Extracorporeal membrane oxygenation support for postcardiotomy cardiogenic shock

Review of anticoagulation considerations in extracorporeal membrane oxygenation support

Since its first success in 1975, extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency for pulmonary and cardiopulmonary bypass. Use in adults has increased exponentially since the early 2000s, but despite thousands of international cannulations using both veno-arterial (VA) and veno-venous (VV) ECMO, there are still significant hemocompatibility-related adverse events. Current management of anticoagulation has been based on the Extracorporeal Life Support Organization guidance published in 2014 with recent updates published in 2022. Despite this guidance, there is still limited international consensus on how to manage anticoagulation in ECMO. For this review, we completed a comprehensive search of multiple electronic databases to identify studies pertaining to anticoagulation of adult patients on VV or VA-ECMO. The highest priority was given to sources that were prospective, randomized, controlled studies, but in the absence of such resources, observational studies, retrospective uncontrolled studies, and case series/reports were considered for inclusion. This document serves to provide a comprehensive review of the current understanding of management pertaining to anticoagulation relating to ECMO.

Understanding the "extracorporeal membrane oxygenation gap" in veno-arterial configuration for adult patients: Timing and causes of death

Timing and causes of hospital mortality in adult patients undergoing veno‐arterial extracorporeal membrane oxygenation (V‐A ECMO) have been poorly described. Aim of the current review was to investigate the timing and causes of death of adult patients supported with V‐A ECMO and subsequently define the “V‐A ECMO gap,” which represents the patients who are successfully weaned of ECMO but eventually die during hospital stay. A systematic search was performed using electronic MEDLINE and EMBASE databases through PubMed. Studies reporting on adult V‐A ECMO patients from January 1993 to December 2020 were screened. The studies included in this review were studies that reported more than 10 adult, human patients, and no mechanical circulatory support other than V‐A ECMO. Information extracted from each study included mainly mortality and causes of death on ECMO and after weaning. Complications and discharge rates were also extracted. Sixty studies with 9181 patients were included for analysis in this systematic review. Overall mortality was 38.0% (95% confidence intervals [CIs] 34.2%‐41.9%) during V‐A ECMO support (reported by 60 studies) and 15.3% (95% CI 11.1%‐19.5%, reported by 57 studies) after weaning. Finally, 44.0% of patients (95% CI 39.8‐52.2) were discharged from hospital (reported by 60 studies). Most common causes of death on ECMO were multiple organ failure, followed by cardiac failure and neurological causes. More than one‐third of V‐A ECMO patients die during ECMO support. Additionally, many of successfully weaned patients still decease during hospital stay, defining the “V‐A ECMO gap.” Underreporting and lack of uniformity in reporting of important parameters remains problematic in ECMO research. Future studies should uniformly define timing and causes of death in V‐A ECMO patients to better understand the effectiveness and complications of this support.

Successful Extracorporeal Membrane Oxygenation (ECMO) Use without Systemic Anticoagulation for Acute Respiratory Distress Syndrome in a Patient with Aneurysmal Subarachnoid Hemorrhage

Extracorporeal membrane oxygenation (ECMO) is an important life-saving technology for patients with severe acute respiratory distress syndrome (ARDS). Unfortunately, ECMO has been traditionally contraindicated in patients with hemorrhagic neurologic diseases. The recent improvement in ECMO devices, increased utilization and experience with venovenous ECMO technologies among healthcare teams, and the use of ECMO without anticoagulation has expanded the potential populations that may benefit from ECMO. We present a case of successful utilization of venovenous ECMO for severe respiratory failure secondary to ARDS in a patient with aneurysmal subarachnoid hemorrhage and severe, episodic cerebral vasospasm. We also discuss important limitations and considerations for future successful use of ECMO in hemorrhagic stroke. This case report highlights the potential for this life-saving technology in patients with hemorrhagic stroke.

