ECMO cannulation controversies and complications

Extracorporal Membrane Oxygenation in Massive Pulmonary Embolism

BACKGROUND

Massive pulmonary embolism (MPE) carries significant 30-day mortality risk, and a change in societal guidelines has promoted the increasing use of extracorporeal membrane oxygenation (ECMO) in the immediate management of MPE-associated cardiovascular shock. This narrative review examines the current status of ECMO in MPE.

METHODS

A literature review was performed from 1982 to 2022 searching for the terms "Pulmonary embolism" and "ECMO," and the search was refined by examining those publications that covered MPE.

RESULTS

In the patient with MPE, veno-arterial ECMO is now recommended as a bridge to interventional therapy. It can reliably decrease right ventricular overload, improve RV function, and allow hemodynamic stability and restoration of tissue oxygenation. The use of ECMO in MPE has been associated with lower mortality in registry reviews, but there has been no significant difference in outcomes between patients treated with and without ECMO in meta-analyses. Applying ECMO is also associated with substantial multisystem morbidity due to systemic inflammatory response, bleeding with coagulopathy, hemorrhagic stroke, renal dysfunction, and acute limb ischemia, which must be factored into the outcomes.

CONCLUSIONS

The application of ECMO in MPE should be combined with an aggressive interventional pulmonary interventional program and should strictly adhere to the current selection criteria.

Flow capabilities of arterial and drainage cannulae during venoarterial extracorporeal membrane oxygenation: A simulation model

BACKGROUND

Large cannulae can increase cannula-related complications during venoarterial extracorporeal membrane oxygenation (VA ECMO). Conversely, the ability for small cannulae to provide adequate support is poorly understood. Therefore, we aimed to evaluate a range of cannula sizes and VA ECMO flow rates in a simulated patient under various disease states.

METHODS

Arterial cannulae sizes between 13 and 21 Fr and drainage cannula sizes between 21 and 25 Fr were tested in a VA ECMO circuit connected to a mock circulation loop simulating a patient with severe left ventricular failure. Systemic and pulmonary hypertension, physiologically normal, and hypotension were simulated by varying systemic and pulmonary vascular resistances (SVR and PVR, respectively). All cannula combinations were evaluated against all combinations of SVR, PVR, and VA ECMO flow rates.

RESULTS

A 15 Fr arterial cannula combined with a 21 Fr drainage cannula could provide >4 L/min of total flow and a mean arterial pressure of 81.1 mmHg. Changes in SVR produced marked changes to all measured parameters, while changes to PVR had minimal effect. Larger drainage cannulae only increased maximum circuit flow rates when combined with larger arterial cannulae.

CONCLUSION

Smaller cannulae and lower flow rates could sufficiently support the simulated patient under various disease states. We found arterial cannula size and SVR to be key factors in determining the flow-delivering capabilities for any given VA ECMO circuit. Overall, our results challenge the notion that larger cannulae and high flows must be used to achieve adequate ECMO support.

Using Signal Features of Functional Near-Infrared Spectroscopy for Acute Physiological Score Estimation in ECMO Patients

Extracorporeal membrane oxygenation (ECMO) is a vital emergency procedure providing respiratory and circulatory support to critically ill patients, especially those with compromised cardiopulmonary function. Its use has grown due to technological advances and clinical demand. Prolonged ECMO usage can lead to complications, necessitating the timely assessment of peripheral microcirculation for an accurate physiological evaluation. This study utilizes non-invasive near-infrared spectroscopy (NIRS) to monitor knee-level microcirculation in ECMO patients. After processing oxygenation data, machine learning distinguishes high and low disease severity in the veno-venous (VV-ECMO) and veno-arterial (VA-ECMO) groups, with two clinical parameters enhancing the model performance. Both ECMO modes show promise in the clinical severity diagnosis. The research further explores statistical correlations between the oxygenation data and disease severity in diverse physiological conditions, revealing moderate correlations with the acute physiologic and chronic health evaluation (APACHE II) scores in the VV-ECMO and VA-ECMO groups. NIRS holds the potential for assessing patient condition improvements.

Mechanical Support Strategies for High-Risk Procedures in the Invasive Cardiac Catheterization Laboratory: A State-of-the-Art Review

Thanks to advancements in percutaneous cardiac interventions, an expanding patient population now qualifies for treatment through percutaneous endovascular procedures. High-risk interventions far exceed coronary interventions and include transcatheter aortic valve replacement, endovascular management of acute pulmonary embolism and ventricular tachycardia ablation. Given the frequent impairment of ventricular function in these patients, frequently deteriorating during percutaneous interventions, it is hypothesized that mechanical ventricular support may improve periprocedural survival and subsequently patient outcome. In this narrative review, we aimed to provide the relevant evidence found for the clinical use of percutaneous mechanical circulatory support (pMCS). We searched the Pubmed database for articles related to pMCS and to pMCS and invasive cath lab procedures. The articles and their references were evaluated for relevance. We provide an overview of the clinically relevant evidence for intra-aortic balloon pump, Impella, TandemHeart and ECMO and their role as pMCS in high-risk percutaneous coronary intervention, transcatheter valvular procedures, ablations and high-risk pulmonary embolism. We found that the right choice of periprocedural pMCS could provide a solution for the hemodynamic challenges during these procedures. However, to enhance the understanding of the safety and effectiveness of pMCS devices in an often high-risk population, more randomized research is needed.

