The impact of small movements with dual lumen cannulae during venovenous extracorporeal membrane oxygenation: A computational fluid dynamics analysis.

BACKGROUND AND OBJECTIVES: Venovenous Extracorporeal Membrane Oxygenation (VV ECMO) provides respiratory support to patients with severe lung disease failing conventional medical therapy. An essential component of the ECMO circuit are the cannulas, which drain and return blood into the body. Despite being anchored to the patient to prevent accidental removal, minor cannula movements are common during ECMO. The clinical and haemodynamic consequences of these small movements are currently unclear. This study investigated the risk of thrombosis and recirculation caused by small movements of a dual lumen cannula (DLC) in an adult using computational fluid dynamics. METHODS: The 3D model of an AVALON Elite DLC (27 Fr) and a patient-specific vena cava and right atrium were generated for an adult patient on ECMO. The baseline cannula position was generated where the return jet enters the tricuspid valve. Alternative cannula positions were obtained by shifting the cannula 5 and 15 mm towards inferior (IVC) and superior (SVC) vena cava, respectively. ECMO settings of 4 L/min blood flow and pulsatile flow at SVC and IVC were applied. Recirculation was defined as a scalar value indicating the infused oxygenated blood inside the drainage lumen, while thrombosis risk was evaluated by shear stress, stagnation volume, washout, and turbulent kinetic energy. RESULTS: Recirculation for all models was less than 3.1 %. DLC movements between -5 to 15 mm increased shear stress and turbulence kinetic energy up to 24.7 % and 11.8 %, respectively, compared to the baseline cannula position leading to a higher predicted thrombosis risk. All models obtained a complete washout after nine seconds except for when the cannula migrated 15 mm into the SVC, indicating persisting stasis and circulating zones. CONCLUSION: In conclusion, small DLC movements were not associated with an increased risk of recirculation. However, they may increase the risk of thrombosis due to increased shear rate, turbulence, and slower washout of blood. Developing effective cannula securement devices may reduce this risk.

Blood flow and emboli transport patterns during venoarterial extracorporeal membrane oxygenation: A computational fluid dynamics study.

PROBLEM: Despite advances in Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO), a significant mortality rate persists due to complications. The non-physiological blood flow dynamics of VA-ECMO may lead to neurological complications and organ ischemia. Continuous retrograde high-flow oxygenated blood enters through a return cannula placed in the femoral artery which opposes the pulsatile deoxygenated blood ejected by the left ventricle (LV), which impacts upper body oxygenation and subsequent hyperoxemia. The complications underscore the critical need to comprehend the impact of VA-ECMO support level and return cannula size, as mortality remains a significant concern. AIM: The aim of this study is to predict and provide insights into the complications associated with VA-ECMO using computational fluid dynamics (CFD) simulations. These complications will be assessed by characterising blood flow and emboli transport patterns through a comprehensive analysis of the influence of VA-ECMO support levels and arterial return cannula sizes. METHODS: Patient-specific 3D aortic and major branch models, derived from a male patient's CT scan during VA-ECMO undergoing respiratory dysfunction, were analyzed using CFD. The investigation employed species transport and discrete particle tracking models to study ECMO blood (oxygenated) mixing with LV blood (deoxygenated) and to trace emboli transport patterns from potential sources (circuit, LV, and aorta wall). Two cannula sizes (15 Fr and 19 Fr) were tested alongside varying ECMO pump flow rates (50%, 70%, and 90% of the total cardiac output). RESULTS: Cannula size did not significantly affect oxygen transport. At 90% VA-ECMO support, all arteries distal to the aortic arch achieved 100% oxygen saturation. As support level decreased, oxygen transport to the upper body also decreased to a minimum saturation of 73%. Emboli transport varied substantially between emboli origin and VAECMO support level, with the highest risk of cerebral emboli coming from the LV with a 15 Fr cannula at 90% support. CONCLUSION: Arterial return cannula sizing minimally impacted blood oxygen distribution; however, it did influence the distribution of emboli released from the circuit and aortic wall. Notably, it was the support level alone that significantly affected the mixing zone of VA-ECMO and cardiac blood, subsequently influencing the risk of embolization of the cardiogenic source and oxygenation levels across various arterial branches.