Extra-corporeal membrane oxygenation for refractory cardiogenic shock after adult cardiac surgery: a systematic review and meta-analysis

BACKGROUND

Postcardiotomy cardiogenic shock (PCCS) refractory to inotropic support and intra-aortic balloon pump (IABP) occurs rarely but is almost universally fatal without mechanical circulatory support. In this systematic review and meta-analysis we looked at the evidence behind the use of veno-arterial extra-corporeal membrane oxygenation (VA ECMO) in refractory PCCS from a patient survival rate and determinants of outcome viewpoint.

METHODS

A systematic review was performed in January 2017 using PubMed (with no defined time period) using the keywords "postcardiotomy", "cardiogenic shock", "extracorporeal membrane oxygenation" and "cardiac surgery". We excluded papers pertaining to ECMO following paediatric cardiac surgery, medical causes of cardiogenic shock, as well as case reports, review articles, expert opinions, and letters to the editor. Once the studies were collated, a meta-analysis was performed on the proportion of survivors in those papers that met the inclusion criteria. Meta-regression was performed for the most commonly reported adverse prognostic indicators (API).

RESULTS

We identified 24 studies and a cumulative pool of 1926 patients from 1992 to 2016. We tabulated the demographic data, including the strengths and weaknesses for each of the studies, outcomes of VA ECMO for refractory PCCS, complications, and APIs. All the studies were retrospective cohort studies. Meta-analysis of the moderately heterogeneous data (95% CI 0.29 to 0.34, p < 0.01, I 2  = 60%) revealed overall survival rate to hospital discharge of 30.8%. Some of the commonly reported APIs were advanced age (>70 years, 95% CI -0.057 to 0.001, P = 0.058), and long ECMO support (95% CI -0.068 to 0.166, P = 0.412). Postoperative renal failure, high EuroSCORE (>20%), diabetes mellitus, obesity, rising lactate whilst on ECMO, gastrointestinal complications had also been reported.

CONCLUSION

Haemodynamic support with VA ECMO provides a survival benefit with reasonable intermediate and long-term outcomes. Many studies had reported advanced age, renal failure and prolonged VA ECMO support as the most likely APIs for VA ECMO in PCCS. EuroSCORE can be utilized to anticipate the need for prophylactic perioperative VA ECMO in the high-risk category. APIs can be used to aid decision-making regarding both the institution and weaning of ECMO for refractory PCCS.

Anticoagulation practices and the prevalence of major bleeding, thromboembolic events, and mortality in venoarterial extracorporeal membrane oxygenation: A systematic review and meta-analysis

PURPOSE

The purpose was to evaluate the safety of anticoagulation in venoarterial extracorporeal membrane oxygenation (VA-ECMO).

DESIGN

We performed a systematic review and meta-analysis using multiple electronic databases. Studies were from 1977 to September 27, 2016. We evaluated the effect of anticoagulation in VA-ECMO on outcomes including major bleeding, thromboembolic events, and in-hospital mortality using a random effects model meta-analysis.

RESULTS

Twenty-six studies (1496 patients) were included. Ten studies only had patients with postcardiotomy shock, 4 studies only included extracorporeal cardiopulmonary resuscitation patients, and 10 studies had a mixture of patients. Most studies (n=17) were low quality with a Newcastle-Ottawa Scale score ≤5. The summary prevalence of major bleeding was 27% (95% confidence interval [CI], 18%-35%), with considerable between-study heterogeneity (I²=91%). Major bleeding requiring reoperation was the most common bleeding event. The summary prevalence of thromboembolic events was 8% (95% CI, 4%-13%; I²=83%). Limb ischemia, circuit-related clotting, and stroke were the most commonly reported events. The summary prevalence for in-hospital mortality was 59% (95% CI, 52%-67%; I²=78%).

CONCLUSIONS

The optimal targets and strategies for anticoagulation in VA-ECMO are unclear. Evaluation of major bleeding and thromboembolic events is limited by study quality and between-study heterogeneity. Clinical trials are needed to investigate the optimal anticoagulation strategy.

