The Millennium Scientific Meeting, Manchester, 9–11 October 2000 (Hosted by the Faculty of Accident and Emergency Medicine)

Abstract

The Millennium Scientific Meeting, Manchester, 9–11 October 2000 (Hosted by the Faculty of Accident and Emergency Medicine) EMRS/SSL International plc Prize Session Use of plasma DNA analysis to derive early prediction rules for post-traumatic organ failure T H RAINER, Y M D LO, L Y S CHAN, P K W LAM, E K WONG, N M HJELM, R A COCKS Accident and Emergency Medicine Academic Unit and Department of Chemical Pathology,The Chinese University of Hong Kong and Prince of Wales Hospital, Hong Kong Background—The discovery of eVective treatments preventing or mimising post-traumatic complications may be hampered by our inability to target high risk patients early after injury. The purpose of this study was to derive a guideline for the prediction of posttraumatic organ failure using cell free (plasma) DNA and other predictors of post-traumatic complications. Methods—The research ethics committee approved a prospective, observational study investigating molecular responses of patients to injury. Plasma DNA was measured using a real time, quantitative, polymerase chain reaction assay for the â globin gene in 84 patients (mean age 38 (SD 16) years; 83% male) triaged to an emergency department resuscitation room within a median time of 60 minutes (interquartile range 50, 90; range 30–240) from injury. Other variables were injury severity scores, white cell count (WCC) and shock index (SI). Organ failure (OF) and multiple organ dysfunction syndrome (MODS) occurred in 21 of 84 (25%) and 9 of 84 (11%) cases respectively. After univariate and receiver operator curve analysis, data were further analysed using a classification and regression tree. Results—Within four hours of injury, OF could be correctly predicted (predictive value positive, PV+) in 85.7% cases (n = 18 of 21; 95%CI 62.6% to 96.2%) by: (1) cell free DNA > 140 000 genome equivalents/ml, (2) injury severity score (ISS) > 27 and (3) WCC > 13.4 (×10/l). OF could be correctly excluded (predictive value negative, PV−) in 95.2% cases (n = 60 of 63; 95%CI 85.8% to 98.8%) by (1) cell free DNA < 141 000 genome equivalents/ml, (2) ISS < 27 and (3) WCC < 13.4. Sensitivity and specificity were 85.7% (95%CI, 62.6% to 96.2%) and 95.2% (95% CI, 85.8% to 98.8%) respectively. MODS could be correctly predicted (PV+) in 87.5% cases (n = 7 of 8; 95%CI 46.7% to 99.3%) by: (1) cell free DNA > 108 000 copies/ml, (2) maximal abbreviated injury score (MAIS) > 3, and (3) SI > 0.72. MODS could be correctly excluded (PV−) in 97.3% cases (n = 71 of 73; 95%CI 89.6% to 99.5%) by (1) cell free DNA < 108 000 copies/ml, (2) MAIS < 3.0 and (3) SI < 0.72. Sensitivity and specificity were 77.8% (95%CI, 40.2% to 96.1%) and 98.6% (95% CI, 91.5% to 99.9%) respectively. Conclusion—Plasma DNA analysis allows the development of early accurate guidelines for the prediction of post-traumatic OF and MODS. These guidelines now require prospective validation. The eVects of in vivo haemodilution with 0.9% sodium chloride and Gelofusine on whole blood coagulation and platelet function E V BRAZIL*, U SHAH**, M MACEY**, T J COATS* *Academic Unit, Accident and Emergency Department, and **Department of Haematology, Royal London Hospital, Whitechapel, London, E1 1BB Introduction—In vitro haemodilution with Gelofusine reduces clot quality in contrast with saline, which has a procoagulant eVect. These coagulation changes are poorly understood but may involve alterations in platelet function. The Sonoclot analyser allows measurement of a number of parameters of whole blood coagulation. After platelet activation CD62P (P selectin) expression is increased on the surface membrane of the platelet. CD42a (GPIX) is also expressed on the platelet surface and CD45 on leucocytes but not platelets. Platelet-leucocyte aggregates (CD45-CD42a positive events) may be increased in thrombotic states. Monoclonal antibodies to these antigens can be conjugated to fluorescent molecules and analysed by flow cytometry. Aim—The purpose of this study was to investigate the eVect of in vivo haemodilution with 0/9% sodium chloride and Gelofusine on whole blood coagulation, platelet activation and platelet-leucocyte interaction. Methods—The study was performed as a randomised, controlled, crossover study. Eight adult volunteers received 1000 ml of each solution over 30 minutes on separate occasions with a one week washout period between tests. Atraumatic blood sampling was performed from a free flowing upper limb vein before and immediately after fluid infusion. Fresh blood was used for Sonoclot analysis. Blood for platelet analysis was collected into sodium citrate containing vacutainers and analysed within 10 minutes of collection. Results—Mean Sonoclot values and platelet molecule expression pre/post solution are presented in table 1. Conclusions—In vivo haemodilution with Gelofusine significantly prolongs the time to reach maximum clot strength. Other whole blood coagulation parameters are unaltered. Both platelet activation and platelet-leucocyte interaction are impaired by Gelofusine in contrast with saline, which promotes these changes. A prospective randomised controlled trial to investigate the clinical and cost eVectiveness of emergency physiotherapy SUSAN J BUTTRESS, KEVIN MACKWAY-JONES, JACKIE