Flow characterization of Maquet and Bio-Medicus multi-stage drainage cannulae during venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Drainage cannulae extract blood from a patient during venoarterial extracorporeal membrane oxygenation (VA ECMO), a treatment that temporarily supports patients undergoing severe heart and/or lung dysfunction. Currently, the two most commonly used multi-stage drainage cannulae are manufactured by Maquet and Bio-Medicus, but their designs vary in many aspects which impacts the generated flow dynamics. Therefore, this study aimed to use computational fluid dynamics (CFD) to explore the flow characteristics of the aforementioned cannulae and their impact on complications such as thrombosis. METHODS: The Maquet and Bio-Medicus cannulae were 3D modelled within a patient-specific geometry of the venous vasculature taken from a computed tomography scan of a patient undergoing VA ECMO. A drainage flow rate of 4 L/min was assigned to each cannula. Lastly, a stress blended eddy simulation turbulence model was employed to resolve bulk flow turbulence. RESULTS: The proximal row of side holes in both cannulae generated high intensity counter-rotating vortices, thus generating supraphysiological shear. These proximal rows were also responsible for the majority of flow extraction in both cannulae (>1.6 L/min). Despite identical simulation settings, each cannulae had differing impacts on global flow dynamics. For instance, the Bio-Medicus model produced a total stagnant blood volume of 25.6 ml, compared to 17.8 ml the Maquet cannula, thereby increasing the risk of thrombosis. CONCLUSIONS: Overall, our results demonstrate that differences in design clearly impact flow dynamics and risk of complications. Therefore, further work in optimizing cannula design may be beneficial to prevent harmful flow characteristics.

Effect of RVAD Cannulation Length on Right Ventricular Thrombosis Risk: An In Silico Investigation.

Left ventricular assist devices (LVADs) have been used off-label as long-term support of the right heart due to the lack of a clinically approved durable right VAD (RVAD). Whilst various techniques to reduce RVAD inflow cannula protrusion have been described, the implication of the protrusion length on right heart blood flow and subsequent risk of thrombosis remains poorly understood. This study investigates the influence of RVAD diaphragmatic cannulation length on right ventricular thrombosis risk using a patient-specific right ventricle in silico model validated with particle image velocimetry. Four cannulation lengths (5, 10, 15 and 25 mm) were evaluated in a one-way fluid-structure interaction simulation with boundary conditions generated from a lumped parameter model, simulating a biventricular supported condition. Simulation results demonstrated that the 25-mm cannulation length exhibited a lower thrombosis risk compared to 5-, 10- and 15-mm cannulation lengths due to improved flow energy distribution (25.2%, 24.4% and 17.8% increased), reduced stagnation volume (72%, 68% and 49% reduction), better washout rate (13.0%, 11.6% and 9.1% faster) and lower blood residence time (6% reduction). In the simulated scenario, our findings suggest that a longer RVAD diaphragmatic cannulation length may be beneficial in lowering thrombosis risk; however, further clinical studies are warranted.

Use of Sutureless Valve in Aortic Root Enlargement.

