES

The objectives of this paper are to discuss ECMO physiology and configurations used for patients with ARDS, review evidence supporting the use of ECMO for ARDS, and discuss aspects of management during ECMO.

CONCLUSION

Current evidence supports the use of ECMO, combined with an ultra-lung-protective approach to mechanical ventilation, in patients with ARDS who have refractory hypoxemia or hypercapnia with severe respiratory acidosis. Furthermore, data suggest that center volume and experience are important factors in the care of patients receiving ECMO. The use of extracorporeal technologies in expanded patient populations and the optimal management of patients during ECMO remain areas of investigation. This article is freely available.

Use of bivalirudin after initial heparin management among adult patients on long-term venovenous extracorporeal support as a bridge to lung transplant: A case series

A growing body of evidence supports the use of bivalirudin as an alternative to unfractionated heparin (UFH) for the prevention of thrombotic events in patients on venovenous (VV) extracorporeal membrane oxygenation (ECMO). However, data in patients bridged to lung transplantation are limited. In this case series, we describe the outcomes of six patients who were transitioned from UFH to bivalirudin during their course of VV ECMO support as a bridge to lung transplantation. All six patients were on VV ECMO support until transplant, with a median duration of 73 days. Bivalirudin demonstrated a shorter time to first therapeutic activated thromboplastin time (aPTT) level. Additionally, time in therapeutic range was longer while patients were receiving bivalirudin compared to UFH (median 92.9% vs. 74.6%). However, major bleeding and thrombotic events occurred while patients were receiving either anticoagulant. Based on our experience, bivalirudin appears to be a viable option for anticoagulation in VV ECMO patients bridged to lung transplantation. Larger studies evaluating the optimal anticoagulation strategy in patients bridged to transplant are needed.

Anticoagulation and Bleeding during Veno-Venous Extracorporeal Membrane Oxygenation: Insights from the PROTECMO Study

Rationale: Definitive guidelines for anticoagulation management during veno-venous extracorporeal membrane oxygenation (VV ECMO) are lacking, whereas bleeding complications continue to pose major challenges. Objectives: To describe anticoagulation modalities and bleeding events in adults receiving VV ECMO. Methods: This was an international prospective observational study in 41 centers, from December 2018 to February 2021. Anticoagulation was recorded daily in terms of type, dosage, and monitoring strategy. Bleeding events were reported according to site, severity, and impact on mortality. Measurements and Main Results: The study cohort included 652 patients, and 8,471 days on ECMO were analyzed. Unfractionated heparin was the initial anticoagulant in 77% of patients, and the most frequently used anticoagulant during the ECMO course (6,221 d; 73%). Activated partial thromboplastin time (aPTT) was the most common test for monitoring coagulation (86% of days): the median value was 52 seconds (interquartile range, 39 to 61 s) but dropped by 5.3 seconds after the first bleeding event (95% confidence interval, -7.4 to -3.2; P < 0.01). Bleeding occurred on 1,202 days (16.5%). Overall, 342 patients (52.5%) experienced at least one bleeding event (one episode every 215 h on ECMO), of which 10 (1.6%) were fatal. In a multiple penalized Cox proportional hazard model, higher aPTT was a potentially modifiable risk factor for the first episode of bleeding (for 20-s increase; hazard ratio, 1.07). Conclusions: Anticoagulation during VV ECMO was a dynamic process, with frequent stopping in cases of bleeding and restart according to the clinical picture. Future studies might explore lower aPTT targets to reduce the risk of bleeding.

Extracorporeal membrane oxygenation circuits in parallel for refractory hypoxemia in patients with COVID-19

OBJECTIVES

Refractory hypoxemia can occur in patients with acute respiratory distress syndrome from COVID-19 despite support with venovenous (VV) extracorporeal membrane oxygenation (ECMO). Parallel ECMO circuits can be used to increase physiologic support. We report our clinical experience using ECMO circuits in parallel for select patients with persistent severe hypoxemia despite the use of a single ECMO circuit.

METHODS

We performed a retrospective cohort study of all patients with COVID-19-related acute respiratory distress syndrome who received VV-ECMO with an additional circuit in parallel at Vanderbilt University Medical Center between March 1, 2020, and March 1, 2022. We report demographic characteristics and clinical characteristics including ECMO settings, mechanical ventilator settings, use of adjunctive therapies, and arterial blood gas results after initial cannulation, before and after receipt of a second ECMO circuit in parallel, and before removal of the circuit in parallel, and outcomes.

RESULTS

Of 84 patients with COVID-19 who received VV-ECMO during the study period, 22 patients (26.2%) received a circuit in parallel. The median duration of ECMO was 40.0 days (interquartile range, 31.6-53.1 days), of which 19.0 days (interquartile range, 13.0-33.0 days) were spent with a circuit in parallel. Of the 22 patients who received a circuit in parallel, 16 (72.7%) survived to hospital discharge and 6 (27.3%) died before discharge.

CONCLUSIONS

In select patients, the additional use of an ECMO circuit in parallel can increase ECMO blood flow and improve oxygenation while allowing for lung-protective mechanical ventilation and excellent outcomes.

Extracorporeal Membrane Oxygenation Patient Outcomes Following Restrictive Blood Transfusion Protocol

OBJECTIVES

To investigate the effect of a restrictive blood product utilization protocol on blood product utilization and clinical outcomes.

DESIGN

We retrospectively reviewed all adult extracorporeal membrane oxygenation (ECMO) patients from January 2019 to December 2021. The restrictive protocol, implemented in March 2020, was defined as transfusion of blood products for a hemoglobin level less than 7, platelet levels less than 50, and/or fibrinogen levels less than 100. Subgroup analysis was performed based on the mode of ECMO received: venoarterial ECMO, venovenous ECMO, and ECMO support following extracorporeal cardiopulmonary resuscitation (ECPR).

SETTING

M Health Fairview University of Minnesota Medical Center.

PATIENTS

The study included 507 patients.

INTERVENTIONS

One hundred fifty-one patients (29.9%) were placed on venoarterial ECMO, 70 (13.8%) on venovenous ECMO, and 286 (56.4%) on ECPR.

MEASUREMENTS AND MAIN RESULTS

For patients on venoarterial ECMO (48 [71.6%] vs. 52 [63.4%]; p = 0.374), venovenous ECMO (23 [63.9%] vs. 15 [45.5%]; p = 0.195), and ECPR (54 [50.0%] vs. 69 [39.2%]; p = 0.097), there were no significant differences in survival on ECMO. The last recorded mean hemoglobin value was also significantly decreased for venoarterial ECMO (8.10 [7.80-8.50] vs. 7.50 [7.15-8.25]; p = 0.001) and ECPR (8.20 [7.90-8.60] vs. 7.55 [7.10-8.88]; p < 0.001) following implementation of the restrictive transfusion protocol.

CONCLUSIONS

These data suggest that a restrictive transfusion protocol is noninferior to ECMO patient survival. Additional, prospective randomized trials are required for further investigation of the safety of a restrictive transfusion protocol.

The low hemoglobin levels were associated with mortality in post-cardiotomy patients undergoing venoarterial extracorporeal membrane oxygenation

BACKGROUND

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is used as a rescue strategy for patients with refractory post-cardiotomy cardiogenic shock (PCS). These patients often have varying degrees of reduced hemoglobin levels, and there are few detailed investigations about the impact of hemoglobin level on their mortality. The objective of this study was to evaluate whether hemoglobin levels at day 1 from VA-ECMO initiation were associated with in-hospital mortality.

