Search

The Louisiana Emergency Response Network (LERN), a statewide trauma system, has a single communication center with real-time data on hospital capacity across the state. With these data, scene information, and a standardized triage protocol, prehospital providers are directed to the most appropriate hospital. The purpose of our study was to compare outcomes between those patients who complied with the LERN communication center direction and those who did not.Trauma patients directed by LERN from the field in 2014 were included. Patients who followed the LERN communication center direction were considered the compliant group. Patients brought to a hospital inconsistent with the LERN direction were considered the noncompliant group. Chi-square analysis was used to compare differences between groups and a p value of0.05 was considered statistically significant.During the study period, LERN directed 14,071 patients to a destination hospital. Prehospital providers were compliant with the LERN direction in 13,037 (92.7%) patients and noncompliant in 1,034 (7.3%) patients. There were fewer patients in the compliant group (570 of 13,037 [4.3%]) requiring transfer to a second hospital than in the noncompliant group (312 of 1,034 [30.2%]) (p0.01). The mortality rate was lower in the compliant group (81 of 13,037 [0.6%]) than in the noncompliant group (21 of 1,034 [2.03%]) (p0.01).Following direction from a central communication center with real-time hospital capacity data yielded a 6-fold decrease in secondary transfer and a 3-fold decrease in mortality. These data emphasize the value of an organized statewide trauma network that routes patients to the appropriate facilities.

Introduction: Diaphragmatic rupture (DR) is an uncommon, potentially serious complication following blunt or penetrating ab- dominal trauma. Even with a high index of suspicion, the diagnosis of DR can easily be missed for a long period post injury. Delayed or missed diagnosis (delayed diagnosis of diaphragmatic rupture (DDDR)) and delayed diaphragmatic rupture (DDR) are possible explanations in cases where the initial operative exploration fails to show the diaphragmatic damage. Case Presentation: Here we present a patient with suspected DR that was not seen on initial open abdominal exploration, but was suggested by subsequent serial imaging. This injury was ultimately identified on laparoscopic exploration. The procedure was converted to open (celiotomy) due to poor tolerance of the pneumoperitoneum required for laparoscopy, and the laceration was primarily repaired. We propose that DDR and DDDR be considered as a dierential diagnosis in patients with a previous thoraco- abdominal trauma when presenting with radiologic/clinical signs suspicious for DR, even when the immediate post traumatic ex- ploration failed to demonstrate a DR. Conclusions: A high index of suspicion is essential for early detection of DDR and DDDR. Patients with high impact injuries or surrounding organ damage should be followed with serial clinical examinations, follow-up radiologic assessments, and even re- exploration in situations highly suspicious for diaphragmatic injuries.

Central venous catheters (CVCs) are associated with occlusive, infectious, and thrombotic complications. The aim of this study was to determine if internal CVC tip position was correlated with subsequent complications. This was an institutional review board approved single-center retrospective review of 169 consecutive patients who underwent placement of 203 semipermanent CVCs. Using post-placement chest X-rays, a de novo scale of internal catheter tip position was developed. Major complications were recorded. A logistic regression analysis was used to determine if catheter tip position predicted subsequent complications. There were 78 men and 91 women with a mean age of 48 ± 11 years. There were 21 catheter tips placed in the subclavian/innominate veins, 32 in the upper superior vena cava, 113 in the atriocaval junction, and 37 in the right atrium. There were 83 complications occurring in 61 (36.1 %) patients, including sepsis in 40 (23.7 %), venous thrombosis in 18 (10.7 %), catheter occlusion in 16 (9.5 %), internal catheter repositioning in 6 (3.6 %), pneumothorax in 2 (1.2 %), and death in 1 (0.6 %). An internal catheter tip position peripheral to the atriocaval junction resulted in a catheter that was more likely to undergo internal repositioning (p < 0.001) and venous thrombosis (p < 0.001). Patients with femoral catheters were more likely to develop sepsis (45 %) than patients whose catheters were inserted through the upper extremity veins (18 %) (p < 0.01). In conclusion, to reduce catheter-associated morbidity and potentially mortality, the internal catheter tip should be positioned at the atriocaval junction or within the right atrium and femoral insertion sites should be avoided whenever possible.

Heparin-induced thrombocytopenia (HIT) is a complication caused by antibodies directed to the heparin-platelet factor 4 (PF4) complex with a seemingly paradoxical high risk of thrombosis. Discontinuation of heparin and administration of an alternative anticoagulant is important in prevention of catastrophic thrombosis. Diagnosis is challenging and based on clinical probability models (Warkentin 4 Ts and Chong scale) and, to a lesser degree, laboratory testing. Enzyme-linked immunosorbent assay (ELISA) measurement of heparin-PF4 antibodies is commonly used but has low predictive values for thrombosis. We analyzed 105 cases of suspected HIT and compared optical density values and the Warkentin 4 Ts for sensitivity, specificity, positive predictive value, and negative predictive value (NPV). The predictive value of ELISA alone was inferior to the Warkentin 4 Ts score. The sensitivity and NPV of the clinical score was improved by incorporating ELISA results. The combination of a negative ELISA result with low probability 4 Ts resulted in an NPV of 94%.

BACKGROUND: Transfusion of trauma patients can result in long-term survival of donor white blood cells (WBCs) or “transfusion-associated microchimerism” (TA-MC). The aim was to determine whether leukoreduction of blood transfusions, advocated to reduce the immunomodulatory effect of transfusion, decreases the likelihood of developing TA-MC. STUDY DESIGN AND METHODS: A subgroup of trauma patients from a randomized trial was examined, evaluating the risk of infection following leukoreduced versus nonleukoreduced blood transfusion. Patients’ blood was sampled at least 1 month after hospital discharge, and TA-MC was assessed with quantitative allele-specific polymerase chain reaction detection of differences at the HLA-DR locus or a panel of insertion-deletion polymorphism loci distributed throughout the chromosomal complement. At the time of blood sampling, a scripted interview was used to ascertain symptoms suggestive of chronic graft-versus host disease (cGVHD). RESULTS: For 67 patients evaluated, the mean age was 43 ± 17 years and mean Injury Severity Score was 24 ± 12. Median time from injury to blood sampling for TA-MC was 240 (interquartile range, 116-360) days. Nine of 32 patients (28%) in the nonleukoreduced transfusion group developed TA-MC compared to 13 of 35 patients (37%) in the leukoreduced group (p = 0.43). Subjects with TA-MC were no more likely than subjects without TA-MC to have at least one symptom suggestive of cGVHD (64% vs. 76%, respectively). CONCLUSIONS: TA-MC seems to be a prevalent condition among injured patients at the second of two regional trauma centers evaluated, suggesting that it is a common phenomenon after transfusion in the setting of injury. Although leukoreduction removes greater than 99.9 percent of donor WBCs, it fails to prevent or even substantially reduce the likelihood of developing TA-MC. TA-MC does not appear to be strongly associated with symptoms suggestive of cGVHD several months after transfusion.

BACKGROUND: Long-term white blood cell (WBC) microchimerism (MC), of at least 2 years, has been reported in trauma patients receiving fresh nonleukoreduced (non-LR) blood. It is unknown, however, whether this occurs with LR blood products that are nearly devoid of WBCs. Twenty-seven patients transfused with LR and non-LR blood products were studied after severe traumatic injury. A secondary aim was to explore donor-recipient mixed lymphocyte reactivity in vitro. STUDY DESIGN AND METHODS: To quantify MC, allele-specific real-time polymerase chain reaction assays were developed targeting HLA Class II sequence polymorphisms. Extensive validation showed that these assays reliably detect a single copy of target sequence in a complex allogeneic background without false positivity. RESULTS: At a median follow-up of 26 months (range, 24-39 months), long-term MC was observed in 3 of 20 patients (15%) who received non-LR blood products and 2 of 7 (29%) who received LR blood products. The maximum MC ranged from 0.40 to 4.90 percent of circulating WBCs and appeared, by Class II genotype analysis, to be attributable to a single donor. CONCLUSION: It is concluded that robust levels of long-term MC, apparently traceable to a single donor, occur at similar frequency despite leukoreduction of transfused blood products. Exploratory analysis of donor-recipient mixed lymphocyte reactivity suggests that long-term MC may require a state of bidirectional tolerance before transfusion.

