Veno-venous ECMO: a synopsis of nine key potential challenges, considerations, and controversies

Neutrophil-to-Lymphocyte Ratio as a Predictor of Mortality for COVID-19-Related Acute Respiratory Distress Syndrome (ARDS) Patients Requiring Extracorporeal Membrane Oxygenation Therapy

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) has been studied as an indicator of systemic inflammation and as a prognostic tool in multiple areas of medicine. Previous research has suggested that higher NLR and rapid increase to peak NLR are associated with poorer outcomes in patients with coronavirus disease 2019 (COVID-19), particularly in those experiencing acute respiratory distress syndrome (ARDS). Within vascular surgery, there is data to suggest a positive correlation between elevated pre-extracorporeal membrane oxygenation (ECMO) NLR and higher rates of mortality following major procedures. This study explores the prognostic value of peri-ECMO NLR in patients requiring veno-venous ECMO (VV-ECMO) therapy for COVID-19-related ARDS. The objective of this study was to explore the utility of pre-ECMO NLR as an easily accessible prognostic factor for patients suffering from COVID-19-associated ARDS that require VV-ECMO.

METHODS

This was a retrospective cohort study within a tertiary care hospital conducted between April 2020 and January 2021. Patients requiring VV-ECMO therapy for COVID-19-associated ARDS were included. Peri-ECMO NLR values, length of stay (LOS), duration on VV-ECMO, and discharge status were recorded. Receiver operating characteristic (ROC) curve analysis and Youden's J statistics were performed to calculate a cut-off value of 11.005 for pre-ECMO NLR and 17.616 for on-ECMO NLR. Pre-ECMO and on-ECMO Kaplan-Meyer curves were generated for two groups of patients, those above and below NLR cutoff thresholds. Two-sample T-test was performed to test for significant differences in LOS and duration on VV-ECMO.

RESULTS

Twenty-six patients were included in the study for final analyses. There was an overall mortality of 39% (n = 10). ROC curve analysis and Youden's J statistic revealed an optimal cut-off value of pre-ECMO NLR = 11.005 and on-ECMO NLR = 17.616. Results showed that the patient group placed on VV-ECMO with a pre-ECMO NLR less than 11.005 experienced no mortality (n = 7) and a median LOS of 28 days (IQR = 14.5-64.5 days). The patient group on VV-ECMO with a pre-ECMO NLR greater than 11.005 (n = 19) included all mortality (n = 10) and had a median LOS of 49 days (IQR = 25.5-63.5 days). The patient group with on-ECMO NLR less than 17.616 also conferred a survival advantage. There was no significant difference in LOS or duration on VV-ECMO between the two groups, pre-ECMO or on-ECMO.

CONCLUSIONS

 A pre-ECMO NLR cutoff was identified and offered statistically significant prognostic value in predicting mortality. A lower on-ECMO NLR value also indicated a survival advantage. Future studies should include NLR within multivariate models to better discern the effect of NLR and elucidate how it can be factored into clinical decision-making. Importantly, this data can be expanded to assess the predictive value of NLR pertaining to the COVID-19-induced ARDS population and matched cohorts.

Extracorporeal Membrane Oxygenation in Acute Respiratory Failure

Venovenous (VV) extracorporeal membrane oxygenation (ECMO) is a form of mechanical life support that provides full respiratory bypass in patients with severe respiratory failure as a bridge to recovery or lung transplantation. The use of ECMO for respiratory failure and capable centers offering ECMO has expanded over the years, increasing its availability. As VV-ECMO provides an artificial mechanism for oxygenation and decarboxylation of native blood, it allows for an environment in which safer mechanical ventilatory care may be provided, allowing for treatment and resolution of underlying respiratory pathologies. Landmark clinical trials have provided a framework for better understanding patient selection criteria, resource utilization, and outcomes associated with ECMO when applied in settings of refractory respiratory failure. Maintaining close vigilance and management of complications during ECMO as well as identifying strategies post-ECMO (e.g., recovery, transplantation, etc.), are critical to successful ECMO support. In this review, we examine considerations for candidate selection for VV-ECMO, review the evidence of utilizing VV-ECMO in respiratory failure, and provide practical considerations for managing respiratory ECMO patients, including complication identification and management, as well as assessing for the ability to separate from ECMO support and the procedures for decannulation.

Continuous renal replacement therapy and extracorporeal membrane oxygenation: implications in the COVID-19 era

The novel severe acute respiratory syndrome coronavirus 2, SARS-CoV-2 (coronavirus Disease 19 (COVID-19)) was identified as the causative agent of viral pneumonias in Wuhan, China in December 2019, and has emerged as a pandemic causing acute respiratory distress syndrome (ARDS) and multiple organ dysfunction. Interim guidance by the World Health Organization states that extracorporeal membrane oxygenation (ECMO) should be considered as a rescue therapy in COVID-19-related ARDS. International registries tracking ECMO in COVID-19 patients reveal a 21%-70% incidence of acute renal injury requiring renal replacement therapy (RRT) during ECMO support. The indications for initiating RRT in patients on ECMO are similar to those for patients not requiring ECMO. RRT can be administered during ECMO via a temporary dialysis catheter, placement of a circuit in-line hemofilter, or direct connection of continuous RRT in-line with the ECMO circuit. Here we review methods for RRT during ECMO, RRT initiation and timing during ECMO, anticoagulation strategies, and novel cytokine filtration approaches to minimize COVID-19's pathophysiological impact.

