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.

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.

Effects of adding the second drainage cannula in severely hypoxemic patients supported with VV ECMO due to COVID-19-associated ARDS.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) is a recognized method of support in patients with severe and refractory acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 infection. While veno-venous (VV) ECMO is the most common type, some patients with severe hypoxemia may require modifications to the ECMO circuit. In this study, we aimed to investigate the effects of adding a second drainage cannula to the circuit in patients with refractory hypoxemia, on their gas exchange, mechanical ventilation, ECMO settings, and clinical outcomes. METHODS: We conducted an observational retrospective study based on a single-center institutional registry including all consecutive cases of COVID-19 patients requiring ECMO admitted to the Centre of Extracorporeal Therapies in Warsaw between March 1, 2020 and March 1, 2022. We selected patients who had an additional drainage cannula inserted. Changes in ECMO and ventilator settings, blood oxygenation, and hemodynamic parameters, as well as clinical outcomes were assessed. RESULTS: Of 138 VV ECMO patients, 12 (9%) patients met the inclusion criteria. Ten patients (83%) were men, and mean age was 42.2 ± 6.8. An addition of drainage cannula resulted in a significant raise in ECMO blood flow (4.77 ± 0.44 to 5.94 ± 0.81 [L/min]; p = 0.001), and the ratio of ECMO blood flow to ECMO pump rotations per minute (RPM), whereas the raise in ECMO RPM alone was not statistically significant (3432 ± 258 to 3673 ± 340 [1/min]; p = 0.064). We observed a significant drop in ventilator FiO2 and a raise in PaO2 to FiO2 ratio, while blood lactates did not change significantly. Nine patients died in hospital, one was referred to lung transplantation center, two were discharged uneventfully. CONCLUSIONS: The use of an additional drainage cannula in severe ARDS associated with COVID-19 allows for an increased ECMO blood flow and improved oxygenation. However, we observed no further improvement in lung-protective ventilation and poor survival.

Chemotherapy induced phlebitis experienced by women with breast cancer following administration of epirubicin using a volumetric infusion pump: an observational study.

OBJECTIVE: To establish the incidence and severity of chemotherapy-induced phlebitis (CIP) following administration of epirubicin chemotherapy using a volumetric infusion pump (Hospira Plum 360), compared to a previous study of manual injection of epirubicin. Also the study aimed to gain insight into staff perceptions of ease of use and safety of infusion pump administration. METHODS: An observational study of women with breast cancer (n = 47) receiving epirubicin via volumetric infusion pump. Phlebitis was reported through a participant self-assessment questionnaire and graded by clinical assessment three weeks after each chemotherapy cycle. Staff perceptions were explored using questionnaires. RESULTS: Infusion pump administration delivered a significantly higher concentration of epirubicin (p < 0.001), a significantly higher rate of grade 3 and 4 participant reported CIP between cycles (p = 0.003) but demonstrated no significant difference in grade 3 and 4 CIP when assessed clinically three weeks after treatment (p = 0.157). CONCLUSION: Peripheral epirubicin administration will result in severe CIP being experienced by a proportion of patients irrespective of whether infusion pump or manual injection method is used. Those at high risk of severe CIP should be informed of the risk and offered a central line. For those with a lower risk of severe phlebitis use of the infusion pump appears to be a safe option.

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.

Comparison of the efficacy of different venous intubation in venous-arterial extracorporeal membrane oxygenation assisted lung transplantation / 中华危重病急救医学