Background: Blood transfusion can result in long-term survival of donor leukocyte subpopulations, or microchimerism, in the peripheral blood of injured patients. Neither injury severity nor the number of transfusions is associated with its occurrence. We sought to determine whether changes in general or antigen-specific lymphocyte activation may be associated with the subsequent development of microchimerism. Methods: We evaluated 63 transfused trauma patients, which we compared with 10 non-transfused trauma patients and 10 healthy control subjects. Of the 63 transfused patients, 31 were known to have evidence of microchimerism at hospital discharge with real-time quantitative PCR for non-recipient HLA DR alleles. We assessed lymphocyte response to phytohemagglutinin (PHA) using blood sampled upon arrival to the hospital (before transfusion) and at discharge. We performed one-way mixed leukocyte cultures (MLC) with pre-transfusion recipient specimens to assess recipient lymphocyte response to mitomycin-C treated donor cells and vice versa. Results: Lymphocyte response to PHA in microchimeric transfusion recipients was lower at admission (before transfusion) and discharge than in non-microchimeric recipients. Lymphocytes from microchimeric patients had less response to donor cells than did lymphocytes from non-microchimeric patients. Microchimeric patients also more frequently had diminished lymphocyte response to a single blood donor on MLC. Conclusions: Transfusion-associated microchimerism is correlated with diminished response to mitogen challenge as well as to specific alloantigenic challenges. This microchimerism is predated by diminished lymphocyte response to a specific blood donor in many instances. The blood donor associated with this diminished alloantigenic lymphocyte response may be the source of microchimeric cells present in the recipient.

BACKGROUND: Patients with heparin-induced thrombocytopenia and thrombosis may be acutely anticoagulated with direct thrombin inhibitors (DTIs). The anticoagulation is typically monitored using the activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). OBJECTIVE: To compare 14 methods for measuring aPTT, as well as ECT and thrombin inhibitor management test (TIM), in samples containing DTIs. METHODS: DTIs were added to pooled normal plasma to achieve low (0.1–1.2 μg/mL) and high (1.5–8.0 μg/mL) drug concentrations. Each low-concentration DTI sample was tested using all aPTT reagents, while each low- and high-concentration DTI was tested using the ECT and TIM. RESULTS: All aPTT reagents had a significant dose-dependent correlation with drug concentration. Only Actin FSL and APTT-S demonstrated equivalent aPTT ratios obtained from any DTI. The TAS-aPTT was the most sensitive aPTT reagent to argatroban, with the aPTT ranging from 52.7 to 121.2 seconds corresponding to 0.1 to 1.2 μg/mL of drug concentration. The TAS-aPTT and Pathromtin were the most sensitive aPTT reagents to bivalirudin, with aPTTs of 87.4 seconds and 101.5 seconds, respectively, at 1.2 μg/mL of drug. Pathromtin was the most sensitive aPTT reagent to lepirudin, with a maximum aPTT of 108.9 seconds at 1.2 μg/mL of drug. There was no statistically significant difference between the TIM and ECT clotting times for each DTI. Lepirudin and bivalirudin ECT and TIM clotting times were equivalent. CONCLUSIONS: There are unique differences between reagent manufacturers in the monitoring of DTIs. Acceptable alternatives to aPTT monitoring of DTI anticoagulation include the ECT and TIM.

Antithrombin deficiency is a hypercoagulable state that can increase the risk for thrombosis, especially in the presence of other procoagulant triggers. Unfractionated heparin and low-molecular-weight heparins may not provide effective anticoagulation since they require antithrombin for activity. Direct thrombin inhibitors, however, work independently of antithrombin. A 21-year-old man with a history of heavy alcohol consumption had thrombosis of the superior mesenteric vein. Infusion with unfractionated heparin was started, and despite repeated boluses and increases to 21 U/kg/hour, the maximum activated partial thromboplastin time reached was 39 seconds. The unfractionated heparin was discontinued, and the direct thrombin inhibitor argatroban was infused at rates of 0.4-0.5 microg/kg/minute. Over the course of several weeks, the patient had numerous operations to remove and repair necrotic bowel. When no further surgery was anticipated, warfarin therapy was started; the argatroban infusion was discontinued when the patient reached the therapeutic target international normalized ratio with warfarin. No recurrent thrombosis or major bleeding occurred. Direct thrombin inhibitors, such as argatroban, seem to be suitable alternatives for acute anticoagulation in patients with antithrombin deficiency.

We evaluated six D-dimer methods to determine their sensitivity, specificity, and negative predictive values (NPV) in symptomatic patients suspected of deep vein thrombosis (DVT). In patients suspected of DVT a whole blood D-dimer test (SimpliRED, Agen) was performed, and then tested using enzyme-linked immunosorbent assay (VIDAS D-Dimer, BioMerieux; Asserachrome D-Di, Stago International; Dimertest Gold, Agen) and automated immunoturbidometric methods (Advanced D-Dimer, Dade Behring; MiniQuant, Biopool). Each D-dimer method was independently compared with radiographic results to determine sensitivity and NPV. There were 151 patients enrolled in the study. Thirty-five (23.2%) patients had a positive Doppler ultrasound, with 26 proximal, eight distal, and one patient with both proximal and distal thrombus. Two patients (1.3%) had inconclusive studies and were excluded from the analyses. For all patients, the sensitivities for the rapid D-dimer methods were: SimpliRED, 82.3% [95% confidence interval (CI), 80.3-84.3%]; VIDAS D-Dimer, 91.4% (95% CI, 89.9-92.9%); MiniQuant D-Dimer, 96.3% (95% CI, 95.1-97.5%); and Advanced D-Dimer, 97.1% (95% CI, 96.3-97.9%). The sensitivity improved for SimpliRED (86.4%; 95% CI, 83.3-89.4%), VIDAS D-Dimer (95.5%; 95% CI, 85.0-100%), MiniQuant D-Dimer (100%; 95% CI, 96.9-100%) and Advanced D-Dimer (100%; 95% CI, 98.9-100%) in the inpatient population. The automated immunoturbidometric methods, the MiniQuant D-Dimer and Advanced D-Dimer, demonstrated comparable sensitivities and NPV with the VIDAS D-Dimer method in symptomatic patients suspected of DVT, which would suggest that these newer D-dimer methods could be used as part of the diagnostic algorithm for patients suspected of DVT.

Study Objective: We sought to determine the utility of laboratory testing after adjusting for physical examination findings in the identification of children with intra-abdominal injuries after blunt trauma. Methods: The study was a prospective observational series of children younger than 16 years old who sustained blunt trauma and were at risk for intra-abdominal injuries during a 2½-year period at an urban Level I trauma center. Patients were examined by faculty emergency physicians and underwent standardized laboratory testing. Clinical and laboratory findings were recorded on a standardized data sheet. Intra-abdominal injury was considered present if an injury was documented to the spleen, liver, pancreas, kidney, adrenal glands, or gastrointestinal tract. We performed multiple logistic regression and binary recursive partitioning analyses to identify which physical examination findings and laboratory variables were independently associated with intra-abdominal injury. Results: Of 1,095 enrolled patients, 107 (10%, 95% confidence interval [CI] 8% to 12%) had intra-abdominal injuries. The mean age was 8.4±4.8 years. From both analyses, we identified 6 findings associated with intra-abdominal injury: low systolic blood pressure (adjusted odds ratio [OR] 4.1; 95% CI 1.1 to 15.2), abdominal tenderness (adjusted OR 5.8; 95% CI 3.2 to 10.4), femur fracture (adjusted OR 1.3; 95% CI 0.5 to 3.7), serum aspartate aminotransferase concentration more than 200 U/L or serum alanine aminotransferase concentration more than 125 U/L (adjusted OR 17.4; 95% CI 9.4 to 32.1), urinalysis with more than 5 RBCs per high-powered field (adjusted OR 4.8; 95% CI 2.7 to 8.4), and an initial hematocrit of less than 30% (adjusted OR 2.6; 95% CI 0.9 to 7.5). Conclusion: After adjusting for physical examination findings, laboratory testing contributes significantly to the identification of children with intra-abdominal injuries after blunt trauma. [Holmes JF, Sokolove PE, Brant WE, Palchak MJ, Vance CW, Owings JT, Kuppermann N. Identification of children with intra-abdominal injuries after blunt trauma. Ann Emerg Med. May 2002;39:500-509.]

