| 1. |
- Albrektsson, Ann, 1949, et al.
(author)
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Peritoneal dialysis fluid-induced angiogenesis in rat mesentery is increased by lactate in the presence or absence of glucose
- 2006
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In: ASAIO journal (1992). - : Lippincott Williams & Wilkins. - 1058-2916 .- 1538-943X. ; 52:3, s. 276-281
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Journal article (peer-reviewed)abstract
- Angiogenesis may be an important mechanism behind the functional deterioration of the peritoneum leading to ultrafiltration failure in peritoneal dialysis. The present study was designed to compare the angiogenic properties of lactate-, bicarbonate-, and pyruvate-buffered fluids, evaluated separately with and without glucose. Five different fluids (lactate and bicarbonate with and without 2.5% glucose and pyruvate without glucose) were studied for 5 weeks of twice-daily injections in rats. The respective buffers (40 mmol/l) were adjusted to pH 7.2, and sodium, chloride, calcium, and magnesium were present at standard concentrations. The mesenteric window model, based on observation of the translucent peritoneal sections of the small intestine mesentery, was used for immunohistochemical imaging of microvessels (RECA-1 antigen) and macrophages (ED1 and ED2 antigens). All fluids induced angiogenesis as compared with untreated controls. The lactate-buffered fluids induced larger vascularized zones than did their bicarbonate- and pyruvate-buffered counterparts. Angiogenesis was accompanied by a local recruitment of ED1 macrophages from blood. Addition of glucose to the lactate- and bicarbonate-buffered fluids did not seem to alter their pro-angiogenic properties. In conclusion, intraperitoneal exposure to lactate buffer, compared with bicarbonate, stimulates angiogenesis in the presence or absence of glucose.
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| 2. |
- Donker, Dirk W., et al.
(author)
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Left Ventricular Unloading During Veno-Arterial ECMO : A Simulation Study
- 2019
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In: ASAIO journal (1992). - : Lippincott Williams and Wilkins. - 1058-2916 .- 1538-943X. ; 65:1, s. 11-20
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Journal article (peer-reviewed)abstract
- Veno-arterial extracorporeal membrane oxygenation (VA ECMO) is widely used in cardiogenic shock. It provides systemic perfusion, but left ventricular (LV) unloading is suboptimal. Using a closed-loop, real-time computer model of the human cardiovascular system, cardiogenic shock supported by peripheral VA ECMO was simulated, and effects of various adjunct LV unloading interventions were quantified. After VA ECMO initiation (4 L/min) in cardiogenic shock (baseline), hemodynamics improved (increased to 85 mm Hg), while LV overload occurred (10% increase in end-diastolic volume [EDV], and 5 mm Hg increase in pulmonary capillary wedge pressure [PCWP]). Decreasing afterload (65 mm Hg mean arterial pressure) and circulating volume (-800 mL) reduced LV overload (12% decrease in EDV and 37% decrease in PCWP) compared with baseline. Additional intra-aortic balloon pumping only marginally decreased cardiac loading. Instead, adjunct Impella T enhanced LV unloading (23% decrease in EDV and 41% decrease in PCWP). Alternative interventions, for example, left atrial/ventricular venting, yielded substantial unloading. We conclude that real-time simulations may provide quantitative clinical measures of LV overload, depending on the degree of VA ECMO support and adjunct management. Simulations offer insights into individualized LV unloading interventions in cardiogenic shock supported by VA ECMO as a proof of concept for potential future applications in clinical decision support, which may help to improve individualized patient management in complex cardiovascular disease.
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| 3. |
- Fiusco, Francesco, 1994-, et al.
