91 Is CT the Only Way? Can the S-100 Protein Be Used inthe Emergency Department to Decrease the Number ofCTs?

Lind K, Klein K, Likourezos A, Lam S, Nevarez C, Evelsizer S, Motov S, Jacob J,Jacob T/Maimonides Medical Center, Brooklyn, NY

Background: Every day in the US, thousands of people come to the ED and get aCT scan of the brain. The majority of which are negative. This not only exposespatients to large doses of ionizing radiation, but incurs high costs to the health caresystem in general and can cause large slow downs of patient flows with in a busy ED.

Study Objective: To examine the potential use of the S100B protein, a biomarkerof class C ACEP recommendation, for use in patients with traumatic brain injury, asa possible tool to help sort out patients who might not need a CT scan in the EDsetting.

Methods: This was a prospective observational study utilizing a conveniencesample in a large urban ED for patients for whom a head CT was ordered and whocould consent. An extra tube of blood was drawn, coded and placed in a lockedrefrigerator. The samples were centrifuged and the serum was stored at -70oC.Quantitative measurement of S100B levels was performed by a 2-site, 1 step ELISA.The investigator coding the head CT results and the laboratory investigator wereblinded to each other’s results. One Way ANOVA was used to compare the 3 headCT impression groups and mean S100B protein.

Results: To date 168 patient are enrolled into the study. The mean age of thepatients is 66 years (range: 20 to 105); 54% are female. The primary reasons for CTexam were altered mental status (23.8%), CVA/TIA (23.2%), and trauma/injury(16.7%). The CT impression were categorized as 40.5% no pathology, 12.5%chronic pathology, and 47.0% acute pathology. The mean S100B protein values forthe 3 groups were 3.13�g/l, 2.69�g/l, and 2.76�g/l respectively (P�.801).

Conclusion: Although a biomarker to help determine acute brain injury is neededin the acute care setting, the S100B protein was not found to be sensitive enough forour ED setting.

92 Can Quantitative Brain Electrical Activity Aid in theTriage of Mild Traumatic Brain-Injured Patients

O’Neil BJ, Prichep LS, Naunheim R, Chabot, R/Wayne State University, Detroit,MI; NYU School of Medicine, NY, NY; Washington University School of Medicine,St. Louis, MO

Study Objectives: The incidence of US emergency department (ED) visits fortraumatic brain injury (TBI) exceeds 1,000,000 cases/year, with the vast majority of thesefor mild injury (mTBI). Using existing CT scan decision rules, such as the New OrleansCriteria (NOC), results in approximately 70% negative CT scan rate. The present studyinvestigates the use of quantified brain electrical activity to assess its possible role in theinitial triage of ED mTBI patients as compared to decision rules such as NOC.

Methods: 119 patients who reported to the ED with mTBI and who received CTscans were studied. Using a hand-held EEG acquisition device, data was collected fromfrontal leads, and the NOC were recorded. The EEG was processed off-line to generate asingle index (TBI-Index, biomarker). A previously validated index value found to besensitive for significant brain dysfunction in mTBI patients was utilized. This TBI-Indexvalue was compared to the NOC for the ability to predict positive CT findings.

Results: This sample had a mean age of 48.32 (range 18-92 years) and contained38 patients with positive CT scans (CT�) and 81 with negative CT scans (CT-).Both the brain electrical activity TBI-Index and the NOC had sensitivities �90%.However, the specificity of the TBI-Index was more than twice as high as that ofNOC. Other performance measures (PPV, NPV, pLR, nLR and odds ratio) were alsosuperior using the TBI-Index.

When the TBI index and NOC are used in combination the sensitivity topositive CT goes to 97%.

Conclusions: In patients presenting to the ED with mTBI, the TBI-Index used inthis study had a high NPV, odds ratio and sensitivity for positive CT findings, and Aspecificity which outperformed the NOC. Combining the index with NOC resultedin a sensitivity of 97.0% (only 1 false negative). This study suggests a potentialclinical utility in aiding in the initial triage of mTBI patients.

93 The Use of Pulse Oximetry as a Quick Screening Tool forLimb Ischemia in the Emergency Department

Rao K, Tan Z, Chong C/Changi General Hospital, Singapore, Singapore

Study Objective: To determine the role of pulse oximetry as a screening tool forlimb ischemia in the emergency department (ED).