Prehospital helicopter use and its impact on outcomes in snowboarders and skiers incurring traumatic brain injury (TBI) is unknown. The present study investigates the association of helicopter transport with survival of snowboarders and skiers with TBI, in comparison with ground emergency medical services (EMS), by using data derived from the National Trauma Data Bank (2007-2014).Primary and secondary endpoints were defined as in-hospital survival and absolute risk reduction based upon number needed to transport (treat) respectively. Multivariable regression models including traditional logit model, model fitted with generalized estimating equations, and those incorporating results from propensity score matching methods were used to investigate the association of helicopter transport with survival compared with ground EMS.Of the 1018 snowboarders and skiers who met the criteria, 360 (35.4%) were transported via helicopters whereas 658 (64.6%) via ground EMS with a mortality rate of 1.7% and 1.5%, respectively. Multivariable log-binomial models demonstrated association of prehospital helicopter transport with increased survival (odds ratio 8.58; 95% confidence interval 1.09-67.64; P = 0.041; absolute risk reduction: 10.06%). This finding persisted after propensity score matching (odds ratio 24.73; 95% confidence interval 5.74-152.55; P0.001). The corresponding absolute risk reduction implies that approximately 10 patients need to be transported via helicopter to save 1 life.Based on our robust statistical analysis of retrospective data, our findings suggest prehospital helicopter transport improved survival in patients incurring TBI after snowboard- or ski-related falls compared with those transported via ground EMS. Policies directed at using helicopter services at remote winter resorts or ski or snowboarding locations should be implemented.

Background: Abnormal hemostasis is associated with many of the complications of trauma-associated morbidity and mortality. Platelets are integral in the maintenance of hemostasis. Methods: Samples were obtained from 100 trauma patients on arrival at the emergency room (initial time) and at 24, 48, and 72 hours later. Samples were also obtained from 10 healthy controls at the same time intervals. Using flow cytometry, three parameters were used to measure platelet activation: platelet microparticles, expression of P-selectin (CD62P), and expression of the activated conformation of glycoprotein IIb-IIIa (PAC-1 binding). Platelet function was measured using a platelet function analyzer (PFA-100, Dade International Inc., Miami, FL). ). Results: One hundred trauma patients were enrolled. The average age was 40 years, 75% were men, and 84% had blunt injuries. The mean Injury Severity Score was 22.3 ± 10.9 (mean ± SD) and the average Glasgow Coma Scale score was 11 ± 4. All three platelet activation parameters were increased in trauma patients versus controls for all time periods (p < 0.001). Trauma patients had a trend toward a shorter initial collagen/epinephrine closure time versus controls (p = 0.096). Compared with the 24-, 48-, and 72-hour time intervals, initial collagen/ epinephrine closure times were shortened (p < 0.001, p < 0.001, and p < 0.001). Platelet function returned to normal reference ranges within 24 hours but platelet activation parameters remained elevated at least 72 hours after initial trauma. In contrast, when trauma patients with and without brain injury were compared, brain injury patients had increased platelet activation but decreased platelet function (increased collagen/epinephrine closure times). In addition, there was a significant prolongation in collagen/epinephrine closure times for the 24-, 48-, and 72-hour time points in nonsurviving patients versus survivors. There was no association between platelet activation and function and other adverse outcomes including pulmonary embolism, deep venous thrombosis, and disseminated intravascular coagulation. Conclusion: Severe injury usually results in increased platelet activation and function. However, the combination of increased platelet activation with decreased function was associated with increased mortality.

Hypothesis: Children who undergo cardiopulmonary bypass (CPB) are proportionally more hemodiluted than adults who undergo CPB. Current methods of monitoring high-dose heparin sulfate anticoagulation are dependent on fibrinogen level. Because of the decreased fibrinogen levels in children, current methods of monitoring heparin anticoagulation overestimate their level of anticoagulation. Design: Prospective controlled trial. Main Outcome Measure: Production of thrombin (adequacy of anticoagulation). Methods: Children and adults undergoing cardiac surgery who received CPB were anticoagulated in the standard fashion as directed by activated clotting time (ACT) results. Each subject had blood sampled at baseline; heparinization; start of the CPB; CPB at 30, 60, and 90 minutes; and at termination of CPB. Samples were used to assess anticoagulation with the Heparin Management Test (less dependent on fibrinogen level than ACT). We also assessed 2 subclinical markers of thrombosis, thrombin-antithrombin complexes and prothrombin fragment F1.2; a marker of procoagulant reserve, fibrinogen; the natural antithrombotic, anti-thrombin; and heparin concentration. Results: Ten children and 10 adults completed the study. Children had lower fibrinogen levels than adults throughout CPB (P

Background The whole blood D-dimer assay has gained recognition as a noninvasive test to rule out pulmonary embolism (PE) in medical patients. Methods We performed a whole blood D-dimer assay in medical and surgical patients undergoing either pulmonary angiogram or pulmonary ventilation perfusion scan for suspected PE or duplex Doppler or venogram for suspected deep venous thrombosis (DVT). Results A total of 483 patients were enrolled; 16 were excluded because of an equivocal pulmonary ventilation perfusion scan. The 467 remaining patients had a mean age of 56 +/- 27 years. There were 258 women and 209 men. A total of 353 patients were admitted to a medical service and 114 to surgery/ trauma. A total of 82 patients (18%) developed thromboembolism: 20 had PE, and 62 had DVT. Conclusion No surgical patient with PE or DVT (n = 27) had a negative D-dimer. A negative D-dimer result in a stable surgical patient should be considered conclusive evidence to rule out thromboembolism and, thus, negate the need for further diagnostic studies. In our surgical patients suspected of DVT or PE, had D-dimer been used, one third of the patients would have avoided an expensive or invasive diagnostic test.

SummaryOur study compared point-of-care (POC) device monitoring with traditional clinical laboratory methods device of patients on oral anticoagulant therapy. The POC devices used in the study were Coumatrak, CoaguChek, CoaguChek Plus, Thrombolytic Assessment System (TAS) PT-One, TAS PTNC, TAS PT, Hemachron Jr. Signature, Protime Microcoagulation System, and Medtronics ACT II. The clinical laboratory method used thromboplastins with different ISI values: Innovin and Thromboplastin C Plus (TPC). All POC INRs showed strong correlation with both laboratory methods, with correlation coefficients of >0.900. All POC methods demonstrated a significant (p 0.93), but there were still significant (p

Background: T-cell response to trauma has been assessed primarily by sampling peripheral blood lymphocytes. We hypothesized that lymphocytes residing in tissue and traveling through lymph vessels are more likely to be activated by tissue injury and hemorrhage-induced hypoperfusion. We compared peripheral blood T-cell response with tissue or lymph T-cell response in an ovine model of multiple injury. Methods: Anesthetized adult sheep instrumented with a chronic prefemoral lymph fistula were subjected to lower-extremity fractures, fixed-volume hemorrhage, resuscitation, and fracture stabilization. Peripheral blood and tissue T-cell receptor expression was determined at baseline and after injury. Results: At baseline, we found significant differences in the expression of CD4, CDS, and L selectin between peripheral blood T cells and tissue T cells. After trauma, the percentage of tissue T cells expressing CD8 decreased from 19 ± 9 to 14 ± 5 (p < 0.05) and the percentage expressing γδ-TcR receptors decreased from 12 ± 4 to 7 ± 2 (p < 0.05). T-cell phenotype composition in peripheral blood was not affected by trauma. Conclusion: Peripheral blood T-cell composition differs from tissue T-cell composition before and after trauma. Trauma produced changes in tissue T-cell phenotypes but not in peripheral blood T-cell phenotypes.