(author)
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Blood pumps for extracorporeal membrane oxygenation : Platelet activation during different operating conditions
- 2021
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In: ASAIO journal (1992). - : Ovid Technologies (Wolters Kluwer Health). - 1058-2916 .- 1538-943X. ; Publish Ahead of Print
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Journal article (peer-reviewed)abstract
- Extracorporeal membrane oxygenation (ECMO) is a therapy used in severe cardiopulmonary failure. Blood is pumped through an artificial circuit exposing it to nonphysiologic conditions, which promote platelet activation and coagulation. Centrifugal pumps used at lower flow rates than their design point may lose pump efficiency and increase the risk of hemolysis. In this study, thrombogenic properties of two ECMO pumps designed for adult and neonatal use were evaluated using simulations in different flow scenarios. Three scenarios, adult pump in adult mode (4 L/min), adult pump in baby mode (300 ml/min), and neonatal pump used in its design point (300 ml/min), were simulated using computational fluid dynamics. The flow was numerically seeded with platelets, whose activation state was computed considering the stress history that acted along their respective path lines. Statistical distributions of activation state and residence time were drawn. The results showed that using the adult pump in baby mode increased the fraction of platelets with higher activation state confirming that low-pump flow rate impacts thrombogenicity. The neonatal pump showed a backflow at the inlet, which carried platelets in a retrograde motion contributing to an increased thrombogenic potential compared with the adult mode scenario.
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| 4. |
- Frithiof, Robert, et al.
(author)
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Central Venous Line and Dialysis Catheter Position Affects Drug Clearance during Continuous Renal Replacement Therapy in an Animal Model.
- 2019
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In: ASAIO journal (1992). - 1058-2916 .- 1538-943X. ; 65:4, s. 408-413
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Journal article (peer-reviewed)abstract
- In intensive care, drugs are commonly administered through central venous catheters (CVC). These catheters and central venous dialysis catheters (CVDC) are often placed in the same vessel for practical reasons. The aim of this experimental study was to investigate if the position of CVC and CVDC influences the elimination of infused drugs, during continuous renal replacement therapy (CRRT). In a randomized, cross-over model, anesthetized piglets received both a CVC and a CVDC in a jugular vein. Another CVDC was placed in a femoral vein for comparison. After baseline measurements, CRRT was performed in either of the CVDC, each CRRT-period separated by another baseline period. Hypotension was induced by peripherally given sodium nitroprusside. In the CVC, both gentamicin and noradrenaline were administered. Noradrenaline was titrated to reach a target blood pressure. When CRRT was performed using the CVDC in the same vessel as the drugs were infused, the plasma concentration of gentamicin was reduced compared with when the infusion and CVDC were in different vessels (5.66 [standard deviation (SD) ± 1.23] vs. 7.76 [SD ± 2.30] mg/L [p = 0.02]). The noradrenaline infusion rate needed to reach the target blood pressure was more than doubled (0.32 [SD ± 0.16] vs. 0.15 [SD ± 0.08] µg/kg/min [p = 0.006]). This experimental study indicates that the removal of drugs is increased if infusion is in close vicinity of the CVDC, during CRRT.
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| 5. |
- Hübbert, Laila, et al.
(author)
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Axial flow pump treatment during myocardial depression in calves : an invasive hemodynamic and echocardiographic tissue Doppler study.
- 2008
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In: ASAIO journal (1992). - Philadelphia, PA USA : Lippincott Williams & Wilkins. - 1058-2916 .- 1538-943X. ; 54:4, s. 367-371
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of beta-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.
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| 6. |
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| 7. |
- Hubbert, Laila, et al.