Inflow from a Cardiopulmonary Assist System to the Pulmonary Artery and Its Implications for Local Hemodynamics-a Computational Fluid Dynamics Study

When returning blood to the pulmonary artery (PA), the inflow jet interferes with local hemodynamics. We investigated the consequences for several connection scenarios using transient computational fluid dynamics simulations. The PA was derived from CT data. Three aspects were varied: graft flow rate, anastomosis location, and inflow jet path length from anastomosis site to impingement on the PA wall. Lateral anastomosis locations caused abnormal flow distribution between the left and right PA. The central location provided near-physiological distribution but induced higher wall shear stress (WSS). All effects were most pronounced at high graft flows. A central location is beneficial regarding flow distribution, but the resulting high WSS might promote detachment of local thromboembolisms or influence the autonomic nervous innervation. Lateral locations, depending on jet path length, result in lower WSS at the cost of an unfavorable flow distribution that could promote pulmonary vasculature changes. Case-specific decisions and further research are necessary.

Research progress of portable extracorporeal membrane oxygenation

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO) is primarily used for the supportive treatment of patients suffering from severe cardiopulmonary failure. With the continued development of ECMO technology, the relevant scenarios also extend pre-hospital and inter-hospital. In order to meet the needs of emergency treatment in communities, disaster sites and battlefields, inter-hospital transfer and evacuation; miniaturized and portable ECMO has become a current research hotspot.

AREA COVERED

The paper first introduces the principle, composition and common modes of ECMO and summarizes the research status of portable ECMO, Novalung and wearable ECMO, analyzes the characteristics and shortcomings of existing equipment. finally, we discussed the focus and development trend of portable ECMO technology.

EXPERT OPINION

Currently, portable ECMO has many applications in interhospital transport and there are various studies on portable and wearable ECMO devices, but the development of portable ECMO still faces many challenges. In the future, research related to integrated components, rich sensor arrays, Intelligent ECMO system and lightweight technology can make future portable ECMO more suitable for pre-hospital emergency and interhospital transport.

Peripherally inserted concomitant surgical right and left ventricular support, the Propella, is associated with low rates of limb ischemia, with mortality comparable with peripheral venoarterial extracorporeal membrane oxygenation

BACKGROUND

Mechanical circulatory support effectively treats adult cardiogenic shock. Whereas cardiogenic shock confers high mortality, acute limb ischemia is a known complication of mechanical circulatory support that confers significant morbidity. We compared our novel approach to peripheral mechanical circulatory support with a conventional femoral approach, with a focus on the incidence of acute limb ischemia.

METHODS

This was a retrospective cohort study of patients treated with mechanical circulatory support between January 1, 2015 and December 5, 2021 at our institution. Patients receiving any femoral peripheral venoarterial extracorporeal membrane oxygenation were compared with those receiving minimally invasive, peripherally inserted, concomitant right and left ventricular assist devices. These included the Impella 5.0 (Abiomed, Danvers, MA) left ventricular assist device and the ProtekDuo (LivaNova, London, UK) right ventricular assist device used concomitantly (Propella) approach. The primary outcome was incidence of acute limb ischemia. The baseline patient characteristics, hemodynamic data, and post-mechanical circulatory support outcomes were collected. Fisher exact test and Wilcoxon rank sum test was used for the categorical and continuous variables, respectively. Kaplan-Meier curves and log-rank test were used to estimate overall survival probabilities and survival experience, respectively.

RESULTS

Fifty patients were treated with mechanical circulatory support at our institution for cardiogenic shock, with 13 patients supported with the novel Propella strategy and 37 with peripheral venoarterial extracorporeal membrane oxygenation. The baseline characteristics, including patient organ function and medical comorbidities, were similar among the groups. Nine patients suffered mortality in ≤48 hours of mechanical circulatory support initiation and were excluded. Twenty patients (69%) suffered acute limb ischemia in the peripheral venoarterial extracorporeal membrane oxygenation group; 0 patients receiving Propella suffered acute limb ischemia (P < .001). The percentages of patients surviving to discharge in peripheral venoarterial extracorporeal membrane oxygenation and Propella groups were 24% and 69%, respectively (P = .007).

CONCLUSION

Patients treated with the Propella experienced a lower incidence of acute limb ischemia compared with patients treated with peripheral venoarterial extracorporeal membrane oxygenation.