Background: Studies have shown right ventricular end-diastolic volume (RVEDV) to be a more accurate estimate of left ventricular preload than pulmonary artery wedge pressure. We prospectively evaluated the ability of RVEDV to predict left ventricular end-diastolic volume (LVEDV) in critically ill patients. Methods: Thirty critically ill patients in the surgical intensive care unit underwent concurrent measurement of RVEDV and LVEDV. RVEDV was measured using a residual fraction SwanGanz catheter (RF Swan). LVEDV was measured using transesophageal echocardiography with acoustic quantification. Intracardiac, intra-abdominal, and ventilatory pressures were also measured. Results: RVEDV as measured by the RF Swan was significantly larger (by a factor of 2) than LVEDV (p < 0.0001 analysis of variance). However, the RVEDV and LVEDV were strongly correlated (r = 0.71, p < 0.0001, Pearson's correlation). Conclusions: RVEDV from the RF Swan markedly overestimated left ventricular preload. If RVEDV is is used as an absolute value for determining preload, patients may be underresuscitated. Transesophageal echocardiography in conjunction with RF Swan can be used to more accurately determine preload and cardiac performance than RF Swan alone in critically ill patients.

Hepatic abscess is a known complication following packing for massive liver injury. Posttraumatic hepatic arterial pseudoaneurysms are rare. The trend in management in each individual complication has been toward minimally invasive techniques. We present a case wherein the two processes occurred together and were managed safely with a transcatheter approach.

This review describes the approaches taken for patient with massive hemorrhage, a derangement of hemostasis, and anemia. For hemorrhage, control of the source of bleeding, restoration of the blood volume, and management of the coagulopathy is presented. Exclusion of technical causes of bleeding, an initial assessment of potential coagulopathy, and an interpretation of coagulation parameters is described for derangements of hemostasis. For anemia, acute coronary artery ischemic syndromes and neurologic conditions are described. Additionally, bleeding disorders are presented. Figures depict various algorithms related to decision-making and treatment. Tables show the management of the patient with an increased International Normalized Ratio, coagulopathy scores, classification and management of Von Willebrand disease, and tests of platelet function. This review contains 83 references.

Introduction: Blood transfusion can result in survival of donor leukocyte subpopulations in the recipient. Persistence of donor leukocytes in the transfusion recipient is termed microchimerism. Microchimerism likely reflects engraftment of the recipient with donor hematopoietic stem cells and is very uncommon with transfusion for elective surgery, sickle cell anemia, thalassemia, and HIV. We have found, however, that microchimerism may be more common in trauma patients. Objective: To determine how frequently transfusion after trauma is associated with microchimerism. Methods: We prospectively enrolled 45 trauma patients who were transfused ≥2 units of PRBCs. We sampled blood before hospital discharge and determined microchimerism by polymerase chain reaction (PCR) analysis of specimens using quantitative allele-specific HLA DR assays to detect non-recipient alleles. Data are expressed as median with interquartile range. Results: Patients had a median age of 38 (interquartile range 25, 58) years, ISS of 19 (13, 29), and mortality of 7%. Seventy-eight percent were men, and 84% had blunt trauma. Patients received a median of 6 (4, 16) (range 2, 87) units of PRBCs. Of the 45 patients, 24 (53%) had evidence of microchimerism. Compared with patients without evidence of microchimerism, these patients had no difference in mean age, gender, ISS, units of PRBCs transfused, time from transfusion to blood sampling, or proportion that underwent splenectomy. Twenty-one of the 24 patients with microchimerism had only 1 or 2 non-recipient DR alleles identified by PCR. Conclusions: Transfusion after trauma is associated with over half of recipients having evidence of microchimerism. Age, sex, ISS, and splenectomy of the recipient and the number of transfused units did not correlate with microchimerism. Because the median time from trans' fusion to sampling for PCR analysis was not longer in the group without microchimerism, it is unlikely microchimerism is due merely to failure of the recipient to clear transfused donor leukocytes.

BACKGROUND Previous studies have indicated the variability of anti-Xa activity in different sources of heparin and the variability of different methods used for measuring anti-Xa activity. Manufacturers of low-molecular-weight heparins (LMWHs) determine each lot's anti-Xa activity against the World Health Organization standard, but little information is known about anti-Xa activity variation between lots of LMWH and the impact on reported anti-Xa activity in patient samples. OBJECTIVE To determine the variation of plasma anti-Xa activity in patients receiving enoxaparin when different lots of enoxaparin are used for test calibration. METHODS We obtained 7 lots of enoxaparin containing approximately 10 000 IU/mL and one lot containing approximately 15 000 IU/mL of anti-Xa activity. For each lot, a 2.0 anti-Xa IU/mL dilution was prepared and a calibration curve performed using a chromogenic method. To test the variation in reported results between the different calibration lots, 20 patient samples were tested. Nineteen patients receiving enoxaparin and one patient not receiving enoxaparin (negative control) were tested in a blinded fashion, and the changes in light absorbance recorded. Anti-Xa activity results from tested plasmas were then extrapolated from each enoxaparin lot calibration curve. RESULTS Using Student's paired t-test, there were statistically significant differences between the plasma anti-Xa activities generated from the various enoxaparin lots. In the range of 0.5–1.0 IU/mL of anti-Xa activity, 3 (4.2%) samples had a >0.2 IU/mL difference (maximum difference 0.33 IU/mL) in anti-Xa activity between 2 lots of enoxaparin. For samples that had supratherapeutic anti-Xa activities (1.0–1.5 IU/mL anti-Xa activity), there was a wider variation (>0.2 IU/mL) in anti-Xa activity, which may have resulted in a dosing change. CONCLUSIONS The statistical differences in plasma anti-Xa activities noted between enoxaparin lots are not clinically significant. However, anti-Xa activities in the upper therapeutic and supratherapeutic ranges (>1.0 IU/mL of anti-Xa activity) resulted in a deviation of >0.3 IU/mL in reported anti-Xa activity, which may result in dosing changes.

Background: Pulmonary angiography (PA-gram) has long been the accepted criterion standard for diagnosing pulmonary embolism (PE). Computed tomographic angiography has recently been advocated as an equivalent alternative to PA-gram. CT angiography is known to be insensitive for peripheral (segmental and subsegmental) emboli. We have previously found that a significant number of posttraumatic PEs occur early. We therefore hypothesized that because of the fragmentation of these early (soft) clots, posttraumatic PEs would be found disproportionately in the lung periphery. Methods: Trauma patients with PE confirmed by PA-gram were identified from our trauma database and medical records. PA-grams and reports were rereviewed and the location of all emboli was documented. Results: We identified 45 patients, with an average age of 46 ± 19 years; two thirds of the patients were men and 82% had a blunt mechanism of injury. Patients had PE diagnosed between days 0 and 57. Overall, PE was confined to segmental or smaller vessels in 27 (60%) patients and to subsegmental vessels in 7 (16%) patients. Twelve patients (27%) had a PE within the first 4 days. Furthermore, 32 patients (71%) had unilateral clot and 22 patients (48.9%) had clot confined to one region. Conclusion: PE frequently occurs soon after injury. The majority of PEs after trauma are found peripherally (in segmental or subsegmental vessels). Right/ left pulmonary artery embolisms are likely to be found only later in a trauma patient's course. Any diagnostic study used to diagnose pulmonary embolism in trauma patients must have sufficient resolution capacity to reliably detect segmental and subsegmental clot. A diagnostic modality such as CT scanning that is insensitive to peripheral embolisms may miss a significant number of posttraumatic PEs.