Bivalirudin Versus Unfractionated Heparin in Patients With Cardiogenic Shock Requiring Venoarterial Extracorporeal Membrane Oxygenation

This study evaluated differences in efficacy and safety outcomes with bivalirudin compared with unfractionated heparin (UFH) in patients with cardiogenic shock requiring venoarterial extracorporeal membrane oxygenation (VA ECMO). We performed a retrospective study at an academic medical center that included patients greater than 18 years of age supported with VA ECMO due to cardiogenic shock from January 2009 to February 2021. The primary endpoint was ECMO-associated thrombotic events normalized to duration of ECMO support. Secondary safety endpoints included major bleeding (per ELSO criteria) and blood product administration. Overall, 143 patients were included in our analysis with 54 having received bivalirudin and 89 having received UFH. Median duration of ECMO support was 92 (interquartile range, 56-172) hours. ECMO-associated thrombotic events per ECMO day were significantly less among those that received bivalirudin ( P < 0.001). In adjusted regression, bivalirudin was independently associated with an increased time to thrombosis when compared with UFH (Exp[B] -3.8; 95% confidence interval, 1.7-8.8; P = 0.002). Patients receiving bivalirudin experienced less major bleeding events ( P = 0.02) with less total red blood cell and fresh frozen plasma administration ( P = 0.04 and P = 0.03, respectively). Bivalirudin is a safe and efficacious alternative to UFH in patients requiring VA ECMO for cardiogenic shock.

Advances in nanotechnology application in biosafety materials: A crucial response to COVID-19 pandemic

The outbreak of coronavirus disease 2019 (COVID-19) has adversely affected the public domain causing unprecedented cases and high mortality across the globe. This has brought back the concept of biosafety into the spotlight to solve biosafety problems in developing diagnostics and therapeutics to treat COVID-19. The advances in nanotechnology and material science in combination with medicinal chemistry have provided a new perspective to overcome this crisis. Herein, we discuss the efforts of researchers in the field of material science in developing personal protective equipment (PPE), detection devices, vaccines, drug delivery systems, and medical equipment. Such a synergistic approach of disciplines can strengthen the research to develop biosafety products in solving biosafety problems.

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.

A novel therapeutic strategy using extracorporeal membrane oxygenation in patients with anti-neutrophil cytoplasmic antibodies-associated vasculitis: a case report and literature review

Diffuse alveolar hemorrhage (DAH) secondary to anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) often results in severe respiratory failure which requires emergent management. In patients who are resistant to traditional mechanical respiratory support, extracorporeal membrane oxygenation (ECMO) can be used to maintain gas exchange, thereby providing time for the administration of immunosuppressive therapy to control the inflammation. Herein, we report the application of ECMO to support an adult patient with AAV complicated by severe respiratory failure due to DAH. Similar cases in the literature were identified and discussed. The patient in our case study was successfully treated with ECMO in the acute phase and relieved by immunosuppressive therapy after withdrawal of ECMO. A search in the PubMed database revealed 32 similar cases with DAH, of which 11 cases were microscopic polyangiitis (MPA), 2 cases were eosinophilic granulomatosis with polyangiitis (EGPA), and 19 cases were granulomatosis with polyangiitis (GPA). These patients were all treated with ECMO. Therefore, to date, we identified 33 patients who were effectively treated with ECMO, including 13 (39.4%) males and 20 (60.6%) females, with a ratio of 1:1.54. The average age was 32.4±17.5 and 36.0±16.1 years for males and females, respectively (t=0.610, P=0.547). Most patients received ECMO on the first day of admission to the intensive care unit (ICU) and it appeared that early initiation of ECMO was associated with a shorter duration of ECMO. In general, complications of ECMO in these patients were mild and were not often seen in the clinical setting. This study suggested that early recognition of respiratory failure and referral for ECMO are vital to achieve a satisfactory outcome in AAV patients with DAH.

Individualized Multimodal Physiologic Approach to Mechanical Ventilation in Patients With Obesity and Severe Acute Respiratory Distress Syndrome Reduced Venovenous Extracorporeal Membrane Oxygenation Utilization

Supplemental Digital Content is available in the text.

OBJECTIVE:

To investigate whether individualized optimization of mechanical ventilation through the implementation of a lung rescue team could reduce the need for venovenous extracorporeal membrane oxygenation in patients with obesity and acute respiratory distress syndrome and decrease ICU and hospital length of stay and mortality.

DESIGN:

Single-center, retrospective study at the Massachusetts General Hospital from June 2015 to June 2019.

PATIENTS:

All patients with obesity and acute respiratory distress syndrome who were referred for venovenous extracorporeal membrane oxygenation evaluation due to hypoxemic respiratory failure.

INTERVENTION:

Evaluation and individualized optimization of mechanical ventilation by the lung rescue team before the decision to proceed with venovenous extracorporeal membrane oxygenation. The control group was those patients managed according to hospital standard of care without lung rescue team evaluation.

MEASUREMENT AND MAIN RESULTS:

All 20 patients (100%) allocated in the control group received venovenous extracorporeal membrane oxygenation, whereas 10 of 13 patients (77%) evaluated by the lung rescue team did not receive venovenous extracorporeal membrane oxygenation. Patients who underwent lung rescue team evaluation had a shorter duration of mechanical ventilation (p = 0.03) and shorter ICU length of stay (p = 0.03). There were no differences between groups in in-hospital, 30-day, or 1–year mortality.

CONCLUSIONS:

In this hypothesis-generating study, individualized optimization of mechanical ventilation of patients with acute respiratory distress syndrome and obesity by a lung rescue team was associated with a decrease in the utilization of venovenous extracorporeal membrane oxygenation, duration of mechanical ventilation, and ICU length of stay. Mortality was not modified by the lung rescue team intervention.

Neurological complications during veno-venous extracorporeal membrane oxygenation: Does the configuration matter? A retrospective analysis of the ELSO database

Background

Single- (SL) and double-lumen (DL) catheters are used in clinical practice for veno-venous extracorporeal membrane oxygenation (V-V ECMO) therapy. However, information is lacking regarding the effects of the cannulation on neurological complications.

