Anticoagulation for Extracorporeal Life Support: Direct Thrombin Inhibitors and Heparin

Fingerprint analysis of dang-gui-Si-Ni decoction and its anticoagulant activity in vivo-in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Dang-Gui-Si-Ni (DGSN) decoction is a classic prescription in the clinical practice of traditional Chinese Medicine (TCM). DGSN decoction is often used to relieve symptoms of cold coagulation and blood stasis recorded by Treatise on Febrile Diseases (Shang Han Lun) and treat Raynaud's disease, dysmenorrhea, arthritis, migraine in TCM clinic. Accumulated evidences have suggested that this diseases are related to microcirculation disturbance. However, the anticoagulant activity and underlying mechanisms of DGSN decoction responsible for the therapeutic not well understood.

AIM OF THE STUDY

The fingerprint and anticoagulant activity in vivo-in vitro of DGSN decoction were evaluated to strengthen the quality control and activity study of formulas.

MATERIALS AND METHODS

The chemical components of DGSN decoction were analyzed by HPLC and its fingerprint similarity were evaluated by "Chinese Medicine Chromatographic Fingerprint Similarity Evaluation Software (2012 Edition)". The anticoagulant activity of DGSN decoction was assessed by measuring four coagulation factors (PT, TT, APTT, FIB) in vitro. Zebrafish thrombosis model induced by punatinib was established to evaluate the activity of improving microvascular hemodynamics in vivo. Quantitative real-time polymerase chain reaction (q-PCR) were adopted to compare the changes in the RNA expression levels of coagulation factor II (FII), VII (FVII), IX (FIX) and X (FX) in zebrafish thrombosis model.

RESULTS

The fingerprint similarity evaluation method of DGSN decoction was established. The results showed that 18 samples had higher similarity (S1-S18 > 0.878). Pharmacodynamic results showed that DGSN decoction could extend PT, TT and APTT, and reduce FIB content in vitro. Meanwhile, it markedly enhanced the cardiac output and blood flow velocity at low dosage (500 μg mL-1) in vivo. q-PCR data demonstrated that DGSN decoction (500 μg mL-1) could downregulate the RNA expression of FII, FVII, FIX and FX. Interestingly, there were a bidirectional regulation of FII, FIX and FX in a certain concentration range. In general, DGSN decoction can significantly improve hemodynamics and downregulate coagulation factors, and the results were consistent both in vitro - in vivo.

CONCLUSION

The fingerprint study provide a new perspective for improving the quality control of DGSN decoction. DGSN decoction possess anticoagulant activity by regulating multiple coagulation factors simultaneously. Thus, it has the potential to develop into the novel raw material of anticoagulant drugs.

Anticoagulation Strategies during Extracorporeal Membrane Oxygenation: A Narrative Review

The development of extracorporeal life support technology has added a new dimension to the care of critically ill patients who fail conventional treatment options. Extracorporeal membrane oxygenation (ECMO)—specialized temporary life support for patients with severe cardiac or pulmonary failure—plays a role in bridging the time for organ recovery, transplant, or permanent assistance. The overall patient outcome is dependent on the underlying disease, comorbidities, patient reaction to critical illness, and potential adverse events during ECMO. Moreover, the contact of the blood with the large artificial surface of an extracorporeal system circuit triggers complex inflammatory and coagulation responses. These processes may further lead to endothelial injury and disrupted microcirculation with consequent end-organ dysfunction and the development of adverse events like thromboembolism. Therefore, systemic anticoagulation is considered crucial to alleviate the risk of thrombosis and failure of ECMO circuit components. The gold standard and most used anticoagulant during extracorporeal life support is unfractionated heparin, with all its benefits and disadvantages. However, therapeutic anticoagulation of a critically ill patient carries the risk of clinically relevant bleeding with the potential for permanent injury or death. Similarly, thrombotic events may occur. Therefore, different anticoagulation strategies are employed, while the monitoring and the balance of procoagulant and anticoagulatory factors is of immense importance. This narrative review summarizes the most recent considerations on anticoagulation during ECMO support, with a special focus on anticoagulation monitoring and future directions.