Basics of Extracorporeal Membrane Oxygenation

OVERVIEW

The use of extracorporeal membrane oxygenation (ECMO) is becoming commonplace worldwide in ICUs for the care of patients with respiratory and/or cardiac failure. Understanding the use of ECMO and the management of these complex patients will be vital to current and future clinicians as ECMO use continues to grow.

Intraoperative Management of Adult Patients on Extracorporeal Membrane Oxygenation: An Expert Consensus Statement From the Society of Cardiovascular Anesthesiologists-Part II, Intraoperative Management and Troubleshooting

In the second part of the Society of Cardiovascular Anesthesiologists Extracorporeal Membrane Oxygenation (ECMO) working group expert consensus statement, venoarterial (VA) and venovenous (VV) ECMO management and troubleshooting in the operating room are discussed. Expert consensus statements are provided about intraoperative monitoring, anesthetic drug dosing, and management of intraoperative problems in VA and VV ECMO patients.

Joint Society of Critical Care Medicine-Extracorporeal Life Support Organization Task Force Position Paper on the Role of the Intensivist in the Initiation and Management of Extracorporeal Membrane Oxygenation

OBJECTIVES

To define the role of the intensivist in the initiation and management of patients on extracorporeal membrane oxygenation.

DESIGN

Retrospective review of the literature and expert consensus.

SETTING

Series of in-person meetings, conference calls, and emails from January 2018 to March 2019.

SUBJECTS

A multidisciplinary, expert Task Force was appointed and assembled by the Society of Critical Care Medicine and the Extracorporeal Life Support Organization. Experts were identified by their respective societies based on reputation, experience, and contribution to the field.

INTERVENTIONS

A MEDLINE search was performed and all members of the Task Force reviewed relevant references, summarizing high-quality evidence when available. Consensus was obtained using a modified Delphi process, with agreement determined by voting using the RAND/UCLA scale, with score ranging from 1 to 9.

MEASUREMENTS AND MAIN RESULTS

The Task Force developed 18 strong and five weak recommendations in five topic areas of extracorporeal membrane oxygenation initiation and management. These recommendations were organized into five areas related to the care of patients on extracorporeal membrane oxygenation: patient selection, management, mitigation of complications, coordination of multidisciplinary care, and communication with surrogate decision-makers. A common theme of the recommendations is extracorporeal membrane oxygenation is best performed by a multidisciplinary team, which intensivists are positioned to engage and lead.

CONCLUSIONS

The role of the intensivist in the care of patients on extracorporeal membrane oxygenation continues to evolve and grow, especially when knowledge and familiarity of the issues surrounding extracorporeal membrane oxygenation selection, cannulation, and management are applied.

ECPella: Concept, Physiology and Clinical Applications

Addition of Impella on top of venoarterial extracorporeal membrane oxygenation (VA-ECMO) has gained wide interest as it might portend improved outcomes in patients with cardiogenic shock. This has been consistently reported in retrospective propensity-matched studies, case series, and meta-analyses. The pathophysiologic background is based on the mitigation of ECMO-related side effects and the additive benefit of myocardial unloading. In this perspective, thorough knowledge of these mechanisms is required to optimize the management of mechanical circulatory support with this approach and introduce best practices, as the interplay between the two devices and the implantation-explantation strategies are key for success.

Right Atrial Cannulation via Thoracotomy for Emergent Extracorporeal Membrane Oxygenation in Pediatric Patients with Prior Sternotomy

Extracorporeal membrane oxygenation (ECMO) is the most common mechanical circulatory support strategy used to treat pediatric patients presenting with low cardiac output or cardiogenic shock. While transthoracic central cannulation is feasible and mostly utilized for early postoperative support, peripheral cannulation is preferred as a primary strategy in the late postoperative period. Redo-sternotomy and venous cannulation are difficult to achieve in patients with occluded peripheral veins or complex venous anatomy like Glenn circulation. In pediatric patients with multiple prior sternotomy and catheterization procedures, vascular access for cannulation is frequently limited. Peripheral cannulation for venoarterial ECMO (VA-ECMO) may be challenging or even impossible. In our case series, four pediatric patients with prior sternotomy underwent right atrial cannulation emergently in patients to secure venous drainage for ECMO support. Extracorporeal membrane oxygenation support could be established rapidly with adequate venous drainage in all cases. We conclude that right atrial cannulation via right thoracotomy can be a useful technique for venous cannulation in cases with prior sternotomy and is particularly useful in cases with Glenn circulation.