Methods

A retrospective observational study based on data from the Extracorporeal Life Support Organization (ELSO) registry. All adult patients included in the ELSO registry from 2011 to 2018 submitted to a single run of V-V ECMO were analyzed. Propensity score (PS) inverse probability of treatment weighting estimation for multiple treatments was used. The average treatment effect (ATE) was chosen as the causal effect estimate of outcome. The aim of the study was to evaluate differences in the occurrence and the type of neurological complications in adult patients undergoing V-V ECMO when treated with SL or DL cannulas.

Results

From a population of 6834 patients, the weighted propensity score matching included 6245 patients (i.e., 91% of the total cohort; 4175 with SL and 20,270 with DL cannulation). The proportion of patients with at least one neurological complication was similar in the SL (306, 7.2%) and DL (189, 7.7%; odds ratio 1.10 [95% confidence intervals 0.91–1.32]; p = 0.33). After weighted propensity score, the ATE for the occurrence of least one neurological complication was 0.005 (95% CI − 0.009 to 0.018; p = 0.50). Also, the occurrence of specific neurological complications, including intracerebral hemorrhage, acute ischemic stroke, seizures or brain death, was similar between groups. Overall mortality was similar between patients with neurological complications in the two groups.

Conclusions

In this large registry, the occurrence of neurological complications was not related to the type of cannulation in patients undergoing V-V ECMO.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03533-5.

Comparison of Anticoagulation Strategies in Patients Requiring Venovenous Extracorporeal Membrane Oxygenation

OBJECTIVES

Extracorporeal membrane oxygenation is a life-sustaining therapy for severe respiratory failure. Extracorporeal membrane oxygenation circuits require systemic anticoagulation that creates a delicate balance between circuit-related thrombosis and bleeding-related complications. Although unfractionated heparin is most widely used anticoagulant, alternative agents such as bivalirudin have been used. We sought to compare extracorporeal membrane oxygenation circuit thrombosis and bleeding-related outcomes in respiratory failure patients receiving either unfractionated heparin or bivalirudin for anticoagulation on venovenous extracorporeal membrane oxygenation support.

DESIGN

Retrospective cohort study.

SETTING

Single-center, cardiothoracic ICU.

PATIENTS

Consecutive patients requiring venovenous extracorporeal membrane oxygenation who were maintained on anticoagulation between 2013 and 2020.

INTERNVENTIONS

IV bivalirudin or IV unfractionated heparin.

MEASUREMENTS AND MAIN RESULTS

Primary outcomes were the presence of extracorporeal membrane oxygenation in-circuit-related thrombotic complications and volume of blood products administered during extracorporeal membrane oxygenation duration. One hundred sixty-two patients receiving unfractionated heparin were compared with 133 patients receiving bivalirudin for anticoagulation on venovenous extracorporeal membrane oxygenation. In patients receiving bivalirudin, there was an overall decrease in the number of extracorporeal membrane oxygenation circuit thrombotic complications (p < 0.005) and a significant increase in time to circuit thrombosis (p = 0.007). Multivariable Cox regression found that heparin was associated with a significant increase in risk of clots (Exp[B] = 2.31, p = 0.001). Patients who received bivalirudin received significantly less volume of packed RBCs, fresh frozen plasma, and platelet transfusion (p < 0.001 for each). There was a significant decrease in the number major bleeding events in patients receiving bivalirudin, 40.7% versus 11.7%, p < 0.001.

CONCLUSIONS

Patients receiving bivalirudin for systemic anticoagulation on venovenous extracorporeal membrane oxygenation experienced a decrease in the number of extracorporeal membrane oxygenation circuit-related thrombotic events as well as a significant decrease in volume of blood products administered.

A materials-science perspective on tackling COVID-19

The ongoing SARS-CoV-2 pandemic highlights the importance of materials science in providing tools and technologies for antiviral research and treatment development. In this Review, we discuss previous efforts in materials science in developing imaging systems and microfluidic devices for the in-depth and real-time investigation of viral structures and transmission, as well as material platforms for the detection of viruses and the delivery of antiviral drugs and vaccines. We highlight the contribution of materials science to the manufacturing of personal protective equipment and to the design of simple, accurate and low-cost virus-detection devices. We then investigate future possibilities of materials science in antiviral research and treatment development, examining the role of materials in antiviral-drug design, including the importance of synthetic material platforms for organoids and organs-on-a-chip, in drug delivery and vaccination, and for the production of medical equipment. Materials-science-based technologies not only contribute to the ongoing SARS-CoV-2 research efforts but can also provide platforms and tools for the understanding, protection, detection and treatment of future viral diseases.

Bedside veno-venous ECMO cannulation: A pertinent strategy during the COVID-19 pandemic

Background

Patient selection and cannulation arguably represent the key steps for the successful implementation of extracorporeal membrane oxygenation (ECMO) support. Cannulation is traditionally performed in the operating room or the catheterization laboratory for a number of reasons, including physician preference and access to real‐time imaging, with the goal of minimizing complications and ensuring appropriate cannula positioning. Nonetheless, the patients' critical and unstable conditions often require emergent initiation of ECMO and preclude the safe transport of the patient to a procedural suite.

Aims

Therefore, with the objective of avoiding delay with the initiation of therapy and reducing the hazard of transport, we implemented a protocol for bedside ECMO cannulation.

Matherial and Methods

A total of 89 patients required ECMO support at Hennepin County Medical Center between March 2015 and December 2019. Twenty‐eight (31%) required veno‐venous support and were all cannulated at the bedside. Overall survival was 71% with no morbidity or mortality related to the cannulation procedure.

Conclusion

In the current pandemic, the strategy of veno‐venous bedside cannulation may have additional benefits for the care of patients with refractory acute respiratory distress syndrome due to coronavirus disease‐2019, decreasing the risk of exposure of health care worker or other patients to the novel severe acute respiratory syndrome coronavirus‐2 occurring during patient transport, preparation, or during disinfection of the procedural suite and the transportation pathway after ECMO cannulation.