METHODS

We performed a retrospective analysis of adult VA-ECMO patients over approximately a 2-year period. We divided patients into survival and death groups based on their clinical outcomes and compared the differences in parameters between the two groups. Multivariate logistic regression analyses were performed to estimate whether hemoglobin level was related to the mortality.

RESULTS

One hundred and sixteen patients were included in final analysis. There were 52 patients in the survival group and 64 in the death group. The patients were younger in the survival group than the death group (58 vs 63, p = .023). The median (IQR) hemoglobin level at day 1 was 80 (73-89) × g/L, and the median (IQR) RelΔ hemoglobin was 41% (32-48%). Survival patients had a higher hemoglobin level at day 1 and a lower RelΔ hemoglobin than the death patients (91 vs 76 g/L, p < .001; 35% vs 45%, p < .001). The multivariable logistic regression analyses showed that the low hemoglobin levels at day 1 were independently associated with in-hospital mortality (OR 0.808; 95% CI, 0.747-0.874; p < .001). The AUROC for hemoglobin level was 0.89 (95% CI, 0.83-0.95) which was better than that of RelΔ hemoglobin (0.77, 95% CI, 0.68-0.86).

CONCLUSIONS

In patients receiving VA-ECMO for PCS, the low hemoglobin levels at day 1 were independently associated with in-hospital mortality.

Standard Versus Restrictive Transfusion Strategy for Pediatric Cardiac ECLS Patients: Single Center Retrospective Cohort Study

This retrospective cohort study aimed to compare blood component transfusion before and after the implementation of a restrictive transfusion strategy (RTS) in pediatric cardiac Extracorporeal Life Support (ECLS) patients. The study included children admitted to the pediatric cardiac intensive care unit (PCICU) at the Stollery Children's Hospital who received ECLS between 2012 and 2020. Children on ECLS between 2012 and 2016 were treated with standard transfusion strategy (STS), while those on ECLS between 2016 and 2020 were treated with RTS. During the study, 203 children received ECLS. Daily median (interquartile range [IQR]) packed red blood cell (PRBC) transfusion volume was significantly lower in the RTS group; 26.0 (14.4-41.5) vs. 41.5 (26.6-64.4) ml/kg/day, p value <0.001. The implementation of a RTS led to a median reduction of PRBC transfusion of 14.5 (95% CI: 6.70-21.0) ml/kg/day. Similarly, the RTS group received less platelets: median (IQR) 8.4 (4.50-15.0) vs. 17.5 (9.40-29.0) ml/kg/day, p value <0.001. The implementation of a RTS resulted in a median reduction of platelet transfusion of 9.2 (95% CI: 5.45-13.1) ml/kg/day. The RTS resulted in less median (IQR) fluid accumulation in the first 48 hours: 56.7 (2.30-121.0) vs. 140.4 (33.8-346.2) ml/kg, p value = 0.001. There were no significant differences in mechanical ventilation days, PCICU/hospital days, or survival. The use of RTS resulted in lower blood transfusion volumes, with similar clinical outcomes.

Outcomes of patients with coronavirus disease versus other lung infections requiring venovenous extracorporeal membrane oxygenation

Background

Patients with Coronavirus Disease (COVID-19) often develop severe acute respiratory distress syndrome (ARDS) requiring prolonged mechanical ventilation (MV), and venovenous extracorporeal membrane oxygenation (V-V ECMO).Mortality in COVID-19 patients on V-V ECMO was exceptionally high; therefore, whether survival can be ameliorated should be investigated.

Methods

We collected data from 85 patients with severe ARDS who required ECMO support at the University Hospital Magdeburg from 2014 to 2021. The patients were divided into the COVID-19 group (52 patients) and the non-COVID-19 group (33 patients). Demographic and pre-, intra-, and post-ECMO data were retrospectively recorded. The parameters of mechanical ventilation, laboratory data before using ECMO, and during ECMO were compared.

Results

There was a significant difference between the two groups regarding survival: 38.5% of COVID-19 patients and 63.6% of non-COVID-19 patients survived 60 days (p = 0.024). COVID-19 patients required V-V ECMO after 6.5 days of MV, while non-COVID-19 patients required V-V ECMO after 2.0 days of MV (p = 0.048). The COVID-19 group had a greater proportion of patients with ischemic heart disease (21.2% vs 3%, p = 0.019). The rates of most complications were comparable in both groups, whereas the COVID-19 group showed a significantly higher rate of cerebral bleeding (23.1 vs 6.1%, p = 0.039) and lung bacterial superinfection (53.8% vs 9.1%, p = <0.001).

Conclusion

The higher 60-days mortality among patients with COVID-19 with severe ARDS was attributable to superinfection, a higher risk of intracerebral bleeding, and the pre-existing ischemic heart disease.

Haematological Trends and Transfusion during Adult Extracorporeal Membrane Oxygenation: A Single Centre Study

The temporal trends in haematological parameters and their associations with blood product transfusion requirements in patients supported with extracorporeal membrane oxygenation (ECMO) are poorly understood. We performed a retrospective data analysis to better understand the behaviour of haematological and coagulation parameters and their associations with transfusion requirements during ECMO.

METHODS

Patient demographics, haematological and coagulation parameters, plasma haemoglobin and fibrinogen concentrations, platelet count, the international normalised ratio (INR), the activated partial thromboplastin time (APTT), and blood product transfusion data from 138 patients who received ECMO in a single high-volume centre were analysed.

RESULTS

Ninety-two patients received venoarterial (VA) ECMO and 46 patients received venovenous (VV) ECMO. The median (IQR) duration of VA, and VV ECMO was 8 (5-13) days and 13 (8-23) days, respectively. There were significant reductions in haemoglobin, the platelet count, and the fibrinogen concentration upon initiation of ECMO. On average, over time, patients on VV ECMO had platelet counts 44 × 109/L higher than those on VA ECMO (p ≤ 0.001). Fibrinogen and APTT did not vary significantly based on the mode of ECMO (p = 0.55 and p = 0.072, respectively). A platelet count < 50 × 109/L or a fibrinogen level < 1.8 g/L was associated with 50% chance of PRBC transfusion, regardless of the ECMO type, and packed red blood cell (PRBC) transfusion was more common with VA ECMO. APTT was predictive of the transfusion requirement, and the decrement in APTT was discriminatory between VVECMO survivors and nonsurvivors.

CONCLUSION

ECMO support is associated with reductions in haemoglobin, platelet count, and fibrinogen. Patients supported with VA ECMO are more likely to receive a PRBC transfusion compared to those on VV ECMO. Thrombocytopaenia, hypofibrinogenaemia, and anticoagulation effect the likelihood of requiring PRBC transfusion. Further research is needed to define optimal blood management during ECMO, including appropriate transfusion triggers and the anticoagulation intensity.

Transfusion practice in patients receiving VV ECMO (PROTECMO): a prospective, multicentre, observational study

BACKGROUND

In patients receiving venovenous (VV) extracorporeal membrane oxygenation (ECMO) packed red blood cell (PRBC) transfusion thresholds are usually higher than in other patients who are critically ill. Available guidelines suggest a restrictive approach, but do not provide specific recommendations on the topic. The main aim of this study was, in a short timeframe, to describe the actual values of haemoglobin and the rate and the thresholds for transfusion of PRBC during VV ECMO.