Polymerized bovine hemoglobin is currently under investigation as an alternative to blood-banked human red blood cells. Because of the dark red hemolyzed appearance of hemoglobin-based oxygen carrier (HBOC)-201, we sought to describe the effects of HBOC-201 on coagulation analyzers that perform prothrombin times, activated partial thromboplastin times, fibrinogen, and antithrombin. Pooled normal plasma was combined with HBOC-201 to achieve plasma hemoglobin levels of 1.4, 2.6, 3.8, 4.8, and 6.2 g/dL. Results for each test using HBOC-201-prepared plasma were compared with results using saline-matched controls. Two consecutive absolute result differences of >10% between saline controls and HBOC-201 samples were used for determining interference in test accuracy by the concentration of HBOC-201. Mechanical detection methods (fibrometer, STA, CS-190) and the MDA-180 method were less affected by increasing levels of HBOC-201 than optical detection devices for all test parameters.

Hypothesis Use of the vacuum assisted closure device (VAC) for securing split-thickness skin grafts (STSGs) is associated with improved wound outcomes compared with bolster dressings. Design Consecutive case series. Patients and Setting Consecutive patients at a level I trauma center requiring STSG due to traumatic or thermal tissue loss during an 18-month period. Main Outcome Measure Repeated skin grafting due to failure of the initial graft. Secondary outcome measures included dressing-associated complications, percentage of graft take, and length of hospital stay. Results Sixty-one patients underwent STSG placement. Indications for STSG were burn injury (n = 32), soft tissue loss (n = 27), and fasciotomy-site coverage (n = 2). Patients were treated with the VAC (n = 34) or the bolster dressing (n = 27). The VAC group required significantly fewer repeated STSGs (1 [3%] vs 5 [19%]; P = .04). Two additional graft failures occurred in the no-VAC group, but repeated STSGs were refused by these patients. No difference was seen between the groups in age, percentage of graft take, or hospital length of stay. The no-VAC group had significantly larger grafts (mean ± SD, 984 ± 996 vs 386 ± 573 cm 2 ; P = .006). The patients requiring repeated STSGs (n = 6)did not have significantly larger grafts than those not requiring repeated STSGs (mean ± SD, 617 ± 717 vs 658 ± 857 cm 2 ; P = .62). No dressing-associated complications occurred in the VAC group. Conclusions The VAC provides a safe and effective method for securing STSGs and is associated with improved graft survival as measured by a reduction in number of repeated STSGs.

Background: Activated monocytes are able to express tissue factor (TF), a potent procoagulant. The effect of injury on monocyte TF expression is not known. We have found that patients with head injury (HI) have increased antithrombin activity and decreased platelet function compared with non-head-injured trauma patients. Our objective was to determine whether injury increases TF expression by monocytes and whether this increased TF expression is attenuated in patients with HI. Methods: We prospectively enrolled 37 trauma patients (meeting the entry criterion of an Injury Severity Score [ISS] ≥ 9) and 11 healthy control subjects. We sampled blood on arrival and then at 24, 48, and 72 hours. We performed flow cytometry with antibody markers for monocytes (CD14), platelets (CD42a), and TF. We compared results of patients with HI (Glasgow Coma Scale score ≤ 9 and Abbreviated Injury Scale Head/Neck score ≥ 3) with patients without HI and with controls. Results: Patients had a mean ISS of 23.9 ± 2.3 (± SEM), mean age of 45 ± 3 years, and mean length of stay of 17.9 ± 3.2 days. Seventy-six percent were men, and 97% had blunt trauma. The overall mortality rate was 11%. Trauma patients had greater monocyte TF expression than controls for all time periods (p < 0.05). Trauma patients with HI had elevated monocyte TF expression compared with controls for the initial and 24-hour time periods, but they subsequently had more rapid return of monocyte TF expression to baseline (despite a higher ISS) than trauma patients without HI. Trauma patients both with and without HI had increased platelet-monocyte binding at each time versus controls. Conclusion: Trauma induces TF expression on monocytes. Patients with HI have attenuation of this expression by 24 hours after injury. The attenuation of TF expression by monocytes in HI parallels the increase in AT and the decrease in platelet function seen after HI. The correlation of TF expression with platelet-monocyte binding suggests that platelet binding may lead to monocyte activation.

The objective of our study was to evaluate the performance characteristics of a new automated d-dimer, the Advanced D-Dimer (Dade Behring Inc., Deerfield, IL) for use in the diagnosis of venous thromboembolism (VTE). To do this we compared the Advanced D-Dimer to existing d-dimer methods using established target cut-off values in patients suspected of VTE who were to undergo definitive radiographic studies for VTE. We studied hospitalized patients and outpatients who were suspected of having VTE and who had whole blood d-dimer performed. The patients who underwent a diagnostic study for VTE had their D-dimer results used to determine sensitivity, specificity and negative predictive values. There was relatively poor correlation between the Advanced D-Dimer and D-Dimer Gold (r = 0.63; t-test: P < 0.005) and Asserachrome D-Di (r = 0.58; t-test: P < 0.005). The Advanced D-Dimer target cutoff values for excluding VTE in hospitalized and outpatients were < or = 1800 microg/L and < or = 1500 microg/l respectively. There were 139 patients suspected with pulmonary embolism (PE) and 328 evaluated for deep vein thrombosis (DVT). There were 24 patients with PE, and 43 with DVT. The Advanced D-Dimer had comparable sensitivity, specificity and negative predictive values (96, 43, 98% for PE and 96, 48, 99% for DVT respectively) to other d-dimer methods used for that purpose. We conclude that the Advanced D-Dimer correlates relatively poorly with enzyme-linked immunosorbent assay methods. This poor correlation is likely due to incorrect reporting units and concentration. When these factors are corrected correlations improved. Compared to existing d-dimer methods used for VTE exclusion, the high sensitivity and negative predictive value would suggest that this method can be used as part of a diagnostic algorithm for the exclusion of PE and DVT.

Background: We have advocated the use of a D-dimer assay to exclude the diagnosis of pulmonary embolism (PE) and deep venous thrombosis (DVT) in surgical and trauma patients suspected of having these diagnoses. Injury is known to increase D-dimer levels independent of thromboembolism. The purpose of this study was to assess the period after injury over which the D-dimer assay remains positive because of injury exclusive of thromboembolism. Methods: We prospectively sampled the plasma of severely injured patients for D-dimer using an enzyme-linked immunosorbent assay method at admission; at hours 8, 16, 24, and 48; and at days 3, 4, 5, and 6. Patients were then screened for DVT with a routine duplex Doppler at day 7. Patients were followed for PE, adult respiratory distress syndrome, and disseminated intravascular coagulation. Results: One hundred fifty-four patients (mean Injury Severity Score of 23) underwent a total of 1,230 D-dimer assays. Twenty-six (17%) had thromboembolism. Nine (6%) patients developed DVT, 2 (1%) developed PE, 13 (8%) developed disseminated intravascular coagulation, and 11 (7%) developed severe adult respiratory distress syndrome. None of the trauma patients with thromboembolism had a (false) negative D-dimer at or after the time of their thromboembolic complication. True-negative D-dimer results as a function of time from injury are: 0 hours, 18%; 8 hours, 16%; 16 hours, 17%; 24 hours, 22%; 48 hours, 37%; day 3, 34%; day 4, 32%; day 5, 30%; and day 6, 30%. The negative predictive value of the assay was 100%. D-dimer levels were significantly higher in those who developed a thromboembolic complication than in those who did not (independent of Injury severity Score). Conclusion: These data serve to validate D-dimer as a means of excluding thromboembolism, specifically in patients with severe injury (100% negative predictive value). Before 48 hours after injury, however, the vast majority of these patients without thromboembolism had positive D-dimer assays. Because of the high false-positive rate early after severe injury, the D-dimer assay may be of little value before postinjury hour 48.