Effects of Renal Replacement Therapy in Patients Receiving Extracorporeal Membrane Oxygenation: A Meta-Analysis

The use of renal replacement therapy (RRT) in patients receiving extracorporeal membrane oxygenation (ECMO) is increasing, but the effect of RRT on ECMO is controversial. We performed a meta-analysis to determine whether RRT is related to higher mortality in patients receiving ECMO. We searched MEDLINE, EMBASE, the Cochrane Library, and KoreaMed and found 43 observational studies with 21,624 patients receiving ECMO and then compared inpatient mortality rates of patients receiving ECMO both with and without RRT. The risk ratio (RR) of mortality between patients receiving RRT and those not receiving RRT tended to decrease as the mortality of the group not receiving RRT increased. Among patients with RRT use rates of 30% and higher, the overall mortality rates for all patients receiving ECMO tended to decrease. We found that the increase in the RR for RRT tended to be greater the longer the initiation of RRT was delayed. We suggest that in patients receiving ECMO who have high RRT use rates, RRT may decrease mortality rates.

A case of survival after cardiac arrest and 3½ hours of resuscitation

Although survival rates after cardiac arrest remain low, new techniques are improving patients' outcomes. We present the case of a 40-year-old man who survived a cardiac arrest that lasted approximately 3½ hours. Resuscitation was performed with strict adherence to American Heart Association/American College of Cardiology Advanced Cardiac Life Support guidelines until bedside extracorporeal membrane oxygenation could be placed. A hypothermia protocol was initiated immediately afterwards. The patient had a full neurologic recovery and was bridged from dual ventricular assist devices to a total artificial heart. On hospital day 160, he underwent orthotopic heart and cadaveric kidney transplantation. On day 179, he was discharged from the hospital in ambulatory condition. To our knowledge, this is the only reported case in which a patient survived with good neurologic outcomes after a resuscitation that lasted as long as 3½ hours. Documented cases of resuscitation with good recovery after prolonged arrest give hope for improved overall outcomes in the future.

A review of the fundamental principles and evidence base in the use of extracorporeal membrane oxygenation (ECMO) in critically ill adult patients

Extracorporeal membrane oxygenation (ECMO) comprises a commonly used method of extracorporeal life support. It has proven efficacy and is an accepted modality of care for isolated respiratory or cardiopulmonary failure in neonatal and pediatric populations. In adults, there are conflicting studies regarding its benefit, but it is possible that ECMO may be beneficial in certain adult populations beyond postcardiotomy heart failure. As such, all intensivists should be familiar with the evidence-base and principles of ECMO in adult population. The purpose of this article is to review the evidence and to describe the fundamental steps in initiating, adjusting, troubleshooting, and terminating ECMO so as to familiarize the intensivist with this modality.

Extracorporeal Membrane Oxygenation Hybrid With Various Ventricular Assist Devices as Double Bridge to Heart Transplantation

Ventricular assist devices (VAD) have benefitted patients with end-stage heart failure as a bridge to heart transplantation (HTx). We present our experience with HTx after an extracorporeal membrane oxygenation (ECMO) hybrid with various ventricular assist devices (VAD). From May 1996 to December 2003, mechanical circulatory support with a Biopump VAD was performed in eight patients, HeartMate left VAD in eight patients, and Thoratec VAD in eight patients. Before VAD implantation, 19 patients maintained their circulation with ECMO. Half of the 24 patients were implanted with VAD to await a suitable donor for HTx. We observed that half of the patients supported by ECMO hybrid with various VAD awaited a suitable donor for HTx. In our experience, we recommend the application of ECMO for short-term support within 1 week and the Biopump VAD, Thoractec VAD, or HeartMate VAD for medium-term or long-term support as a bridge to HTx.

Systematic review of percutaneous cardiopulmonary bypass for cardiac arrest or cardiogenic shock states

BACKGROUND

Cardiogenic shock and cardiac arrest are common, lethal, debilitating and costly. Percutaneous cardiopulmonary bypass is an innovative strategy for treating these disorders that consists of rapid initiation of cardiopulmonary bypass and extracorporeal maintenance of circulation until restoration of an effective cardiac output. Multiple case reports suggest that percutaneous bypass is efficacious in patients with these disorders but these experiences have not been collated. Therefore, we have reviewed systematically the published experience with percutaneous bypass in patients with cardiogenic shock or cardiac arrest.