METHODS

PROTECMO was a multicentre, prospective, cohort study done in 41 ECMO centres in Europe, North America, Asia, and Australia. Consecutive adult patients with acute respiratory distress syndrome (ARDS) who were receiving VV ECMO were eligible for inclusion. Patients younger than 18 years, those who were not able to provide informed consent when required, and patients with an ECMO stay of less than 24 h were excluded. Our main aim was to monitor the daily haemoglobin concentration and the value at the point of PRBC transfusion, as well as the rate of transfusions. The practice in different centres was stratified by continent location and case volume per year. Adjusted estimates were calculated using marginal structural models with inverse probability weighting, accounting for baseline and time varying confounding.

FINDINGS

Between Dec 1, 2018, and Feb 22, 2021, 604 patients were enrolled (431 [71%] men, 173 [29%] women; mean age 50 years [SD 13·6]; and mean haemoglobin concentration at cannulation 10·9 g/dL [2·4]). Over 7944 ECMO days, mean haemoglobin concentration was 9·1 g/dL (1·2), with lower concentrations in North America and high-volume centres. PRBC were transfused on 2432 (31%) of days on ECMO, and 504 (83%) patients received at least one PRBC unit. Overall, mean pretransfusion haemoglobin concentration was 8·1 g/dL (1·1), but varied according to the clinical rationale for transfusion. In a time-dependent Cox model, haemoglobin concentration of less than 7 g/dL was consistently associated with higher risk of death in the intensive care unit compared with other higher haemoglobin concentrations (hazard ratio [HR] 2·99 [95% CI 1·95-4·60]); PRBC transfusion was associated with lower risk of death only when transfused when haemoglobin concentration was less than 7 g/dL (HR 0·15 [0·03-0·74]), although no significant effect in reducing mortality was reported for transfusions for other haemoglobin classes (7·0-7·9 g/dL, 8·0-9·9 g/dL, or higher than 10 g/dL).

INTERPRETATION

During VV ECMO, there was no universally accepted threshold for transfusion, but PRBC transfusion was invariably associated with lower mortality only when done with haemoglobin concentration of less than 7 g/dL.

FUNDING

Extracorporeal Life Support Organization.

Restrictive and liberal transfusion strategies in extracorporeal membrane oxygenation: A retrospective observational study

BACKGROUND

To compare the outcomes of patients requiring extracorporeal membrane oxygenation (ECMO) support who had a restrictive transfusion strategy with those who had a liberal strategy.

STUDY DESIGN AND METHODS

We retrospectively reviewed all adult patients from 2010 to 2019 who received a minimum of one packed red blood cell (pRBC) during ECMO. Hemoglobin values before each transfusion were retrieved. Restrictive transfusion strategy was defined as a transfusion threshold ≤8.5 g/dl in all transfusion episodes for a single patient, while liberal transfusion strategy was defined as a transfusion threshold >8.5 g/dl in any transfusion episode.

RESULTS

The analysis included 763 patients, with 138 (18.1%) patients in the restrictive and 625 (81.9%) in the liberal transfusion strategy group. The median hemoglobin level, taking into account all measured hemoglobin values, during ECMO support was 8.3 and 9.9 g/dl, and the average units of pRBC received per day were 0.7 (0.3-1.8) and 1.2 (0.6-2.3), respectively. There were no significant differences in intensive care unit (ICU) mortality (adjusted odds ratio (OR), 0.86; 95% CI 0.56-1.30; p = .47), hospital mortality (adjusted OR, 0.79; 95% CI 0.52-1.21; p = .28), and 90-day mortality (adjusted OR, 0.84; 95% CI 0.55-1.28; p = .42) between the two groups. Among subgroup analyses, a restrictive transfusion strategy was associated with decreased risk of ICU mortality in patients on veno-venous ECMO (adjusted OR, 0.36; 95% CI 0.17-0.73; p = .005). There was no heterogeneity on outcomes across patients stratified by age, APACHE IV score, or need for large volume transfusion.

DISCUSSION

Our data suggested it may be safe to adopt a restrictive red cell transfusion threshold of 8.5 g/dl in patients on ECMO, and highlighted the need for prospective trials in this heavily-transfused population.

Successful management of hemodynamic instability secondary to saddle pulmonary embolism-induced cardiac arrest using VA-ECMO in advanced malignancy with brain metastases

BACKGROUND

Saddle pulmonary embolism (SPE) represents a rare type of venous thromboembolism that frequently causes circulation collapse and sudden death. While venoarterial extracorporeal membrane oxygenation (VA-ECMO) has been well established as a salvage treatment for SPE-induced circulatory shock, it is infrequently administered in patients with advanced malignancy, especially those with brain metastases, given the potential bleeding complications and an uncertain prognosis. As far, there are rare case reports regarding the successful management of hemodynamic instability secondary to SPE-induced cardiac arrest using VA-ECMO in advanced malignancy patients with brain metastases.

CASE PRESENTATION

A 65-year-old woman presenting with cough and waist discomfort who had a history of lung cancer with brain metastases was admitted to the hospital to receive chemoradiotherapy. She suffered sudden cardiac arrest during hospitalization and returned to spontaneous circulation after receiving a 10-min high-quality cardiopulmonary resuscitation. Pulmonary embolism was suspected due to the collapsed hemodynamics and a distended right ventricle identified by echocardiography. Subsequent computed tomographic pulmonary angiography revealed a massive saddle thrombus straddling the bifurcation of the pulmonary trunk. VA-ECMO with adjusted-dose systemic heparinization was initiated to rescue the unstable hemodynamics despite receiving thrombolytic therapy with alteplase. Immediately afterward, the hemodynamic status of the patient stabilized rapidly. VA-ECMO was successfully discontinued within 72 h of initiation without any clotting or bleeding complications. She was weaned off invasive mechanical ventilation on the 6th day of intensive care unit (ICU) admission and discharged from the ICU 3 days later with good neurological function.

CONCLUSION

VA-ECMO may be a 'bridging' therapy to circulation recovery during reperfusion therapy for SPE-induced hemodynamic collapse in malignancy patients with brain metastases.

Extracorporeal Membrane Oxygenation Circuits in Parallel for Refractory Hypoxemia in COVID-19: A Case Series

Refractory hypoxemia despite the use of extracorporeal membrane oxygenation (ECMO) for coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome remains a challenging problem. A single ECMO circuit may not provide adequate physiologic support in the setting of an elevated cardiac output, physiologic demand, and impaired gas exchange. In select patients with refractory hypoxemia, addition of a second ECMO circuit in parallel can improve oxygenation, facilitate lung protective ventilation, awakening, and physical rehabilitation. We report the largest case series to date of patients receiving ECMO circuits in parallel and the first to report this approach in COVID-19.

