No abstract

Blood oxygenized by veno-arterial extracorporeal membrane oxygenation (ECMO) can be returned to the aorta (central cannulation) or to peripheral arteries (axillar, femoral). Hemodynamic effects of these cannulation types were analyzed in a mock loop with an aortic model representative of normal anatomy and compliance under physiological pressures and flow rates. Pressures, flow rates, and contribution of ECMO flow to total flow as a measure of oxygen supply were monitored in the carotids. Steady or pulsatile ECMO flow, residual or no cardiac output, and intraaortic balloon pump counterpulsation were tested as independent factors. With residual heart function, central cannulation provided the best oxygenated flow and pressure to the carotid arteries (CA). Axillar cannulation preferentially perfused the right CA at the expense of the left CA. Femoral cannulation provided only lower amounts of oxygenated blood to both CA. Pulsation increased the surplus hemodynamic energy. Counterpulsation reduced flow with femoral cannulation but improved flow and pressure with axillar cannulation. Femoral cannulation failed to provide oxygenated blood to coronary and supraaortic arteries with residual heart function. Central cannulation provided the best hemodynamics and oxygen supply to the brain. With a resting heart but not with an ejecting heart, pulsatile ECMO flow enhanced CA hemodynamics.

No abstract

Background -Peripheral neuropathy and alterations in diaphragmatic muscle function are frequently caused by uraemia. Phrenic nerve function in patients with end stage renal failure, however, has not

Introduction: Pulsatile extracorporeal circulation may improve organ perfusion during cardiac surgery. Some minimally invasive extracorporeal circulation (MiECC) systems allow pulsatile perfusion. The present study investigated the influence of arterial tubing compliance on hemodynamic energy transfer into the patient. Methods: Aortic models with adult human geometry were perfused in a mock circulation. A MiECC system was connected using either high-compliance silicone tubing or standard kit tubing. Energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) were computed from flow and pressure data. Aortic models with physiological and sub-physiological compliance were tested to assess the influence of the pseudo-patient. Results: Non-pulsatile flow did not generate SHE. SHE during pulsatile flow in the compliant aortic model was significantly higher with kit tubing compared to silicone tubing. Maximum SHE was achieved at 1.6 L/min with kit tubing (7.7% of mean arterial pressure) and with silicone tubing (4.9%). Using the low-compliance aortic model, SHE with kit tubing reached a higher maximum of 14.2% at 1.8 L/min compared to silicone tubing (11.8% at 1.5 L/min). Conclusions: Flexible arterial tubing did not preserve more hemodynamic energy from a pulsatile pump compared to standard kit tubing in a model of adult extracorporeal circulation. The pseudo-patient’s compliance significantly affected the properties of the mock circulation.

Background: Minimal invasive extracorporeal circulation (MiECC) reduces the impact of cardiopulmonary bypass during cardiac surgery on inflammation and hemostasis. Pulsatile perfusion may enhance organ perfusion and help to prevent renal and neuronal damage. The present study investigated the impact of pulsatile MiECC in low-risk coronary artery bypass grafting (CABG) patients. Methods: CABG patients were prospectively randomized for non-pulsatile (np: n=19) and pulsatile (p: n=21) MiECC. Blood and urine samples were collected at several time points until 72 h post-operative and analyzed for biochemical markers of fibrinolytic capacity, renal damage, and neuronal damage.Results: Although intraoperative tissue plasminogen activator (tPA) levels tended to be higher in the p group, none of the fibrinolysis markers including plasminogen activator inhibitor (PAI-1) and the PAI-1/ tPA ratio were significantly affected by pulsation. Hemolysis and markers of renal and neuronal damage were comparable between groups. Intraoperative urinary excretion [np: 400 mL (355 to 680) vs. p: 530 mL (360 to 900)] and cumulative 24 h volume intake [np: 7,090 mL (5,492 to 7,544) vs. p: 7,155 mL (6,682 to 8,710)] were increased by pulsation whereas blood losses up to 12 h post-operative [np: 365 mL (270 to 515) vs. p: 310 mL (225 to 470)] and up to 24 h post-operative [np: 760 mL (555 to 870) vs. p: 520 mL (460 to 670)] were attenuated. Conclusions: The present study did not find evidence for a beneficial effect of pulsation on markers of fibrinolysis, renal damage, and neuronal damage. However, pulsatile perfusion increased intraoperative urinary secretion and reduced post-operative blood losses.

No abstract

No abstract