Viscoelastic blood coagulation measurement with Sonoclot predicts postoperative bleeding in cardiac surgery after heparin reversal.

OBJECTIVES: The aim of the study was to determine if Sonoclot with its sensitive glass bead-activated, viscoelastic test can predict postoperative bleeding in patients undergoing cardiac surgery at predefined time points. DESIGN: A prospective, observational clinical study. SETTING: A teaching hospital, single center. PARTICIPANTS: Consecutive patients undergoing cardiac surgery (N = 300). INTERVENTIONS: Besides routine laboratory coagulation studies and heparin management with standard (kaolin) activated clotting time, additional native blood samples were analyzed on a Sonoclot using glass bead-activated tests. Glass bead-activated clotting time, clot rate, and platelet function were recorded immediately before anesthesia induction and at the end of surgery after heparin reversal but before chest closure. MEASUREMENTS AND MAIN RESULTS: Primary outcome was postoperative blood loss (chest tube drainage at 4, 8, and 12 hours postoperatively). Secondary outcome parameters were transfusion requirements, need for surgical re-exploration, time of mechanical ventilation, length of intensive care unit and hospital stay, and hospital morbidity and mortality. Patients were categorized into "bleeders" and "nonbleeders." Patient characteristics, operations, preoperative standard laboratory parameters, and procedural times were comparable between bleeders and nonbleeders except for sex and age. Bleeders had higher rates of transfusions, surgical re-explorations, and complications. Only glass bead measurements by Sonoclot after heparin reversal before chest closure but not preoperatively were predictive for increased postoperative bleeding. CONCLUSIONS: Sonoclot with its glass bead-activated tests may predict the risk for postoperative bleeding in patients undergoing cardiac surgery at the end of surgery after heparin reversal but before chest closure.

Systematic quantitative overviews of the literature to determine the value of diagnostic tests for predicting acute appendicitis: study protocol.

BACKGROUND: Suspected acute appendicitis is the most frequent cause for emergency operations in visceral surgery worldwide. In approximately twenty percent of all cases however, the diagnosis is incorrect and patients undergo surgery without having acute appendicitis. Operations of bland appendices put patients at risk and entail a serious waste of resources. Several highly accurate tests have been introduced to diagnose acute appendicitis. The false positive rate however, has not changed over the last twenty years. Given the variation that exists in both practice and research, the uncertainty regarding the quality of the underlying evidence, there is a clear need for comprehensive, systematic and quantitative overviews of the diagnostic value of the various tests purported to be predictive of acute appendicitis. METHODS: Literature will be identified searching general bibliographic databases (MEDLINE and EMBASE), specialist computer databases (DARE, Cochrane Database of Systematic Reviews, conference proceedings, MEDION, SCISEARCH, BIOSIS) without language restrictions. We will contact experts and the manufacturers of tests. Hand-searching will complete our searches. Identified articles will be selected according to populations, tests, outcomes and study design. Papers meeting the selection criteria will be appraised to rate their methodological quality. Analysis will include exploration of heterogeneity in results. We will conduct meta-analyses to generate summary estimates of test accuracy measures and summary ROC curves where appropriate. If meta-analysis is considered to be inappropriate, we will describe the identified evidence in the context of appraised quality. DISCUSSION: These reviews should lead to formulation of recommendations for current practice and future research.