Prevalence and outcomes of patients developing heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

Objectives

Unfractionated heparin (UFH) is the commonly used anticoagulant to prevent clotting of the ECMO circuit and thrombosis of the cannulated vessels. A side effect of UFH is heparin-induced thrombocytopenia (HIT). Little is known about HIT during ECMO and the impact of changing anticoagulation in ECMO patients with newly diagnosed HIT. The aim of the study was to determine the prevalence, complications, impact of switching anticoagulation to argatroban and outcomes of patients developing heparin-induced thrombocytopenia (HIT) during either veno-venous (VV) or veno-arterial (VA) ECMO.

Methods

Retrospective observational single centre study of prospectively collected data of consecutive patients receiving VV ECMO therapy for severe respiratory failure and VA ECMO for circulatory failure from January 2006 to December 2016 of the Medical intensive care unit (ICU) of the University Hospital of Regensburg. Treatment of HIT on ECMO was done with argatroban.

Results

507 patients requiring ECMO were included. Further HIT-diagnostic was conducted if HIT-4T-score was ≥4. The HIT-confirmed group had positive HIT-enzyme-linked-immunosorbent-assay (ELISA) and positive heparin-induced-platelet-activation (HIPA) test, the HIT-suspicion group a positive HIT-ELISA and missing HIPA but remained on alternative anticoagulation until discharge and the HIT-excluded group a negative or positive HIT-ELISA, however negative HIPA. These were compared to group ECMO-control without any HIT suspicion. The prevalence of HIT-confirmed was 3.2%, of HIT-suspicion 2.0% and HIT-excluded 10.8%. Confirmed HIT was trendwise more frequent in VV than in VA (3.9 vs. 1.7% p = 0.173). Compared to the ECMO control group, patients with confirmed HIT were longer on ECMO (median 13 vs. 8 days, p = 0.002). Different types of complications were higher in the HIT-confirmed than in the ECMO-control group, but in-hospital mortality was not different (31% vs. 41%, p = 0.804).

Conclusion

HIT is rare on ECMO, should be suspected, if platelets are decreasing, but seems not to increase mortality if treated promptly.

Successful Application of Argatroban During VV-ECMO in a Pregnant Patient Complicated With ARDS due to Severe Tuberculosis: A Case Report and Literature Review

Severe tuberculosis during pregnancy may progress to acute respiratory distress syndrome (ARDS), and venovenous (VV) extracorporeal membrane oxygenation (ECMO) should be considered if conventional lung-protective mechanical ventilation fails. However, thrombocytopenia often occurs with ECMO, and there are limited reports of alternative anticoagulant therapies for pregnant patients with thrombocytopenia during ECMO. This report describes the first case of a pregnant patient who received argatroban during ECMO and recovered. Furthermore, we summarized the existing literature on VV-ECMO and argatroban in pregnant patients. A 31-year-old woman at 17 weeks of gestation was transferred to our hospital with ARDS secondary to severe tuberculosis. We initiated VV-ECMO after implementing a protective ventilation strategy and other conventional therapies. Initially, we selected unfractionated heparin anticoagulant therapy. However, on ECMO day 3, the patient’s platelet count and antithrombin III (AT-III) level declined to 27 × 103 cells/μL and 26.9%, respectively. Thus, we started the patient on a 0.06 μg/kg/min argatroban infusion. The argatroban infusion maintenance dose ranged between 0.9 and 1.2 μg/kg/min. The actual activated partial thromboplastin clotting time and activated clotting time ranged from 43 to 58 s and 220–260 s, respectively, without clinically significant bleeding and thrombosis. On day 27, the patient was weaned off VV-ECMO and eventually discharged. VV-ECMO may benefit pregnant women with refractory ARDS, and argatroban may be an alternative anticoagulant for pregnant patients with thrombocytopenia and AT-III deficiency during ECMO.