A Comparison of Anticoagulation Strategies in Veno-venous Extracorporeal Membrane Oxygenation

Bleeding remains a major source of morbidity associated with veno-venous extracorporeal membrane oxygenation (VV-ECMO). Moreover, there remains significant controversy, and a paucity of data regarding the ideal anticoagulation strategy for VV-ECMO patients. All patients undergoing isolated, peripheral VV-ECMO between January 2009 and December 2014 at our institution were retrospectively reviewed. Patients (n = 123) were stratified into one of three sequential eras of anticoagulation strategies: activated clotting time (ACT: 160-180 seconds, n = 53), high-partial thromboplastin time (H-PTT: 60-80 seconds, n = 25), and low-PTT (L-PTT: 45-55 seconds, n = 25) with high-flow (>4 L/min). Pre-ECMO APACHE II scores, SOFA scores, and Murray scores were not significantly different between the groups. Patients in the L-PTT group required less red blood cell units on ECMO than the ACT or H-PTT group (2.1 vs. 1.3 vs. 0.9; p < 0.001) and patients in the H-PTT and L-PTT group required less fresh frozen plasma than the ACT group (0.33 vs. 0 vs. 0; p = 0.006). Overall, major bleeding events were significantly lower in the L-PTT group than in the ACT and H-PTT groups. There was no difference in thrombotic events. In this single-institution experience, a L-PTT, high-flow strategy on VV-ECMO was associated with fewer bleeding and no difference in thrombotic events than an ACT or H-PTT strategy.

2021 ELSO Adult and Pediatric Anticoagulation Guidelines

DISCLAIMER

These guidelines for adult and pediatric anticoagulation for extracorporeal membrane oxygenation are intended for educational use to build the knowledge of physicians and other health professionals in assessing the conditions and managing the treatment of patients undergoing ECLS / ECMO and describe what are believed to be useful and safe practice for extracorporeal life support (ECLS, ECMO) but these are not necessarily consensus recommendations. The aim of clinical guidelines are to help clinicians to make informed decisions about their patients. However, adherence to a guideline does not guarantee a successful outcome. Ultimately, healthcare professionals must make their own treatment decisions about care on a case-by-case basis, after consultation with their patients, using their clinical judgment, knowledge and expertise. These guidelines do not take the place of physicians' and other health professionals' judgment in diagnosing and treatment of particular patients. These guidelines are not intended to and should not be interpreted as setting a standard of care or be deemed inclusive of all proper methods of care nor exclusive of other methods of care reasonably directed to obtaining the same results. The ultimate judgment must be made by the physician and other health professionals and the patient in light of all the circumstances presented by the individual patient, and the known variability and biological behavior of the clinical condition. These guidelines reflect the data at the time the guidelines were prepared; the results of subsequent studies or other information may cause revisions to the recommendations in these guidelines to be prudent to reflect new data, but ELSO is under no obligation to provide updates. In no event will ELSO be liable for any decision made or action taken in reliance upon the information provided through these guidelines.

How we manage blood product support and coagulation in the adult patient requiring extracorporeal membrane oxygenation

Use of extracorporeal membrane oxygenation (ECMO) is increasing among critically ill adults with cardiac and/or respiratory failure. Use of ECMO is associated with hemostatic alterations requiring use of anticoagulation and blood product support. There are limited guidelines to direct transfusion management in the adult patient supported with ECMO. The objective of this article is to describe (1) the role of the transfusion service in providing transfusion support and current understanding of transfusion thresholds, (2) the complexities of monitoring anticoagulation, and (3) the consideration regarding additional factor concentrates and antifibrinolytics within the context of ECMO support. The information provided should assist ECMO care teams in informing transfusion and anticoagulation practice while highlighting key areas for future research and collaboration.

Bleeding and thrombotic events in adults supported with venovenous extracorporeal membrane oxygenation: an ELSO registry analysis

PURPOSE

This study aimed at analyzing the prevalence, mortality association, and risk factors for bleeding and thrombosis events (BTEs) among adults supported with venovenous extracorporeal membrane oxygenation (VV-ECMO).

METHODS

We queried the Extracorporeal Life Support Organization registry for adults supported with VV-ECMO from 2010 to 2017. Multivariable logistic regression modeling was used to assess the association between BTEs and in-hospital mortality and the predictors of BTEs.

RESULTS

Among 7579 VV-ECMO patients meeting criteria, 40.2% experienced ≥ 1 BTE. Thrombotic events comprised 54.9% of all BTEs and were predominantly ECMO circuit thrombosis. BTE rates decreased significantly over the study period (p < 0.001). The inpatient mortality rate was 34.9%. Bleeding events (1.69 [1.49-1.93]) were more strongly associated with in-hospital mortality than thrombotic events (1.23 [1.08-1.41]) p < 0.01 for both. The BTEs most strongly associated with mortality were ischemic stroke (4.50 [2.55-7.97]) and medical bleeding, including intracranial (5.71 [4.02-8.09]), pulmonary (2.02 [1.54-2.67]), and gastrointestinal (1.54 [1.2-1.98]) hemorrhage, all p < 0.01. Risk factors for bleeding included acute kidney injury and pre-ECMO vasopressor support and for thrombosis were higher weight, multisite cannulation, pre-ECMO arrest, and higher PaCO₂ at ECMO initiation. Longer time on ECMO, younger age, higher pH, and earlier year of support were associated with bleeding and thrombosis.

CONCLUSIONS

Although decreasing over time, BTEs remain common during VV-ECMO and have a strong, cumulative association with in-hospital mortality. Thrombotic events are more frequent, but bleeding carries a higher risk of inpatient mortality. Differential risk factors for bleeding and thrombotic complications exist, raising the possibility of a tailored approach to VV-ECMO management.

Mortality after Lung Transplantation for Children Bridged with Extracorporeal Membrane Oxygenation

RATIONALE

Extracorporeal membrane oxygenation (ECMO) is increasingly used to bridge waitlisted children failing conventional respiratory support to lung transplantation.

OBJECTIVES

To compare in-hospital mortality and a composite outcome of 1-year mortality or re-transplantation in children bridged with ECMO with those on mechanical ventilation (MV), and neither support.

METHODS

The United Network for Organ Sharing (UNOS) was used to analyze lung transplant recipients, aged ≤ 20 y, from January 2004 to August 2019. Recipients were categorized according to level of respiratory support at time of transplant, including ECMO, MV, or neither. Multivariable analysis was used to evaluate support type and in-hospital mortality.

RESULTS

Of 1,014 children undergoing lung transplant, 68 (6.7%) required ECMO as a bridge-to-transplant, 144 (14.2%) MV, and 802 (79.1%) neither. Primary diagnosis in the ECMO cohort included cystic fibrosis (43%), pneumonia/ARDS (10.3%), interstitial pulmonary fibrosis (7.4%) and pulmonary hypertension (5.9%). Number of patients bridged with ECMO increased throughout the study period from none in 2004 to 16.7% in 2018. Multivariable analysis showed bridging with both ECMO (aOR = 3.57; 95% CI: 1.42, 8.97) and MV (aOR = 2.67; 95% CI: 1.26, 5.57) increased in-hospital mortality after lung transplantation. However, there was no difference in composite outcome of mortality and re-transplantation at 1-year between the three groups.

CONCLUSIONS

ECMO to bridge children to lung transplantation has increased. Despite this, ECMO is a high-risk bridge strategy for children awaiting lung transplantation. Future research should target interventions that can be focused on improving survival in these patients.

Simple and Effective Blood Salvage Technique for Extracorporeal Membrane Oxygenation Circuit

Return of circuit blood after discontinuing extracorporeal membrane oxygenation (ECMO) is an important blood conservation strategy for reducing the need for blood transfusion. This follows the current standard of circuit blood salvaging after cardiopulmonary bypass (CPB). There is a variety of strategies and techniques of blood salvage described associated with CPB but not with ECMO. We describe a simplified technique to salvage the blood in the ECMO circuit that requires no special equipment, is safe, and maximizes blood salvage.