Objective:To compare the curative effects of different venous cannulas and drainage to improve patient's whole body oxygenation during the auxiliary process of venous-arterial extracorporeal membrane oxygenation (VA-ECMO) in lung transplantation.Methods:From December 2016 to December 2019, 12 patients who were assisted by VA-ECMO in one lung transplantation in People's Hospital of Henan Province were selected as the research objects. According to the number of side holes of venous cannulas, they were divided into two groups: one group with few side holes and other group with multiple side holes. The differences in blood gas indexes among the right radial artery, left radial artery, and right internal jugular vein before and after assistance were compared, and the assistance effect was evaluated.Results:The arterial partial pressure of oxygen (PaO 2) of blood gas indexes of the right and left radial arteries in both groups were significantly higher than that before assistance [mmHg (1 mmHg = 0.133 kPa): right and left radial artery in few side holes group: 79.5±4.2 vs. 48.3±3.8 and 88.1±3.5 vs. 48.3±3.8; right and left radial artery in multiple side holes group: 67.7±5.9 vs. 48.7±3.2 and 84.0±3.8 vs. 48.7±3.2, all P < 0.05]. The arterial partial pressure of carbon dioxide (PaCO 2) of blood gas index was significantly lower than that before assistance (mmHg: 44.2±2.6 vs. 71.7±4.4 for the right radial artery and 44.7±1.4 vs. 71.7±4.4 for the left radial artery in the group with few side holes; 46.2±2.1 vs. 71.2±3.5 for the right radial artery and 44.1±1.9 vs. 71.2±3.5 for the left radial artery in the group with multiple side holes, all P < 0.05). The partial pressure of oxygen in venous blood (PvO 2) of blood gas index of ECMO system in the group with few side holes was significantly lower than that of the multiport side holes group (mmHg: 56.4±3.2 vs. 88.7±1.5, P < 0.01), and the partial pressure of carbon dioxide in venous blood (PvCO 2) was significantly higher than that of multiport side holes group (mmHg: 63.6±3.7 vs. 44.2±1.7, P < 0.01). Conclusions:When VA-ECMO is used in lung transplantation, the superior vena cava blood flow can be fully drained by using intravenous cannula with few side holes. It can effectively improve the oxygenation of the upper body of lung transplant patients, avoid the dilemma of hypoxemia in the upper body and hyperxemia in the lower body, provide more effective assistance to patients undergoing single lung transplantation, and is more meaningful for improving the oxygenation status of the whole body in patients undergoing single lung transplantation.

[Ultrasound-guided peripheral venous puncture in patients with a poor venous status]. / Die ultraschallgesteuerte periphere Venenpunktion bei schlechtem Venenstatus.

BACKGROUND: In the case of a poor peripheral venous status the use of conventional approaches is associated with several failed attempts, delay of treatment, increased pain and escalation to more invasive techniques. Ultrasound-guided venous access has become increasingly popular for difficult venous access; however, in German-speaking countries it has not yet become as popular as in English-speaking countries. First attempt success rates are high, but the factors contributing to the time needed for ultrasound-guided venous access are not well investigated. It is hypothesized that body mass index (BMI), vein diameter and depth contribute to the time needed for successfully establishing a peripheral vein access in patients with a difficult venous status. METHODS: This study included 68 patients with a poor venous status. After written consent was obtained patient characteristics were documented and upper extremity veins eligible for access were scanned with ultrasound with the aim of performing an ultrasound-guided venous access. The following time periods were documented: 1) first skin contact with the ultrasound probe, 2) time to identify an accessible vein, 3) time for venous access. RESULTS: Of the patients 67 were successfully punctured by ultrasound-guided venous access, 65 at the first attempt and 2 at the second attempt. In one patient conventional venous access was obtained at the same time. A higher BMI was associated with a significantly shorter total puncture time (+1 BMI point ≙ -2.25 s) and a shorter vein identification time (+1 BMI point ≙ -1.82 s). A greater vein diameter correlated with a shorter total time (-14.23 s/mm) and a greater depth correlated with an increased total time (+1.65 s/mm). CONCLUSION: A greater vein diameter and a higher BMI contribute to a shorter time period for ultrasound-guided venous access. Obese patients with difficult venous access may benefit from ultrasound-guided venous access, which could be explained by the imaging contrast with a higher proportion of subcutaneous fatty tissue.

Blood sampled from existing peripheral IV cannulae yields results equivalent to venepuncture: a systematic review.

OBJECTIVES: To establish whether blood samples taken from used peripheral intravenous cannulae are clinically interchangeable with venepuncture. DESIGN: Systematic review. PubMed, Web of Science and Embase were searched for relevant trials. SETTING: Trials which compared blood samples from used peripheral intravenous cannulae to venepuncture and provided limits of agreement or data which allowed calculation of limits of agreement. PARTICIPANTS: Seven trials with 746 participants. Blood tests included 13 commonly ordered biochemistry, haematology and blood gas measurements. MAIN OUTCOME MEASURES: 95% limits of agreement. Data were pooled using inverse variance weighting and compared to a clinically acceptable range estimated by expert opinion from previous trials. RESULTS: Limits of agreement for blood samples from used peripheral intravenous cannulae were within the clinically acceptable range for sodium, chloride, urea, creatinine and haematology samples. Limits of agreement for potassium were ±0.47 mmol/L which exceeded the clinically acceptable range. Peripheral intravenous cannula samples for blood gas analysis gave limits of agreement which far exceeded the clinically acceptable range. CONCLUSIONS: Blood sampling from used peripheral intravenous cannulae is a reasonable clinical practice for haematology and biochemistry samples. Potassium samples from used peripheral intravenous cannulae can be used in situations where error up to ±0.47 mmol/L is acceptable. Peripheral intravenous cannula samples should not be used for blood gas analysis.