Hemoglobin trigger and approach to red blood cell transfusions during veno-venous extracorporeal membrane oxygenation: the international TRAIN-ECMO survey

INTRODUCTION

Optimal red blood cell transfusion practice during veno-venous extracorporeal membrane oxygenation (VV ECMO) is still under debate. This survey aimed to assess the Hb trigger (also comparing with other critically ill patients) and major physiologic determinants considered for transfusions during veno-venous extracorporeal membrane oxygenation.

METHODS

Voluntary Web-based survey, endorsed by the European Society of Intensive Care Medicine, conducted among VV ECMO pratictioners worldwide.

RESULTS

A total of 447 respondents worldwide answered the questionnaire: 277 (61.9%) from Europe, 99 (22.1%) from North America, 36 (8.2%) from Asia and Oceania, and 35 (7.8%) from Central and South America. Among the respondents, 59.2% managed less than 12 venous extracorporeal membrane oxygenation runs/year, 19.4% between 12 and 24 runs/year, and 21.4% more than 24 runs/year. Of the respondents, 54.4% do not use a predefined Hb trigger in veno-venous extracorporeal membrane oxygenation, and, while the rate of adoption of a defined trigger varied worldwide, the effective value of Hb did not differ significantly among macro-regions. In patients on veno-venous extracorporeal membrane oxygenation, the Hb trigger to initiate red blood cell transfusion, was higher than in other critically ill patients: 9.1 ± 1.8 g/dL versus 8.3 ± 1.7 g/dL, p < 0.01. The Hb trigger was lower in centers with more than 24 venous extracorporeal membrane oxygenation runs/year (8.4 mg/dL (95% CI: 7.7-8.9)); (8.9 mg/dL (95% CI: 8.2-9.7)) in centers with between 12 and 24 venous extracorporeal membrane oxygenation runs/year; and (9.6 mg/dL (95% CI: 9.1-10.0)) in centers with fewer than 12 venous extracorporeal membrane oxygenation runs/year (p < 0.01). Several and variable adjunctive parameters are considered in cases of uncertainty for transfusion: the principal are hemodynamic status, SvO2, lactates, and fluid balance.

CONCLUSION

Although the use of a predefined Hb trigger is still under-adopted among centers with low or median extracorporeal membrane oxygenation case volume, the majority of respondents use a higher Hb trigger for veno-venous extracorporeal membrane oxygenation patients compared with other critically ill patients. Higher volume centers tolerate lower Hb levels.

Contemporary approaches in the use of extracorporeal membrane oxygenation to support patients waiting for lung transplantation

The introduction of the lung allocation score in 2005 prioritized patients with decreased transplant-free survival as the recipients of donor organs and effectively increased the number of critically-ill patients with end-stage lung disease waiting for transplantation. This change presented transplant programs with the challenge of how to both extend the lives of critically-ill, end-stage lung disease patients waiting for donor organs and maintain patient vitality to survival through the rigors of surgery and post-transplant recovery. Motivated by the dismal outcomes of patients maintained on mechanical ventilation pre-transplant, transplant centers increasingly deploy extracorporeal membrane oxygenation (ECMO) as a means of supporting patients with advanced disease as a bridge to successful lung transplantation. ECMO is an extracorporeal gas exchange device providing delivery of oxygen and removal of carbon dioxide from blood passed through the circuit. The specific cannulation strategy determines whether ECMO provides primarily respiratory or circulatory support. The cannulation approach is tailored to the specific physiological manifestations of the pre-lung transplant candidate's disease process. For patients with profound hypoxic respiratory failure, a cannulation strategy that captures a large fraction of the venous return is required to maintain adequate support whereas lower circuit flows are sufficient for patients with predominantly hypercapnic respiratory failure. Improving outcomes and increasing experience with ECMO is motivating transplant centers to initiate support before patients require mechanical ventilation. Awake cannulation is increasingly common and is used to avoid the complications associated with intubation in advanced lung failure. Determining criteria for initiation of support and identifying the optimal approach to support patients with right heart failure in need of circulatory support are avenues of active investigation. Use of ECMO and other forms of extracorporeal support are rapidly becoming a mainstay in the care of the pre-lung transplant patient with advanced disease.

Extracorporeal Membrane Oxygenation in ARDS

Extracorporeal membrane oxygenation (ECMO) has become a key tool in the management of cardiac and/or respiratory failure refractory to conventional management. Although ECMO has multiple indications, it has been widely studied for the management of acute respiratory distress syndrome in adults. ECMO provides rest and support while the damaged lungs heal. It is an invasive modality with risks of serious complications; therefore, clinicians should be vigilant during patient selection. Furthermore, users should be familiar with different components of the ECMO machinery and the management of different organ systems while patients are on the circuit. ECMO is a relatively new modality that has shown good results when used in certain circumstance, and its use is becoming more popular across the United States.

Heparin-Sparing Anticoagulation Strategies Are Viable Options for Patients on Veno-Venous ECMO

BACKGROUND

Extracorporeal membrane oxygenation (ECMO), a rescue therapy for pulmonary failure, has traditionally been limited by anticoagulation requirements. Recent practice has challenged the absolute need for anticoagulation, expanding the role of ECMO to patients with higher bleeding risk. We hypothesize that mortality, bleeding, thrombotic events, and transfusions do not differ between heparin-sparing and full therapeutic anticoagulation strategies in veno-venous (VV) ECMO management.

MATERIALS AND METHODS

Adult VV ECMO patients between October 2011 and May 2018 at a single center were reviewed. A heparin-sparing strategy was implemented in October 2014; we compared outcomes in an as-treated fashion. The primary end point was survival. Secondary end points included bleeding, thrombotic complications, and transfusion requirements.