The Evolution of the Use of Extracorporeal Membrane Oxygenation in Respiratory Failure

Extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency to support patients with acute respiratory failure, most commonly, and severe forms of acute respiratory distress syndrome (ARDS). The marked increase in the global use of ECMO followed the publication of a large randomized trial in 2009 and the experience garnered during the 2009 influenza A (H1N1) pandemic, and has been further supported by the release of a large, randomized clinical trial in 2018, confirming a benefit from using ECMO in patients with severe ARDS. Despite a rapid expansion of ECMO-related publications, optimal management of patients receiving ECMO, in terms of patient selection, ventilator management, anticoagulation, and transfusion strategies, is evolving. Most recently, ECMO is being utilized for an expanding variety of conditions, including for cases of severe pulmonary or cardiac failure from coronavirus disease 2019 (COVID-19). This review evaluates modern evidence for ECMO for respiratory failure and the current challenges in the field.

A Systematic Literature Review of Packed Red Cell Transfusion Usage in Adult Extracorporeal Membrane Oxygenation

Background: Blood product administration plays a major role in the management of patients treated with extracorporeal membrane oxygenation (ECMO) and may be a contributor to morbidity and mortality. Methods: We performed a systematic review of the published literature to determine the current usage of packed red cell transfusions. Predefined search criteria were used to identify journal articles reporting transfusion practice in ECMO by interrogating EMBASE and Medline databases and following the PRISMA statement. Results: Out of 1579 abstracts screened, articles reporting ECMO usage in a minimum of 10 adult patients were included. Full texts of 331 articles were obtained, and 54 were included in the final analysis. All studies were observational (2 were designed prospectively, and two were multicentre). A total of 3808 patients were reported (range 10–517). Mean exposure to ECMO was 8.2 days (95% confidence interval (CI) 7.0–9.4). A median of 5.6% was not transfused (interquartile range (IQR) 0–11.3%, 19 studies). The mean red cell transfusion per ECMO run was 17.7 units (CI 14.2–21.2, from 52 studies) or 2.60 units per day (CI 1.93–3.27, from 49 studies). The median survival to discharge was 50.8% (IQR 40.0–64.9%). Conclusion: Current evidence on transfusion practice in ECMO is mainly drawn from single-centre observational trials and varies widely. The need for transfusions is highly variable. Confounding factors influencing transfusion practice need to be identified in prospective multicentre studies to mitigate potential harmful effects and generate hypotheses for interventional trials.

Red blood cell transfusion requirements for patients on extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a rescue procedure used for cardiac and pulmonary dysfunction. Patients on ECMO often require blood transfusions to maintain oxygen delivery and recover from bleeding complications. Goals of the current study were to determine transfusion requirements while on ECMO, and incidence and transfusion requirements for bleeding complications.

METHODS

Packed red blood cell (PRBC) transfusions and bleeding complications were identified by retrospective chart review of patients on ECMO from 2010 to 2018 at our institution. Patients were categorized into those who did not bleed (group A) and those who bled (group B). Incidence, sites of bleed, and transfusion requirement for each bleeding were analyzed.

RESULTS

Among 217 patients including veno-arterial (VA) (n = 148) and veno-venous (VV) (n = 69) ECMO, we identified 62 patients without bleeding complications (group A) and 155 patients with bleeding complications (group B). In group A, transfusion requirement was 0.6 PRBC/day for VA-ECMO (n = 42) and 0.2 PRBC/day for VV-ECMO (n = 20) (p = 0.0015). In group B, number of PRBC given per event per day for bleeding complications during ECMO was mediastinal/thoracic bleed (83 events, 4.7 PRBC/event/day), gastrointestinal bleed (59 events, 4.8 PRBC/event/day), cannulation site bleed (88 events, 3.6 PRBC/event/day), and nasopharyngeal bleed (103 events, 2.8 PRBC/event/day). Thirty-day hospital mortality rate was co-related to transfusion requirement (area under ROC curve: 0.70).

CONCLUSION

Patients without clinical bleeding still required transfusion, with higher rates observed with VA- than VV-ECMO. Transfusion requirements dramatically increased when patients developed various bleeding complications and had a significant impact on 30-day mortality rate.

Extracorporeal Membrane Oxygenation for Coronavirus Disease 2019: Crisis Standards of Care

The coronavirus disease 2019 (COVID-19) pandemic has placed extraordinary strain on global healthcare systems. Use of extracorporeal membrane oxygenation (ECMO) for patients with severe respiratory or cardiac failure attributed to COVID-19 has been debated due to uncertain survival benefit and the resources required to safely deliver ECMO support. We retrospectively investigated adult patients supported with ECMO for COVID-19 at our institution during the first 80 days following New York City's declaration of a state of emergency. The primary objective was to evaluate survival outcomes in patients supported with ECMO for COVID-19 and describe the programmatic adaptations made in response to pandemic-related crisis conditions. Twenty-two patients with COVID-19 were placed on ECMO during the study period. Median age was 52 years and 18 (81.8%) were male. Twenty-one patients (95.4%) had severe ARDS and seven (31.8%) had cardiac failure. Fifteen patients (68.1%) were managed with venovenous ECMO while 7 (31.8%) required arterial support. Twelve patients (54.5%) were transported on ECMO from external institutions. Twelve patients were discharged alive from the hospital (54.5%). Extracorporeal membrane oxygenation was used successfully in patients with respiratory and cardiac failure due to COVID-19. The continued use of ECMO, including ECMO transport, during crisis conditions was possible even at the height of the COVID-19 pandemic.

Point-of-care testing of plasma free hemoglobin and hematocrit for mechanical circulatory support

Hematological analysis is essential for patients who are supported by a mechanical circulatory support (MCS). The laboratory methods used to analyze blood components are conventional and accurate, but they require a mandatory turn-around-time for laboratory results, and because of toxic substances, can also be hazardous to analysis workers. Here, a simple and rapid point-of-care device is developed for the measurement of plasma free hemoglobin (PFHb) and hematocrit (Hct), based on colorimetry. The device consists of camera module, minimized centrifuge system, and the custom software that includes the motor control algorithm for the centrifuge system, and the image processing algorithm for measuring the color components of blood from the images. We show that our device measured PFHb with a detection limit of 0.75 mg/dL in the range of (0–100) mg/dL, and Hct with a detection limit of 2.14% in the range of (20–50)%. Our device had a high correlation with the measurement method generally used in clinical laboratories (PFHb R = 0.999, Hct R = 0.739), and the quantitative analysis resulted in precision of 1.44 mg/dL for PFHb value of 14.5 mg/dL, 1.36 mg/dL for PFHb value of 53 mg/dL, and 1.24% for Hct 30%. Also, the device can be measured without any pre-processing when compared to the clinical laboratory method, so results can be obtained within 5 min (about an 1 h for the clinical laboratory method). Therefore, we conclude that the device can be used for point-of-care measurement of PFHb and Hct for MCS.