The Effect of Additional Stepwise Venous Inflow on Differential Hypoxia of Veno-Arterial Extracorporeal Membrane Oxygenation

Use of femoral-femoral veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) for cardiopulmonary support during lung transplantation can be inadequate for efficient distribution of oxygenated blood into the coronary circulation. We hypothesized that creating a left-to-right shunt flow using veno-arterio-venous (VAV) ECMO would alleviate the differential hypoxia. Total 10 patients undergoing lung transplantation were enrolled in this study. An additional inflow cannula was inserted into the right internal jugular (RIJ) vein for VAV ECMO. During left one-lung ventilation using a 1.0 inspired oxygen fraction (FiO₂), the left-to-right shunt flow was incrementally increased from 0 to 500, 1,000, and 1,500 ml/min. The arterial oxygen partial pressure (PaO₂) and oxygen saturation (SaO₂) were measured at the proximal ascending aorta and right radial artery. The ascending aorta gas analysis revealed that six patients had a PaO₂/FiO₂ ratio less than 200 mm Hg at a 0 ml/min shunt flow. The PaO₂ (SaO₂) values were 48.5 ± 14.8 mm Hg (80.9 ± 11.6%) at the ascending aorta and 77.8 ± 69.7 mm Hg (83.3 ± 13.2%) at the right radial artery. As the left-to-right shunt flow rate increased over 1,000 ml/min, the PaO₂ and SaO₂ values for the ascending aorta and right radial artery significantly increased. In conclusion, femoral-femoral VA ECMO can produce suboptimal coronary oxygenation in patients unable to tolerate one-lung ventilation. A left-to-right shunt using VAV ECMO can alleviate the differential hypoxia.

Determination of local flow ratios and velocities in a femoral venous cannula with computational fluid dynamics and 4D flow-sensitive magnetic resonance imaging: A method validation

Cannulas with multi-staged side holes are the method of choice for femoral cannulation in extracorporeal therapies today. A variety of differently designed products is available on the market. While the preferred tool for the performance assessment of such cannulas are pressure-flow curves, little is known about the flow and velocity distribution. Within this work flow and velocity patterns of a femoral venous cannula with multi-staged side holes were investigated. A mock circulation loop for cannula performance evaluation was built and reproduced using a computer-aided design system. With computational fluid dynamics, volume flows and fluid velocities were determined quantitatively and visually with hole-based precision. In order to ensure the correctness of the flow simulation, the results were subsequently validated by determining the same parameters with four-dimensional flow-sensitive magnetic resonance imaging. Measurement data and numerical solution differed 7% on average throughout the data set for the examined parameters. The highest inflow and velocity were detected at the most proximal holes, where half of the total volume flow enters the cannula. At every hole stage a Y-shaped inflow profile was detected, forming a centered stream in the middle of the cannula. Simultaneously, flow separation creates zones with significant lower flow velocities. Numerical simulation, validated with four-dimensional flow-sensitive magnetic resonance imaging, is a valuable tool to examine flow and velocity distributions of femoral venous cannulas with hole-based accuracy. Flow and velocity distribution in such cannulas are not ideal. Based on this work future cannulas can be effectively optimized.

The evolving role of the modern perfusionist: insights from transesophageal echocardiography

Transesophageal echocardiography is a relatively non-invasive, mobile, safe imaging technique that is ideal for providing real-time information on cardiac anatomy and function during heart surgery. The technology has evolved from two-dimensional to real-time three-dimensional imaging during cardiac procedures, which has significantly benefited preoperative planning, intraoperative guidance, evaluation, and postoperative follow-up. Transesophageal echocardiography may serve the clinical perfusionist by providing imaging guidance for identifying potential problems before cardiopulmonary bypass, guiding the proper placement of cannulas, monitoring cardiac performance on cardiopulmonary bypass, and providing useful feedback during weaning from cardiopulmonary bypass. Although the perfusionist should be able to understand all echocardiographic images and measurements in depth, perfusion-related echocardiographic information can or should be used to optimize the clinical practice of the modern perfusionist. Vice versa, whenever the perfusionist suspects a problem, the surgical team including the sonographer should verify this "clinical treat" by echocardiography whenever possible.

Neurological Monitoring and Complications of Pediatric Extracorporeal Membrane Oxygenation Support

Extracorporeal membrane oxygenation is extracorporeal life support for life-threatening cardiopulmonary failure. Since its introduction, the use of extracorporeal membrane oxygenation has expanded to patients with more complex comorbidities without change in patient mortality rates. Although many patients survive, significant neurological complications like seizures, ischemic strokes, and intracranial hemorrhage can occur during extracorporeal membrane oxygenation care. The risks of these complications often add to the complexity of decision-making surrounding extracorporeal membrane oxygenation support. In this review, we discuss the pathophysiology and incidence of neurological complications in children supported on extracorporeal membrane oxygenation, factors influencing the incidence of these complications, commonly used neurological monitoring modalities, and outcomes for this complex patient population. We discuss the current literature on the use of electroencephalography for both seizure detection and monitoring of background electroencephalographic changes, in addition to the use of less commonly used imaging modalities like transcranial Doppler. We summarize the knowledge gaps and the lack of clinical consensus guidelines for managing these potentially life-changing neurological complications. Finally, we discuss future work to further understand the pathophysiology of extracorporeal membrane oxygenation-related neurological complications.