AIM: The small aortic annulus is a surgical challenge in patients undergoing aortic valve replacement which may lead to patient prosthesis mismatch. Management options include aortic root enlargement, aortic root replacement, and the use of sutureless valves. In this case series, we report our results with aortic root enlargement, sutureless valve implantation, and benchtop modelling of the radial forces exerted. METHODS: Five patients underwent aortic root enlargement and insertion of the Perceval valve as part of the management strategy to enlarge their effective orifice area. We further investigate this strategy with a benchtop model to quantify the radial forces exerted by the Perceval valve on the aortic annulus. Radial and hoop forces on the aortic annulus and inner ring of the Perceval valve were recorded using a Mylar force tester. RESULTS: Five female patients with native annulus between 18mm-20mm underwent root enlargement and insertion of a Perceval S valve. The postoperative course was uncomplicated for all patients except for one who required a permanent pacemaker insertion. Transvalvular pressure gradients remained low at up to 4 years of follow-up (12 mmHg-21 mmHg), with no evidence of paravalvular leak. Benchtop testing demonstrated radial forces exerted at the annulus in all-size Perceval S valves to be within physiological variables, whereas compressive forces required to deform the valves were supraphysiological. CONCLUSIONS: The deployment of a sutureless valve within a surgical enlarged aortic root is a feasible solution in patients with a small aortic root.

Smaller Return Cannula in Venoarterial Extracorporeal Membrane Oxygenation Does Not Increase Hemolysis: A Single-Center, Cohort Study.

The aim of this study was to explore the association between arterial return cannula diameter and hemolysis during peripheral VA ECMO. We identified 158 adult patients who received peripheral VA ECMO at our institution from the national ECMO database (EXCEL) between January 2019 and July 2021. We classified patients into a small cannula group (15 Fr diameter, n = 45) and a large cannula group (≥17 Fr diameter, n = 113), comparing incidences of clinical hemolysis and plasma free hemoglobin ( pf Hb). Moderate hemolysis is defined as having pf Hb 0.05-0.10 g/L and severe hemolysis as having pf Hb >0.10 g/L sustained for at least two consecutive readings or leading to a circuit change. There were no significant differences in rates of moderate hemolysis between small and large cannula groups (1 vs . 6; p = 0.39) and severe hemolysis (0 vs . 3; p = 0.27), nor was the pf Hb level significantly different at 4 hours (0.086 ± 0.096 vs . 0.112 ± 0.145 g/L; p = 0.58) and at 24 hours (0.042 ± 0.033 vs . 0.051 ± 0.069 g/L; p = 0.99). There were no increased rates of hemolysis when comparing small versus large arterial return cannula diameter in peripheral VA ECMO.

Computational analysis of thrombosis risk with variations in left ventricular assist device inflow cannula design in a multi-patient model.

BACKGROUND AND OBJECTIVES: Left ventricular assist devices (LVADs) are mechanical pumps used to support patients with end-stage heart failure. The inflow cannula is a critical component of the LVAD as it connects the pump to the left ventricle, allowing blood to be drawn from the heart. However, the design of the cannula can significantly impact LV hemodynamics and cause complications, including thrombosis. Therefore, this study aimed to analyze the numerical effects of left ventricle (LV) size on cannula design in order to enhance hemodynamic performance using post-operative left ventricular assist device (LVAD) models. METHODS: A parametric design evaluation of two different inflow cannulas were carried out on left ventricles (LV) of varying sizes (ranging from 154 to 430 ml) constructed from computerized tomography (CT) data from VAD patients using computational fluid dynamics (CFD) simulations. The study analyzed three key factors contributing to thrombosis formation: blood residence time, blood stagnation ratio, and wall shear stress. RESULTS: Results showed higher blood residence time and stagnation ratio for larger left ventricular sizes. In addition, increasing the insertion length of the cannula reduced the average wall shear stress. CONCLUSION: Overall, the study's findings suggest that the optimal cannula shape for LVADs varies with left ventricular size.

ECMO PAL: using deep neural networks for survival prediction in venoarterial extracorporeal membrane oxygenation.