Mortality and Transfusion Requirements in COVID-19 Hospitalized Italian Patients According to Severity of the Disease

There is paucity of data on the transfusion need and its impact on the overall mortality in patients with COVID-19. We explored mortality in hospitalized patients with COVID-19 who required transfusions. Information on clinical variables and in-hospital mortality were obtained from medical records of 422 patients admitted to medical wards or the Intensive Care Unit (ICU). In-hospital mortality occurred in 147 (34.8%) patients, 94 (63.9%) of whom were admitted to the ICU. The median fatalities age was 77 years (IQR 14). Overall, 100 patients (60 males) received transfusion during hospitalization. The overall mortality was significantly and independently associated with age, ICU admission, Chronic Kidney Disease (CKD), and the number of transfused Red Blood Cell (RBC) units. Specifically, CKD was associated with mortality in patients admitted to medical wards, whereas the number of transfused RBC units predicted mortality in those admitted to the ICU. Transfusion strongly interacted with the admission to ICU (OR: 9.9; 95% CI: 2.5–40.0). In patients with COVID-19, age is one of the strongest risk factors in predicting mortality independently of the disease’s severity. CKD confers a higher risk of mortality in patients admitted to medical wards. In those admitted to the ICU, the more RBC units are transfused, the more mortality increases.

Unfractionated Heparin Versus Subcutaneous Nadroparin in Adults Supported With Venovenous Extracorporeal Membrane Oxygenation: a Retrospective, Multicenter Study

Extracorporeal membrane oxygenation (ECMO) requires constant management of coagulation. Whereas unfractionated heparin remains the anticoagulant of choice, experienced centers report high bleeding rates. Biocompatibility of the extracorporeal circuit enables management of anticoagulation with subcutaneous low-molecular-weight heparins only. The aim of this study was to evaluate the safety and feasibility of anticoagulation with subcutaneous nadroparin compared with unfractionated heparin during respiratory ECMO in patients. We assessed for thrombotic complications and number of bleeding and life-threatening bleeding events. Additionally, we evaluated the change in resistance to flow in the oxygenator and the number of transfused blood products. Nadroparin and unfractionated heparin were comparable in terms of number of bleeding (34 vs. 53%; p = 0.12), life-threatening bleeding (2.8 vs. 9.3%; p = 0.26) events, and daily red blood cell transfusion rates (0.79 units/patient/day vs. 0.71 units/patient/day in nadroparin group; p = 0.87) during respiratory ECMO. The relative change in resistance to flow in the oxygenator was similar between groups (8.03 vs. 11.6%; p = 0.27). Nadroparin seemed equivalent to unfractionated heparin in the number of thrombotic and hemorrhagic events as well as in the daily red blood cell transfusion rates during venovenus-ECMO.

Venoarterial extra corporeal membrane oxygenation and blood component usage in pediatric patients undergoing cardiac surgery: Single centre experience

Background

Extra Corporeal Membrane Oxygenation (ECMO) is a well-known tool for providing life-saving support in patients developing post cardiotomy cardiogenic shock in post cardiac surgeries. The current study was designed to evaluate blood transfusion requirements and its relation to mortality in neonate and pediatric cardiac patients requiring venoarterial cardiac ECMO during post-operative period following cardiac surgery.

Materials and Methods

Overall 24 pediatric patients (including neonates) who underwent VA ECMO in post cardiac surgery at our institute from January 2016 to October 2017 were included in the study. The details of demographics, blood transfusion, ECMO, and morbidity and mortality were collected for all the patients.

Objective of the Study

The primary objective of our study was to assess the outcome of patients on ECMO in post pediatric cardiac surgery. The secondary objective of the study was to assess the effect of blood transfusion on the outcome of the patients.

Results

Overall mortality rate was 50% (n = 12). The overall transfusion rate of packed red blood cells was higher in patients who did not survive even after institution of VA ECMO. The transfusion of other blood products like platelets, cryoprecipitate, and fresh frozen plasma were also higher in this group of patients though it was statistically non-significant except for packed red cell transfusion. Though statistically non-significant, the patients who didn't survive even after institution of VA ECMO post-surgery had relatively higher mean age (703.88 ± 998.94 days) as compared to their counterparts (510.63 ± 384.36 days).

Conclusion

The use of ECMO is associated with considerable morbidity and mortality. Packed red cell transfusion is definitely higher in expired patients, indicative of deteriorated status of the patient. However, considering non-significant association of other blood components, except packed red cell it is recommended that patients' overall clinical condition should be taken into consideration for transfusion of blood products and not only targeting the transfusion triggers.

Lower versus higher hemoglobin threshold for transfusion in ARDS patients with and without ECMO

BACKGROUND

Efficacy and safety of different hemoglobin thresholds for transfusion of red blood cells (RBCs) in adults with an acute respiratory distress syndrome (ARDS) are unknown. We therefore assessed the effect of two transfusion thresholds on short-term outcome in patients with ARDS.

METHODS

Patients who received transfusions of RBCs were identified from a cohort of 1044 ARDS patients. After propensity score matching, patients transfused at a hemoglobin concentration of 8 g/dl or less (lower-threshold) were compared to patients transfused at a hemoglobin concentration of 10 g/dl or less (higher-threshold). The primary endpoint was 28-day mortality. Secondary endpoints included ECMO-free, ventilator-free, sedation-free, and organ dysfunction-free composites.

MEASUREMENTS AND MAIN RESULTS

One hundred ninety-two patients were eligible for analysis of the matched cohort. Patients in the lower-threshold group had similar baseline characteristics and hemoglobin levels at ARDS onset but received fewer RBC units and had lower hemoglobin levels compared with the higher-threshold group during the course on the ICU (9.1 [IQR, 8.7-9.7] vs. 10.4 [10-11] g/dl, P < 0.001). There was no difference in 28-day mortality between the lower-threshold group compared with the higher-threshold group (hazard ratio, 0.94 [95%-CI, 0.59-1.48], P = 0.78). Within 28 days, 36.5% (95%-CI, 27.0-46.9) of the patients in the lower-threshold group compared with 39.5% (29.9-50.1) of the patients in the higher-threshold group had died. While there were no differences in ECMO-free, sedation-free, and organ dysfunction-free composites, the chance for successful weaning from mechanical ventilation within 28 days after ARDS onset was lower in the lower-threshold group (subdistribution hazard ratio, 0.36 [95%-CI, 0.15-0.86], P = 0.02).

CONCLUSIONS

Transfusion at a hemoglobin concentration of 8 g/dl, as compared with a hemoglobin concentration of 10 g/dl, was not associated with an increase in 28-day mortality in adults with ARDS. However, a transfusion at a hemoglobin concentration of 8 g/dl was associated with a lower chance for successful weaning from the ventilator during the first 28 days after ARDS onset.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03871166.

Platelet transfusion is associated with 90-day and 1-year mortality for adult patients requiring veno-arterial extracorporeal membrane oxygenation

BACKGROUND

Studies examining one-year mortality respecting component blood transfusion are sparse. We hypothesize that component blood product transfusions are negatively associated with 90-day and 1-year survival for all patients requiring veno-arterial (VA) or veno-venous (VV) ECMO.

STUDY DESIGN AND METHODS

This was an IRB-approved retrospective cohort analysis of 676 consecutive patients requiring ECMO at the University of Pittsburgh between 2005 and 2016. Patients were analysed both as an entire cohort and as two subsets with respect to ECMO modality (VA vs. VV). Additional data collected and analysed included patient characteristics, laboratory values and blood product transfusion.