RESULTS

Forty VV ECMO patients were included: 17 (147 circuit-days) before and 23 (214 circuit-days) after implementation of a heparin-sparing protocol. Patients treated with heparin-sparing anticoagulation had a lower body mass index (28.5 ± 7.1 versus 38.1 ± 12.4, P = 0.01), more often required inotropic support before ECMO (82 versus 50%, P = 0.05), and had a lower mean activated clotting time (167 ± 15 versus 189 ± 15 s, P < 0.01). There were no significant differences in survival to decannulation (59 versus 83%, P = 0.16) or discharge (50 versus 72%, P = 0.20), bleeding (32 versus 33%, P = 1.0), thromboembolic events (18 versus 39%, P = 0.17), or transfusion requirements (median 1.1 versus 0.9 unit per circuit-day, P = 0.48).

CONCLUSIONS

Survival, bleeding, thrombotic complications, and transfusion requirements did not differ between heparin-sparing and full therapeutic heparin strategies for management of VV ECMO. VV ECMO can be a safe option in patients with traditional contraindications to anticoagulation.

Retrieval of critically ill adults using extracorporeal membrane oxygenation: the nine-year experience in New South Wales

In New South Wales, a coordinated extracorporeal membrane oxygenation (ECMO) retrieval program has been in operation since 2007. This study describes the characteristics and outcomes of patients transported by this service. We performed a retrospective observational study and included patients who were transported on ECMO to either of two adult tertiary referral hospitals in Sydney, New South Wales, between February 28, 2007 and February 29, 2016. One hundred and sixty-four ECMO-facilitated transports occurred, involving 160 patients. Of these, 118 patients (74%) were treated with veno-venous (VV) ECMO and 42 patients (26%) were treated with veno-arterial ECMO. The mean (standard deviation, SD) age was 40.4 (15.0) years. Seventy-seven transports (47%) occurred within metropolitan Sydney, 52 (32%) were from rural or regional areas within NSW, 17 (10%) were interstate transfers and 18 (11%) were international transfers. Transfers were by road (58%), fixed wing aircraft (27%) or helicopter (15%). No deaths occurred during transport. The median (interquartile range) duration of ECMO treatment was 8.9 (5.2-15.3) days. One hundred and nineteen patients (74%) were successfully weaned from ECMO and 109 (68%) survived to hospital discharge or transfer. In patients treated with VV ECMO, age, sequential organ failure assessment score, pre-existing immunosuppressive disease, pre-existing diabetes, renal failure requiring dialysis and failed prone positioning prior to ECMO were independently associated with increased mortality. ECMO-facilitated patient transport is feasible, safe, and results in acceptable short-term outcomes. The NSW ECMO Retrieval Service provides specialised support to patients with severe respiratory and cardiovascular illness, who may otherwise be too unstable to undergo inter-hospital transfer to access advanced cardiovascular and critical care services.

Impact of cannula design on packed red blood cell transfusions: technical advancement to improve outcomes in extracorporeal membrane oxygenation

Background

Technological improvement has contributed to making veno-venous extracorporeal membrane oxygenation (VV-ECMO) safer and easier, spreading its use in acute respiratory failure (ARF).

Methods

This is a retrospective observational study carried out in the ECMO center at IRCCS-ISMETT, a medical center focused on end-stage organ failure treatment in Italy. We investigated the effect of different cannula designs on the amount of blood product transfused. Eighty-nine consecutive patients affected with ARF on VV-ECMO from 2008 to 2016 were compared according to type of cannulation: older percutaneous cannula (Standard group, 52 patients) and HLS^© BIOLINE-coated, but with shorter drainage cannula (BIOLINE group, 37 patients).

Results

The two study groups were comparable in terms of baseline characteristics [age, body mass index (BMI), Simplified Acute Physiology Score (SAPS-II), Sequential Organ Failure Assessment (SOFA), Predicting Death For Severe ARDS on VV-ECMO (PRESERVE) score] and ECMO management [median hematocrit (Htc), platelet nadir, antithrombin III (AT III), heparin, activated partial thromboplastin time (APTT)]. In the BIOLINE group, a lower amount of packed red blood cells (pRBC) was transfused considering both total number [4 units, interquartile range (IQR) 1-9 vs. 12 units, IQR 5.5-21; P<0.01] and mL of pRBC/day of ECMO support (91, IQR 21-158 vs. 193.5, IQR 140.5-254; P<0.01). In the BIOLINE group, a trend in reduction of ECMO days (P=0.05) and length of intensive care unit (ICU) stay was found (P=0.06), but no differences in rates of ECMO weaning and ICU discharge were evidenced. The BIOLINE group constituted a saving of €1,295.20 per patient/treatment, counting the costs for cannulation and pRBC administration.

Conclusions

More biocompatible and shorter drainage cannula may represent one of the contributing factors to a reduction in transfusions and costs of VV-ECMO in the current ongoing technological improvement in ECMO.

Outcomes of extracorporeal membrane oxygenation in adult patients with hypoxemic respiratory failure refractory to mechanical ventilation

Introduction

Extracorporeal membrane oxygenation (ECMO) is a mode of extracorporeal life support that has been used to support cardiopulmonary disease refractory to conventional therapy. The experience with the use of ECMO in acute hypoxemic respiratory failure is still limited. The aim of this study was to report clinical outcomes in adult patients with acute hypoxemic respiratory failure refractory to mechanical ventilation treated with ECMO.

Methods

Between July 2011 and October 2017, 18 adult patients with hypoxemic respiratory failure refractory to mechanical ventilation were admitted to the Intensive Care Unit of an acute care tertiary hospital in Barcelona, Spain. These patients were treated with ECMO as salvage respiratory therapy. Outcomes included clinical data, ventilatory and blood gas characteristics, survival, and complications.