Hypothesis: Laparoscopic gastric bypass (GBP) induces a postoperative hypercoagulable state that is similar or reduced compared with open GBP. Setting: University hospital. Patients: Between May 1999 and June 2000, 70 patients were randomly assigned to laparoscopic (n=36) or open (n=34) GBP. Deep venous thrombosis (DVT) prophylaxis consisted of antiembolism stockings and sequential pneumatic compression devices. Main Outcome Measures: Plasminogen, thrombin-antithrombin complex (TAT), prothrombin fragment 1.2 (F1.2), fibrinogen, D-dimer, antithrombin III (AT), and protein C levels were measured at baseline and at 1, 24, 48, and 72 hours postoperatively. A venous duplex examination of both lower extremities was performed preoperatively and between the third and fifth day postoperatively. Results: The 2 groups were similar in age, weight, and body mass index. Plasminogen levels decreased, and TAT, F1.2, and fibrinogen levels increased after laparoscopic and open GBP. There was no significant difference in these levels between groups. D-dimer levels increased in both groups, but the levels were significantly higher after open GBP than after laparoscopic GBP (P

D-Dimer testing has been suggested as a non-invasive method for the exclusion of pulmonary embolism (PE) and deep vein thrombosis (DVT). In this study, we compared a new method, the Miniquant D-dimer (Biopool International, Ventura, California, USA) to other previously validated D-dimer methods used for the purpose. Patients who were undergoing a definitive diagnostic study for thromboembolism had a blood sample drawn at that time. A whole-blood D-dimer (SimpliRed; Agen Biomedical Ltd, Brisbane, Australia) test was performed, and residual plasma was frozen and later analyzed using two enzyme-linked immunosorbent assay (ELISA) methods (D-dimer Gold; Agen, and Asserachrome D-Di; Stago International, Parsippany, New Jersey, USA) and the Miniquant D-dimer. Once all samples were analyzed, the correlation and accuracy of the Miniquant was compared with the ELISA method using Spearman's regression and Dunn's multiple paired comparison. All D-dimer methods were compared with radiographic studies. The data was analyzed collectively and segregated into in-patient (n = 112) and out-patient (n = 143) populations. The Miniquant D-dimer sensitivity, specificity and negative predictive value (NPV) for all patients were 95, 21, and 94% for DVT, and 100, 26, and 100% for PE. This new D-dimer method demonstrates acceptable sensitivity in patients with PE and DVT and, based on the high NPV of this method, it can be used for the exclusion of thromboembolism.

Background: Recent studies have reported that placement of vena cava filters (VCFs) early after injury may decrease the incidence of pulmonary embolism (PE) in high-risk trauma patients. Study Design: This was a retrospective review of all trauma patients with placement of VCFs admitted to a single level-1 trauma center between 1989 and 1997. Two cohorts corresponding to years of high or low prophylactic VCF use (PVCF) were compared. Results: Records were reviewed for 299 trauma patients identified as having had placement of a VCF. Two hundred forty-eight filters were placed before the diagnosis of PE. During years of low PVCF use, the overall PE incidence was 0.31%; during years of high PVCF use, the incidence of PE was higher at 0.48% (p = 0.045, chi-square). Conclusions: Increased use of PVCFs failed to decrease the overall rate of PE in our trauma patient population.

Background The need for cardiopulmonary bypass in the treatment of penetrating heart injuries is debated. Objectives To review our experience with penetrating heart injuries and determine the indications and outcome for cardiopulmonary bypass. Design Retrospective review. Setting A university-based, level I trauma center. Patients All victims of penetrating heart injury presenting between July 1, 1989, and December 31, 1995. Methods Medical records were reviewed for demographic and physiological data, operative findings, and outcome. Results Overall survival for 106 patients with penetrating heart injury was 55%. In an effort to resuscitate the heart, 4 patients with unresponsive cardiogenic shock were placed on cardiopulmonary bypass; none survived. Of 30 patients with multiple-chamber injuries, 11 presented with signs of life and 7 survived. Cardiopulmonary bypass was essential to repair complex injuries in 2 of the 7 survivors. Conclusion Cardiopulmonary bypass was ineffective in salvaging patients with cardiogenic shock but was essential in some patients with complex multiple-chamber cardiac injuries that could not be exposed and repaired by other means.

But: Comparer la mesure du pHi gastrique par tonometrie a son estimation chez les patients traumatises et correler le pHi avec les variables hemodynamiques. Type d'etude: Prospective, non interventionnelle. Provenance: USI d'un trauma center, USA. Principaux criteres de jugement: Le pHi mesure par tonometrie a ete compare dans 154 cas a l'appreciation de l'efficacite de la reanimation par le medecin. La reanimation a ete jugee inefficace (pHi ou=7.35). Les pHi mesures et estimes ont ete egalement compares au transport d'oxygene, a la consomation d'oxygene, a l'index cardiaque, a la saturation en oxygene du sang veineux mele, et aux scores de gravite. Resultats: Les quatres medecins de l'unite de soins intensifs chirurgicale ont souvent surestime le pHi par rapport a sa valeur mesuree. Le pHi mesure etait correle de facon positive a la tension en 02 du sang veineux mele (r=0,21). Le pHi mesure etait inversement correle avec le transport d'oxygene et avec la consomation en oxygene (r= -0.28). Le pHi estime etait correle avec la pression arterielle moyenne (r=0,21) et la duree d'hospitalisation (r=0,26); il etait inversement correle a l'elastance arterielle pulmonaire (r=-0,35 ). Conclusions. Les medecins urgentistes experimentes ont tendance a surestimer la perfusion viscerale, suggerant que la tonometrie gastrique apporte des informations utiles et supplementaires par rapport aux parametres hemodynamiques habituels. La pression arterielle et la saturation du sang veineux en oxygene etaient mieux correlees a la mesure du pHi qu'aux autres indices de perfusion.

Objective : Determine whether severe injury results in decreased plasma antithrombin (AT) activity and whether this decreased AT activity is associated with thromboembolic complications. Design : Prospective observational. Subjects : A total of 157 critically injured trauma patients. Methods : Each patient underwent laboratory analysis on arrival to the emergency room at hours 8, 16, 24, and 48, and days 3, 4, 5, and 6. Laboratory analyses included AT, tissue factor pathway inhibitor, protein C, prothrombin fragment 1.2, thrombin-antithrombin complex, and D-dimer. Patients were followed for thromboembolic complications including : deep venous thrombosis (DVT), pulmonary embolus, disseminated intravascular coagulation (DIC) and adult respiratory distress syndrome (ARDS). Results : Mean Injury Severity Score was 23 (±11). AT activity fell below normal in 95 (61%) patients ; AT activity rose to greater than normal in 51 (32%) patients. Nine (6%) patients developed DVT, two (1%) pulmonary embolus, 13 (8%) DIC and 26 (17%) ARDS. Using logistic regression analysis, low AT levels were a significant predictor of DVT, DIC, and ARDS (p < 0.05). Supranormal AT levels were associated with closed head injury (p < 0.05). D-dimer levels were inversely correlated with AT (p < 0.05). Conclusions : AT activity was depressed in critically injured patients. Patients with head injury developed supranormal AT activity. The risk factors for AT deficiency mimicked those for thromboembolism. Patients with decreased AT activity were at increased risk for thromboembolic complications. Given heparin's dependence on AT, these data call into question the use of unmonitored heparin thromboembolism prophylaxis.