OBJECTIVES

The objectives were to describe the proportion of patients with cardiogenic shock or cardiac arrest who achieved restoration of spontaneous circulation or survival to discharge with percutaneous bypass. A secondary objective was to describe adverse effects associated with percutaneous bypass, if feasible.

DESIGN

Articles were identified by using a comprehensive search of English-language MEDLINE from 1966 to September 2005.

PATIENTS

Individuals in cardiogenic shock or cardiac arrest.

INTERVENTIONS

Percutaneous cardiopulmonary bypass.

ANALYSIS

Effects were summarized as inverse-variance weighted means, standard errors, median and interquartile range.

RESULTS

Included were 85 studies of 1494 patients with cardiogenic shock, cardiac arrest or both. Studies were case reports, case-series or case-control studies of heterogeneous interventions in heterogeneous patients. The proportion of patients weaned was mean, 76.8+/-4.2%, and median, 66.0% (IQR 50%, 100%). The proportion of patients who survived to discharge was mean, 47.4+/-4.5%, and median 40.0% (IQR 20%, 75%). Fifty-two studies included 533 patients in cardiogenic shock. The proportion of patients who survived to discharge was mean, 51.6+/-6.5%, and median 38.5% (IQR 23.4%, 76.3%). Fifty-four studies included 675 patients in cardiac arrest. The proportion of patients who survived to discharge was mean, 44.9+/-6.7%, and median, 42.3% (IQR 15.4%, 75%). Five studies with 286 subjects had both patients with cardiogenic shock or cardiac arrest.

CONCLUSIONS

Percutaneous bypass is an efficacious intervention in patients with cardiac arrest or cardiogenic shock. Adequately-powered experimental studies of current percutaneous bypass technologies are required to demonstrate whether it is safe, effective and cost-effective.

Risk factor screening scale to optimize treatment for potential heart transplant candidates under extracorporeal membrane oxygenation

We developed a risk factor-scaling score (RFSS) to select which patients supported by extracorporeal membrane oxygenation (ECMO) were suitable for ventricular assist device (VAD) implantation or heart transplantation (HTx). A total of 78 patients supported with ECMO for more than 48 h due to cardiac origin were included in this study. Patients were categorized into two groups based on the outcomes: the poor outcome group (n = 33) consisted of for those who later died or were later excluded from VAD or HTx; the favorable outcome group (n = 45) consisted of those who were weaned off ECMO finally and survived or were deemed suitable candidates for VAD or HTx. Seven risk factors were significant according to univariate analyses. Based on the regression coefficients of multivariate analysis, the RFSS was developed: (lung dysfunction x 7) + (systemic infection x 3) + (peak lactate > 3 mmole/L x 3) + (kidney dysfunction x 2) + (creatine kinase > 10,000 U/L x 1). Patients with an RFSS of 7 or more were be allocated to the poor outcome group. The RFSS was validated by another group of 30 patients with good correlation. The RFSS provides a way to predict which ECMO-supported patients are suitable candidates for VAD implantation or HTx.

Clinical Use of the Abiomed BVS 5000 as a Pulsatile Extracorporeal Membrane Oxygenation Unit

The traditional extracorporeal membrane oxygenation circuit uses a centrifugal pump. These pumps require close monitoring and are subject to complications. In addition, they do not take advantage of the potential benefits of pulsatile flow. These extracorporeal membrane oxygenation circuits use a single pump with an inline oxygenator. If cardiac failure persists after respiratory recovery has occurred, removal of the oxygenator requires an additional procedure to convert the patient to biventricular support. This report describes a circuit in which an oxygenator is connected to a pulsatile ventricular assist device. Single and dual circuit configurations are illustrated. Recommendations for pulmonary care during support are also described.