Results

Fifteen patients (83.3%) were previously treated in prone position. The indication of VV-ECMO was established at an early stage after a mean (SD) of 3.8 (2.5) days on mechanical ventilation. The mean duration of ECMO was 10.4 days, and 16 patients (88.9%) required venous cannulation, mostly femoral-internal jugular. The mean length of ICU stay was 27 days and the mean hospital stay was 42.1 days. The ICU survival rate was 55.5% (n = 10) and the hospital survival rate was 50% (n = 9).

Conclusions

This clinical study in a small series of ICU patients treated with ECMO confirms the usefulness of this technique as a ventilatory support in patients with refractory hypoxemic respiratory failure. However, the indication of this procedure is also committed to an ethical reflection considering the possible futility of the measure on a case-by-case basis and associated complications.

The role of extra-corporeal membrane oxygenation (ECMO) in the treatment of diffuse alveolar haemorrhage secondary to ANCA-associated vasculitis: report of two cases and review of the literature

Diffuse alveolar haemorrhage (DAH) secondary to anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) is a rare life-threatening condition presenting with severe respiratory failure. The management of AAV-related DAH consists of remission induction immunosuppressive therapy, which requires time to be effective, with significant fatality rates despite appropriate treatment. Extracorporeal membrane oxygenation (ECMO) can support gas exchanges providing the time necessary for immunosuppressive treatment to control the underlying disease in cases refractory to the conventional ventilation techniques. Despite severe preexisting bleeding has been considered a relative contraindication, ECMO has proven to be life-saving in several cases of respiratory failure associated with pulmonary haemorrhage due to various causes, including AAV. We reviewed the clinical presentation and course of two patients affected by AAV-related DAH treated at our Institution between 2012 and 2017, whose management required the use of veno-venous ECMO. We reviewed the current literature on the role of ECMO in the support of these patients. In both patients, ECMO provided life support and allowed disease control, in combination with immunosuppressive treatment. Despite systemic anticoagulation, clinical improvement was achieved without exacerbation of the pulmonary bleeding. We performed a literature review, and summarized available data confirming the effectiveness and safety of ECMO in AAV-related DAH. ECMO has a life-saving role in the management of patients with severe respiratory failure due to ANCA-associated pulmonary capillaritis.

Use of venovenous ECMO for neonatal and pediatric ECMO: a decade of experience at a tertiary children's hospital

BACKGROUND

Advances in extracorporeal membrane oxygenation (ECMO) have led to increased use of venovenous (VV) ECMO in the pediatric population. We present the evolution and experience of pediatric VV ECMO at a tertiary care institution.

METHODS

A retrospective cohort study from 01/2005 to 07/2016 was performed, comparing by cannulation mode. Survival to discharge, complications, and decannulation analyses were performed.

RESULTS

In total, 160 patients (105 NICU, 55 PICU) required 13 ± 11 days of ECMO. VV cannulation was used primarily in 83 patients with 64% survival, while venoarterial (VA) ECMO was used in 77 patients with 54% survival. Overall, 74% of patients (n = 118) were successfully decannulated; 57% survived to discharge. VA ECMO had a higher rate of intra-cranial hemorrhage than VV (22 vs 9%, p = 0.003). Sixteen VA patients (21%) had radiographic evidence of a cerebral ischemic insult. No cardiac complications occurred with the use of dual-lumen VV cannulas. There were no differences in complications (p = 0.40) or re-operations (p = 0.85) between the VV and VA groups.

CONCLUSION

Dual-lumen VV ECMO can be safely performed with appropriate image guidance, is associated with a lower rate of intra-cranial hemorrhage, and may be the preferred first-line mode of ECMO support in appropriately selected NICU and PICU patients.

LEVEL OF EVIDENCE

II.

Cannulation technique: femoro-femoral

The cannulation technique used during veno-venous extracorporeal membrane oxygenation (VV ECMO) insertion can have a major impact on a patients' overall outcome. We have developed a technique that aims to combine speed and effectiveness, with minimal risk. The steps include: (I) percutaneous cannulation using the Seldinger technique; (II) ultrasound guided access and positioning of cannulas; (III) femoro-femoral circuit configuration with a later option of high flow; (IV) a no skin cut serial dilation technique; (V) non-suturing securing of cannulas and (VI) a non-surgical manual pressure technique of explantation. The following is a discussion around these techniques and their various advantages and disadvantages.

Perioperative Management of the Adult Patient on Venovenous Extracorporeal Membrane Oxygenation Requiring Noncardiac Surgery

The use of venovenous extracorporeal membrane oxygenation is increasing worldwide. These patients often require noncardiac surgery. In the perioperative period, preoperative assessment, patient transport, choice of anesthetic type, drug dosing, patient monitoring, and intraoperative and postoperative management of common patient problems will be impacted. Furthermore, common monitoring techniques will have unique limitations. Importantly, patients on venovenous extracorporeal membrane oxygenation remain subject to hypoxemia, hypercarbia, and acidemia in the perioperative setting despite extracorporeal support. Treatments of these conditions often require both manipulation of extracorporeal membrane oxygenation settings and physiologic interventions. Perioperative management of anticoagulation, as well as thresholds to transfuse blood products, remain highly controversial and must take into account the specific procedure, extracorporeal membrane oxygenation circuit function, and patient comorbidities. We will review the physiologic management of the patient requiring surgery while on venovenous extracorporeal membrane oxygenation.

Medication Complications in Extracorporeal Membrane Oxygenation

The need for extracorporeal membrane oxygenation (ECMO) therapy is a marker of disease severity for which multiple medications are required. The therapy causes physiologic changes that impact drug pharmacokinetics. These changes can lead to exposure-driven decreases in efficacy or increased incidence of side effects. The pharmacokinetic changes are drug specific and largely undefined for most drugs. We review available drug dosing data and provide guidance for use in the ECMO patient population.

