Robert C. Jacoby

Injury induces increased monocyte expression of tissue factor: factors associated with head injury attenuate the injury-related monocyte expression of tissue factor.

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] > or = 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 < or = 9 and Abbreviated Injury Scale Head/Neck score > or = 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.

A new method for measuring D-dimer using immunoturbidometry: a study of 255 patients with suspected pulmonary embolism and deep vein thrombosis

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 Spearmans regression and Dunns 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.

Comparison of six D-dimer methods in patients suspected of deep vein thrombosis

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.

Evaluation of a new automated quantitative d-dimer, advanced D-dimer, in patients suspected of venous thromboembolism

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 ⩽ 1800 μg/L and ⩽ 1500 μg/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.

Mass Casualty Disasters: Who Should Run the Show?

BACKGROUND A clear command structure ensures quality patient care despite overwhelmed resources during a mass casualty incident (MCI). The American College of Surgeons has stated that surgeons should strive to occupy these leadership roles. OBJECTIVE We sought to identify whether surgeons, as compared to emergency physicians, are sufficiently prepared to assume command in the event of a mass disaster. METHODS We surveyed hospital-affiliated surgeons and emergency physicians to assess their knowledge of MCI response principles and to gauge opinions regarding who should be in charge during a disaster. RESULTS One hundred and forty-nine (58%) surveys were completed, 78 by surgeons and 71 by emergency physicians. Both groups demonstrated a critical lack of knowledge regarding fundamental principles and key logistical components of preparedness and MCI response. Surgeons as a group were even less prepared than emergency physicians. Of those surgeons who had reviewed their hospitals disaster plan, half (50%) still did not know where to report for an MCI activation. Nonetheless, both groups believed they had sufficient training and both asserted they ought to occupy command positions during a disaster scenario. CONCLUSIONS Errors in disaster triage have been known to increase mortality as well as the monetary cost of disaster response. Funding exists to improve hospital preparedness, but surgeons are lagging behind emergency physicians in taking advantage of these opportunities. Overall, it is imperative that physicians improve their understanding of the MCI response protocols they will be tasked to implement should disaster strike.

Diagnosis of posttraumatic pulmonary embolism: Is chest computed tomographic angiography acceptable?

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 re-reviewed 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 patients 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.

AbstractAre surgical residents prepared for mass casualty incidents

Introductory Sentence. We hypothesize that resident education is inadequate with respect to management of multiple/mass casualty incidents that may involve chemical, biological, and nuclear exposures. Methods. After IRB approval, chief level residents in Surgery (10), Emergency Medicine (10), and Anesthesia (8) at our university based level-one trauma center were asked to anonymously complete a survey questionnaire. Responses were tabulated and statistically analyzed with Mann-Whitney rank sum, Fisher exact test, and Kruskal-Wallis one-way ANOVA. Results. Every chief resident responded. All the residents were similar with respect to age, sex, and intended setting of clinical practice. Only a single resident reported military experience. Two residents (7.1%), including the one with military experience, had administered medical care while wearing a protective suit. Compared to emergency medicine residents, surgical residents reported significantly less formal teaching in mass casualty incidents (P = 0.0249), trauma triage (P = 0.0139), and nuclear, biological, chemical agents (P = 0.0027). When surgical residents were compared to anesthesia residents, there was significantly less training for surgical residents in nuclear, chemical, and biological agents (P = 0.0295). Multiple/mass casualty incident experience did not differ between residents. However, the most common incidents involved only 3–5 patients with blunt trauma. Emergency medicine residents were significantly more comfortable in treating patients with exposure to anthrax (P = 0.0110), sarin (P = 0.048), and nuclear exposure (P = 0.0108). Conclusions. Surgical residents have significantly less formal training in mass casualties, triage, and chemical, biological, and nuclear exposures than residents in other specialties. Therefore, surgical residents are less comfortable treating these types of patients. Since surgeons are often expected to take leadership roles in mass casualty incidents, surgical education should be modified to match or exceed that of other residents.