RESULTS

Multivariable analysis revealed that platelet transfusion was associated with 90-day mortality (OR: 1·05, P = 0·037) and one-year mortality for the entire cohort (OR = 1·05, P = 0·046,). Platelet transfusion volume was also associated with mortality in the VA-ECMO subset of patients at both 90 days (OR = 1·08, P = 0·03) and one year (OR: 1·11, P = 0·014). Age, peak International Normalized Raton ECMO, nadir haemoglobin (on ECMO) and final haemoglobin (after ECMO) were significantly associated with mortality for patients requiring VA-ECMO. For VV-ECMO patients, age, INR and peak creatinine on ECMO were associated with mortality. No individual component blood product was associated with one-year mortality for patients requiring VV-ECMO.

CONCLUSION

Platelet transfusion was associated with increased 90-day and 1-year mortality for patients requiring VA-ECMO.

Blood Utilization and Clinical Outcomes in Extracorporeal Membrane Oxygenation Patients

BACKGROUND

Patients requiring extracorporeal membrane oxygenation (ECMO) support are critically ill and have substantial transfusion requirements, which convey both risks and benefits. A retrospective analysis was conducted to assess the association between blood component administration and adverse outcomes in adult, pediatric, and neonatal ECMO patients.

METHODS

We evaluated 217 ECMO patients at a single center hospitalized between January 2009 and June 2016. Three cohorts (88 adult, 57 pediatric, and 72 neonatal patients) were included for assessment of patient characteristics, blood utilization, and clinical outcomes. Univariable and multivariable analyses were used to assess the association between transfusions and clinical outcomes (primary outcome: mortality and secondary outcomes: morbid events). The analysis included the main exposure of interest (total number of blood component units transfused) and potential confounding variables (age group cohort, case mix index, sex, ECMO mode and duration, and primary ECMO indication).

RESULTS

After adjustment for confounders, with each additional blood component unit transfused, there was an estimated increase in odds for mortality by 1% (odds ratio [OR] = 1.01; 95% confidence interval [CI], 1.00-1.02; P = .013) and an increase in odds for thrombotic events by 1% (OR = 1.01; 95% CI, 1.00-1.02; P = .007). Mortality was higher in the adult (57 of 88; 64.8%) and pediatric (37 of 57; 64.9%) than in the neonatal cohort (19 of 72; 26.4%) (P < .0001). Median total blood components transfused per day followed a similar pattern for the adult (2.3 units; interquartile range [IQR] = 0.8-7.0), pediatric (2.9 units; IQR = 1.1-10), and neonatal (1.0 units; IQR = 0.7-1.6) cohorts (P < .0001). Over the entire hospitalization, the total median blood components transfused was highest in the neonatal (41 units; IQR = 24-94) and pediatric (41 units; IQR = 17-113) compared to the adult (30 units; IQR = 9-58) cohort (P = .007). There was no significant interaction between total units transfused over the hospital stay and age cohort for mortality (P = .35).

CONCLUSIONS

Given the association between transfusion and adverse outcomes, effective blood management strategies may be beneficial in ECMO patients.

Protocol-driven daily optimisation of venovenous extracorporeal membrane oxygenation blood flows: an alternate paradigm?

Venovenous extracorporeal membrane oxygenation (VV ECMO) is now an established modality of support for patients with the who are failing evidence-based conventional therapies. Minimising ventilator-induced lung injury is the guiding principle behind patient management with VV ECMO. Patients with acute respiratory distress syndrome (ARDS) supported with VV ECMO are liberated from ECMO at a stage when native lungs have recovered sufficiently to support physiologic demands and the risks of iatrogenic lung injuries after discontinuation of ECMO are perceived to be small. However, native lung recovery is a dynamic process and patients rely on varying degrees of contributions from both native lungs and ECMO for gas exchange support. Patients often demonstrate near total ECMO dependence for oxygenation and decarboxylation early in the course of the illness and this may necessitate higher ECMO blood flow rates (EBFRs). Although, reliance on high EBFR for oxygenation support may remain variable over the course of ECMO, blood flow requirements typically diminish over time as native lungs start to recover. Currently, protocol-driven modulation of the EBFR based on changing physiologic needs is not common practice and consequently patients may remain on higher than physiologically necessary EBFR. This exposes the patient to potential risks because maintaining higher blood flows often requires a less restrictive fluid balance and deeper sedation. Both may be harmful in the setting of recovery from ARDS. In this article, we propose a strategy that involves daily assessments of native lung function and a protocol-driven daily optimisation of EBFR. This is followed by optimisation of sweep gas flow rate (SGFR) and the fraction of delivered oxygen in the sweep gas (FdO₂). This staged approach to weaning VV ECMO allows us to fully utilise the “decoupling” of oxygenation and decarboxylation that is possible only during extracorporeal support. This approach may benefit patients by allowing for greater fluid restriction, more aggressive fluid removal, expedited weaning of sedation and neuromuscular blocking agents (NMBAs), and early physical rehabilitation. Ultimately, prospective studies are needed to evaluate optimal VV ECMO weaning practices

Blood component use in critical care in patients with COVID-19 infection: a single-centre experience

There has been a significant surge in admissions to critical care during the coronavirus disease 2019 (COVID‐19) pandemic. At present, the demands on blood components have not been described. We reviewed their use during the first 6 weeks of the outbreak from 3 March 2020 in a tertiary‐level critical care department providing venovenous extracorporeal membrane oxygenation (vv‐ECMO). A total of 265 patients were reviewed, with 235 not requiring ECMO and 30 requiring vv‐ECMO. In total, 50 patients required blood components during their critical care admission. Red cell concentrates were the most frequently transfused component in COVID‐19‐infected patients with higher rates of use during vv‐ECMO. The use of fresh frozen plasma, cryoprecipitate and platelet transfusions was low in a period prior to the use of convalescent plasma.

Blood Transfusion Threshold in Patients Receiving Extracorporeal Membrane Oxygenation Support for Cardiac and Respiratory Failure-A Systematic Review and Meta-Analysis

OBJECTIVE

To review studies that have evaluated the effects of liberal or restrictive red cell transfusion thresholds on clinical outcomes in patients requiring extracorporeal membrane oxygenation (ECMO) support for cardiac or respiratory failure.

DESIGN

A systematic review and meta-analysis.

SETTING AND PARTICIPANTS

The study comprised 1,070 patients from observational studies and randomized controlled trials analyzing transfusion policies in venoarterial (VA) and venovenous (VV) ECMO adult populations.

MEASUREMENTS AND MAIN RESULTS

Eligible studies were identified by searching the Cochrane Central Register of Controlled Trials, Medline, and EMBASE until March 4, 2020, using a combination of subject headings and text words. Risk of bias assessment was performed to assess study quality according to the ROBINS-I tool and the case series studies appraisal checklist. There was high risk of bias in the studies analyzed, and none had methodologic adequacy. Three studies analyzed VA ECMO and VV ECMO patients separately. Five datasets were related exclusively or mostly to VA ECMO. Four were retrospective analyses, and one was conducted as a prospective observational study; the median transfusion threshold reported was 8 g/dL, with a mean mortality of 52%. Eight datasets were related either exclusively or mostly to VV ECMO. Six were retrospective and two were prospective observational studies; the median transfusion threshold was 8 g/dL, and the mean mortality rate was 33%.