New Trends, Advantages and Disadvantages in Anticoagulation and Coating Methods Used in Extracorporeal Life Support Devices

The use of extracorporeal life support (ECLS) devices has significantly increased in the last decades. Despite medical and technological advancements, a main challenge in the ECLS field remains the complex interaction between the human body, blood, and artificial materials. Indeed, blood exposure to artificial surfaces generates an unbalanced activation of the coagulation cascade, leading to hemorrhagic and thrombotic events. Over time, several anticoagulation and coatings methods have been introduced to address this problem. This narrative review summarizes trends, advantages, and disadvantages of anticoagulation and coating methods used in the ECLS field. Evidence was collected through a PubMed search and reference scanning. A group of experts was convened to openly discuss the retrieved references. Clinical practice in ECLS is still based on the large use of unfractionated heparin and, as an alternative in case of contraindications, nafamostat mesilate, bivalirudin, and argatroban. Other anticoagulation methods are under investigation, but none is about to enter the clinical routine. From an engineering point of view, material modifications have focused on commercially available biomimetic and biopassive surfaces and on the development of endothelialized surfaces. Biocompatible and bio-hybrid materials not requiring combined systemic anticoagulation should be the future goal, but intense efforts are still required to fulfill this purpose.

Extracorporeal Life Support Organization (ELSO): Guidelines for Pediatric Cardiac Failure

These guidelines are applicable to neonates and children with cardiac failure as indication for extracorporeal life support. These guidelines address patient selection, management during extracorporeal membrane oxygenation, and pathways for weaning support or bridging to other therapies. Equally important issues, such as personnel, training, credentialing, resources, follow-up, reporting, and quality assurance, are addressed in other Extracorporeal Life Support Organization documents or are center-specific.

Argatroban versus heparin in patients without heparin-induced thrombocytopenia during venovenous extracorporeal membrane oxygenation: a propensity-score matched study

BACKGROUND

During venovenous extracorporeal membrane oxygenation (vvECMO), direct thrombin inhibitors are considered by some potentially advantageous over unfractionated heparin (UFH). We tested the hypothesis that Argatroban is non-inferior to UFH regarding thrombosis and bleeding during vvECMO.

METHODS

We conducted a propensity-score matched observational non-inferiority study of consecutive patients without heparin-induced-thrombocytopenia (HIT) on vvECMO, treated between January 2006 and March 2019 in the medical intensive care unit at the University Hospital Regensburg. Anticoagulation was realized with UFH until August 2017 and with Argatroban from September 2017 onwards. Target activated partial thromboplastin time was 50 ± 5seconds in both groups. Primary composite endpoint was major thrombosis and/or major bleeding. Major bleeding was defined as a drop in hemoglobin of ≥ 2 g/dl/day or in transfusion of ≥ 2 packed red cells/24 h, or retroperitoneal, cerebral, or pulmonary bleeding. Major thrombosis was defined as obstruction of > 50% of the vessel lumen diameter by means of duplex sonography. We also assessed technical complications such as oxygenator defects or pump head thrombosis, the time-course of platelets, and the cost of anticoagulation (including HIT-testing).

RESULTS

Out of 465 patients receiving UFH, 78 were matched to 39 patients receiving Argatroban. The primary endpoint occurred in 79% of patients in the Argatroban group and in 83% in the UFH group (non-inferiority for Argatroban, p = 0.026). The occurrence of technical complications was equally distributed (Argatroban 49% vs. UFH 42%, p = 0.511). The number of platelets was similar in both groups before ECMO therapy but lower in the UFH group after end of ECMO support (median [IQR]: 141 [104;198]/nl vs. 107 [54;171]/nl, p = 0.010). Anticoagulation costs per day of ECMO were higher in the Argatroban group (€26 [13.8;53.0] vs. €0.9 [0.5;1.5], p < 0.001) but not after accounting for blood products and HIT-testing (€63 [42;171) vs. €40 [17;158], p = 0.074).

CONCLUSION

In patients without HIT on vvECMO, Argatroban was non-inferior to UFH regarding bleeding and thrombosis. The occurrence of technical complications was similarly distributed. Argatroban may have less impact on platelet decrease during ECMO, but this finding needs further evaluation. Direct drug costs were higher for Argatroban but comparable to UFH after accounting for HIT-testing and transfusions.