Pilot Feasibility Study of Therapeutic Hypothermia for Moderate to Severe Acute Respiratory Distress Syndrome

OBJECTIVES

Prior studies suggest hypothermia may be beneficial in acute respiratory distress syndrome, but cooling causes shivering and increases metabolism. The objective of this study was to assess the feasibility of performing a randomized clinical trial of hypothermia in patients with acute respiratory distress syndrome receiving treatment with neuromuscular blockade because they cannot shiver.

DESIGN

Retrospective study and pilot, prospective, open-label, feasibility study.

SETTING

Medical ICU.

PATIENTS

Retrospective review of 58 patients with acute respiratory distress syndrome based on Berlin criteria and PaO2/FIO2 less than 150 who received neuromuscular blockade. Prospective hypothermia treatment in eight acute respiratory distress syndrome patients with PaO2/FIO2 less than 150 receiving neuromuscular blockade.

INTERVENTION

Cooling to 34-36°C for 48 hours.

MEASUREMENTS AND MAIN RESULTS

Core temperature, hemodynamics, serum glucose and electrolytes, and P/F were sequentially measured, and medians (interquartile ranges) presented, 28-day ventilator-free days, and hospital mortality were calculated in historical controls and eight cooled patients. Average patient core temperature was 36.7°C (36-37.3°C), and fever occurred during neuromuscular blockade in 30 of 58 retrospective patients. In the prospectively cooled patients, core temperature reached target range less than or equal to 4 hours of initiating cooling, remained less than 36°C for 92% of the 48 hours cooling period without adverse events, and was lower than the controls (34.35°C [34-34.8°C]; p < 0.0001). Compared with historical controls, the cooled patients tended to have lower hospital mortality (75% vs 53.4%; p = 0.26), more ventilator-free days (9 [0-21.5] vs 0 [0-12]; p = 0.16), and higher day 3 P/F (255 [160-270] vs 171 [120-214]; p = 0.024).

CONCLUSIONS

Neuromuscular blockade alone does not cause hypothermia but allowed acute respiratory distress syndrome patients to be effectively cooled. Results support conducting a randomized clinical trial of hypothermia in acute respiratory distress syndrome and the feasibility of studying acute respiratory distress syndrome patients receiving neuromuscular blockade.

ECMO in major burn patients: feasibility and considerations when multiple modes of mechanical ventilation fail

BACKGROUND

We report two cases of acute respiratory distress syndrome in burn patients who were successfully managed with good outcomes with extra corporeal membrane oxygenation (ECMO) after failing multiple conventional modes of ventilation, and review the relevant literature.

CASE PRESENTATION

The two patients were a 39-year-old male and 53-year-old male with modified Baux Scores of 79 and 78, respectively, with no known inhalation injury. After the initial modified Parkland-based fluid resuscitation and partial escharotomy, both patients developed worsening hypoxemia and acute respiratory distress syndrome. The hypoxemia continued to worsen on multiple modes of ventilation including volume control, pressure regulated volume control, pressure control, airway pressure release ventilation and volumetric diffusive ventilation. In both cases, the PaO₂ ≤ 50 mm Hg on a FiO₂ 100% during the trial of mechanical ventilation. The deterioration was rapid (<12 h since onset of worsening oxygenation) in both cases. A decision was made to trial the patients on ECMO. Veno-Venous ECMO (V-V ECMO) was successfully initiated following cannulation-under transesophgeal echo guidance-with the dual lumen Avalon® (Maquet, NJ, USA) cannula. ECMO support was maintained for 4 and 24 days, respectively. Both patients were successfully weaned off ECMO and were discharged to rehabilitation following their complex hospital course.

CONCLUSION

Early ECMO for isolated respiratory failure in the setting on maintained hemodynamics resulted in a positive outcome in our two burn patients suffered from acute respiratory distress syndrome.

Elective Use of Veno-venous Extracorporeal Membrane Oxygenation and High-flow Nasal Oxygen for Resection of Subtotal Malignant Distal Airway Obstruction

We describe the use of peripheral veno-venous extracorporeal membrane oxygenation (VV ECMO) and high-flow nasal oxygen as procedural support in a patient undergoing debulking of a malignant tumour of the lower airway. Due to the significant risk of complete airway obstruction upon induction of anaesthesia, ECMO was established while the patient was awake, and was maintained without systemic anticoagulation to minimise the risk of intraoperative bleeding. This case illustrates that ECMO support with high-flow nasal oxygen can be considered as part of the algorithm for airway management during surgery for subtotal lower airway obstruction, as it may be the only viable option for maintaining adequate gas exchange.

Veno-venous extracorporeal membrane oxygenation: cannulation techniques

The development of extracorporeal membrane oxygenation (ECMO) technology allows a new approach for the intensive care management of acute cardiac and/or respiratory failure in adult patients who are not responsive to conventional treatment. Current ECMO therapies provide a variety of options for the multidisciplinary teams who are involved in the management of these critically ill patients. In this regard, veno-venous ECMO (VV-ECMO) can provide quite complete respiratory support, even if this highly complex technique presents substantial risks, such as bleeding, thromboembolic events and infection. While VV-ECMO circuits usually include the cannulation of two vessels (double cannulation) in its classic configuration, the use of a single cannula is now possible for VV-ECMO support. Recently, experienced centers have employed more advanced approaches by cannulating three vessels (triple cannulation) which follows veno-arterio-venous (VAV) or veno-arterio-pulmonary-arterial cannulation (VAPa). However, 'triple' cannulation expands the field of application but increases the complexity of ECMO systems. In the present review, the authors focus on the indications for VV-ECMO, patient assessment prior to cannulation, the role of ultrasound-guided vessel puncture, double lumen single bicaval cannulations, and finally triple cannulation in VV-ECMO.