Contemporary analysis of charges and mortality in the use of extracorporeal membrane oxygenation: A cautionary tale

Objective

The use of extracorporeal membrane oxygenation (ECMO) has increased exponentially. Costs and outcomes, however, vary considerably by indication. We sought to elucidate and quantify these differences.

Methods

Adult patients supported on ECMO between 2008 and 2016 were analyzed using the Nationwide Inpatient Sample. We divided the study period into an early (2008-2013) and late period (2013-2016). The primary outcome was hospital charges, and the secondary outcomes were mortality, length of stay (LOS), and duration of ECMO support. These were stratified by the 5 most common indications: postcardiotomy shock (PCS), cardiogenic shock (CS), severe acute respiratory failure (SARF), heart (HT), and lung transplantation (LT). Both patient and hospital characteristics were assessed. Charges were adjusted for inflation and analyzed using a generalized linear model with gamma distribution. Pairwise comparison with Bonferroni correction was used to evaluate the cost and multivariate logistic regression to assess the risk of mortality.

Results

Data pertaining to 15,829 adult patients were evaluated. Mean age of the entire cohort was 52.8 years, 8895 (56%) were white, and 10,278 (65%) were male. PCS was the predominant indication for ECMO (39%), followed by CS (37%). SARF accounted for 15% and HT and LT accounted for 3.9% and 5.4%, respectively. Mean LOS and duration of ECMO support were 23.4 days and 5.3 days respectively. Mean hospital charges per hospitalization for the entire cohort were USD 731,914 per patient. Charges per patient pertaining to hospitalizations in which ECMO was used in transplant patients were the highest: USD 1,448,931 and USD 1,574,378 (P = .99) for HT and LT, respectively. Charges were lower for the other indications: PCS USD 798,909, CS USD 655,099, and SARF USD 824,852. Overall mortality for the entire cohort was 55%. PCS and CS (53% vs 58%, P = .34) had similar survival, whereas SARF was 45%, LT was 39% and HT 32%. There were no differences in survival in these latter indications (SARF, LT and HT). The cumulative charges (proportion × hospital charges) reveal that PCS and CS (39% and 37%) account for both the majority of charges as well as the greatest mortality. Conversely, SARF and transplantation accounted for the smaller proportion of charges and the lower mortality. Patients undergoing HT had the longest LOS (51.7 days) and duration on ECMO (15.9 days), followed by LT (35.4 and 8.8 days respectively), and patients with SARF (28.6 and 6.6 respectively). LOS and duration of ECMO for those with PCS were 18.7 days and 4.8 days, respectively. Those on ECMO for CS were hospitalized for 19.7 days and spent an average of 3.8 days on ECMO. Mortality decreased, whereas charges increased in the late era.

Conclusions

The use of ECMO is associated with high hospital charges and a wide variation in outcomes. Hospitalizations, in which ECMO is used to support patients with cardiogenic shock (PCS and CS), are individually associated with lower LOS and charges. Cumulatively, however, these account for greater charges and greater mortality. Although mortality may be decreasing, overall charges are increasing with time. These variations may influence reimbursement decisions in value-based healthcare.

Venoarterial Extracorporeal Membrane Oxygenation in Cardiogenic Shock: Lifeline of Modern Day CICU

Cardiogenic shock (CS) portends an extremely high mortality of nearly 50% during index hospitalization. Prompt diagnoses of CS, its underlying etiology, and efficient implementation of treatment modalities, including mechanical circulatory support (MCS), are critical especially in light of such high predicted mortality. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) provides the most comprehensive cardiopulmonary support in critically ill patients and hence has seen a steady increase in its utilization over the past decade. Hence, a good understanding of VA-ECMO, its role in treatment of CS, especially when compared with other temporary MCS devices, and its complications are vital for any critical care cardiologist. Our review of VA-ECMO aims to provide the same.

Survey of the American Pediatric Surgical Association on cannulation practices in pediatric ECMO

AIMS

Extracorporeal membrane oxygenation (ECMO) is a commonly used modality of life support for children with cardiopulmonary failure. Consensus on pediatric cannulation strategies and management does not currently exist. The goal of this study was to investigate individual surgeon approaches towards ECMO cannulations in children.

METHODS

A 21-question online survey was developed and disseminated to the American Pediatric Surgical Association (APSA) membership. Participant responses were summarized as counts and percentages. Effect of ECMO volume and surgeon experience on responses was assessed.