Argatroban Anticoagulation for Adult Extracorporeal Membrane Oxygenation: A Systematic Review

BACKGROUND

Heparin is the widely used anti-coagulation strategy for patients on extracorporeal membrane oxygenation (ECMO). Nevertheless, heparin-induced thrombocytopenia (HIT) and acquired anti-thrombin (AT) deficiency preclude the use of heparin requiring utilization of an alternative anticoagulant agent. Direct thrombin inhibitors are being proposed as potential alternatives with argatroban as one of the main agents. We aimed to review the evidence with regard to safety and efficacy of argatroban as a potential definitive alternative to heparin in the adult patient population undergoing ECMO support.

METHODS

A web-based systematic literature search was performed in Medline (PubMed) and Embase from inception until June 18, 2020.

RESULTS

The search identified 13 publications relevant to the target (4 cohort studies and 9 case series). Case reports and case series with less than 3 cases were not included in the qualitative synthesis. The aggregate number of argatroban treated patients on ECMO was n = 307. In the majority of studies argatroban was used as a continuous infusion without loading dose. Starting doses on ECMO varied between 0.05 and 2 μg/kg/min and were titrated to achieve the chosen therapeutic target range. The activated partial thormboplastin time (aPTT) was the anticoagulation parameter used for monitoring purposes in most studies, whereas some utilized the activated clotting time (ACT). Optimal therapeutic targets varied between 43-70 and 60-100 seconds for aPTT and between 150-210 and 180-230 seconds for ACT. Bleeding and thromboembolic complication rates were comparable to patients treated with unfractionated heparin (UFH).

CONCLUSIONS

Argatroban infusion rates and anticoagulation target ranges showed substantial variations. The rational for divergent dosing and monitoring approaches are discussed in this paper. Argatroban appears to be a potential alternative to UFH in patients requiring ECMO. To definitively establish its safety, efficacy and ideal dosing strategy, larger prospective studies on well-defined patient populations are warranted.

Extracorporeal Membrane Oxygenation for Respiratory Failure

This review focuses on the use of veno-venous extracorporeal membrane oxygenation for respiratory failure across all blood flow ranges. Starting with a short overview of historical development, aspects of the physiology of gas exchange (i.e., oxygenation and decarboxylation) during extracorporeal circulation are discussed. The mechanisms of phenomena such as recirculation and shunt playing an important role in daily clinical practice are explained.Treatment of refractory and symptomatic hypoxemic respiratory failure (e.g., acute respiratory distress syndrome [ARDS]) currently represents the main indication for high-flow veno-venous-extracorporeal membrane oxygenation. On the other hand, lower-flow extracorporeal carbon dioxide removal might potentially help to avoid or attenuate ventilator-induced lung injury by allowing reduction of the energy load (i.e., driving pressure, mechanical power) transmitted to the lungs during mechanical ventilation or spontaneous ventilation. In the latter context, extracorporeal carbon dioxide removal plays an emerging role in the treatment of chronic obstructive pulmonary disease patients during acute exacerbations. Both applications of extracorporeal lung support raise important ethical considerations, such as likelihood of ultimate futility and end-of-life decision-making. The review concludes with a brief overview of potential technical developments and persistent challenges.

Antithrombin use during pediatric cardiac extracorporeal membrane oxygenation admission: insights from a national database

INTRODUCTION

The frequency of extracorporeal membrane oxygenation in pediatric patients continues to increase, especially in patients with complex congenital heart disease. Providing adequate anticoagulation is necessary for patients on extracorporeal membrane oxygenation and is achieved with adequate heparin administration. Antithrombin is administered to potentiate heparin's effects. However, the efficacy of antithrombin supplementation is unclear and a clear clinical benefit has not been established. We present a large retrospective study examining the effects of antithrombin on pediatric patients receiving extracorporeal membrane oxygenation.

METHODS

Data for this study were obtained from the Pediatric Health Information System and Pediatric Health Information System+ databases from 2004 to 2015. Pediatric patients receiving extracorporeal membrane oxygenation with a congenital heart disease diagnosis were included and divided into groups that did or did not utilize antithrombin. For all admissions, the following were captured: age of admission, gender, year of admission, length of stay, billed charges, inpatient mortality, the presence of specific congenital malformations of the heart, specific cardiac surgeries, and comorbidities.

