Research Forum Abstracts

Midwest. Site two was an urban tertiary care receiving center in the Southeast. Sitethree was a suburban university hospital in the Northeast. StO2 measurements wereobtained using an InSpectra StO2 Tissue Oxygenation Monitor Model 650. Overfour consecutive days, an StO2 was measured on all patients over the age of 65 whohad been admitted to a non monitored floor bed. All patients requiring ICUevaluation were excluded. A reading was taken by applying an StO2 monitor to thethenar eminence until a stable reading was received, generally within two minutes. Insome cases, management was changed based upon the reading, but this was not arequirement.

Results: A total of 127 patients received an StO2 reading. At site one, 5 of 39(13%) patients had an StO2 below 75%. At site 2, 10 of 47 (21%) patients had anStO2 below 75%. At site three, 10 of 41 (24%) had an StO2 below 75%. In total,20% of patients had an StO2 below 75% in all three sites.

Conclusion: StO2 has been shown to correlate to ScvO2, and has also beenshown to correlate an increased risk of mortality. There is a significant incidence oflow StO2 in the patient population most at risk for hypoperfusion and for under-resuscitation. These findings suggest that patients who are awaiting floor admissionmay require additional urgent interventions. This tool may allow the emergencyphysician, or the medical team caring for the held patient, to identify patients most atrisk for decompensation. Additional research needs to be performed to ascertain ifthis tool can also be used to guide resuscitation in the ED, such as early research isshowing in the ICU and trauma setting.

409 Sensitivity of a Rapid Antigen Detection Test forthe Diagnosis of Group a Streptoccal Pharyngitis Inthe Emergency Department

Hinfey P, Nicholls BH, Garcia F, Ripper J, Cameron Y, Joshi S/Newark BethIsrael Medical Center, Newark, NJ

Study Objectives: Sore throat is a common presenting complaint in theemergency department (ED). Emergency physicians often consider the possibility ofGroup A Streptococcal (GAS) pharyngitis. Guidelines for the evaluation andmanagement of patients with possible GAS pharyngitis differ significantly in theirrecommendations for testing. We use the Binax NOW® Strep A (Inverness MedicalInnovations, Cranfield, England) rapid antigen detection test (RADT) in the NewarkBeth Israel Medical Center (NBIMC) ED. Many of our physicians believed the BinaxNOW® Strep A RADT was performing poorly, with frequent false-negative resultswhen compared to the gold standard of throat culture. We performed a retrospectivechart review to determine the performance characteristics of the Binax NOW® StrepA RADT.

Methods: We obtained a waiver of informed consent from the NBIMCInstitutional Review Board (IRB) for this study since it was a study of existingdocuments and did not involve actual patient care. We queried the lab and EDdatabases for patients who were seen in the ED for sore throat during the calenderyear 2009 and who had RADT and/or throat culture performed. We entered thefollowing information into an Excel (Microsoft, Inc; Redmond, WA) spreadsheet:name, date of service, age in years, presence or absence of criteria of the modifiedCentor score (mCs), total mCs, RADT results, throat culture results (if performed),organism, and degree of growth on throat culture. The prevalence, sensitivity, andspecificity were calculated for the RADT as compared to throat culture. Since weroutinely did not perform throat culture when the RADT was positive, we treated allpositive RADT as true positives when calculating performance characteristics of theassay. We feel this was justified since 23/26 patients who had positive RADT also hadpositive throat cultures for GAS.

Results: A total of 1464 patients who came to the NBIMC ED for sore throat in2009 were analyzed. Age ranged from less than 1 year to 74 years. Fifty-two percentwere female. The prevalence of GAS pharyngitis was 31.6%. The sensitivity of theBinax NOW® Strep A RADT was 43.6% (95% CI 39.1-48.2%). The specificity ofthe RADT was 99.7% (95% CI 99.0-100%). When we stratified the data bymodified Centor score (mCs), we did see increasing prevalence with higher score andevidence of spectrum bias, with better sensitivity as the mCs increased, but the bestsensitivity was seen in 232 patients who had mCs of 4 where it was 66.7% (95% CI55.2-76.5%)

Conclusion: The Binax NOW® Strep A RADT exhibited low sensitivity in ourstudy. The reason for this low sensitivity is unclear. The test may be insensitive or thecollection or processing of specimens may not be adequate. Further study is needed to

determine the cause of the low sensitivity.

