G. Soro

Multiple electrode whole-blood aggregometry and bleeding in cardiac surgery patients receiving thienopyridines

BACKGROUND Preoperative treatment with thienopyridines is associated with increased postoperative bleeding in cardiac surgery patients. Patients under treatment with thienopyridines have different levels of platelet dysfunction and the effects of discontinuation are not totally predictable. The present study aimed to determine if a preoperative assessment of platelet function in these patients could provide clinically relevant information regarding the risks of excessive postoperative bleeding and transfusion requirements. METHODS This is a retrospective analysis of prospectively collected data. Patients (n=87) under thienopyridine treatment until at least one week before cardiac surgery were enrolled in the study. Platelet function was assessed preoperatively with multiple electrode aggregometry: the adenosine diphosphate (ADP) test and TRAP (thrombin receptor-associated peptide) test were performed for all patients. RESULTS Univariate analysis revealed that postoperative bleeding was associated (p<0.1) with preoperative serum creatinine level, platelet count, CPB (cardiopulmonary bypass) duration, and results from the ADP test and the TRAP test. Multivariable linear regression analysis confirmed the CPB duration (p=0.049) and ADP test (p=0.007) as independently associated with postoperative bleeding. The relationship between the ADP test and postoperative bleeding was investigated with polynomial regression analysis, and a logarithmic equation provided the best fit. The accuracy of prediction was good (area under the curve 0.71, p=0.013), with a cutoff value for the ADP test at 31 U (sensitivity 72%, specificity 66%, negative predictive value 92%, and positive predictive value 29%). CONCLUSIONS The multiple electrode aggregometry ADP test in patients under thienopyridine treatment and undergoing cardiac surgery is associated with postoperative bleeding and platelet transfusion and provides an accurate preoperative prediction of postoperative bleeding risk.

Predictors for heparin resistance in patients undergoing coronary artery bypass grafting

Heparin resistance (HR) is a common event in cardiac operations. At present, no clear recognition of the risk factors for HR has been reached. The aim of this study was to determine a predictive model for HR, based on the preoperative patient’s profile. Two hundred consecutive patients scheduled for elective coronary artery bypass operations were enrolled in a prospective trial. Demographics, type of preoperative anticoagulation therapy and preoperative coagulation profile were collected and statistically analysed with respect to the evidence of a HR. Heparin resistance was defined as at least one activated clotting time < 400 s after heparinization and/or the need for purified antithrombin III (AT-III) administration. With a multivariate analysis we could identify five predictors for HR: AT-III ≤ 60%; preoperative subcutaneous heparin therapy; intravenous heparin therapy; platelet count ≥ 300 000 cells/mm3; age ≥ 65 years. We conclude that HR is a predictable event. In the presence of all the risk factors, the likelihood of HR is 99%; in the absence of all of them, it is 10%. Predicting HR allows us to apply many possible therapeutic strategies.

Efficacy and safety of recombinant activated factor vii in major surgical procedures: systematic review and meta-analysis of randomized clinical trials.

OBJECTIVE To investigate the efficacy and safety of recombinant activated factor VII (rFVIIa) treatment in patients undergoing major surgical procedures. DATA SOURCES Relevant studies were searched in BioMedCentral, CENTRAL, PubMed, and PubMed Central. STUDY SELECTION Only randomized controlled trials on humans undergoing major surgery were included. Efficacy was determined as the rate of patients receiving allogeneic packed red blood cells; safety was assessed in terms of thromboembolic complications and mortality rate. DATA EXTRACTION We followed the Cochrane Collaboration method for data extraction and internal validity procedures, as well as the Quality of Reporting of Meta-analyses statement. DATA SYNTHESIS Seven randomized controlled trials met the inclusion criteria. Treatment with rFVIIa is associated with a reduced risk of receiving allogeneic packed red blood cells (odds ratio, 0.29; 95% confidence interval, 0.10-0.80). In a subgroup analysis, only patients receiving at least 50 mug/kg of rFVIIa had a significant benefit (odds ratio, 0.43; 95% confidence interval, 0.23-0.78). No differences in thromboembolic complications and mortality rates were observed. CONCLUSIONS Treatment with rFVIIa is effective in reducing the rate of patients undergoing transfusion with allogeneic packed red blood cells. However, the cost-benefit ratio is favorable only in patients who need a huge number of packed red blood cell units. No safety concerns arise from the present study.

