Impact of Distinct Oxygenators on Pulsatile Energy Indicators in an Adult Cardiopulmonary Bypass Model.

The quantification of pulse energy during cardiopulmonary bypass (CPB) post-oxygenator is required prior to the evaluation of the possible beneficial effects of pulsatile flow on patient outcome. We therefore, evaluated the impact of three distinctive oxygenators on the energy indicators energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) in an adult CPB model under both pulsatile and laminar flow conditions. The pre- and post-oxygenator pressure and flow were measured at room temperature using a 40% glycerin-water mixture at flow rates of 1, 2, 3, 4, 5, and 6 L/min. The pulse settings at frequencies of 40, 50, 60, 70, and 80 beats per minute were according to the internal algorithm of the Sorin CP5 centrifugal pump. The EEP is equal to the mean pressure, hence no SHE is present under laminar flow conditions. The Quadrox-i Adult oxygenator was associated with the highest preservation of pulsatile energy irrespective of flow rates. The low pressure drop-high compliant Quadrox-i Adult oxygenator shows the best SHE performance at flow rates of 5 and 6 L/min, while the intermediate pressure drop-low compliant Fusion oxygenator and the high pressure drop-low compliant Inspire 8F oxygenator behave optimally at flow rates of 5 L/min and up to 4 L/min, respectively. In conclusion, our findings contributed to studies focusing on SHE values post-oxygenator as well as post-cannula in clinical practice. In addition, our findings may give guidance to the clinical perfusionist for oxygenator selection prior to pulsatile CPB based on the calculated flow rate for the individual patient.

Effect of high or low protamine dosing on postoperative bleeding following heparin anticoagulation in cardiac surgery. A randomised clinical trial.

While experimental data state that protamine exerts intrinsic anticoagulation effects, protamine is still frequently overdosed for heparin neutralisation during cardiac surgery with cardiopulmonary bypass (CPB). Since comparative studies are lacking, we assessed the influence of two protamine-to-heparin dosing ratios on perioperative haemostasis and bleeding, and hypothesised that protamine overdosing impairs the coagulation status following cardiac surgery. In this open-label, multicentre, single-blinded, randomised controlled trial, patients undergoing on-pump coronary artery bypass graft surgery were assigned to a low (0.8; n=49) or high (1.3; n=47) protamine-to-heparin dosing group. The primary outcome was 24-hour blood loss. Patient haemostasis was monitored using rotational thromboelastometry and a thrombin generation assay. The low protamine-to-heparin dosing ratio group received less protamine (329 ± 95 vs 539 ± 117 mg; p<0.001), while post-protamine activated clotting times were similar among groups. The high dosing group revealed increased intrinsic clotting times (236 ± 74 vs 196 ± 64 s; p=0.006) and the maximum post-protamine thrombin generation was less suppressed in the low dosing group (38 ± 40 % vs 6 ± 9 %; p=0.001). Postoperative blood loss was increased in the high dosing ratio group (615 ml; 95 % CI 500-830 ml vs 470 ml; 95 % CI 420-530 ml; p=0.021) when compared to the low dosing group, respectively. More patients in the high dosing group received fresh frozen plasma (11 % vs 0 %; p=0.02) and platelet concentrate (21 % vs 6 %; p=0.04) compared to the low dosing group. Our study confirms in vitro data that abundant protamine dosing is associated with increased postoperative blood loss and higher transfusion rates in cardiac surgery.

Individualized heparin and protamine management improves rotational thromboelastometric parameters and postoperative hemostasis in valve surgery.

OBJECTIVES: This study investigated whether a tailored approach to heparin and protamine management improved thromboelastometric parameters after cardiopulmonary bypass and reduced postoperative blood loss compared with activated coagulation time (ACT)-based fixed target heparin and protamine management. DESIGN: Randomized controlled study. SETTING: Tertiary university hospital. PARTICIPANTS: Patients undergoing elective valve surgery (n = 38). INTERVENTIONS: Heparin and protamine management were based either on the ACT (n = 19) or hemostasis management system (HMS) measurements (n = 19; HMS Plus; Medtronic, Minneapolis, MN). MEASUREMENTS AND MAIN RESULTS: The target ACT for initiation of cardiopulmonary bypass was 480 seconds. Study variables included rotational thromboelastometry EXTEM (extrinsic coagulation), HEPTEM (intrinsic coagulation with heparinase), and FIBTEM (fibrin part of clot formation) tests and 24-hour blood loss. The use of HMS reduced the median protamine-to-heparin ratio from 1.00 (1.00-1.00) to 0.62 (0.56-0.66; p<0.001). The ACT group showed a prolonged postbypass clotting time for both EXTEM (86 ± 13 seconds v 78 ± 10 seconds; p = 0.05) and HEPTEM (217 ± 58 seconds v 183 ± 24 seconds; p = 0.03) tests. There was a moderate correlation between protamine dosing with the EXTEM and HEPTEM clotting time (r = 0.42; p = 0.009 and r = 0.38; p = 0.02, respectively). The number of patients with more than 450 mL/24 hours was higher in the ACT than in the HMS group (42% v 12%; p = 0.04). CONCLUSIONS: Individualized heparin and protamine management decreased the protamine-to-heparin ratio, improved postbypass thromboelastometric hemostatic parameters, and reduced the incidence of severe blood loss compared with an ACT-based strategy, supporting the added value of this approach for hemostatic optimization during cardiac surgery.

Residual blood processing by centrifugation, cell salvage or ultrafiltration in cardiac surgery: effects on clinical hemostatic and ex-vivo rheological parameters.

The study compared the effects of three blood concentration techniques after cardiopulmonary bypass on clinical hemostatic and ex-vivo rheological parameters. Residual blood of patients undergoing elective cardiac surgery was processed by centrifugation, cell salvage or ultrafiltration, and retransfused (n = 17 per group). Study parameters included blood loss, (free) hemoglobin, hematocrit, fibrinogen and erythrocyte aggregation, deformability and 2,3-diphosphoglycerate content. Patient characteristics were similar between groups. Ultrafiltration was associated with the highest weight of the transfusion bag [649 ± 261 vs. 320 ± 134 g (centrifugation) and 391 ± 158 g (cell salvage); P < 0.01]. Cell salvage resulted in the lowest hemolysis levels in the transfusion bag. Retransfusion of cell saver blood induced the largest gain in postoperative patient hemoglobin levels when compared to centrifugation and ultrafiltration, and was associated with the largest increase in 2,3-diphosphoglycerate when compared to ultrafiltration (Δ2,3-diphosphoglycerate 1.34 ± 1.92 vs. -0.77 ± 1.56 mmol/l; P = 0.03). Cell salvage is superior with respect to postoperative hemoglobin gain and washout of free hemoglobin when compared to centrifugation or ultrafiltration.