S132 Annals of Emergency Medicine

410 Incidence of Biphasic Reaction and Need forHospitalization In Patients Admitted to anEmergency Department Observation Unit AfterEvaluation for Anaphylaxis

Meyer MK, Kanthala AR, Decker WW, Campbell RL/Mayo Clinic, Rochester, MN

Study Objectives: Anaphylaxis is a potentially life-threatening allergic reactioncommonly managed in the emergency department (ED). Biphasic reactions havebeen reported to occur in 1-23% of patients. Guidelines recommend patientobservation after anaphylaxis, but very little data is available describing patientoutcomes. We sought to determine the incidence of biphasic reactions and need forinterventions or hospital admission in patients admitted to the ED observation unit(EDOU) after evaluation for anaphylaxis.

Methods: A retrospective cohort study was conducted from April 2008-March2010 in an academic ED setting with approximately 80,000 ED visits per year. Adultpatients admitted to the EDOU after ED evaluation for anaphylaxis were included.All patients met National Institutes of Allergy and Infectious Diseases/Food Allergyand Anaphylaxis Network (NIAID/FAAN) criteria for anaphylaxis. Data wascollected on patient demographics, inciting allergens, symptoms, management, lengthof stay, incidence of biphasic reactions and disposition.

Results: A total of 174 patients met NIAID/FAAN criteria during the studyperiod. Of these 58 (33%) patients were admitted to the EDOU and were included.Median age was 37.3 years (IQR 29-51) and 34 (59%) were female. The incitingallergens were food in 17 (29.3%), medications in 14 (24.1%), insect stings in 9(15.5%), unknown in 10 (17.2%), and other in 8 (13.8%). Median length of stayduring the initial ED evaluation was 1.8 hours. In the ED, 30 patients (51.7%)received epinephrine, with repeat dosing in 2 patients. H1 blockers were given to 57(98%) patients, 44 (76%) received H2 blockers, 57 (98%) received steroids, and 22(38%) received bronchodilators. In the EDOU, median length of stay was 5.3 hours(IQR: 3.8 - 7.9), where 36 (62%) patients received additional H1 blockers, 8(13.1%) received H2 blockers, 7 (12.1%) received steroids, and 2 (3.4%) patientshad bronchodilators. Medications were given for symptom recurrence or as continuedtherapy for the initial reaction. Hospital admission occurred in 4 (6.9%) patients,with one requiring intensive care. Eight (13.8%) patients had a biphasic reaction. Six(75%) of the patients who had a biphasic reaction, had onset of the biphasicsymptoms while in the EDOU with time of onset ranging from 1.5 - 5.2 hours afterinitial symptom resolution. Ultimately, 4 of the 8 patients received epinephrine forthe biphasic reaction. Two received epinephrine in the EDOU. The third patient hadmultiple mild recurrent symptoms in the EDOU that had resolved prior to EDOUdismissal. The patient returned to the ED 4.5 hours later, received epinephrine andwas admitted. The fourth patient had no symptoms in the EDOU, but had a multi-day reaction requiring epinephrine on day 3 and was admitted.

Conclusion: No evidence currently predicts a biphasic reaction. The utilization ofthe EDOU after evaluation for anaphylaxis allows observation time without impedingpatient flow and avoids unnecessary hospitalizations. In our study, 75% of biphasicreactions occurred within 1.5-5.2 hours during the EDOU stay. This is within therecommended 4-6 hours observation guideline. Our study is limited by theretrospective design but suggest that EDOU utilization after evaluation for ananaphylactic reaction is effective. Prospective studies are needed.

411 Inter-Rater Reliability and False Positive ResultRates of Ankle Brachial Index MeasurementsPerformed by Emergency Providers

Ewing TE, Higgins III GL, Perron AD, Strout TD/Maine Medical Center, Portland,ME

Study Objectives: The ankle brachial index (ABI) is used to evaluate patients fortraumatic vascular injuries of the lower extremities. The calculated ABI measurementresult can drive potentially invasive management decisions. However, this ispredicated on the assumption that precise measurement and calculation protocols arefollowed. It is not unreasonable to assume that ABIs are currently being performed inemergency departments (EDs) using nontraditional methods, depending on availableequipment, and that measurements and calculations are not always uniformlyconducted. Using an established measurement method, we sought to determine thepercentage of study subjects, in the age group most likely to experience lowerextremity trauma, who have a baseline ABI of �0.9. In addition, we compared theinter-rater reliability of ABI calculations.

Methods: A convenience sample of healthy volunteers and patients presenting to

our ED with low acuity complaints not related to lower extremity trauma were

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