RESULTS

There were 252 APSA members who participated in this study for a response rate of 21%, with 225 (89.3%) performing ECMO. Sixty respondents (28.3%) reported using neck vessels exclusively for cannulation regardless of age or weight of the patient. After neck decannulation, 13 (6.6%) repaired the carotid artery for all patients, and 21 (10.7%) repaired only for children older than 5years. Of those performing femoral cannulation, 56 (26.4%) would perform at 5years or older and 66 (31.1%) at 12years. The most common challenge for femoral cannulation was the need for distal perfusion (n=119; 59.8%). Assistance from vascular surgery was requested by 32 (16.4%) for distal perfusion catheter placement, and by 79 (40.5%) for decannulation. Regarding femoral cannulation, lack of training was more likely to be a challenge if performing <5 cannulations per year (25.2% vs 12.5%; p=0.03). Surgeons with <10years of experience were more likely to consult vascular surgery compared to those with >10years of experience (18.5% vs 8%; p=0.03).

CONCLUSION

Considerable variation exists in individual surgeon cannulation practices in pediatric ECMO, in particular in the management of school age and adolescent VA ECMO. Mixed approaches across several ECMO management case study questions indicate that further work is needed to evaluate specific risks with cannulations in children.

LEVEL OF EVIDENCE

IV.

Evaluation of Two Femoral Arterial Cannulae With Conventional Non-Pulsatile and Alternative Pulsatile Flow in a Simulated Adult ECLS Circuit

The objective of this study is to evaluate the hemodynamic characteristics of two femoral arterial cannulae in terms of circuit pressure, pressure drop, and hemodynamic energy transmission under non-pulsatile and pulsatile modes in a simulated adult extracorporeal life support (ECLS) system. The ECLS circuit consisted of i-cor diagonal pump and console (Xenios AG, Heilbronn, Germany), an iLA membrane ventilator (Xenios AG), an 18 Fr or 16 Fr femoral arterial cannula (Xenios AG), and a 23/25 Fr Estech remote access perfusion (RAP) femoral venous cannula (San Ramon, CA, USA). The circuit was primed with lactated Ringer's solution and packed red blood cells to achieve a hematocrit of 35%. All trials were conducted at room temperature with flow rates of 1-4 L/min (1 L/min increments). The pulsatile flow settings were set at pulsatile frequency of 75 bpm and pulsatile amplitudes of 1000-4000 rpm (1000 rpm increments). Flow and pressure data were collected using a custom data acquisition system. Total hemodynamic energy (THE) is calculated by multiplying the ratio between the area under the hemodynamic power curve (∫flow × pressure dt) and the area under the pump flow curve (∫flow dt) by 1332. The pressure drop across the arterial cannula increased with increasing flow rate and decreasing cannula size. The pressure drops of 18 Fr and 16 Fr cannulae were 19.4-24.5 and 38.4-45.3 mm Hg at 1 L/min, 55.2-56.8 and 110.9-118.3 mm Hg at 2 L/min, 94.1-105.1 and 209.7-215.1 mm Hg at 3 L/min, and 169.2-172.6 and 376.4 mm Hg at 4 L/min, respectively. Pulsatile flow created more hemodynamic energy than non-pulsatile flow, especially at lower flow rates. The percentages of THE loss across 18 Fr and 16 Fr cannula were 16.0-18.7 and 27.5-30.8% at 1 L/min, 35.1-35.7 and 52.3-53.8% at 2 L/min, 48.3-50.3 and 67.3-68.4% at 3 L/min and 62.9-63.1 and 79.0% at 4 L/min. The hemodynamic performance of the arterial cannula should be evaluated before use in clinical practice. The pressure drops and percentages of THE loss across two cannulae tested using human blood were higher compared to the manufacturer's data tested using water. The cannula size should be chosen to match the expected flow rate. In addition, this novel i-cor ECLS system can provide non-pulsatile and ECG-synchronized pulsatile flow without significantly increasing the cannula pressure drop and hemodynamic energy loss.

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.

Percutaneous Vascular Cannulation for Extracorporeal Life Support (ECLS): A Modified Technique

Purpose

Vascular access and cannulation are crucial issues to maximize the efficiency of extracorporeal circulation techniques and to preserve patients' safety. Techniques of cannulation have changed over the years, from surgical cutdown to percutaneous approaches, which are now considered standard practice. We describe an original modified percutaneous cannulation technique developed in our Department and we report our clinical experience and complications observed.

Methods

A Seldinger technique utilizing 3 guidewires with passage of a dilator over each guidewire was used. Two concentric pursestring sutures, prepared before cannulation, minimize procedure-associated bleeding. Cannulation is performed under direct fluoroscopic control.

Results

From 1997 to 2009, 38 patients (31 VV-ECLS, 7 VA-ECLS) have been cannulated using our technique, resulting in a total of 69 venous cannulations. Average external caliber of venous cannulae was 23 Fr (15–29 Fr). Mean duration of the entire cannulation procedure was 40 minutes (20–60 min). Adverse events occurred in 3 patients.