Impact of cannula size and line length on venous line pressure in pediatric VA-/VV-ECLS circuits.

The objective of this study was to do an in vitro evaluation of venous line pressure using different venous line lengths and venous cannula sizes in pediatric venoarterial extracorporeal life support (VA-ECLS) and venovenous ECLS (VV-ECLS) circuits. The pediatric VA-ECLS circuit consisted of a Xenios i-cor diagonal pump, a Maquet Quadrox-i pediatric oxygenator, a Medtronic Biomedicus arterial cannula, a Biomedicus venous cannula, and 1/4″ ID arterial and venous tubing. The pediatric VV-ECLS circuit was similar, except it included a Maquet Avalon ELITE bi-caval dual lumen cannula. Circuits were primed with lactated Ringer's solution and packed red blood cells (hematocrit 40%). Trials were conducted at various flow rates (VA-ECLS: 250-1250 mL/min, VV-ECLS: 250-2000 mL/min) using different venous tubing lengths (2, 4, and 6 feet) and cannula sizes (VA-ECLS: A8Fr/V10Fr, A10Fr/V12Fr and A12Fr/V14Fr, VV-ECLS: 13Fr, 16Fr, 19Fr, 20Fr and 23Fr) at 36°C. Real-time pressure and flow data were recorded for analysis. The use of a small-caliber venous cannula significantly increased the venous line pressure in the 2 pediatric circuits (P < 0.01). Shorter venous tubing lengths significantly reduced the venous line pressure at high flow rates (P < 0.01). The VV-ECLS circuit had larger negative pre-pump pressure drops (7.2 to -102.2 mm Hg) when compared to the VA-ECLS circuit (0.7 to -60.7 mm Hg). Selecting an appropriate venous cannula and a shorter venous tubing when feasible may significantly reduce the pressure drop of the venous line in pediatric VA-ECLS and VV-ECLS circuits and improve venous drainage.

Effect of inflow cannula side-hole number on drainage flow characteristics: flow dynamic analysis using numerical simulation.

BACKGROUND: Venous drainage in cardiopulmonary bypass is a very important factor for safe cardiac surgery. However, the ideal shape of venous drainage cannula has not been determined. In the present study, we evaluated the effect of side-hole number under fixed total area and venous drainage flow to elucidate the effect of increasing the side-hole numbers. METHOD: Computed simulation of venous drainage was performed. Cannulas were divided into six models: an end-hole model (EH) and models containing four (4SH), six (6SH), eight (8SH), 10 (10SH) or 12 side-holes (12SH). Total orifice area of the side-holes was fixed to 120 mm2 on each side-hole cannula. The end-hole orifice area was 36.3 mm2. The total area of the side-holes was kept constant when the number of side-holes was increased. RESULT: The mean venous drainage flow rate of the EH, 4SH, 6SH, 8SH, 10SH and 12SH was 2.57, 2.52, 2.51, 2.50, 2.49, 2.41 L/min, respectively. The mean flow rate decreased in accordance with the increased number of side-holes. CONCLUSION: We speculate that flow separation at the most proximal site of the side-hole induces stagnation of flow and induces energy loss. This flow separation may hamper the main stream from the end-hole inlet, which is most effective with low shear stress. The EH cannula was associated with the best flow rate and flow profile. However, by increasing side-hole numbers, flow separation occurs on each side-hole, resulting in more energy loss than the EH cannula and flow rate reduction.

Single Femoral Venous Drainage Versus Both Vena Cava Drainage in Isolated Repeat Tricuspid Valve Surgery.