RESULTS

A total of 9,193 admissions were included and 865 (9.4%) utilized antithrombin. Between groups, there were significantly different frequencies of co-morbidities, cardiac lesion types and antithrombin usage over the study period. There were significantly lower odds in the antithrombin group of venous thrombosis. Antithrombin was not significantly associated with hemorrhage; however, antithrombin was associated with increased inpatient mortality and a decrease in length of stay and billed charges.

CONCLUSION

Antithrombin administration is associated with increased mortality, a shorter length of stay, and decreased billing cost. Recently, antithrombin usage has been decreasing-potentially due to the reported lack of clinical benefit. Together, these results reinforce that antithrombin may not be indicated for all pediatric extracorporeal membrane oxygenation patients.

Bivalirudin Dosing Requirements in Adult Patients on Extracorporeal Life Support With or Without Continuous Renal Replacement Therapy

Systemic anticoagulation with unfractionated heparin is standard of care for patients receiving extracorporeal life support (ECLS); however, an alternative anticoagulant may be necessary when challenges with heparin therapy arise. Evidence for alternative anticoagulation in ECLS patients is limited. This retrospective analysis evaluated the dosing and outcomes associated with bivalirudin use in 14 adult ECLS patients. Indications for bivalirudin included heparin-induced thrombocytopenia, heparin resistance, or persistent clotting or bleeding while on heparin. The median initial bivalirudin dose to achieve target activated partial thromboplastin time was 0.15 mg/kg/h (range 0.04-0.26 mg/kg/h). Dosing requirements increased by 75-125% when renal replacement was included. Median time on bivalirudin was 5.2 days (range 0.9-28 days). Five patients (36%) required a circuit change while on bivalirudin because of clotting or failing oxygenation, and four (28.6%) had bleeding significant enough to require either reduction in activated partial thromboplastin time goals or temporary holding of anticoagulation. Bivalirudin appears to be a potential option for adult patients on ECLS who are unable to receive or fail heparin therapy; however, the wide variation in dosing suggests the need for careful management.

Impact of anticoagulation strategy and agents on extracorporeal membrane oxygenation therapy

Introduction:

Extracorporeal membrane oxygenation mandates balancing the risk of thromboembolic complications with bleeding. We aimed to evaluate pragmatic anticoagulation regimens during extracorporeal membrane oxygenation and compare thromboembolic and bleeding outcomes.

Methods:

This retrospective, single-center study reviewed patients on venovenous or venoarterial extracorporeal membrane oxygenation for a minimum of 24 hours over a 5-year period. The primary outcome was composite thromboembolic events per day of extracorporeal membrane oxygenation. Secondary outcomes included composite bleeding complications, percent of measured activated partial thromboplastin times in goal range, and comparing events with therapeutic anticoagulation for the majority of the extracorporeal membrane oxygenation run (>50% of time on extracorporeal membrane oxygenation) versus non-therapeutic anticoagulation (therapeutic anticoagulation <50% of time).

Results:

For the primary analysis, 100 patients received heparin, 10 received bivalirudin, and 43 were transitioned between heparin and bivalirudin. No significant differences were identified comparing the heparin group to the bivalirudin (RR = 0.427, p = 0.156) or transitioned group (RR = 1.274, p = 0.325). There were no differences in the rate of bleeding events when comparing the heparin group to the bivalirudin (RR = 0.626, p = 0.250) or transitioned group (RR = 0.742, p = 0.116). An increased number of adjustments to the anticoagulants was associated with a statistically higher rate of bleeding events per day (p = 0.006).

Conclusion:

There were no differences in thromboembolic or bleeding events when comparing different anticoagulant regimens. Adjustments to the anticoagulants are more likely to occur when bleeding is observed. Due to variability in anticoagulation, there is a need to standardize anticoagulation with extracorporeal membrane oxygenation.