Methods: A prospective cohort study that involved healthy volunteers. The pulseoximetry probe was placed on the left index finger of volunteers to determine theirrespective oxygen saturation (Sp02) readings on room air at baseline. Limb ischemiawas simulated by applying the blood pressure cuff around the left arm of volunteers asa tourniquet and inflating the cuff up to 25%, 50%, 75% and 100% of thevolunteer’s own systolic blood pressure (SBP) reading. The corresponding Sp02readings were recorded at various levels of cuff inflation.

Results: 95 volunteers were recruited in our study. 62% were females and themean age was 25.8 years. Scatter plot and linear regression line of the SpO2readings against the amount of SBP occlusion demonstrates the drop in SpO2with increasing external pressures applied. When the SpO2 index (defined as theratio of the SpO2 reading at different compression pressures compared to theSpO2 reading at baseline) is plotted against the percentage of SBP occlusion, theregression coefficient (taken to mean the rate of change of SpO2 ratio as afunction of a change in the compression pressure) is obtained. The regressioncoefficients at 25%, 50%, 75%, and 100% SBP occlusion were 0.991 (95%confidence intervals 0.990 to 0.993), 0.981 (0.979 to 0.983), 0.967 (0.963 to0.971) and 0.959 (0.952 to 0.966) respectively.

Conclusion: There is potential for the use of pulse oximetry as a quick and costeffective screening tool for limb ischemia in the ED. The Sp02 index derived frompulse oximetry readings may help quantify the degree of limb ischemia and will bemore applicable in the setting of an ED compared to the ankle-brachial index, andpotentially more advantageous compared to Buerger’s test.

94 Young Adult Patients With Chest Pain: Utility of theEmergency Department Observation Unit

Holly J, Johnson E, Hamilton D, Black K, Robbins R, Davis V, Barton E, MadsenT/University of Utah Health Sciences, Salt Lake City, UT

Study Objectives: Recent studies have suggested that patients 40 years old andyounger with chest pain may not benefit from routine cardiac stress testing.Additional studies have proposed rapid risk stratification tools for younger chest painpatients. Still, physicians may choose to utilize the emergency department observationunit (ED observation unit) for risk stratification and evaluation of younger patients.We sought to describe the utilization of our ED observation unit for young patientswith chest pain and evaluate the utility of this approach for risk stratification in thispatient population.

Methods: We performed a prospective, observational analysis for all chest painpatients admitted to our ED observation unit during the 12-month period from June1, 2009, to May 31, 2010. Information regarding presentation, baselinedemographics, and risk factors was obtained at the time of admission. Outcomesrelated to ED observation unit stay [positive troponin, provocative testing,revascularization procedures including stent and coronary artery bypass grafting(CABG), and death] and inpatient admission were recorded. A 30-day follow-up wasperformed by telephone and review of the electronic medical record for outcomes

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(myocardial infarction, stent, CABG, death) occurring in the 30-days following EDobservation unit admission.

Results: 552 patients were admitted to our ED observation unit during the studyperiod, including 77 (13.9%) patients age 40 years or younger. Mean patient age was54.1 years (range 19-80 years). Of the 77 patients age 40 years or younger (age range:19-40 years), 34 (44.2%) were male, 10 (13.0%) reported a history of diabetes, 8(10.4%) reported a history of coronary artery disease [previous myocardial infarction(MI), stent, or coronary artery bypass grafting (CABG)], and 19 (24.7%) reportedcurrent tobacco use. None of the 77 patients in the younger cohort ruled in for MIduring the observation period nor reported a MI during the 30-day follow-up period.30 (39.0%) patients underwent cardiac stress testing. 2 of these patients (6.7%) had apositive stress test, and, in 1 case, the patient also had a negative computerizedtomography angiography (CTA) of the coronary vessels and was discharged. Theother patient with a positive stress test was 40 years old and reported a history ofprevious MI and stent and later underwent stent placement. 3 patients (3.9%)were admitted to an inpatient unit from the ED observation unit.

Conclusion: Younger patients composed a significant percentage of the patientsevaluated for chest pain in our ED observation unit but had very low rates of positivetesting. This low rate may support previous studies suggesting the utility of a lessaggressive approach to cardiac testing and appropriate ED-based risk stratificationtools in this population.

95 Nuclear Stress Testing in Emergency Department ChestPain Patients With Suspected Acute Coronary Syndrome:Who Should We Stress?

