Tiepu Liu

Cincinnati Prehospital Stroke Scale: Reproducibility and Validity

STUDY OBJECTIVE The Cincinnati Prehospital Stroke Scale (CPSS) is a 3-item scale based on a simplification of the National Institutes of Health (NIH) Stroke Scale. When performed by a physician, it has a high sensitivity and specificity in identifying patients with stroke who are candidates for thrombolysis. The objective of this study was to validate and verify the reproducibility of the CPSS when used by prehospital providers. METHODS The CPSS was performed and scored by a physician certified in the use of the NIH Stroke Scale (gold standard). Simultaneously, a group of 4 paramedics and EMTs scored the same patient. RESULTS A total of 860 scales were completed on a convenience sample of 171 patients from the emergency department and neurology inpatient service. Of these patients, 49 had a diagnosis of stroke or transient ischemic attack. High reproducibility was observed among prehospital providers for total score (intraclass correlation coefficient [rI],.89; 95% confidence interval [CI],.87 to.92) and for each scale item: arm weakness, speech, and facial droop (.91,.84, and.75, respectively). There was excellent intraclass correlation between the physician and the prehospital providers for total score (rI,.92; 95% CI,.89 to.93) and for the specific items of the scale (.91,.87, and.78, respectively). Observation by the physician of an abnormality in any 1 of the 3 stroke scale items had a sensitivity of 66% and specificity of 87% in identifying a stroke patient. The sensitivity was 88% for identification of patients with anterior circulation strokes. CONCLUSION The CPSS has excellent reproducibility among prehospital personnel and physicians. It has good validity in identifying patients with stroke who are candidates for thrombolytic therapy, especially those with anterior circulation stroke.

Acute Stroke: Delays to Presentation and Emergency Department Evaluation

STUDY OBJECTIVE To document prehospital and inhospital time intervals from stroke onset to emergency department evaluation and to identify factors associated with presentation to the ED within 3 hours of symptom onset, the current time window for thrombolytic therapy. METHODS Patients admitted through the ED with a diagnosis of stroke were identified through admitting logs. Time intervals were obtained from EMS runsheets and ED records. Information regarding first medical contact, education, and income was obtained by patient interview. Baseline variables were analyzed to assess association with ED arrival within 3 hours of symptom onset; variables significant on univariate analysis were placed in a multivariable model. RESULTS There were 151 stroke patients (59% white and 41% black). Time of stroke onset and time to ED arrival were documented for 119 patients (79%). The median time from stroke onset to ED arrival was 5.7 hours; 46 patients (30%) presenting within 3 hours. Of those with times recorded, the median time from stroke onset to EMS arrival was 1.7 hours. Multivariable logistic regression identified use of EMS (odds ratio [OR], 4.0; 95% confidence interval [CI], 1.3 to 12.1) and white race (OR, 3.5; 95% CI, 1.3 to 10) as being independently associated with ED arrival within 3 hours of symptom onset. Median time from ED arrival to physician evaluation was 20 minutes. Median time from ED arrival to computed tomographic evaluation was 72 minutes. When patients were asked the main reason they sought medical attention, 40% (60/141) of those able to be interviewed said that they themselves did not decide to seek medical attention, but rather a friend or family member told them they should go to the hospital. CONCLUSION The median time from stroke onset to ED evaluation was 5.7 hours, with almost a third of patients presenting within 3 hours. Use of EMS and white race were independently associated with arrival within 3 hours.

Measurement of Cardiac Troponin T Is an Effective Method for Predicting Complications Among Emergency Department Patients With Chest Pain