Background: Heparin induced thrombocytopenia (HIT) is a potentially life threatening complication of heparin administration caused by antibodies directed to the heparin-platelet factor 4 (PF4) complex and characterized by thrombocytopenia with a seemingly paradoxical high risk of thrombosis. Diagnosis is challenging, and is based on both clinical suspicion and laboratory detection of heparin-PF4 antibodies. The Warkentin 4 T’s “pre-test” probability and Chong’s “post-test” probability models have been developed to aid the diagnosis of HIT. Enzyme-linked immunoabosorbant assay (ELISA) laboratory measurement of heparin-PF4 antibodies is commonly used but has a low positive predictive value for thrombosis. Recent reports suggest that using an ELISA optical density (OD) value of ≥ 1 may improve the predictive value for thrombosis. Methods: We performed a retrospective analysis of 105 patients with suspected HIT who were treated with a direct thrombin inhibitor and evaluated the anti-heparin-PF4 ELISA OD values and Warkentin 4 T’s scores for sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) using the Chong’s score to define HITBoth the manufacturer’s OD threshold of 0.4 and ≥ 1 were evaluated. Table 1. Comparison of sensitivity, specificity, and predictive values for 4 T’s and OD levels, alone and in combination Sensitivity (%) Specificity (%) NPV (%) PPV (%) For calculations, Chong’s categories of definite/probable and unlikely were used to define presence or absence of HIT. 4T’s score (high and low) 81 100 80 100 OD level 0.4 69 75 65 78 OD level ≥1 38 85 52 77 4T’s + OD 0.4 94 100 94 100 4T’s +OD ≥1 69 85 81 75 Results: The sensitivity, specificity and predictive value of ELISA alone were inferior to the 4 T’s clinical scorings system. The sensitivity and negative predictive values of the 4T’s score were improved by considering positive or negative ELISA test results. Conclusions: Consistent with previous reports, the PPV of a high probability 4T score alone was 100%. Thus, ELISA results might not change clinical decisions in this situation. Alternative anticoagulation might be inappropriately withheld in 20% of patients if a low probability 4T score alone were to be used for decision-making. The addition of ELISA data using an OD level of 0.4 increased the NPV to a threshold that might be considered clinically acceptable (94%) to withhold therapy. Addition of an OD level of ≥ 1 did not improve the PV of the 4 T’s. However, in contrast to other studies that found better predictive value to using this higher OD threshold, our study group was limited to people considered high risk for HIT. Validation of this strategy in a prospective trial with clinical endpoints should be considered.

Background: Laboratory criteria for the antiphospholipid antibody syndrome (APS) include detection of the lupus anticoagulant (LA) by coagulation based tests, or detection of either anti-cardiolipin (aCL), or anti-B2-glycoprotein I (aB2GPI) antibodies by enzyme-linked immunoabsorbant assay (ELISA). Multiplex testing enables simultaneous measurement of multiple serum antibodies with small beads coated with target antigens and small sample volumes (5 μL). We compared the concordance of a prototype multiplex method to standard ELISA methods for measuring IgG and IgM antibodies directed against CL or B2GPI. Methods: Samples from patients with suspected APS were tested for IgG and IgM aCL and aB2GPI antibodies using standard ELISA methods (ELISA, Bio-Rad Laboratories, Hercules, CA) and by a prototype multiplex bead set analyzed on the BioPlex 2200 (Bio-Rad Laboratories, Hercules, CA). The multiplex method used beads coated with either CL alone, B2GPI alone, or CL-B2GPI complex. Results were normalized using ratios (obtained result/upper limit of normal). A positive result was defined as a ratio of > 1. For CL, the multiplex test is considered positive if positive results are present using beads with either the CL alone or the CL-B2GPI complex. Results: Table 1. Concordance of ELISA vs Multiplex tests for antiphospholipid antibody detection Multiplex Test Results Concordance (%) ELISA Test Results Positive Negative Positive Negative All Results aCL-IgG Positive (n=52) 30 22 58 - Negative (n=232) 32 200 - 86 82 aCL-IgM Positive (n=42) 32 10 76 - Negative (n=241) 34 207 - 85 84 aβ2GPI-IgG Positive (n=34) 20 14 59 - Negative (n=249) 17 232 - 93 89 aβ2GPI-IgM Positive (n=61) 31 30 51 - Negative (n=219) 22 197 - 90 81 Conclusions: The overall concordance of multiplex results with ELISA results was good (81–89%). Negative multiplex results showed excellent correlation with ELISA (85–93%). Positive multiplex results had variable correlation with ELISA (51–76%). Evaluation of clinically significant positive results and clinical outcome measures is needed to determine clinical sensitivity and specificity of the multiplex test. Further refinement of the multiplex platform may provide an efficient and cost-effective assay for antibodies associated with the antiphospholipid syndrome.

We have previously observed striking differences in the percentage of activated platelets identified following injury in two similar trauma populations. When a monoclonal antibody (MoAb) to CD61 (glycoprotein Ib-IX) was used to identify platelets, the percentage of activated platelets was higher than when MoAb to CD42a (glycoprotein IIb-IIIa) was used to identify platelets. This discordance is not seen in other non-trauma patient populations. We hypothesized that a plasma component generated by severe injury was responsible for this finding. Fifteen trauma patients, defined as ISS > 9, had blood drawn within 24 hours of injury. Flow cytometry was used to identify platelets via MoAbs to both CD42a and CD61. Activated platelets were identified with the MoAb PAC-1 (binds the active conformation of GPIIb-IIIa). This experiment was then repeated while adding platelet-free plasma from each trauma patient to ABO-matched blood from healthy controls. Lastly, experiments were repeated with the addition of a MoAb that blocks the platelet Fc-gamma receptor, to preclude in-vitro platelet activation (known to occur via this receptor). Platelet activation as expressed by PAC-1 binding was significantly higher when CD61 was used to identify platelets rather than CD42a (p = 0.02, Wilcoxon Signed Rank test). Adding trauma plasma to platelets from healthy controls resulted in the same discordance (p = 0.01). Fc-gamma blockade did not significantly change this discordance. In trauma patients, flow cytometric evaluation of platelet activation is influenced by the MoAb used to identify platelets. Discordance in platelet activation occurred in healthy control with the addition of trauma plasma, and was not fc-gamma dependent. These data suggest the existence of a unique soluble component in the plasma of trauma patients that affects the platelet membrane in the GPIIb-IIIa region.

Hypothesis Cushing syndrome (CS) is associated with a hypercoagulable state that results in a 4-fold increase in the incidence of pulmonary embolism, deep venous thrombosis, and a 4-fold mortality rate compared with the general population. The incidence of CS in humans is approximately 2 to 5 per million per year, whereas in dogs it is much higher. The clinical complications of CS in humans are also manifested in dogs. We used a dog model of CS to better define the biochemical basis for the hypercoagulable state seen in the disease. Design A consecutive sample of dogs with CS and a cohort of healthy control dogs identified at a "well-dog check" were enrolled. All dogs underwent blood assays to identify the levels of procoagulant factors, natural antithrombotics, and the degree of ongoing activation of the coagulation cascade. Setting University veterinary medical teaching hospital. Results A total of 86 dogs were enrolled, 56 with CS and 30 control dogs. Levels of procoagulation factors II, V, VII, IX, X, XII, and fibrinogen were significantly increased in dogs with CS (P Conclusions The hypercoagulable state of CS is demonstrated by an increase in thrombin-antithrombin complexes. This hypercoagulable state may be caused in part by (1) an elevation of procoagulant factors, and (2) a decrease in antithrombin. Because of the similar clinical and biochemical changes between dogs with CS and humans, this canine model may be a useful tool for the future study of the hypercoagulable state in CS.