PURPOSE: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a complex and high-risk life support modality used in severe cardiorespiratory failure. ECMO survival scores are used clinically for patient prognostication and outcomes risk adjustment. This study aims to create the first artificial intelligence (AI)-driven ECMO survival score to predict in-hospital mortality based on a large international patient cohort. METHODS: A deep neural network, ECMO Predictive Algorithm (ECMO PAL) was trained on a retrospective cohort of 18,167 patients from the international Extracorporeal Life Support Organisation (ELSO) registry (2017-2020), and performance was measured using fivefold cross-validation. External validation was performed on all adult registry patients from 2021 (N = 5015) and compared against existing prognostication scores: SAVE, Modified SAVE, and ECMO ACCEPTS for predicting in-hospital mortality. RESULTS: Mean age was 56.8 ± 15.1 years, with 66.7% of patients being male and 50.2% having a pre-ECMO cardiac arrest. Cross-validation demonstrated an inhospital mortality sensitivity and precision of 82.1 ± 0.2% and 77.6 ± 0.2%, respectively. Validation accuracy was only 2.8% lower than training accuracy, reducing from 75.5% to 72.7% [99% confidence interval (CI) 71.1-74.3%]. ECMO PAL accuracy outperformed the ECMO ACCEPTS (54.7%), SAVE (61.1%), and Modified SAVE (62%) scores. CONCLUSIONS: ECMO PAL is the first AI-powered ECMO survival score trained and validated on large international patient cohorts. ECMO PAL demonstrated high generalisability across ECMO regions and outperformed existing, widely used scores. Beyond ECMO, this study highlights how large international registry data can be leveraged for AI prognostication for complex critical care therapies.

Estimation of Left Ventricular Stroke Work for Rotary Left Ventricular Assist Devices.

Continuous monitoring of left ventricular stroke work (LVSW) may improve the medical management of patients with rotary left ventricular assist devices (LVAD). However, implantable pressure-volume sensors are limited by measurement drift and hemocompatibility. Instead, estimator algorithms derived from rotary LVAD signals may be a suitable alternative. An LVSW estimator algorithm was developed and evaluated in a range of in vitro and ex vivo cardiovascular conditions during full assist (closed aortic valve [AoV]) and partial assist (opening AoV) mode. For full assist, the LVSW estimator algorithm was based on LVAD flow, speed, and pump pressure head, whereas for partial assist, the LVSW estimator combined the full assist algorithm with an estimate of AoV flow. During full assist, the LVSW estimator demonstrated a good fit in vitro and ex vivo (R 2 : 0.97 and 0.86, respectively) with errors of ± 0.07 J. However, LVSW estimator performance was reduced during partial assist, with in vitro : R 2 : 0.88 and an error of ± 0.16 J and ex vivo : R 2 : 0.48 with errors of ± 0.11 J. Further investigations are required to improve the LVSW estimate with partial assist; however, this study demonstrated promising results for a continuous estimate of LVSW for rotary LVADs.

Impact of Concomitant Mitral Regurgitation on the Hemodynamic Indicators of Aortic Stenosis.

Background In patients with aortic stenosis (AS), the presence of mitral regurgitation (MR) can lead to underestimation of AS severity and worse clinical outcomes. The objective of this study was to characterize the magnitude of the effects of concomitant MR on hemodynamic indicators of AS severity using clinical data and a computational cardiovascular simulation. Methods and Results Echocardiographic data from 1427 patients with severe AS were used to inform a computational cardiovascular system model, and varying degrees of MR and AS were simulated. Hemodynamic data, including left ventricular and aortic pressure waveforms, were generated for all simulations. Simulated reduction in mean transaortic pressure gradient (MPG) associated with MR was then used to calculate the adjusted MPG in the clinical cohort. MR was present in 861 (60%) patients. Compared with patients without MR, patients with MR had a lower aortic-valve area (0.83±0.2 cm2 versus 0.75±0.2; P<0.001) and were more likely to have a low-gradient pattern (MPG <40 mm Hg) (45% versus 54%; P<0.001). Simulations showed that the presence of concomitant mild, moderate, and severe MR with AS was accompanied by a mean reduction in MPG of 10%, 29%, and 40%, respectively. For patients with MR, their calculated adjusted MPG was on average 24% higher than their MPG (52±22 versus 42±16 mm Hg). Of the 467 patients with low-gradient AS and MR, 240 (51%) would reclassify as high gradient based on their adjusted MPG. Conclusions Concomitant MR results in lower MPG and reduced forward flow compared with isolated AS. Careful quantitation of MR should be factored into the assessment of AS severity to mitigate for potential underestimation.