(author)
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Left atrial pressure monitoring with an implantable wireless pressure sensor following implantation of a left ventricular assist device
- 2017
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In: ASAIO journal (1992). - 1058-2916 .- 1538-943X. ; 63:5, s. E60-E65
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Journal article (peer-reviewed)abstract
- Following implantation of a continuous-flow left ventricular assist device (LVAD), left atrial pressure (LAP) monitoring allows for precise management of intravascular volume, inotropic therapy and pump speed. In this case series of 4 LVAD recipients we report the first clinical use of this wireless pressure sensor for long-term monitoring of LAP during LVAD support. A wireless microelectromechanical system (MEMS) pressure sensor, (Titan™, ISS Inc., Ypsilanti, MI, USA) was placed in the left atrium in four patients at the time of LVAD implantation. Titan sensor LAP was measured in all 4 patients on the ICU and in 3 patients at home. Ramped speed tests were performed using LAP and echocardiography in 3 patients. The left ventricular end diastolic diameter (cm), flow (L/min), power consumption (W) and blood pressure (mmHg) were measured at each step.Measurements were performed over 36, 84, 137, and 180 days, respectively. The three discharged patients had equipment at home and were able to perform daily recordings. There were significant correlations between sensor pressure and pump speed, LV and LA size and pulmonary capillary wedge pressure, respectively (r= 0.92-0.99, p < 0.05). There was no device failure and there were no adverse consequences of its use.
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| 8. |
- Hübbert, Laila, et al.
(author)
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Second Harmonic Echocardiography and Spontaneous Contrast during Implantation of a left Ventricular Assist Device
- 2010
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In: ASAIO journal (1992). - : Wolters Kluwer. - 1058-2916 .- 1538-943X. ; 56:5, s. 417-421
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Journal article (peer-reviewed)abstract
- Implantable mechanical left ventricular assist devices (LVADs) are used as a bridge or alternative to heart transplantation. Peroperative transesophageal echocardiography is commonly applied during implantation. Significant air embolism may occur as a result of air leakage at connections and anastomoses when LV filling becomes inadequate, and this must be prevented. Early suspicion and detection of air is mandatory to avoid negative circulatory effects. We hypothesized that monitoring of heart chamber size and occurrence of single air bubbles using second harmonic imaging (SHI) echocardiography may prevent risk for significant air embolism. After implantation of the LVAD in 10 calves, invasive hemodynamic monitoring and epicardial SHI were performed while increasing pump speed. Air bubbles in the ascending aorta were monitored and the left heart visualized for off-line dimensional analysis. Detection of air bubbles in the ascending aorta preceded their appearance in the left ventricle. They occurred exclusively but not always after a decrease in left atrial (LA) size. Decrease in LA pressure did not predict bubble detection or reduction in LA size. We conclude that SHI detects spontaneous ultrasound contrast during implantation of a LVAD and that a decrease in LA size is a warning that air embolism is imminent.
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| 9. |
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| 10. |
- Myers, T. M., et al.
(author)
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Hemodynamic Evaluation of the Jarvik 2000 Heart During Heart Failure
- 2001
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In: ASAIO journal (1992). - : Wolters Kluwer. - 1058-2916 .- 1538-943X. ; 46:2, s. 167-
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Journal article (peer-reviewed)abstract
- The Jarvik 2000 Heart is an axial flow left ventricular assist system designed for long-term circulatory support. Purpose: To assess the level of hemodynamic support provided by the Jarvik 2000 in an animal model, with acute, severe heart failure. Methods: Heart failure (HF) was induced in 5 calves by progressively ligating the LAD coronary artery. A continuous infusion of esmolol hydrochloride was given to maintain the stability of HF. Compared to normal baseline values, during heart failure CI decreased by 33% (p < 0.02), LAP increased by 16% (p < 0.03), and BP decreased by 28% (p < 0.13). Once stable HF was established, the pump was turned on, and hemodynamic measurements were obtained at pump speed settings that ranged from 8,000 to 12,000 rpm. Results: Selected, mean hemodynamic values are presented in the table, CI, LAP, and BP improved significantly (p < 0.05) at pump speeds >9000 rpm. Pulse pressure (PP) narrowed by 64% (p < 0.009), and the PAP remained unchanged.Image ToolsBlood flow in the femoral artery increased but was not statistically significant. Other hemodynamic parameters such as HR, SVR, PVR, and CVP did not change significantly. Conclusions: The Jarvik 2000 Heart can provide a level of cardiac output support that normalizes the CI and LAP, while maintaining some arterial pressure pulsatility during HF. Systemic perfusion is increased while the left heart is unloaded.
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