Mechanical bridge with extracorporeal membrane oxygenation and ventricular assist device to heart transplantation

The aim of this study was to evaluate the effect of double bridges with extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) in clinical heart transplantation. Between May 1994 and October 2000, 134 patients underwent heart transplantation at the National Taiwan University Hospital. Ten patients received ECMO or VAD support as bridges to transplantation. The ages ranged from 3 to 63 years. The indications included cardiac arrest under cardiopulmonary resuscitation in 2 and profound cardiogenic shock refractory to conventional therapy in 8 patients. Usually ECMO was first set up as rescue therapy. If ECMO could not be weaned off after short-term (usually 1 week) support, suitable VADs (HeartMate or Thoratec VAD) were implanted for medium-term or long-term support. Five patients received ECMO support as emergency rescue for 2 to 9 days, and then moved to Thoratec VAD for 8, 49, and 55 days, respectively, or centrifugal VAD for 31 days, or HeartMate VAD for 224 days. They all survived. The survival rate of double bridges with ECMO and VAD was 100%. In postcardiotomy cardiogenic shock, circulatory collapse from acute myocardial infarction or myocarditis, ECMO is the device of choice for short-term support. If heart transplantation is indicated, VADs should replace ECMO for their superiority as a bridge to heart transplantation. Our preliminary data of double bridges with ECMO and VAD revealed good results and were reliable and effective bridges to transplantation.

New application of heparin-bonded extracorporeal membrane oxygenation in difficult neurosurgery

We wished to evaluate the safety and the advantages of using heparin-bonded extracorporeal membrane oxygenation (ECMO) to replace conventional cardiopulmonary bypass (CPB) in deep hypothermic circulation for complex cerebral aneurysm surgery.Heparin-bonded ECMO without the bridging tube and the cardiotomy reservoir was set up through the femoral vessels. Limited heparin was infused. In deep hypothermia, the ECMO blood flow was temporarily decreased as low as the neurosurgeons' request. It was applied to 4 patients with difficult intracranial aneurysms who were selected for the procedure. Clipping, wrapping, or vascular bypass was implemented to manage the aneurysms under deep hypothermia. The total heparin dosage used in the whole procedure was 9,875 +/- 1,625 U, and the mean ECMO time was 270 +/- 105 min. The blood consumption was packed red blood cell 3.0 +/- 0.5 U and fresh frozen plasma 3.8 +/- 2.3 U. Compared with our previous experiences using conventional CPB, ECMO did need less heparin and blood transfusions. Clipping was applied in 2 patients, wrapping in 1, and venous graft interposition was performed in 1. Mortality occurred in 1 patient (25%) due to brain herniation. This preliminary study suggested that the heparin-bonded ECMO without reservoir in deep hypothermia could be safe in cerebral aneurysm surgery under a low flow circuit.

The use of extracorporeal life support in adult patients with primary cardiac failure as a bridge to implantable left ventricular assist device

BACKGROUND

Extracorporeal life support (ECLS) is an effective technique for providing emergent circulatory assistance, and may represent a life-saving option in patients who might not initially be considered a candidate for other forms of circulatory support (extracorporeal or implantable left ventricular assist device [LVAD]). In the setting of cardiac arrest, ECLS represents the only viable method of initiating circulatory support. However, ECLS has a number of disadvantages that include high complication rates (eg, stroke, bleeding) and a limited duration of potential support, which have prevented its widespread acceptance, particularly in the adult population. With the increased successful application of long-term implantable LVADs as a bridge to transplant, the major limitation of ECLS could be overcome by bridging patients to a long-term implantable LVAD ("bridge to bridge"), thereby reducing the reluctance to utilize ECLS when indicated. After acquisition of the HeartMate LVAD (Thermo Cardiosystems, Inc, Woburn, MA) we investigated the use of ECLS as a bridge to an implantable LVAD and subsequent transplantation in selected high-risk patients.

METHODS AND RESULTS

From Oct 1, 1996 to Sept 30, 2000, 33 adult patients presenting with cardiac arrest or severe hemodynamic instability were placed on ECLS for the bridge to bridge indication. Of the 33 patients, 10 patients survived to LVAD implant, 1 was bridged directly to transplant, 5 weaned from ECLS, and 16 died on ECLS. Overall, 12 patients survived to discharge. One-year actuarial survival from the initiation of ECLS was 36%. One-year actuarial survival from the time of LVAD implant, conditional on surviving ECLS, was 80%.