The effect of drainage cannula tip position on risk of thrombosis during venoarterial extracorporeal membrane oxygenation.

BACKGROUND AND OBJECTIVES: Venoarterial extracorporeal membrane oxygenation (VA ECMO) is able to support critically ill patients undergoing refractory cardiopulmonary failure. It relies on drainage cannulae to extract venous blood from the patient, but cannula features and tip position may impact flow dynamics and thrombosis risk. Therefore, this study aimed to investigate the effect of tip position of single-stage (SS) and multi-stage (MS) VA ECMO drainage cannulae on the risk of thrombosis. METHODS: Computational fluid dynamics was used to model flow dynamics within patient-specific geometry of the venous vasculature. The tip of the SS and MS cannula was placed in the superior vena cava (SVC), SVC-Right atrium (RA) junction, mid-RA, inferior vena cava (IVC)-RA junction, and IVC. The risk of thrombosis was assessed by measuring several factors. Blood residence time was measured via an Eulerian approach through the use of a scalar source term. Regions of stagnant volume were recognised by identifying regions of low fluid velocity and shear rate. Rate of blood washout was calculated by patching the domain with a scalar value and measuring the rate of fluid displacement. Lastly, wall shear stress values were determined to provide a qualitative understanding of potential blood trauma. RESULTS: Thrombosis risk varied substantially with position changes of the SS cannula, which was less evident with the MS cannula. The SS cannula showed reduced thrombosis risk arising from stagnant regions when placed in the SVC or SVC-RA junction, whereas an MS cannula was predicted to create stagnant regions during all tip positions. When positioned in the IVC-RA junction or IVC, the risk of thrombosis was higher in the SS cannula than in the MS cannula due to both high and low shear flow. CONCLUSION: Tip position of the drainage cannula impacts cannula flow dynamics and, subsequently, the risk of thrombosis. The use of MS cannulae can reduce high shear-related thrombosis, but SS cannulae can eliminate stagnant regions when advanced into the SVC. Therefore, the choice of cannula design and tip position should be carefully considered during cannulation.

Ventricular Flow Dynamics With an Intra-Ventricular Balloon Pump: An In Vitro Analysis.

Due to the high treatment costs associated with durable ventricular assist devices, an intra-ventricular balloon pump (IVBP) was developed to provide low-cost, short-term support for patients suffering from severe heart failure. It is imperative that intraventricular flow dynamics are evaluated with an IVBP to ensure stagnation points, and potential regions for thrombus formation, are avoided. This study used particle image velocimetry to evaluate flow patterns within the left ventricle of a simulated severe heart failure patient with IVBP support to assess left ventricle pulsatility as an indicator of the likelihood of flow stasis. Two inflation timings were evaluated against the baseline severe heart failure condition: IVBP co-pulsation and IVBP counter-pulsation with respect to ventricular systole. IVBP co-pulsation was found to have a reduced velocity range compared to the severe heart failure condition (0.44 m/s compared to 0.54 m/s). IVBP co-pulsation demonstrated an increase in peak velocities (0.25 m/s directed toward the aortic valve during systole, as opposed to 0.2 m/s in severe heart failure), indicating constructive energy in systole and cardiac output (1.7 L/min increase with respect to severe heart failure baseline - 3.5 L/min) throughout the cardiac cycle. IVBP counter-pulsation, while exhibiting the greatest peak systolic velocity directed to the aortic valve (0.4 m/s) was found to counterasct the natural vortex flow pattern during ventricular filling, as well as inducing a secondary ventricular pulse during diastole and a 23% increase in left ventricle end-diastolic volume (indicative of dilation). Ideal IVBP actuation timing did not result in reduced intraventricular pulsatility, indicating promising blood washout.

Current and future strategies to monitor and manage coagulation in ECMO patients.