Conclusions

The technique described is safe and feasible and the incidence of procedure-related complications is very low, but it may require longer time to be performed.

Keep Ventilating the Lungs While the Heart is Still Ejecting on Femoro-femoral Cardiopulmonary Bypass

Femoro-femoral cardiopulmonary bypass (CPB) followed by deep hypothermic circulatory arrest is one of the modalities used for ascending aortic pseudoaneurysm repair to achieve cardiac unloading and to avoid severe hemorrhage due to the risk of rupture during the sternal entry. However, due to the limited size of the cannulas, it can be challenging to achieve total cardiopulmonary support. Therefore, despite the achievement of total cardiopulmonary support, the heart may still be able to eject antegrade blood flow that meets the retrograde blood flow from the arterial side of the CPB. The point where the blood flow meets in the aorta is called the watershed area. If the antegrade blood flow is large due to a left ventricular ejection, the watershed area will be located in the descending aorta. Therefore, if ventilation is stopped, deoxygenated blood will be ejected to the cerebral circulation. Cerebral near-infrared spectroscopy (NIRS) may be used as a noninvasive and continuous measurement of regional brain oxygen saturation (rSO₂). This case demonstrates that cerebral desaturation due to discontinued mechanical ventilation, when the heart was still ejecting during the initial phase of femoro-femoral CPB, immediately was detected by a pronounced drop bilaterally: In the left frontal lobe, rSO₂ fell from 56% to 21%, and in the right frontal lobe it fell from 47% to 25%. The authors recommend monitoring cerebral saturation using NIRS in the case of femoro-femoral CPB.

Veno-arterial-ECMO in the intensive care unit: From technical aspects to clinical practice

The use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) as a salvage therapy in cardiogenic shock is becoming of current practice. While VA-ECMO is potentially a life-saving technique, results are sometimes mitigated, emphasising the need for selecting the right indication in the right patient. This relies upon a clear definition of the individual therapeutic project, including the potential for recovery as well as the possible complications associated with VA-ECMO. To maximise the benefits of VA-ECMO, the basics of extracorporeal circulation should be perfectly understood since VA-ECMO can sometimes be detrimental. Hence, to be successful, VA-ECMO should be used by teams with sufficient experience and initiated after a thorough multidisciplinary discussion considering patient's medical history, pathology as well the anticipated evolution of the disease.

Cannulation techniques for extracorporeal life support

The article reviews cannulation strategy for different modes of extracorporeal life support. Technical aspects, pitfalls and complications are discussed for central and peripheral extracorporeal membrane oxygenation (VA, VV, VAV, VVA), biventricular assist device support and extracorporeal CO₂ removal.

The "Central Sport Model": Extracorporeal Membrane Oxygenation Using the Innominate Artery for Smaller Patients as Bridge to Lung Transplantation

Venoarterial extracorporeal membrane oxygenation (VA ECMO) may be used in patients with advanced cardiac or pulmonary failure. Arterial cannulation via the femoral arteries is suboptimal in many clinical scenarios because of associated complications and the potential for differential hypoxemia between the upper and lower body. To address these concerns, we typically use an upper body configuration (sport model) with right internal jugular and axillary or subclavian artery cannulation to allow a safe and durable means of providing VA ECMO support without differential hypoxemia. Unfortunately, this approach may not be feasible in smaller patients, whose vessels may preclude optimal use of the axillary or subclavian arteries and in those with systemic vasculopathy associated with connective tissue disorders. We describe a new approach for patients of small stature using the innominate artery through a mini-upper sternotomy in seven patients.

Puncture and wiring of extracorporeal circuit for cannula safe removal or exchange

A previously undescribed technique for removing a cannula used in extracorporeal life support (ECLS) is proposed, using an over-the-wire technique by puncturing the circuit and continuing with a pre-close technique for access site closure.

An Alternative Approach for Perioperative Extracorporeal Life Support Implantation

Central veno-arterial extracorporeal membrane oxygenation (ECMO) is traditionally implanted using direct cannulation of the aorta and right atrium. We aim to summarize the outcome of patients who underwent perioperative central ECMO implantation using an alternative surgical approach, which allows sternum closure and does not require resternotomy at the time of explantation. We retrospectively reviewed patients who required veno-arterial ECMO support at our institution between January 2013 and July 2014. Inclusion criteria were patients undergoing central ECMO implantation using the above-mentioned implantation technique. Nine patients (65 ± 14 years) were supported using this technique. Four patients underwent coronary bypass surgery as a primary surgery and the other five patients had combined coronary and valve surgeries. The average duration of ECMO support was 9 ± 7 days (range 1-24 days). The dominant postoperative complication was renal failure, which occurred in eight patients (89%). In four patients (44%), the ECMO was successfully removed. Survival rate to discharge was 22%. In conclusion, this study showed the feasibility of this alternative ECMO implantation technique. No technical issues were encountered. Extended support duration and reducing resternotomy risks may be the main advantages of this technique compared with conventional ECMO implantation methods.