Concepts from paediatric extracorporeal membrane oxygenation for adult intensivists

Over the last 5 years, there has been a dramatic increase in the use of extracorporeal membrane oxygenation (ECMO) in adult patients with severe respiratory or cardiac failure. This contrasts to the use of the technology in neonatal and paediatric intensive care units, where it has been regarded as a standard of care for a number of conditions for over 25 years. Many innovations in ECMO circuitry or clinical management evolve first in one particular discipline and it may be helpful for individual clinicians to keep abreast of developments in ECMO across the entire age range, from neonatology to older adults. This review addresses nine concepts in ECMO that are better studied or established in paediatric medicine and considers their application in adult patients.

Risk Factors for Acute Kidney Injury and In-Hospital Mortality in Patients Receiving Extracorporeal Membrane Oxygenation

Background and Objectives

Although acute kidney injury (AKI) is the most frequent complication in patients receiving extracorporeal membrane oxygenation (ECMO), few studies have been conducted on the risk factors of AKI. We performed this study to identify the risk factors of AKI associated with in-hospital mortality.

Methods

Data from 322 adult patients receiving ECMO were analyzed. AKI and its stages were defined according to Kidney Disease Improving Global Outcomes (KDIGO) classifications. Variables within 24 h before ECMO insertion were collected and analyzed for the associations with AKI and in-hospital mortality.

Results

Stage 3 AKI was associated with in-hospital mortality, with a hazard ratio (HR) (95% CI) of 2.690 (1.472–4.915) compared to non-AKI (p = 0.001). The simplified acute physiology score 2 (SAPS2) and serum sodium level were also associated with in-hospital mortality, with HRs of 1.02 (1.004–1.035) per 1 score increase (p = 0.01) and 1.042 (1.014–1.070) per 1 mmol/L increase (p = 0.003). The initial pump speed of ECMO was significantly related to in-hospital mortality with a HR of 1.333 (1.020–1.742) per 1,000 rpm increase (p = 0.04). The pump speed was also associated with AKI (p = 0.02) and stage 3 AKI (p = 0.03) with ORs (95% CI) of 2.018 (1.129–3.609) and 1.576 (1.058–2.348), respectively. We also found that the red cell distribution width (RDW) above 14.1% was significantly related to stage 3 AKI.

Conclusion

The initial pump speed of ECMO was a significant risk factor of in-hospital mortality and AKI in patients receiving ECMO. The RDW was a risk factor of stage 3 AKI.

The Acute Respiratory Distress Syndrome: Mechanisms and Perspective Therapeutic Approaches

Acute Respiratory Distress Syndrome (ARDS) is a severe lung inflammatory disorder with a 30-50% mortality. Sepsis and pneumonia are the leading causes of ARDS. On the cellular level there is pulmonary capillary endothelial cell permeability and fluid leakage into the pulmonary parenchyma, followed by neutrophils, cytokines and an acute inflammatory response. When fluid increases in the interstitium then the outward movement continues and protein rich fluid floods the alveolar spaces through the tight junctions of the epithelial cells. Neutrophils play an important role in the development of pulmonary edema associated with acute lung injury or ARDS. Animal studies have shown that endothelial injury appears within minutes to hours after Acute Lung Injury (ALI) initiation with resulting intercellular gaps of the endothelial cells. The Endothelial Cell (EC) gaps allow for permeability of fluid, neutrophils and cytokines into the pulmonary parenchymal space. The neutrophils that infiltrate the lungs and migrate into the airways express pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and contribute to both the endothelial and epithelial integrity disruption of the barriers. Pharmacological treatments have been ineffective. The ARDS Network trial identified low tidal volume mechanical ventilation, positive end expiratory pressure and fluid management guidelines that have improved outcomes for patients with ARDS. Extracorporeal membrane oxygenation is used in specialized centers for severe cases. Prone positioning has recently proven to have significantly decreased ventilator days and days in the intensive care unit. Current investigation includes administration of mesenchymal stem cell therapy, partial fluid ventilation, TIP peptide nebulized administration and the continued examination of pharmacologic drugs.

Extracorporeal membrane oxygenation for Life-threatening ANCA-positive pulmonary capillaritis. A review of UK experience

INTRODUCTION

Anti-neutrophil cytoplasmic antibody positive pulmonary capillaritis complicated by diffuse alveolar hemorrhage is a potentially fatal condition for which extracorporeal membrane oxygenation can facilitate improved outcomes and potential cure. Diffuse alveolar hemorrhage can be the initial presentation of an autoimmune disorder. The management is centered on the use of immunosuppressive therapy, which requires time, with fatality often occurring for these patients. We showed two very young patients with no previous history of vasculitis presenting with life threatening pulmonary hemorrhage due to anti-neutrophil cytoplasmic antibody positive vasculitis, whose management was facilitated with extracorporeal membrane oxygenation.

METHODS

We reviewed the clinical presentation and course of the first two patients with diffuse alveolar hemorrhage for anti-neutrophil cytoplasmic antibody positive vasculitis managed with veno-venous extracorporeal membrane oxygenation. We highlighted and analysed the unique challenges encountered in managing these patients.

RESULTS

The two patients were referred for extracorporeal membrane oxygenation since conventional ventilation was inadequate to provide physiologic support for respiratory failure. Clinical improvement was achieved without exacerbation of the pulmonary hemorrhage despite the use of anticoagulants. This provided time for the immunosuppressants to take effect. Both patients were discharged and were cured of the underlying condition.

CONCLUSIONS

Extracorporeal membrane oxygenation has a role in the management of patients with severe respiratory failure due to anti-neutrophil cytoplasmic antibody positive capillaritis. Early recognition and referral for extracorporeal membrane oxygenation are vital to achieve a favourable outcome.