Extracorporeal membrane oxygenation (ECMO) can provide life-saving support for critically ill patients suffering severe respiratory and/or cardiac failure. However, thrombosis and bleeding remain common and complex problems to manage. Key causes of thrombosis in ECMO patients include blood contact to pro-thrombotic and non-physiological surfaces, as well as high shearing forces in the pump and membrane oxygenator. On the other hand, adverse effects of anticoagulant, thrombocytopenia, platelet dysfunction, acquired von Willebrand syndrome, and hyperfibrinolysis are all established as causes of bleeding. Finding safe and effective anticoagulants that balance thrombosis and bleeding risk remains challenging. This review highlights commonly used anticoagulants in ECMO, including their mechanism of action, monitoring methods, strengths and limitations. It further elaborates on existing anticoagulant monitoring strategies, indicating their target range, benefits and drawbacks. Finally, it introduces several highly novel approaches to real-time anticoagulation monitoring methods including sound, optical, fluorescent, and electrical measurement as well as their working principles and future directions for research.

The effect of arterial cannula tip position on differential hypoxemia during venoarterial extracorporeal membrane oxygenation.

Interaction between native ventricular output and venoarterial extracorporeal membrane oxygenation (VA ECMO) flow may hinder oxygenated blood flow to the aortic arch branches, resulting in differential hypoxemia. Typically, the arterial cannula tip is placed in the iliac artery or abdominal aorta. However, the hemodynamics of a more proximal arterial cannula tip have not been studied before. This study investigated the effect of arterial cannula tip position on VA ECMO blood flow to the upper extremities using computational fluid dynamics simulations. Four arterial cannula tip positions (P1. common iliac, P2. abdominal aorta, P3. descending aorta and P4. aortic arch) were compared with different degrees of cardiac dysfunction and VA ECMO support (50%, 80% and 90% support). P4 was able to supply oxygenated blood to the arch vessels at all support levels, while P1 to P3 only supplied the arch vessels during the highest level (90%) of VA ECMO support. Even during the highest level of support, P1 to P3 could only provide oxygenated VA-ECMO flow at 0.11 L/min to the brachiocephalic artery, compared with 0.5 L/min at P4. This study suggests that cerebral perfusion of VA ECMO flow can be increased by advancing the arterial cannula tip towards the aortic arch.

Tissue-Mimicking Materials for Ultrasound-Guided Needle Intervention Phantoms: A Comprehensive Review.

Ultrasound-guided needle interventions are common procedures in medicine, and tissue-mimicking phantoms are widely used for simulation training to bridge the gap between theory and clinical practice in a controlled environment. This review assesses tissue-mimicking materials from 24 studies as candidates for a high-fidelity ultrasound phantom, including methods for evaluating relevant acoustic and mechanical properties and to what extent the reported materials mimic the superficial layers of biological tissue. Speed of sound, acoustic attenuation, Young's modulus, hardness, needle interaction forces, training efficiency and material limitations were systematically evaluated. Although gelatin and agar have the closest acoustic values to tissue, mechanical properties are limited, and strict storage protocols must be employed to counteract dehydration and microbial growth. Polyvinyl chloride (PVC) has superior mechanical properties and is a suitable alternative if durability is desired and some ultrasound realism to human tissue may be sacrificed. Polyvinyl alcohol (PVA), while also requiring hydration, performs well across all categories. Furthermore, we propose a framework for the evaluation of future ultrasound-guided needle intervention tissue phantoms to increase the fidelity of training programs and thereby improve clinical performance.

Clinician Perspectives on Cannulation for Extracorporeal Cardiopulmonary Resuscitation: A Mixed Methods Analysis.