Clinical Pearls of Venoarterial Extracorporeal Membrane Oxygenation for Cardiogenic Shock

Extracorporeal membrane oxygenation (ECMO) is a technique that uses a pump to drain blood from a body, circulate blood through a membrane lung, and return the oxygenated blood back into the body. Venoarterial (VA) ECMO is a simplified version of the heart-lung machine that assists native pulmonary and/or cardiac function. VA ECMO is composed of a drainage cannula in the venous system and a return cannula in the arterial system. Because VA ECMO can increase tissue perfusion by increasing the arterial blood flow, it is used to treat medically refractory cardiogenic shock or cardiac arrest. VA ECMO has a distinct physiology that is referred to as differential flows. It can cause several complications such as left ventricular distension with pulmonary edema, distal limb ischemia, bleeding, and thromboembolism. Physicians who are using this technology should be knowledgeable on the prevention and management of these complications. We review the basic physiology of VA ECMO, the mechanism of complications, and the simple management of VA ECMO.

Novel Surfaces in Extracorporeal Membrane Oxygenation Circuits

The balance between systemic anticoagulation and clotting is challenging. In normal hemostasis, the endothelium regulates the balance between anticoagulant and prothrombotic systems. It becomes particularly more challenging to maintain this physiologic hemostasis when we are faced with extracorporeal life support therapies, where blood is continuously in contact with a foreign extracorporeal circuit surface predisposing a prothrombotic state. The blood-surface interaction during extracorporeal life support therapies requires the use of systemic anticoagulation to decrease the risk of clotting. Unfractionated heparin is the most common anticoagulant agent widely used in this setting. New trends include the use of direct thrombin inhibitor agents for systemic anticoagulation; and surface modifications that aim to overcome the blood-biomaterial surface interaction by modifying the hydrophilicity or hydrophobicity of the polymer surface; and coating the circuit with substances that will mimic the endothelium or anti-thrombotic agents. To improve hemocompatibility in an extracorporeal circuit, replication of the anti-thrombotic and anti-inflammatory properties of the endothelium is ideal. Surface modifications can be classified into three major groups: biomimetic surfaces (heparin, nitric oxide, and direct thrombin inhibitors); biopassive surfaces [phosphorylcholine, albumin, and poly- 2-methoxyethylacrylate]; and endothelialization of blood contacting surface. The focus of this paper will be to review both present and future novel surface modifications that can obviate the need for systemic anticoagulation during extracorporeal life support therapies.

Use of argatroban for extracorporeal life support in patients with nonheparin-induced thrombocytopenia: Analysis of 10 consecutive patients

Unfractionated heparin (UFH) is currently the standard anticoagulant used in extracorporeal life support (ECLS). However, severe thrombocytopenia occurs frequently during ECLS use and it may be difficult to determine whether this represents heparin-induced thrombocytopenia (HIT) or not. In this case, UFH cannot be continued. Because a confirmatory laboratory test requires time, argatroban is empirically used if HIT is suspected. However, many patients are not found to have HIT. In non-HIT patients, the effectiveness and safety of argatroban are unclear. Thus, we investigated whether argatroban was safe and useful in patients who were suspected of having HIT and were started on argatroban, but were ultimately found to have non-HIT.We retrospectively reviewed all patients on ECLS who received the anticoagulant argatroban as an alternative to UFH between January 2014 and July 2015. The pretest clinical score (4Ts) was calculated, and a score greater than 4 was considered an indication for argatroban. The target-activated clotting time or activated partial thromboplastin time was 1.5 times the patient's upper normal value. Of 191 patients on ECLS during the study period, 10 (5.2%) were treated with argatroban infusion.No patients were found to have antiplatelet factor 4/heparin antibodies. The average maintenance dose of argatroban was 0.1 μg/kg/min. Platelet counts increased significantly following argatroban administration (P = .02). There were no anticoagulation-related complications such as bleeding or thrombosis.Our results suggest that argatroban is a safe alternative to UFH for patients with non-HIT on ECLS. Argatroban may have a more significant platelet-preserving effect than UFH, regardless of whether HIT is present.

Extracorporeal lung support

PURPOSE OF REVIEW

The applications for extracorporeal membrane oxygenation for lung support are constantly evolving. This review highlights fundamental concepts in extracorporeal lung support and describes directions for future research.

RECENT FINDINGS

Since the 1950s, extracorporeal lung support has experienced continuous advancements in circuit design and safety in acute respiratory distress syndrome, chronic obstructive pulmonary disease exacerbations, as a bridge to transplantation, intraoperative cardiopulmonary support, and for transportation to referral centers. Patients on extracorporeal membrane oxygenation are now capable of being awake, extubated, and ambulatory for accelerated recovery or optimization for transplantation.

