Target flow deviations on the cardiopulmonary bypass cause postoperative delirium in cardiothoracic surgery-a retrospective study evaluating temporal fluctuations of perfusion data.

OBJECTIVES: Postoperative delirium (POD) is common, costly and associated with long-term morbidity and increased mortality. We conducted a cohort study to assess the contribution of cardiopulmonary bypass (CPB) to the development of POD by means of algorithm-based data processing. METHODS: A database was compiled from 3 datasets of patients who underwent cardiac surgery between 2014 and 2019: intensive care unit discharge files, CPB protocols and medical quality management records. Following data extraction and structuring using novel algorithms, missing data were imputed. Ten independent imputations were analysed by multiple logistic regression with stepwise deletion of factors to arrive at a minimal adequate model. RESULTS: POD was diagnosed in 456/3163 patients (14.4%). In addition to known demographic risk factors and comorbidities like male sex, age, carotid disease, acute kidney failure and diabetes mellitus, cardiopulmonary parameters like total blood volume at the CPB [adjusted odds ratio (AOR) 1.001; confidence interval (CI) 1.1001-1.002] were independent predictors of POD. Higher values of the minimal blood flow were associated with a lower risk of POD (AOR 0.993; CI 0.988-0.997). Flow rates at least 30% above target did emerge in the minimal adequate model as a potential risk factor, but the confidence interval suggested a lack of statistical significance (AOR 1.819; 95% CI: 0.955-3.463). CONCLUSIONS: CPB data processing proved to be a useful tool for obtaining compact information to better identify the roles of individual operational states. Strict adherence to perfusion limits along with tighter control of blood flow and acid-base balance during CPB may help to further decrease the risk of POD.

Improving adult pulsatile minimal invasive extracorporeal circulation in a mock circulation.

BACKGROUND: Pulsatile extracorporeal circulation (ECC) may improve perfusion of critical organs during cardiac surgery. This study analyzed the influence of the components of a minimal invasive ECC (MiECC) on the transfer of pulsatile energy into the pseudo-patient of a mock circulation. METHODS: An aortic model with human-like geometry and compliance was perfused by a diagonal pump. Surplus hemodynamic energy (SHE) was determined from flow and pressure data. Five adult-size oxygenator models and three sizes of cannulas were compared. Pulsatile pump settings were optimized, and parallel dual-pump configurations were evaluated. RESULTS: Oxygenator models showed up to twofold differences in pressure gradients and influenced SHE at flow rates up to 2.0 L min-1 . Adjustments of frequency, systole duration, and rotational speed gain significantly improved SHE compared with empirical settings, with SHE above 21% of mean arterial pressure at flow rates of 1.0 L min-1 to 1.5 L min-1 and SHE above 5% at 3.5 L min-1 . Small diameter cannula (15 Fr) limited SHE compared with larger cannula (21 Fr and 23 Fr). Two diagonal pumps did not provide higher SHE than a single pump, but permitted additional control over pulse pressure and SHE by varying the total fraction of pulsatile flow and the fraction of flow bypassing the oxygenator. CONCLUSIONS: Proper selection of components and optimizations of pump settings significantly improved pulse pressure and SHE of pulsatile MiECC. Surplus hemodynamic energy depended on flow rate with a maximum at 1.0 L min-1 -1.5 L min-1 . Pulsatile MiECC may specifically assist organ perfusion during phases of low flow.

Effects of pulsatile minimal invasive extracorporeal circulation on fibrinolysis and organ protection in adult cardiac surgery-a prospective randomized trial.

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.

Minimized extracorporeal circulation in non-coronary surgery.

Minimally invasive extracorporeal circulation (MiECC) technology is characterized by improved biocompatibility due to closed-loop design, minimized priming, and markedly reduced artificial surface. Despite well-evidenced clinical advantages in coronary surgery, MiECC penetration in complex open-heart surgery is low. Concerns have been raised by surgeons and perfusionist regarding safety of perfusion in situations when the heart is opened and air is entering the closed system. Moreover, issues of blood and volume management are deemed impractical without having a reservoir. In the evolution of MiECC safety aspects as well as means of air and volume management have been addressed. The integration of active air removal devices, and the possibility of venting and volume buffering made MiECC suitable for valvular or even more complex surgery. However, typical clinical benefits found with MiECC in coronary artery bypass grafting (CABG) surgery, in particular blood sparing effects, were not reproducible. Air handling and blood management remain the main issues of MiECC in non-coronary surgery. With the introduction of modular (type IV) MiECC systems containing a second, accessory circuit for immediate conversion to open cardiopulmonary bypass (CPB), the last obstacles seem to be cleared away. The first reports using this latest development in MiECC technology sound promising. It is now up to the cardiac surgical community to adopt this technology and produce data helping to answer the question whether MiECC is the best perfusion strategy for all comer's cardiac surgery.

Hemodynamic energy during pulsatile extracorporeal circulation using flexible and rigid arterial tubing: a reassessment.

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.

Influence of Cannulation Site on Carotid Perfusion During Extracorporeal Membrane Oxygenation in a Compliant Human Aortic Model.

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.