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.

Duration of red blood cell storage and outcomes in pediatric cardiac surgery: an association found for pump prime blood.

INTRODUCTION: Cardiac surgery using cardiopulmonary bypass in newborns, infants and small children often requires intraoperative red blood cell transfusions to prime the circuit and oxygenator and to replace blood lost during surgery. The purpose of this study was to investigate the influence of red blood cell storage time prior to transfusion on postoperative morbidity in pediatric cardiac operations. METHODS: One hundred ninety-two consecutive children aged five years or less who underwent cardiac operations using cardiopulmonary bypass and who received red blood cells for priming the cardiopulmonary bypass circuit comprised the blood-prime group. Forty-seven patients receiving red blood cell transfusions after cardiopulmonary bypass were separately analyzed. Patients in the blood-prime group were divided into two groups based on the duration of storage of the red blood cells they received. The newer blood group included patients who received only red blood cells stored for less than or equal to four days and the older blood group included patients who received red blood cells stored for more than four days. RESULTS: Patients in the newer blood group had a significantly lower rate of pulmonary complications (3.5% versus 14.4%; P = 0.011) as well as a lower rate of acute renal failure (0.8% versus 5.2%; P = 0.154) than patients in the older blood group. Major complications (calculated as a composite score based on pulmonary, neurological, and gastroenterological complications, sepsis and acute renal failure) were found in 6.9% of the patients receiving newer blood and 17.1% of the patients receiving older blood (P = 0.027). After adjusting for other possible confounding variables, red blood cell storage time remained an independent predictor of major morbidity. The same association was not found for patients receiving red blood cell transfusions after cardiopulmonary bypass. CONCLUSIONS: The storage time of the red blood cells used for priming the cardiopulmonary bypass circuit in cardiac operations on newborns and young infants is an independent risk factor for major postoperative morbidity. Pulmonary complications, acute renal failure, and infections are the main complications associated with increased red blood cell storage time.

Continuous monitoring of central venous oxygen saturation (Pediasat) in pediatric patients undergoing cardiac surgery: a validation study of a new technology.

OBJECTIVE: Mixed venous oxygen saturation and central venous oxygen saturation are considered possible indicators of the adequacy of oxygen delivery with respect to the oxygen needs of critically ill adult and pediatric patients. The present study was aimed at validating the accuracy of a new technology (Pediasat central venous catheter) in providing a continuous measurement of the central venous oxygen saturation in pediatric patients. DESIGN: A prospective observational study. PARTICIPANTS: Thirty pediatric patients (age, 6 days-9 years) undergoing cardiac operations. Data obtained with the Pediasat during and after the operation were compared with simultaneously collected venous blood samples analyzed with standard laboratory techniques. SETTING: A clinical research hospital. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A Bland and Altman analysis was performed on 30 matched sets of data collected before cardiopulmonary bypass, during cardiopulmonary bypass, and during the intensive care unit stay. Before cardiopulmonary bypass, there was a bias of 0.003, with lower and upper limits of agreement, -5.84 and 5.84 (percentage error, 17.3%). During cardiopulmonary bypass, the bias was 0.57 and lower and upper limits of agreement were -7.7 and 8.7 (percentage error, 23.2%). At 2 hours after the arrival in the intensive care unit, the bias was -0.6 and the lower and upper limits of agreement were -8 and 6.8 (percentage error, 20.3%). CONCLUSIONS: Because of the minimal bias and the acceptable value of percentage error, the Pediasat may be considered as an accurate tool for the continuous measurement of the central venous oxygen saturation in neonates and pediatric patients during and after cardiac operations.

Influence of the timing of cardiac catheterization and the amount of contrast media on acute renal failure after cardiac surgery.

Postoperative acute renal failure (ARF) is not uncommon after cardiac surgery and after angiography. However, limited information exists regarding the influence of the interval between cardiac catheterization and subsequent cardiac surgery and amount of contrast agent used during this procedure on the occurrence of postoperative ARF. Data for 423 consecutive adult patients who underwent elective cardiac surgery after cardiac catheterization were examined retrospectively. The influence of interval between cardiac catheterization and cardiac surgery on postoperative ARF (defined as postoperative serum creatinine > or =2 times baseline and >2 mg/dl and/or need for renal replacement therapy) was evaluated using multivariable logistic regression. ARF occurred in 24 patients (5.7%). Median time to angiography was 2 days (interquartile range 1 to 4.5), and median dose of contrast used was 1.36 ml/kg (interquartile range 1.12 to 1.69). Surgery on the day of cardiac catheterization was independently associated with increased risk of ARF (adjusted odds ratio 3.1, 95% confidence interval 1.1 to 8.8). This risk of ARF was highest in patients who underwent surgery on the same day as angiography and with a dose of contrast higher than median (14.6%) and lowest when surgery was delayed beyond 1 day of angiography and contrast dose was median or less (2.4%; adjusted odds ratio for same-day surgery and dose higher than median 4.2, 95% confidence interval 1.2 to 14.2). Cardiac surgery performed on the day of cardiac catheterization and higher dose of contrast agent used were both independently associated with increased risk of postoperative ARF. In conclusion, these findings suggest that delaying cardiac surgery beyond 24 hours of exposure to contrast agents (when feasible) and minimizing the use of these agents have significant potential to decrease the incidence of postoperative ARF in patients undergoing elective cardiac surgery.