Injury in Organs after Cardiopulmonary Bypass: A Comparative Experimental Morphological Study between a Centrifugal and a New Pulsatile Pump

The effect of perioperative magnesium sulfate on blood sugar in patients with diabetes mellitus undergoing cardiac surgery: A double-blinded randomized study

Objective

The aim of the present study was to evaluate the perioperative effect of magnesium infusion on blood sugar level in patients with diabetes mellitus undergoing cardiac surgery.

Design

This was a double-blind randomized study.

Setting

The study was conducted at cardiac center.

Patients

The study included 122 adult patients.

Intervention

Group M - The patients received a continuous infusion of magnesium sulfate (without a loading dose) at 15 mg/kg/h. The infusion rate was started 20 min before induction maintained during surgery and the first postoperative 24 h. The medication was prepared by adding 5 g magnesium sulfate in 50 ml syringe. Group C - The patients received equal amount of normal saline.

Measurements

The monitors included heart rate, mean arterial blood pressure, central venous pressure, urine output, blood levels of magnesium, sugar, and potassium.

Results

The blood sugar level and the required insulin significantly decreased with Group M than Group C (P < 0.05). There were minimal changes in the potassium level in Group M, but potassium decreased in patients of Group C (P < 0.05). The amount of urine output was too much higher in Group M than Group C (P < 0.05). The pharmacological and mechanical support significantly decreased with Group M than Group C (P < 0.05). The hospital and Intensive Care Unit length of stay significantly decreased with Group M than Group C (P < 0.05).

Conclusion

The magnesium sulfate produced a better-controlled effect on the blood sugar level. It decreased the requirement of insulin infusion and minimized the changes in the blood level of potassium.

Insulin binding to the cardiopulmonary bypass biomaterials

Hyperglycemia associated with cardiopulmonary bypass (CPB) is an independent predictor of morbidity and mortality. One suggested cause of hyperglycemia during CPB is a decline of serum insulin concentrations. Since plasma C-proteins are not reduced during CPB — suggesting that pancreatic insulin secretion is not affected — the reduction of insulin concentrations is hypothesized to be due to the binding of the insulin protein to the CPB biomaterials. The hypothesis of this study is that insulin binds to the CPB polyvinyl chloride (PVC) tubing and that selected bio-coatings inhibit this process. Human insulin was diluted to a physiologic concentration of 30 μU/mL in saline and exposed to four types of sterile PVC tubing, namely: uncoated, Terumo X-coated, Medtronic Carmeda, and Cobe SMARxT for 30 minutes at 37°C. Insulin concentrations were determined with ELISA. The recovered insulin concentrations were found to be 9.3 ± 0.6 μU/mL in the uncoated (control), 17.7 ± 1.9 μU/mL in the X-coating, 17.9 ± 1.1 μU/mL in the Carmeda, and 14.28 ± 0.17 μU/mL in the SMARxT coated tubing. These data support the hypothesis that the insulin binding to the PVC tubing can be reduced by 48% and up to 35% with X-coating and Carmeda, and SMARxT coating, respectively. Therefore, the use of coated CPB systems is justified to reduce CPB-associated hyperglycemia. Perfusion (2007) 22, 207—210.

Does pulsatile perfusion improve outcome after cardiac surgery? A propensity-matched analysis of 1959 patients

OBJECTIVE

We analyzed the influence of pulsatile perfusion on recovery after coronary bypass grafting (CABG) or aortic valve replacement (AVR).

PATIENTS AND METHODS

Between January 2008 and December 2010, 1959 consecutive patients underwent CABG, AVR, or both. The choice for pulsatile perfusion (PP, n=220) or non-pulsatile perfusion (NPP, n=1739) was made by the surgeon. Patient propensity score to receive PP or NPP was calculated according to 15 preoperative variables. Resulting propensity scores, logistic EuroSCORE, perfusion type and surgeon were analyzed to evaluate their role for mortality, length of postoperative ICU and hospital stay (LOHS), transfusion requirements and renal function. Risk stratified non-parametric univariate analyses and propensity adjusted multivariate analyses were performed.

RESULTS

EuroSCORE and hospital mortality did not differ significantly between PP and NPP. EuroSCORE was the best predictive factor for all examined variables (p<0.001). PP was superior concerning LOHS (p=0.019) and this benefit increased with higher logistic EuroSCORE. The surgeon significantly influenced ventilation time, ICU stay and transfusion requirements.

CONCLUSION

Pulsatile perfusion did not influence perioperative outcome parameters, renal function and mortality, but resulted in shorter hospital stay, especially in critically ill patients.

Model of arterial tree and peripheral control for the study of physiological and assisted circulation

Peripheral vasomotion, interstitial liquid exchange, and cardiovascular system behaviour are investigated by means of a lumped parameter model of the systemic and peripheral circulation, from the aortic valve to the venules. This modelling work aims at combining arterial tree hemodynamics description, active peripheral flow regulation, and fluid exchange. The arterial compartment is constructed with 63 RCL segments and 30 peripheral districts including myogenic control on arterioles, metabolic control on venules, and Starling filtration through capillary membrane. The arterial behaviour is characterised as to the long term stability of pressure/flow waves in the different segments. Peripheral districts show autoregulatory capabilities against pressure changes over a wide range and also self-sustained oscillations mimicking vasomotor activity. A preliminary study was carried out as to the model response to changes induced by cardiopulmonary bypass (CPB). Among the induced alterations, the system responds mainly to hemodilution, which increased peripheral fluid loss and oedema beyond the compensatory capabilities of local regulation mechanisms. This resulted in an overall increase total arterial resistance. Local transport deficits were assessed for each district according to the different metabolic demand. This study shows the requirement of a suitable description of both arteries and peripheral mechanisms in order to describe cardiovascular response non-physiological conditions, as well as assisted circulation or other pathological conditions.

An Evaluation of the Benefits of Pulsatile versus Nonpulsatile Perfusion during Cardiopulmonary Bypass Procedures in Pediatric and Adult Cardiac Patients

The controversy over the benefits of pulsatile and nonpulsatile flow during cardiopulmonary bypass procedures continues. The objective of this investigation was to review the literature in order to clarify the truths and dispel the myths regarding the mode of perfusion used during open-heart surgery in pediatric and adult patients. The Google and Medline databases were used to search all of the literature on pulsatile vs. nonpulsatile perfusion published between 1952 and 2006. We found 194 articles related to this topic in the literature. Based on our literature search, we determined that pulsatile flow significantly improved blood flow of the vital organs including brain, heart, liver, and pancreas; reduced the systemic inflammatory response syndrome; and decreased the incidence of postoperative deaths in pediatric and adult patients. We also found evidence that pulsatile flow significantly improved vital organ recovery in several types of animal models when compared with nonpulsatile perfusion. Several investigators have also shown that pulsatile flow generates more hemodynamic energy, which maintains better microcirculation compared with nonpulsatile flow. These results clearly suggest that pulsatile flow is superior to nonpulsatile flow during and after open-heart surgery in pediatric and adult patients.