Out-of-hospital cardiac arrest is a leading cause of mortality with survival rates of less than 10%. In selected patients, survival may be improved via timely application of extracorporeal cardiopulmonary resuscitation (ECPR). However, ECPR is a complex and resource intensive intervention with a high risk of complications that impair widespread clinical adoption. This study employed a mixed approach of qualitative interview analysis embedded with quantitative data collection to uncover the major hurdles faced by clinicians during ECPR initiation. We conducted semi-structured interviews with eight ECPR intensive care specialists with 2-10 years of experience working at a large, tertiary ECPR center in Australia. Clinicians identified dilation as the most time-consuming step, followed by draping, and decision-making during extracorporeal membrane oxygenation patient selection. The most challenging step was the decision-making for patient selection, followed by dilation and imaging. These findings uncovered key barriers to ECPR, and identified priority areas for further research and clinical training. Major logistical hindrances will require well-defined protocols and improved clinical training. Engineering innovations in the identified areas may improve the delivery of ECPR, making it simpler and faster to deliver.

In silico Prediction of Thrombosis Risk in a Ventricular Assist Device Supported Right Heart: The Impact of Cannulation Site.

Right ventricular assist device (RVAD) associated thrombosis is a serious complication that may arise due to unfavorable blood flow dynamics (blood stasis) caused by RVAD cannula protrusion within the chambers. This study aims to investigate the thrombosis risk of cannulation via the right atrium (RA) and right ventricle (RV) (diaphragmatic) under full RVAD support using computational fluid dynamics. A HeartWare HVAD inflow cannula was virtually implanted in either the RA or RV of a rigid-walled right heart geometry (including RA, RV, superior, and inferior vena cava) extracted from computed tomography data of a biventricular support patient. Transient simulations, validated with particle image velocimetry, were performed with constant inflow. Thrombosis risk was predicted by analyzing the time-averaged blood velocity, blood stagnation volume, washout rate, and blood residence time (BRT). Results showed that RA cannulation disturbed the physiological swirling flow structure which can be found in an uncannulated RA. This led to a large low-velocity recirculation flow in the RV, increasing the thrombosis risk. Contrarily, RV diaphragmatic cannulation showed better preservation of swirling flow in the RA and flow ejection into the RV. Consequently, RV diaphragmatic cannulation exhibited a better washout rate (99% vs. 57% of old blood was replaced in 12 s), lower blood stagnation volume (0.13 ml vs. 32.85 ml), and BRT (4.2 s vs. 7.1 s) than the RA cannulation in this simulated non-pulsatile case. Our findings suggest that RV diaphragmatic cannulation had a lower thrombosis risk and might be more favorable in a full RVAD-supported setting.

Ex vivo evaluation of personal protective equipment in hands-on defibrillation.

Background: Defibrillation guidelines recommend avoiding patient contact during shock delivery. However, hands-on defibrillation (compressions during shock) and manual pressure augmentation (MPA - pushing on the defibrillator pads during shock) may lead to improved clinical outcomes. There are limited data addressing the protection provided by personal protective equipment (PPE) during hands-on defibrillation and MPA. This study investigated the hand-to-hand and hand-to-knee leakage current experienced by a simulated kneeling provider wearing different PPE. Methods: A defibrillator was used in experiments on a pork shoulder, investigating three different hands-on positions: closed fist on defibrillator pads; open palm on pads with inadvertent finger contact (overhang); and open palm on the chest. Evaluated PPE included single and double gloves (nitrile and latex) and rescuer cargo trousers in wet and dry conditions (N = 126 experiments). Results: Mean hand-to-hand leakage currents in MPA without PPE was 0.41 mA (0.2-0.74 mA) and with PPE was 0.2 mA (0.08-0.58 mA). For experiments involving finger or palm contact on the chest, wearing any PPE resulted in a >99% reduction in mean leakage currents from an average 354.58 mA (258.96-446.22 mA) to an average 0.48 mA (0.16-1.56 mA). Rescuer trousers were insulative in dry conditions even without gloves (0.2-1.2 mA). Conclusion: This study demonstrated that the tested clinical examination gloves markedly reduced leakage current to the rescuer and that the lowest levels of leakage current occurred during MPA attributed to the electrical insulation of the pads.