Obesity and coronary artery surgery

OBJECTIVE To assess whether obesity is a risk factor for morbidity and mortality in patients undergoing elective coronary artery revascularization. DESIGN Prospective, clinical study. SETTING University hospital. PARTICIPANTS Three hundred forty-five consecutive patients who underwent elective coronary revascularization with cardiopulmonary bypass and without associated procedures. INTERVENTIONS Patients were assigned to the obese group if their body mass index was greater than 30 for men and 28.6 for women, according to the World Health Organization indications. MEASUREMENTS AND MAIN RESULTS Preoperative and intraoperative variables were collected and checked for homogeneity of the groups. Postoperative outcome was assessed on the basis of intubation time, intensive care unit (ICU) and postoperative hospital stay, mortality rate, and incidence of transfusions, reoperations, low-output syndrome, minor and major neurologic dysfunction, minor and major lung dysfunctions, renal dysfunction, and superficial and deep infections. The effect of obesity on postoperative outcome was tested with a multivariate logistic regression analysis. Obese and control patients had the same intubation time and ICU and postoperative hospital stay. Mortality and all major complications occurred with the same incidence in the two groups. Obese patients had a significantly (p < 0.05) greater rate of superficial infections and more (24.1% v 7.4%; p < 0.001) minor lung complications. Conversely, they had a significantly lower transfusion rate (27.5% v42.7%; p < 0.01). CONCLUSION Obese patients had only minor complications after coronary artery surgery. The large body surface area because of obesity protects them against the hemodilution-related transfusion risk.

Reduced systemic heparin dose with phosphorylcholine coated closed circuit in coronary operations

In this prospective cohort study we addressed the clinical impact of a reduced anticoagulation protocol on the hospital outcome of patients undergoing coronary revascularization with cardiopulmonary bypass. 364 consecutive low to moderate risk patients scheduled for elective isolated coronary operations were admitted to the study. 184 patients (Control Group) received conventional open circuits and full systemic anticoagulation (target activated clotting time 480 seconds); 180 patients (Intraoperative ECMO group) received closed, phosphorylcholine coated circuits and a reduced systemic heparin dose (target activated clotting time 320 seconds). Patients of the Intraoperative ECMO group had less requirement for allogeneic blood products (odds ratio 0.55, 95% confidence interval 0.34–0.92, p= 0.02), a significant containment of blood loss (374 ± 278 mL vs. 463 ± 321 mL in Control group, p= 0.005) a lower postoperative peak serum creatinine levels (1.19 ± 0.48 mg/dL vs. 1.41 ± 0.94 mg/dL in Control group, p= 0.048), and a significant lower rate of severe morbidity (odds ratio 0.27, 95% confidence interval 0.09–0.81, p= 0.02). A reduction of systemic anticoagulation is feasible with a non-heparin-bonded, closed biocompatible circuit, and results in a significant improvement of the outcome of low to moderate risk coronary patients.

Normothermic perfusion and lung function after cardiopulmonary bypass: effects in pulmonary risk patients

Fifty patients at risk for postoperative lung dysfunction and undergoing elective coronary revascularization have been randomly assigned to receive normothermic (36°C) perfusion with warm heart protection (NP group) or hypothermic (28°C) perfusion with cold heart protection (HP group). Lung function before and after cardiopulmonary bypass (CPB) was studied through the determination of the intrapulmonary shunt (Qs/Qt), the alveolo-arterial oxygen gradient (A-aΔO2), and the artero-alveolar carbon dioxide gradient (a-AΔCO2). The Q s /Q t after CPB was significantly lower in the NP group (27.1 ± 2.6 vs 35.7 ± 2.3) as well as the A-aΔO2 (50.2 ± 1.5 vs 57.6 ±2.4); both data returned to comparable between the groups after 3 h in the intensive care unit. The a-AΔCO2 was significantly lower after CPB in the NP group (5.2 ± 0.74 vs 8.2 ± 0.8). Hospital stay and mortality were comparable in the two groups; intubation time and rate of early extubation showed a trend in favour of the NP group; the rate of patients suffering hypoxia and/or hypercapnia after extubation was significantly lower in the NP group (12%) versus the HP group (44%). Normothermia seems to exert a protective effect against lung dysfunction after CPB. The absence of a rewarming injury associated with reperfusion, a limitation of the hypothermic-induced vasoconstriction due to local cooling of the lung and a better compliance of the normothermic lung are hypothesized as beneficial effects of the ‘all-warm’ strategy.

Trillium biopassive surface: a new biocompatible treatment for extracorporeal circulation circuits.

139 patients undergoing cardiac surgery were included in a prospective, randomized trial. Patients were randomly allocated to receive cardiopulmonary bypass (CPB) with Trillium™ Biopassive Surface (TBS Group) coated oxygenators or conventional circuits (control group). 112 patients were studied with respect to postoperative biochemical profile; a subgroup of 27 patients was studied with respect to perioperative complement (C3a) activation. Patients in the TBS group demonstrated a significantly lower white blood cell count at the end of the operation (p=0.036) and a significantly higher platelet count the day after the operation (p=0.023) when compared to the control group. C3a was significantly higher (p=0.02) in the TBS group after 30 minutes of CPB, but the C3a increase after protamine administration was significantly less pronounced in the TBS group vs. the control group. Further studies involving platelet and leukocyte activation are required to better elucidate the action of this new coating in the setting of routine CPB.