Buchheit RC, Fesmire FM, Cao Y, Severance HW, Heath GW/University ofTennessee College of Medicine Chattanooga, Chattanooga, TN; University ofTennessee Chattanooga, Chattanooga, TN

Study Objectives: Studies have individually reported the relationship of age � 40years, number of cardiac risk factors, and history of presence or absence of preexistingcoronary artery disease for predicting acute coronary syndromes in chest pain patientsundergoing cardiac stress testing. However, no study has reported the interplay of allof these factors in predicting acute coronary syndrome. In this study, we investigatethe influence of age, cardiac risk factors, and presence or absence of pre-existingcoronary artery disease on the incidence of acute coronary syndrome in order todevelop a tool that may assist physicians in the selection of appropriate low-to-intermediate risk chest patients for nuclear stress testing.

Methods: Retrospective analysis of a prospectively acquired database ofconsecutive chest pain patients undergoing nuclear stress testing. All patients werefollowed for 30-day acute coronary syndrome which was defined as acute myocardialinfarction, percutaneous coronary intervention, coronary artery bypass grafting,coronary arteriogram revealing � 70% stenosis not amenable to intervention, orcardiac death within 30-days of the initial emergency department (ED) evaluation.Cardiac risk factors were defined as diabetes, hypertension, cigarette use,hyperlipidemia, family history of coronary artery disease, and obesity. Age subgroupsanalyzed were � 40, 41-50, 51-60, and � 60 years. acute myocardial infarction wasdefined according to current ESC/ACC criteria utilizing the 99th percentile oftroponin as the gold standard. History of pre-existing coronary artery disease wasdefined as prior history of documented acute myocardial infarction, percutaneouscoronary intervention, or coronary artery bypass grafting. Backwards stepwise logisticregression was utilized to develop a model for predicting risk of 30-day acutecoronary syndrome.

Results: A total of 800 chest pain patients underwent nuclear stress testingduring the study time period. Thirty-day acute coronary syndrome occurred in47 out of 267 (17.6%) patients with preexisting coronary artery disease and 27out of 536 (5.1%) patients without preexisting coronary artery disease (P�.001).Patients with history of coronary artery disease were older (58.7 � 12.3 versus51.5 � 12.0; P�.001) but there were no differences in the total number of riskfactors (2.6 � 1.3 vs. 2.4 � 1.2). In patients without preexisting coronary arterydisease, age � 40 or � 1 cardiac risk factor identified a population at � 1% riskof 30-day acute coronary syndrome (Table). There was not a single occurrence ofacute coronary syndrome in patients with the following profile: absence ofpreexisting coronary artery disease, age � 50, and � 1 cardiac risk factor (95%CI 0-4.6%). Logistic Regression analysis found only 6 factors predictive of 30-day acute coronary syndrome: age, male sex, preexisting coronary artery disease,diabetes, and hyperlipidemia. The Table summarizes the regression coefficientsand odds ratios for the individual factors included in the model. Area under the

Receiver Operator Characteristic curve of this model for predicting 30-day acutecoronary syndrome was 0.767 (95% CI 0.719 to 0.815).

Conclusions: A regression model utilizing age, sex, preexisting coronary arterydisease, diabetes, and hyperlipidemia is predictive of 30-day acute coronarysyndrome in patients undergoing nuclear stress testing. Prospective studies needto be performed to determine whether this model can assist physicians inselection of appropriate low-to-intermediate risk chest pain patients for nuclearstress testing.

96 Validation of the TIMI Risk Score in Chinese PatientsPresenting to the Emergency Department With ChestPain

Graham CA, Rotheray KR, Tsay SX, Rainer TH/Chinese University of Hong Kong,Shatin, Hong Kong; University of Melbourne, Melbourne, Australia

Study Objective: The Thrombolysis In Myocardial Infarction (TIMI) risk score isa 7 item tool which has been validated in Western medical literature to help riskstratify chest pain patients. The aim of this study is to establish the relationshipbetween the TIMI risk score and the rate of occurrence of Major AdverseCardiovascular Events (MACE) within 30 days in Chinese patients presenting to theemergency department (ED) with undifferentiated chest pain.

Methods: Design - single center prospective observational study of adult ChineseED patients with undifferentiated chest pain. Setting - University hospital emergencydepartment in Hong Kong with annual census of 140000 patients. Subjects - all adultpatients presenting with undifferentiated chest pain. Data, including patientcharacteristics, medical history and components of the TIMI risk score was collected.All patients were followed up at 30 days, either by review of electronic medicalrecords or telephone interview. MACE was defined as death from any cause;myocardial infarction; troponin elevated acute coronary syndrome or undergoingpercutaneous coronary intervention. Rates of MACE at 30 days were examined inrelation to TIMI risk score.

Results: Follow-up at 30 days was completed for a total of 315 patients.There were a further 37 patients who did not give consent to be included in the

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