To assess the potential advantages of minimally invasive surgery using a single femoral venous drainage method versus femoral venous and superior vena cava or jugular venous drainage method during repeat tricuspid valve surgery.From January 2010 to December 2016, 50 repeat tricuspid valve procedures were performed using a minimally invasive approach without aortic cross-clamping at our institution. The arterial cannula was inserted into the femoral artery, and at the same time, the venous cannula was placed in the femoral vein in 28 patients (FV group) during cardiopulmonary bypass (CPB). The venous cannula was inserted into the femoral vein and the superior vena cava or jugular vein in 22 patients (FSV group).Overall, 36 patients underwent tricuspid valve replacement (TVR) and 14 patients underwent tricuspid valvuloplasty (TVP). The CPB time and operation time, respectively, were 72.96 ± 25.90 minutes versus 78.59 ± 31.95 minutes (P = 0.495) and 170.75 ± 73.31 minutes versus 228.87 ± 61.45 minutes (P = 0.004) in the FV group versus the FVS group. There were no significant differences in the ventilator-assisted time, the first-day LVEF, and the intensive care unit (ICU) stay between the FV group and the FSV group.Both types of drainage were effective and could ensure safety during the operative procedure. The vacuum-assisted single femoral venous drainage method simplified the minimally invasive isolated repeat tricuspid valve surgical process more significantly and is the more appropriate choice.

A New Venous Drainage Technique in Minimally Invasive Redo Tricuspid Surgery: Vacuum-Assist Venous Drainage via a Single Femoral Venous Cannula.

OBJECTIVE: To summarise the experiences of applying vacuum-assist with a single femoral venous cannula drainage technique in minimally invasive isolated redo tricuspid surgery. METHODS: Eight consecutive patients underwent minimally invasive redo tricuspid surgery through a right thoracotomy at our institute. All of the patients had isolated significant tricuspid regurgitation after previous cardiac surgeries, and received minimally invasive redo tricuspid surgery. The arterial cannula was inserted into the femoral artery, and at the same time, the venous cannula was placed into the femoral vein. The venous cannula was guided by transoesophageal echocardiography and reached the superior vena cava (SVC). The caval veins did not need to be snared with the heart beating during the operation, but applying the vacuum-assisted venous drainage (VAVD) controller was necessary. RESULTS: This cannulation makes it possible to achieve adequate drainage (3.48±0.44L/min) and accomplishes complete arterial perfusion. Most importantly, it guarantees a good visual field without blood and allows safe surgery. The average time of cardiopulmonary bypass (CPB) was 68.25±13.84min. The length of ICU and hospital stays were 4.13 ±3.52 days and 8.14±4.98 days, respectively. In eight patients, there was no early death in the hospital. One patient experienced acute renal dysfunction. CONCLUSION: Vacuum-assist venous drainage via a single femoral venous cannula in isolated redo tricuspid surgery is safe, effective, reliable, and significantly simplifies the procedure.

Venous cannula performance assessment in a realistic caval tree model.

OBJECTIVES: A new caval tree system was designed for realistic in vitro simulation. The objective of our study was to assess cannula performance for virtually wall-less versus standard percutaneous thin-walled venous cannulas in a setting of venous collapse in case of negative pressure. METHODS: For a collapsible caval model, a very flexible plastic material was selected, and a model with nine afferent veins was designed according to the anatomy of the vena cava. A flow bench was built including a lower reservoir holding the caval tree, built by taking into account the main afferent vessels and their flow provided by a reservoir 6 cm above. A cannula was inserted in this caval tree and connected to a centrifugal pump that, in turn, was connected to a reservoir positioned 83 cm above the second lower reservoir (after-load = 60 mmHg). Using the same pre-load, the simulated venous drainage for cardiopulmonary bypass was realized using a 24 F wall-less cannula (Smartcanula) and 25 F percutaneous cannula (Biomedicus), and stepwise increased augmentation (1500 RPM, 2000 and 2500 RPM) of venous drainage. RESULTS: For the thin wall and the wall-less cannulas, 36 pairs of flow and pressure measurements were realized for three different RPM values. The mean Q-values at 1500, 2000 and 2500 RPM were: 3.98 ± 0.01, 6.27 ± 0.02 and 9.81 ± 0.02 l/min for the wall-less cannula (P <0.0001), versus 2.74 ± 0.02, 3.06 ± 0.05, 6.78 ± 0.02 l/min for the thin-wall cannula (P <0.0001). The corresponding inlet pressure values were: -8.88 ± 0.01, -23.69 ± 0.81 and -70.22 ± 0.18 mmHg for the wall-less cannula (P <0.0001), versus -36.69 ± 1.88, -80.85 ± 1.71 and -101.83 ± 0.45 mmHg for the thin-wall cannula (P <0.0001). The thin-wall cannula showed mean Q-values 37% less and mean P values 26% more when compared with the wall-less cannula (P <0.0001). CONCLUSIONS: Our in vitro water test was able to mimic a negative pressure situation, where the wall-less cannula design performs better compared with the traditional thin-wall cannula.