CONCLUSIONS

The present study did not resolve uncertainty as to transfusion management in ECMO, although several studies (most of them in VV ECMO) demonstrated that a restrictive threshold has acceptable outcomes in single-center cohorts.

Extracorporeal Life Support Organization Coronavirus Disease 2019 Interim Guidelines: A Consensus Document from an International Group of Interdisciplinary Extracorporeal Membrane Oxygenation Providers

The Extracorporeal Life Support Organization (ELSO) Coronavirus Disease 2019 (COVID-19) Guidelines have been developed to assist existing extracorporeal membrane oxygenation (ECMO) centers to prepare and plan provision of ECMO during the ongoing pandemic. The recommendations have been put together by a team of interdisciplinary ECMO providers from around the world. Recommendations are based on available evidence, existing best practice guidelines, ethical principles, and expert opinion. This is a living document and will be regularly updated when new information becomes available. ELSO is not liable for the accuracy or completeness of the information in this document. These guidelines are not meant to replace sound clinical judgment or specialist consultation but rather to strengthen provision and clinical management of ECMO specifically, in the context of the COVID-19 pandemic.

Transfusion Thresholds for Adult Respiratory Extracorporeal Life Support: An Expert Consensus Document

Severe acute respiratory distress syndrome (ARDS) can complicate novel pandemic coronavirus disease (COVID-19). Extracorporeal life support (ECLS) represents the final possible rescue strategy. Variations in practice, combined with a paucity of rigourous guidelines, may complicate blood-product resource availability and allocation during a pandemic. We conducted a literature review around venovenous extracorporeal membrane oxygenation (VV-ECMO) transfusion practices for platelets, packed red blood cells, fresh frozen plasma, prothrombin complex concentrate, and antithrombin. Pertinent society guidelines were examined, and the practice of Canadian ECLS experts was sampled through an environmental scan. This paper represents a synthesis of these explorations, combined with input from the Canadian Cardiovascular Critical Care (CANCARE) Society, Canadian Society of Cardiac Surgeons, and the Canadian Critical Care Society. We offer a pragmatic guidance document for restrictive transfusion thresholds in nonbleeding patients on VV-ECMO, which may attenuate transfusion-related complications and simultaneously shield national blood product inventory from strain during pandemic-induced activation of the National Plan for the Management of Shortages of Labile Blood Components.

Pressure and flow properties of dual-lumen cannulae for extracorporeal membrane oxygenation

INTRODUCTION

In the last decade, dual-lumen cannulae have been increasingly applied in patients undergoing extracorporeal life support. Well-performing vascular access is crucial for efficient extracorporeal membrane oxygenation support; thus, guidance for proper cannulae size is required. Pressure-flow charts provided by manufacturers are often based on tests performed using water, rarely blood. However, blood is a shear-thinning and viscoelastic fluid characterized by different flow properties than water.

METHODS

We performed a study evaluating pressure-flow curves during standardized conditions using human whole blood in two commonly available dual-lumen cannulae used in neonates, pediatric, and adult patients. Results were merged and compared with the manufacturer's corresponding curves obtained from the public domain.

RESULTS

The results showed that using blood as compared with water predominantly influenced drainage flow. A 10-80% higher pressure-drop was needed to obtain same drainage flow (hematocrit of 26%) compared with manufacturer's water charts in 13-31 Fr bi-caval dual-lumen cannulae. The same net difference was found in cavo-atrial cannulae (16-32 Fr), where a lower drainage pressure was required (Hct of 26%) compared with the manufacturer's test using blood with an Hct of 33%. Return pressure-flow data were similar, independent whether pumping blood or water, to the data reported by manufacturers.

CONCLUSION

Non-standardized testing of pressure-flow properties of extracorporeal membrane oxygenation dual-lumen cannulae prevents an adequate prediction of pressure-flow results when these cannulae are used in patients. Properties of dual-lumen cannulae may vary between sizes within same cannula family, in particular concerning the drainage flow.

Hematologic concerns in extracorporeal membrane oxygenation

This ISTH "State of the Art" review aims to critically evaluate the hematologic considerations and complications in extracorporeal membrane oxygenation (ECMO). ECMO is experiencing a rapid increase in clinical use, but many questions remain unanswered. The existing literature does not address or explicitly state many pertinent details that may influence hematologic complications and, ultimately, patient outcomes. This review aims to broadly introduce modern ECMO practices, circuit designs, circuit materials, hematologic complications, transfusion-related considerations, age- and size-related differences, and considerations for choosing outcome measures. Relevant studies from the 2019 ISTH Congress in Melbourne, which further advanced our understanding of these processes, will also be highlighted.

Transfusion strategies in non-bleeding critically ill adults: a clinical practice guideline from the European Society of Intensive Care Medicine

OBJECTIVE

To develop evidence-based clinical practice recommendations regarding transfusion practices in non-bleeding, critically ill adults.

DESIGN

A task force involving 13 international experts and three methodologists used the GRADE approach for guideline development.

METHODS

The task force identified four main topics: red blood cell transfusion thresholds, red blood cell transfusion avoidance strategies, platelet transfusion, and plasma transfusion. The panel developed structured guideline questions using population, intervention, comparison, and outcomes (PICO) format.

RESULTS

The task force generated 16 clinical practice recommendations (3 strong recommendations, 13 conditional recommendations), and identified five PICOs with insufficient evidence to make any recommendation.

CONCLUSIONS

This clinical practice guideline provides evidence-based recommendations and identifies areas where further research is needed regarding transfusion practices and transfusion avoidance in non-bleeding, critically ill adults.

Risk Factors of Bleeding in Patients Undergoing Venoarterial Extracorporeal Membrane Oxygenation

BACKGROUND

Venoarterial extracorporeal membrane oxygenation (VA ECMO) is increasingly being used for circulatory shock. Bleeding is a frequent complication and is associated with increased mortality. The purpose of our study was to identify factors associated with early major bleeding after VA ECMO initiation.

METHODS

We performed a retrospective observational study based on our database. In accordance with the Extracorporeal Life Support Organization definition, the population was divided in two groups: major bleeding events (group B) and no major bleeding events (group O). We collected data on all major bleeding events occurring during the first 48 hours after VA ECMO initiation.

RESULTS

Of the 243 patients analyzed, 111 patients (46%) had an early major bleeding event. Independent risk factors associated with early major bleeding events were postcardiotomy VA ECMO (odds ratio [OR] 1.98; 95% confidence interval [CI], 1.08 to 3.62; P = .02), body mass index (OR 0.91; 95% CI, 0.85 to 0.98; P = .01), hemoglobinemia (OR 0.8; 95% CI, 0.7 to 0.92; P = .002), fibrinogen (OR 0.67; 95% CI, 0.52 to 0.84; P = .001), and pH (OR 0.15; 95% CI, 0.02 to 1.04; P = .05). By using a receiver-operating characteristics curve analysis, hemoglobin level less than 9 g dL^-1, fibrinogen level less than 2 g L^-1, pH lower than 7.12, and body mass index below 25 kg/m² were identified to predict early major bleeding events. Major bleeding events were independently associated with mortality (OR 2.54; CI 95%, 1.38 to 4.66; P = .01).

CONCLUSIONS

We found that postcardiotomy VA ECMO, hemoglobin levels less than 9 g dL^-1, fibrinogen levels less than 2 g L^-1, pH lower than 7.12, and body mass index below 25 kg/m² were associated with a higher risk for early major bleeding events.

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.