Extracorporeal life support for adult cardiopulmonary failure

The use of extracorporeal life support (ECLS) or extracorporeal membrane oxygenation (ECMO), as it is also known, has rapidly expanded over the past decade. The increase in ECMO use is a consequence of multiple factors including significant advancements in extracorporeal technology, the emergence of data supporting its use, and a growing number of potential clinical applications. This review focuses on the various modes of ECLS as well as the clinical indications and available evidence for the use of extracorporeal support.

The "sport model": extracorporeal membrane oxygenation using the subclavian artery

Venoarterial extracorporeal membrane oxygenation is used for patients with refractory cardiopulmonary failure. Arterial cannulation by means of femoral arteries is fraught with potential complications. We present a technique for subclavian artery cannulation to provide a safe and durable means of venoarterial extracorporeal membrane oxygenation support.

Hybrid configurations via percutaneous access for extracorporeal membrane oxygenation: a single-center experience

Use of extracorporeal membrane oxygenation (ECMO) in adults has surged in recent years. Typical configurations are venovenous (VV), which provides respiratory support, or venoarterial (VA), which provides both respiratory and circulatory support. In patients supported with VV ECMO who develop hemodynamic compromise, an arterial limb can be added (venovenous-arterial ECMO) to provide additional circulatory support. For patients on VA ECMO who develop concomitant respiratory failure in the setting of some residual cardiac function, an oxygenated reinfusion limb can be added to the internal jugular vein (venoarterial-venous ECMO) to improve oxygen delivery to the cerebral and coronary circulation. Such hybrid configurations can provide differential support for various forms of cardiopulmonary failure. We describe 21 patients who ultimately received a hybrid configuration at our institution between 2012 and 2013. Eight patients (38.1%) died during ECMO support, four patients (19.0%) died after decannulation but before hospital discharge, and nine patients (42.9%) survived to hospital discharge. Our modest survival rate is likely related to the complexity and severity of illness of these patients, and this relative success suggests that hybrid configurations can be effective. It serves patients well to maintain a flexible and adaptable approach to ECMO configurations for their variable cardiopulmonary needs.

Arterial vascular complications in peripheral extracorporeal membrane oxygenation support: a review of techniques and outcomes

Peripheral venoarterial extracorporeal membrane oxygenation support provides prolonged support in the event of acute or acute-on-chronic cardiac and/or respiratory failure. This support serves as a bridge to recovery, decision-making, heart transplantation or ventricular-assist device implantation. It can be implanted either through a percutaneous approach using Seldinger's technique or via an open approach via the common femoral artery or the axillary artery. Early and late arterial vascular complications remain an important issue, with rates of up to 28% with femoral and axillary cannulation sites. Among them, limb ischemia requires prompt diagnosis and management to avoid limb amputation. In the case of peripheral artery cannulation, ipsilateral distal limb perfusion to prevent acute limb ischemia can be performed via a single lumen catheter through the artery or via the 'chimney graft' technique during extracorporeal membrane oxygenation implantation.

To ventilate, oscillate, or cannulate?

Ventilatory management of acute respiratory distress syndrome has evolved significantly in the last few decades. The aims have shifted from optimal gas transfer without concern for iatrogenic risks to adequate gas transfer while minimizing lung injury. This change in focus, along with improved ventilator and multiorgan system management, has resulted in a significant improvement in patient outcomes. Despite this, a number of patients develop hypoxemic respiratory failure refractory to lung-protective ventilation (LPV). The intensivist then faces the dilemma of either persisting with LPV using adjuncts (neuromuscular blocking agents, prone positioning, recruitment maneuvers, inhaled nitric oxide, inhaled prostacyclin, steroids, and surfactant) or making a transition to rescue therapies such as high-frequency oscillatory ventilation (HFOV) and/or extracorporeal membrane oxygenation (ECMO) when both these modalities are at their disposal. The lack of quality evidence and potential harm reported in recent studies question the use of HFOV as a routine rescue option. Based on current literature, the role for venovenous (VV) ECMO is probably sequential as a salvage therapy to ensure ultraprotective ventilation in selected young patients with potentially reversible respiratory failure who fail LPV despite neuromuscular paralysis and prone ventilation. Given the risk profile and the economic impact, future research should identify the patients who benefit most from VV ECMO. These choices may be further influenced by the emerging novel extracorporeal carbon dioxide removal devices that can compliment LPV. Given the heterogeneity of acute respiratory distress syndrome, each of these modalities may play a role in an individual patient. Future studies comparing LPV, HFOV, and VV ECMO should not only focus on defining the patients who benefit most from each of these therapies but also consider long-term functional outcomes.