SUMMARY

Extracorporeal lung support is a safe and an easily implemented intervention for refractory respiratory failure. Recent advances have extended its use beyond acute illnesses and the developments for chronic support will facilitate the development of durable devices and possible artificial lung development.

VV extracorporeal life support for the Third Millennium: will we need anticoagulation?

Since the late 1600's medicine and science have entertained the idea of extracorporeal circulation. With this technology to allow for cardiac and pulmonary support came the development of anticoagulation. Although this advanced the technology and capabilities of extracorporeal life support, it was not without complications and risks. The most common complications in extracorporeal life support (ECLS) present day are related to hemorrhage and thrombus due to the need for systemic anticoagulation and the challenges associated with it. This review focuses on present day techniques for anticoagulation for ECLS and what future surface modifications may do to obviate the use of systemic anticoagulation entirely.

Extracorporeal membrane oxygenation (ECMO) during pregnancy and postpartum

Extracorporeal membrane oxygenation (ECMO) can provide respiratory support (VV-ECMO) or both respiratory and circulatory support (VA-ECMO). The use of ECMO has increased dramatically as a result of simpler technology. No level I evidence is yet available reflecting improved outcomes with ECMO. The use of this technology during pregnancy may be indicated in very select cases and should be delivered in centers with dedicated ECMO specialized units.

Veno-arterial extracorporeal membrane oxygenation without therapeutic anticoagulation for intra-operative cardiopulmonary support during lung transplantation

Cardiopulmonary support is frequently required during lung transplantation. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has been recently shown to be an acceptable and, perhaps, safer alternative to cardiopulmonary bypass machine (CBM) for lung transplantation. However, therapeutic anticoagulation used during both these techniques can cause significant bleeding diathesis, especially in the setting of re-transplantation or when severe adhesions are encountered. Technological advances have reduced the thrombogenic potential of VA-ECMO circuits and unlike CBM, VA-ECMO does not include a reservoir containing a stagnant column of blood. Here, we demonstrate that VA-ECMO can be used without therapeutic anticoagulation for short-term intraoperative support.

Identification of berberine as a direct thrombin inhibitor from traditional Chinese medicine through structural, functional and binding studies

Thrombin acts as a key enzyme in the blood coagulation cascade and represents a potential drug target for the treatment of several cardiovascular diseases. The aim of this study was to identify small-molecule direct thrombin inhibitors from herbs used in traditional Chinese medicine (TCM). A pharmacophore model and molecular docking were utilized to virtually screen a library of chemicals contained in compositions of traditional Chinese herbs, and these analyses were followed by in vitro bioassay validation and binding studies. Berberine (BBR) was first confirmed as a thrombin inhibitor using an enzymatic assay. The BBR IC₅₀ value for thrombin inhibition was 2.92 μM. Direct binding studies using surface plasmon resonance demonstrated that BBR directly interacted with thrombin with a K_D value of 16.39 μM. Competitive binding assay indicated that BBR could bind to the same argartroban/thrombin interaction site. A platelet aggregation assay demonstrated that BBR had the ability to inhibit thrombin-induced platelet aggregation in washed platelets samples. This study proved that BBR is a direct thrombin inhibitor that has activity in inhibiting thrombin-induced platelet aggregation. BBR may be a potential candidate for the development of safe and effective thrombin-inhibiting drugs.

Current and future status of extracorporeal life support for respiratory failure in adults

PURPOSE OF REVIEW

The purpose is to review the development and current application of extracorporeal life support [ECLS, extracorporeal membrane oxygenation (ECMO)] in acute severe respiratory failure.

RECENT FINDINGS

Extracorporeal support (ECMO) is used for acute severe respiratory failure in advanced ICUs. The current survival rate is 60-70%. Three controlled trials all demonstrated 20-30% improvement in survival compared to conventional care. Patients may now be maintained awake and ambulatory with spontaneous breathing.

SUMMARY

ECMO is the next step in the algorithm for management of severe respiratory failure unresponsive to conventional care.