Phosphorylcholine Coating of Bypass Systems Used for Young Infants Does Not Attenuate the Inflammatory Response

Effect of additional preoperative administration of the neutrophil elastase inhibitor sivelestat on perioperative inflammatory response after pediatric heart surgery with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response. Our previous reports revealed that prophylactic sivelestat administration at CPB initiation suppresses the postoperative acute inflammatory response due to CPB in pediatric cardiac surgery. The purpose of this study was to compare the effects of sivelestat administration before CPB and at CPB initiation in patients undergoing pediatric open-heart surgery. Twenty consecutive patients weighing 5-10 kg and undergoing ventricular septal defect closure with CPB were divided into pre-CPB (n = 10) and control (n = 10) groups. Patients in the pre-CPB group received a 24 h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the induction of anesthesia and an additional 0.1 mg/100 mL during CPB priming. Patients in the control group received a 24-h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the commencement of CPB. Blood samples were tested. Clinical variables including blood loss, water balance, systemic vascular resistance index, and the ratio between partial pressure of oxygen and fraction of inspired oxygen (P/F ratio) were assessed. White blood cell count and neutrophil count as well as C-reactive protein levels were significantly lower in the pre-CPB group according to repeated two-way analysis of variance, whereas platelet count was significantly higher. During CPB, mixed venous oxygen saturation remained significantly higher and lactate levels lower in the pre-CPB group. Postoperative alanine aminotransferase and blood urea nitrogen levels were significantly lower in the pre-CPB group than in the control group. The P/F ratio was significantly higher in the pre-CPB group than in the control group. Fluid load requirement was significantly lower in the pre-CPB group.Administration of sivelestat before CPB initiation is more effective than administration at initiation for the suppression of inflammatory responses due to CPB in pediatric open-heart surgery, with this effect being confirmed by clinical evidence.

Are any biocompatible coatings capable of attenuating the deleterious effects of cardiopulmonary bypass?

Background:

Biocompatible circuits (BCC) are intended to decrease the activation of blood to the artificial cardiopulmonary bypass (CPB) surface. Typically, the coatings are made of various inert substances or molecules physiologically similar to endothelium. Thromboelastography (TEG) graphically represents clot formation, strength of clotting and fibrinolysis. TEG analysis was undertaken to determine if coagulation could be preserved by the BCC.

Methods:

Five different BCC were studied in clinical applications. These five coated circuits were then compared to an identical circuit where only the oxygenator was coated. A pre- and post-bypass TEG was done for comparison. Six well-studied parameters of TEG analysis were compared: R time, Angle, K, Maximum Amplitude (MA), LY30% and Clot Index (CI). Postoperative bleeding and transfusion requirements were compared to TEG results for comparison.

Results:

All postoperative TEG results were significantly different from preoperative parameters except LY30%. No BCC circuit was able to prevent the significant disruption of the observed TEG coagulation parameters R, K, angle, MA and CI. Of note, the postoperative TEG parameters resulting from the Control and Trillium™ groups – which had the same type of oxygenator – were practically identical. The oxygenator, which represents the largest surface area in the CPB circuit, is the single most important factor influencing coagulation.

Conclusion:

While not harmful, BCC are ineffective in preserving TEG coagulation parameters post CPB. Clinical findings support laboratory TEG results in that there were no differences in bleeding or transfusion requirements between groups.

Experimental research with synthetic copolymer-coated cardiopulmonary bypass circuits: inflammatory and thrombogenicity analysis

This study aimed to assess complement system activation and index of thrombogenicity and platelet aggregation between synthetic copolymer-coated cardiopulmonary bypass (CPB) circuit and conventional CPB circuit. Twenty-six pigs were equally divided into two groups--the conventional group and the coated group. They were placed on CPB for 90 min, and blood samples were collected at three different time points (T0, right before CPB establishment; T1, 45 min after starting CPB; and T2, 90 min after starting CPB) to measure total count of inflammatory cells (leukocytes, neutrophils, lymphocytes, and platelets) and serum levels of fraction C3 of complement system. Upon completion of the 90-min CPB, fragments of different compartments of the CPB circuit were taken for assessing index of thrombogenicity and platelet aggregation. There were no differences between both groups regarding total count of leukocytes, neutrophils, and lymphocytes; however, there was a lower count of platelets at T2 in the coated group (P = 0.020). The serum level of fraction C3 was lower in the coated group at T1 (P = 0.020) and T2 (P = 0.017). Higher index of thrombogenicity and platelet aggregation were detected in the conventional group (77% of the animals within the conventional group) than in the coated group (46% of the animals within the coated group). In conclusion, in heart surgery requiring CPB, the use of synthetic copolymer-coated CPB circuit may be useful to reduce complement system activation, as well as attenuating index of thrombogenicity and platelet aggregation.

Specific requirements for bloodless cardiopulmonary bypass in neonates and infants; a review

A miniaturized cardiopulmonary bypass circuit enables the safe performance, in selected pediatric patients, of bloodless open heart surgery. As the latest survival rates in neonatal and infant cardiac surgery have become satisfactory, investigators have concentrated upon the improvement of existing procedures. Institutional guidelines and multidisciplinary efforts undertaken in the pre- and postoperative periods are of great importance, concerning bloodless CPB and should be seriously pursued by all involved caregivers.

This review reflects upon the selective, most relevant requirements for success of asanguinous neonatal and infant CPB: acceptable level of hemodilution during the CPB, patient preoperative hematocrit value and volume of CPB circuit. We present an assessment of practical measures that were also adapted in our institution to achieve an asanguinous CPB for neonatal and infant patients.

Effect of perfusion temperature on the inflammatory response during pediatric cardiac surgery

BACKGROUND

Cardiopulmonary bypass (CPB) triggers the whole body inflammatory response, and it has been suggested that the degree of hypothermia may influence these responses. The aim of this prospective study was to compare the inflammatory response in children undergoing CPB for repair of congenital heart defects, randomized to mild or moderate hypothermia.

METHODS

We measured inflammatory markers in blood samples of thirty children with body weight less than 10 kg undergoing open heart surgery randomized to surgery at either mild (32 degrees C) or moderate (25 degrees C) hypothermia. Blood was sampled after induction of anesthesia, at skin closure, 2 hours, 24 hours, and 48 hours postoperatively.

RESULTS

Except for an enhanced interleukin-8 response in the moderate hypothermia group, there were no differences in levels of inflammatory mediators between those with mild and those with moderate hypothermia. In contrast to the modest influence of the degree of hypothermia, long CPB time and long aortic cross-clamp time were accompanied by enhanced inflammation involving raised levels of interleukin-8 and myeloperoxidase, as well as increased leukocyte counts.

CONCLUSIONS

Only minor differences in cytokine levels were detected between those with moderate and those with mild hypothermia during CPB. Ischemic aortic cross-clamp time and time on CBP should be as short as possible to avoid an excessive inflammatory response and possibly adverse clinical effects.