Hypothesis: Perihepatic packs used to control hemorrhage after liver injury increase the risk of complications and this risk increases the longer packs are left in place. Design: Retrospective case series. Setting: University level I trauma center. Patients: Consecutive patients with hepatic injury. Main Outcome Measures: Liver-related complications (biliary leak and abscess), rebleeding, and mortality. Results: One hundred twenty-nine of 804 patients with liver injuries were treated with perihepatic packing. Of the 69 who survived more than 24 hours, 75% lived to hospital discharge. Mortality rates were 14% and 30% in patients with and without liver complications, respectively (P =.23). Liver complication rates were similar (P = .83) when packs were removed within 36 hours (early [33%]) or between 36 and 72 hours (late [29%]) after they were placed; the rebleeding rate was greater in the early group (21% vs 4%; P

Hypothesis We hypothesized that late pulmonary dead space fraction (Fd late ) would be a useful tool to screen for pulmonary embolism (PE) in a group of surgical patients, including patients who required mechanical ventilation and patients with adult respiratory distress syndrome. Design We prospectively calculated Fd late in patients with suspected PE who underwent pulmonary angiography. Setting University-based, level I trauma center. Main Outcome Measure Ability of Fd late to identify patients with PE. Results Twelve patients had 14 angiograms for suspected PE. The Fd late was 0.12 or above in all 5 patients who had PE; 4 required mechanical ventilation. The Fd late values were below 0.12 in 8 of 9 patients without PE. Four patients had adult respiratory distress syndrome. The Fd late had 100% sensitivity and 89% specificity for the detection of PE. Conclusions The Fd late is a valuable tool for bedside screening of PE in surgical patients. We were able to accurately detect all PEs.

Hypothesis Trauma patients who are pulseless at the scene of injury and whose electrical cardiac activity is less than 40 beats/min cannot be revived. Design Retrospective review. Setting University hospital, level I trauma center. Patients Pulseless trauma patients who had cardiopulmonary resuscitation at the scene, en route, or in the emergency department and presented between January 1, 1991, and July 1, 1996. Main Outcome Measure Survival after traumatic cardiopulmonary arrest. Results Sixteen thousand seven hundred twenty-four trauma patients were admitted. The study cohort comprised 604 victims of traumatic cardiopulmonary arrest, 304 as a result of blunt injury and 300 as a result of penetrating injury. Transport time for the study patients was 11±6.1 minutes (mean±SD). Cardiopulmonary resuscitation was performed on them for 22±11 minutes. Three hundred four patients (50%) had resuscitative thoracotomy in the emergency department; 160 patients were taken to the operating room for further resuscitation and treatment of their injuries. Sixteen patients (2.6%) survived to discharge from the hospital; 7 had severe neurologic disabilities. No patient (0/212) with electrical asystole survived. Five of 134 patients with an initial electrical heart rate between 1 and 39 beats/min survived long enough to reach the intensive care unit but died within 48 hours (4 died within 24 hours). No patient survived to leave the hospital if the initial electrical heart rate was less than 40 beats/min. All 16 survivors had an initial heart rate of 40 beats/min or greater. Conclusion Trauma victims who are pulseless and have asystole or agonal electrical cardiac activity (heart rate

Objective To determine if isolated transient loss of consciousness is an indicator of significant injury. Setting University-based level I trauma center. Design and Patients Phase 1 retrospective case series of all patients with trauma admitted directly from the emergency department to the operating room or an intensive care unit who had transient loss of consciousness as their only trauma triage criterion. Phase 2 prospective case series of all trauma patients transported by emergency medical system personnel with transient loss of consciousness as their only trauma triage criterion. Main Outcome Measures Emergency operation and intensive care unit admission. Results Phase 1: From January 1, 1992, to March 31, 1995, we admitted 10255 patients with trauma. Three hundred seven (3%) met the enrollment criteria and were admitted to the operating room (n=168) or intensive care unit (n=139). Of these, 58 (18.9%) were taken to the operating room emergently to manage life-threatening injuries: 11 (4%) had craniotomies and 47 (15%) had non-neurosurgical operations. Phase 2: From July 1 to December 31, 1996, 2770 trauma patients were transported to our facility; 135 (4.9%) met the enrollment criteria. Forty-one (30.4%) of these required admission, and 6 (4.4%) were taken emergently to the operating room from the emergency department (1 [1] for a craniotomy, 3 [2.2] for intra-abdominal bleeding, and 2 [1.5] for other procedures). Two (1.5%) of the 135 patients died. Conclusions Patients with isolated transient loss of consciousness are at significant risk of critical surgical and neurosurgical injuries. These patients should be triaged to trauma centers or hospitals with adequate imaging, surgical, and neurosurgical resources.

Background Video-assisted thoracic surgery (VATS) appears to be replacing open thoracotomy for the treatment of posttraumatic thoracic complications. Objective To compare operative times, complication rates, and outcomes in patients who underwent VATS vs open thoracotomy. Design Retrospective review. Setting University hospital, level I trauma center. Patients Trauma patients who between December 1993 and May 1997 underwent open thoracotomy or VATS to drain a persistent thoracic collection. Methods Medical records were reviewed for demographic data, operative times, and clinical outcomes. Results Of the 524 trauma patients requiring tube thoracostomy, 22 underwent 23 procedures to drain empyema (17 VATS, 6 thoracotomies [based on surgeon preference]). There were no differences in age, Injury Severity Score, or mechanism of injury between the 2 groups. Three patients who underwent VATS (18%) required conversion to open thoracotomy for adequate drainage. All remaining patients who underwent VATS had successful treatment of their empyema. Complication rates (VATS=29%, open thoracotomy=33%;P=.99), operative times (VATS=3.4 ± 1.3 hours [mean ± SD], open thoracotomy=3.0 ± 1.5 hours;P=.46), postoperative epidural catheter use (VATS=31%, open thoracotomy=50%;P=.63), duration of chest tube drainage (VATS=5.1 ± 1.7 days [mean ± SD], open thoracotomy=4.5 ± 1.5 days;P=.48), and hospital stay after the procedure (VATS=16±14 days [mean ± SD], open thoracotomy=11 ± 5 days;P=.39) were similar for both groups. Conclusions Video-assisted thoracic surgery was a safe and effective operative strategy for the treatment of posttraumatic empyema. Therefore, because VATS has been shown in nontrauma patients to reduce morbidity and because it provides better cosmesis, we believe that it should be the initial operative approach to trauma patients with suspected posttraumatic empyema.

Prospective Evaluation of the Utility of Laboratory Testing for Detecting Intra-abdominal Injuries in Children with Blunt Trauma • 379

Objective: To determine how soon after trauma pulmonary embolism (PE) occurs and if there is an association between the duration of this interval and mortality. Design: Retrospective case series. Patients: All patients admitted to our trauma service with established PE based on high probability findings on ventilation perfusion scan, positive results on a pulmonary arteriogram, or autopsy from July 1, 1990, to September 30, 1995. Main Outcome Measure: Time interval between injury and PE. Setting: Level I university trauma center. Results: Of 18 255 trauma patients identified, 63 met our criteria for PE (30 using a pulmonary arteriogram; 26, a ventilation perfusion scan; and 7, autopsy). Four patients (6%) had a documented PE on day 1 following injury. Mortality was not correlated with the interval between injury and PE. Of the 63 patients, 58 (92%) had 1 or more established risk factors for thromboembolism. The ratio of PaO 2 to fraction of inspired oxygen was the only factor predictive of mortality ( P =.02, logistic regression analysis). Conclusions: Pulmonary embolism occurs in the immediate period following injury. Aggressive workup in patients with signs consistent with PE should be instituted promptly. Trauma patients who have at least 1 risk factor for thromboembolism should receive prophylaxis as soon after injury as possible. Arch Surg. 1997;132:862-867

We appreciate the comments of Drs Hughes and Gonzalez. However, it seems that they have misunderstood the mechanism of action of LMWH and made an incorrect conclusion in their letter. Increasing the dose of heparin compensates for the reduced bioavailability of antithrombin III, not the reduced bioavailability of heparin. Therefore, even though LMWH have a more predictable bioavailability than unfractionated heparin, the anticoagulant effect of the LMWH is dependent on the bioavailability of antithrombin III. In fact, because LMWH have a greater concentration of the pentasaccharide chain responsible for antithrombin III activation and fewer high-molecular-weight fractions (responsible for the minor direct heparin antithrombotic effect), they are even more critically dependent on the presence of antithrombin III for their effect. To state this another way, if there is inadequate antithrombin III, both unfractionated heparin and LMWH are ineffective. We understand that different LMWH preparations have different ratios of anti-IIa