CONCLUSIONS

The 1-year survival of adult patients placed on ECLS and who subsequently survived to an implantable LVAD was favorable. These data support a strategy of ECLS to implantable LVAD bridge to heart transplant in adult patients who are in need of circulatory support and who are not initially candidates for other forms of mechanical support. The favorable results of this strategy support utilization of ECLS even in situations where myocardial recovery is thought to be unlikely.

Assessment of an extracorporeal life support to LVAD bridge to heart transplant strategy

BACKGROUND

Extracorporeal life support (ECLS) is an effective technique for providing emergent circulatory assistance. However, its use in adult patients is associated with poor survival when myocardial function fails to recover. Due to the prolonged waiting times for heart transplantation, ECLS as a bridge to transplant is associated with poor survival. In addition, ECLS has been reported to be a significant risk factor for death after bridging to an implantable left ventricular assist device (LVAD). After acquisition of the HeartMate LVAD (Thermo Cardiosystems, Inc) in October 1996, we began using ECLS as a bridge to an implantable LVAD and subsequently transplantation in selected high-risk patients.

METHODS

From October 1, 1996 to December 1, 1999, 60 adult patients presenting with cardiogenic shock were evaluated for circulatory assistance.

RESULTS

Twenty-five patients (group 1) with cardiac arrest or severe hemodynamic instability and multiorgan failure were placed on ECLS. Eight patients survived to LVAD implant, 1 was bridged directly to transplant, and 4 weaned from ECLS. Nine patients in group 1 survived to discharge. Thirty patients (group 2) underwent LVAD implant without ECLS. Twenty-three were bridged to transplant, with 22 surviving to discharge. Five patients (group 3) were placed on extracorporeal ventricular assist with 3 bridged to transplant and all surviving to discharge. One-year actuarial survival from the initiation of circulatory support was 36% (group 1), 73% (group 2), and 60% (group 3). One-year actuarial survival from the time of LVAD implant in group 1, conditional on surviving ECLS, was 75% (p = NS compared with group 2).

CONCLUSIONS

In selected high-risk patients, LVAD survival after initial ECLS was not different from survival after LVAD support alone. An initial period of resuscitation with ECLS is an effective strategy to salvage patients with cardiac arrest or extreme hemodynamic instability and multiorgan injury.

Mechanical support for postcardiotomy cardiogenic shock

Postcardiotomy cardiogenic shock (PCCS) results in substantial morbidity and mortality. Despite intraaortic balloon pump and inotropic support, some patients with PCCS continue to have a refractory low cardiac output. For these patients, more effective ventricular assistance is imperative to prevent death. Multiple systems are available for the short-term support of patients with PCCS. Regardless of the device employed, only 25% of these patients survive and are discharged home. Two strategies, however, may improve the outcome of PCCS. One is long-term support by an implantable assist device, which can allow optimal ventricular unloading. Unfortunately, not all cardiac surgery centers offer this type of support. Therefore, the other strategy is the creation of postcardiotomy referral centers that offer long-term support or heart transplantation. Such centers would conserve scarce donor organs, maximize the chance of myocardial recovery, and yield expertise applicable not only to device recipients but also to critically ill heart-failure patients who do not need an implantable pump.

Pathophysiology of cardiac extracorporeal membrane oxygenation

The treatment of cardiogenic shock using inotropic agents and vascular volume expansion places an added burden on the heart. The resultant increase in cardiac work may cause myocardial ischemia and lead to cardiac arrest. Extracorporeal membrane oxygenation (ECMO) may be used to treat cardiogenic shock. It supports systemic circulation, assures diastolic perfusion of the myocardium, and reduces cardiac workload. The rise in blood pressure associated with restoring systemic circulation afterloads the heart and can cause left atrial hypertension and pulmonary edema. ECMO does not automatically reduce cardiac work, especially in the presence of residual shunts. Left atrial drainage or decompression may be essential in certain patients both to avert pulmonary edema and to reduce cardiac work.