Blood Damage Related to Cardiopulmonary Bypass:In Vivo and In Vitro Comparison of Two Different Centrifugal Pumps

Hemolysis and cardiopulmonary bypass: meta-analysis and systematic review of contributing factors

BACKGROUND

The use of cardiopulmonary bypass (CPB) is almost inevitable in cardiac surgery. However, it can cause complications, including hemolysis. Until now, there have not been any standards for reducing hemolysis from CPB. Therefore, this systematic review was conducted to determine the factors that increase or reduce hemolysis in the use of CPB.

METHODS

Keywords Earches (cardiac surgery AND cardiopulmonary bypass AND hemolysis) were done on PubMed databases and Cochrane CENTRAL from 1990-2021 for published randomized controlled trials (RCTs) that studied interventions on CPB, in cardiac surgery patients, and measured hemolysis as one of the outcomes. Studies involving patients with preoperative hematological disorders, prosthetic valves, preoperative use of intra-aortic balloon pumps and extracorporeal circulation, emergency and minimally invasive surgery are excluded RESULTS: The search yielded 64 studies that met the inclusion criteria, which involved a total of 3,434 patients. The most common surgery was coronary revascularization (75%). Out of 64 studies, 33 divided into 7 analyses. Remaining 31 studies were synthesized qualitatively. Significant decreases were found in centrifugal vs roller pumps for PFHb (p = 0.0006) and Hp (p < 0.0001) outcomes, separated vs combined suctioned blood (p = 0.003), CPB alternatives vs conventional CPB (p < 0.0001), and mini extracorporeal circulation (MiniECC) vs conventional CPB for LDH (p = 0.0008). Significant increases were found in pulsatility (p = 0.03) and vacuum-assisted venous drainage (VAVD) vs gravity-assisted venous drainage (GAVD) (p = 0.002).

CONCLUSION

The review shows that hemolysis could be caused by several factors and efforts have been made to reduce it, combining significant efforts could be beneficial. However, this review has limitations, such as heterogeneity due to no standards available for conducting CPB. Therefore, further research with standardized guidelines for CPB is needed to yield more comparable studies. Meta-analyses with more specific parameters should be done to minimize heterogeneity.

Computational investigation of hemodynamics in hardshell venous reservoirs: A comparative study

Extracorporeal circulation using heart-lung-machines is associated with a profound activation of corpuscular and plasmatic components of circulating blood, which can also lead to deleterious events such as systemic inflammatory response and hemolysis. Individual components used to install the extracorporeal circulation have an impact on the level of activation, most predominantly membrane oxygenators and hardshell venous reservoirs as used in extracorporeal systems. The blood flows in two different hardshell reservoirs are computationally investigated. A special emphasis is placed on the prediction of an onset of transition and turbulence generation. Reynolds-averaged numerical simulations (RANS) based on a transitional turbulence model, as well as large eddy simulations (LES) are applied to achieve an accurate prediction. In the LES analysis, the non-Newtonian behavior of the blood is considered via the Carreau model. Blood damage potential is quantified applying the Modified Index of Hemolysis (MIH) based on the predicted flow fields. The results indicate that the flows in both reservoirs remain predominantly laminar. For one of the reservoirs, considerable turbulence generation is observed near the exit site, caused by the specific design for the connection with the drainage tube. This difference causes the MIH of this reservoir to be nearly twice as large as compared to the alternative design. However, a substantial improvement of these performance criteria can be expected by a local geometry modification.

Shear-stress sensitive lenticular vesicles for targeted drug delivery

Atherosclerosis results in the narrowing of arterial blood vessels and this causes significant changes in the endogenous shear stress between healthy and constricted arteries. Nanocontainers that can release drugs locally with such rheological changes can be very useful. Here, we show that vesicles made from an artificial 1,3-diaminophospholipid are stable under static conditions but release their contents at elevated shear stress. These vesicles have a lenticular morphology, which potentially leads to instabilities along their equator. Using a model cardiovascular system based on polymer tubes and an external pump to represent shear stress in healthy and constricted vessels of the heart, we show that drugs preferentially release from the vesicles in constricted vessels that have high shear stress.

A transthoracic Doppler echocardiography study of C-reactive protein and coronary microcirculation in children after open heart surgery

BACKGROUND

Systemic inflammation has been suggested to underlie in part the elevated risk of arrhythmias and myocardial dysfunction during the first weeks after cardiac surgery. Recent transthoracic Doppler studies from our centre indicated increased basal coronary arterial flow in children 5 days after cardiopulmonary bypass surgery. In these children, we investigated whether the inflammatory mediator, C-reactive protein, could influence this association.

METHODS

The peak flow velocity, velocity time-integral in diastole and systole, and basal blood flow in the proximal part of the left anterior descending artery, were assessed by transthoracic Doppler echocardiography 1 day before, and 5 days after, cardiac surgery in 17 children with ventricular and atrioventricular septal defects whose mean age at surgery was 6 months. Levels of C-reactive protein in the plasma were measured at both time-points.

RESULTS

Prior to surgery, all children had levels of C-reactive protein under the limit for detection, that is less than 0.8 milligrams per litre. The levels of the protein had increased significantly by the second day, when the median value was 25, and the range from 20 to 142 milligrams per litre. They remained elevated on the fifth day after surgery, when the median was 11, and the range from 3 to 20 milligrams per litre. On the fifth day, the percentage increase in velocity time integral corrected for left ventricular mass was significantly lower in those patients with C-reactive protein greater than or equal to 10 milligrams per litre than in the remaining patients. Also, both the velocity time integral and the velocity of diastolic peak flow correlated inversely with log C-reactive protein, r being equal to -0.54 and p less than 0.02 and r equal to -0.74 and p less than 0.01, respectively, particularly among those patients in whom clamping of the aorta lasted for more than 1 hour, r for this statistic being equal to -0.8.

CONCLUSION

The postsurgical increase in the velocity of coronary arterial flow in children is inversely associated with rising levels of C-reactive protein. The duration of the aortic cross-clamping during surgery strengthens the association between levels of C-reactive protein and the microcirculatory changes.

Predictors of Hyperkalemia in the Prereperfusion, Early Postreperfusion, and Late Postreperfusion Periods During Adult Liver Transplantation

BACKGROUND

Hyperkalemia poses serious hazards to patients undergoing orthotopic liver transplantation (OLT), and its predictors have not been thoroughly examined.

METHODS

We retrospectively studied 1124 consecutive adult patients who underwent OLT. Hyperkalemia was defined as serum K+ > or =5.5 mmol/L. A total of 47 recipient, donor, intraoperative, and laboratory variables were initially analyzed in univariate analyses. Independent predictors of hyperkalemia in three periods of OLT (prereperfusion, early postreperfusion, and late postreperfusion) were determined in multivariate logistic regression analyses.

RESULTS

Of 1124 patients, 10.2%, 19.1%, and 7.9% had hyperkalemia in the prereperfusion, early postreperfusion, and late postreperfusion periods, respectively. Higher baseline K+ and red blood cell transfusion were independent predictors of prereperfusion hyperkalemia. Higher baseline K+ (or prereperfusion K+) and donation after cardiac death donor were independent predictors of early postreperfusion hyperkalemia. Higher baseline K+, longer warm ischemia time, longer donor hospital stay, lower intraoperative urine output, and the use of venovenous bypass were independent predictors of late postreperfusion hyperkalemia.

CONCLUSIONS

Several laboratory, intraoperative, and donor variables were identified as independent predictors of hyperkalemia in the different periods. Such information may be used for more targeted preemptive interventions in patients who are at risk of developing hyperkalemia during adult OLT.