STUDY OBJECTIVES To determine the test performance characteristics of serum cardiac troponin T (cTnT) measurement for diagnosis of acute myocardial infarction (AMI), and to determine the ability of cTnT to stratify emergency department patients with chest pain into high- and low-risk groups for cardiac complications. METHODS We conducted a prospective observational cohort study with convenience sampling in a tertiary care, urban ED. The study sample comprised 667 patients presenting to the ED with a complaint of chest pain or other symptoms suggesting acute ischemic coronary syndrome (AICS). Patients were assigned to different blood sampling protocols for cTnT therapy on the basis of their ECG at presentation: nondiagnostic for AMI at 0, 3, 6, 9, 12, and 24 hours after ED presentation; or ECG diagnostic for AMI at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 18, and 24 hours after ED presentation. RESULTS Of 667 patients, 34 had AMI diagnosed within 24 hours of ED arrival. Using a .2 microgram/L discrimination level for cTnT, sensitivity for AMI within 24 hours of ED arrival was 97% (95% confidence interval, 91.4% to 99.9%), and specificity was 92% (89.8%-94.1%). When the effects of age, race, sex, and creatine kinase-MB isoenzyme subunit test results were controlled, a patient with cTnT of .2 microgram/L or greater was 3.5 (1.4 to 9.1) times more likely to have a cardiac complication within 60 days of ED arrival than a patient with a cTnT value below .2 microgram/L. CONCLUSION Measurement of cTnT will accurately identify myocardial necrosis in patients presenting to the ED with possible AICS. Elevated cTnT values identify patients at increased risk of cardiac complications.

Identification of patients at risk by graded exercise testing in an emergency department chest pain center

The study applied a retrospective follow-up design to determine the prognostic effect of graded exercise testing (GXT) in patients with low- to moderate-risk chest pain evaluated in an emergency department 9-hour protocol chest pain center (CPC) from January 1, 1993 to August 1, 1996. The cohort of 1,209 patients were followed to the date of death or first adverse cardiac event up to 1 year after CPC admission. Cardiac events were defined as coronary artery bypass graft, percutaneous transluminal coronary angioplasty, cardiogenic shock, cardiac-related death, congestive heart failure admission, ventricular tachycardia/ventricular fibrillation arrest, and myocardial infarction. Patients with acute ST-segment elevation or depression of >1 mm, positive enzyme (creatine kinase myocardial band) testing, or unstable angina during their CPC evaluation were admitted without GXT testing. Statistical analysis included chi-square test for complication rates and Cox proportional-hazards modeling. Nine hundred fifty-eight of 1,209 patients underwent GXT testing. Patients with positive, inconclusive, and normal GXTs had complication rates of 36.8% (7 of 19), 3.4% (9 of 267), and 1.1% (5 of 456), respectively. After adjusting for age, sex, and race, the relative risk of complication was 38.9 (95% confidence interval 11.7 to 129.6) with a positive GXT, and 3.6 (95% confidence interval 1.2 to 10.7) with an inconclusive GXT compared with a normal GXT. The GXT is a good prognostic indicator of adverse cardiac events in low- to moderate-risk chest pain in patients evaluated in an emergency department CPC.

A nationwide prehospital stroke survey

OBJECTIVES To identify deficiencies in stroke knowledge among prehospital providers. METHODS A nationwide multiple-choice survey was sent to 689 paramedics (EMT-Ps) and 294 advanced EMTs (EMT-Is) from a random selection of the National Registry of Emergency Medical Technicians database. Of the 23 questions, five addressed demographic information, four quantity of training, five general knowledge, 6 and seven management, and two open-ended questions addressed the signs, symptoms, and risk factors of stroke. The EMT-P and EMT-I answers were compared using chi-square analysis or Fishers exact test. RESULTS Of the 355 (36%) respondents, 256 (72%) were EMT-Ps and 99 (28%) were EMT-Is. Virtually all the EMT-Ps (99%) and EMT-Is (98%) knew that a stroke injures the brain, but only 199 (78%) of the EMT-Ps and 47 (47%) of the EMT-Is correctly defined a transient ischemic attack (TIA) (p < 0.001). Slurred speech, weakness/ paralysis, and altered mental status were the three most commonly cited symptoms of stroke by both groups. The EMT-Ps were more likely to recognize that dextrose is potentially harmful to stroke patients [EMT-P = 216 (85%), EMT-I = 71 (72%), p = 0.005]; 169 (66%) of the EMT-Ps and 75 (76%) of the EMT-Is felt that elevated blood pressures should be lowered in the prehospital setting. Only 93 (36%) of the EMT-Ps and 22 (22%) of the EMT-Is knew that tissue plasminogen activator (tPA) must be given within three hours of symptom onset (p = 0.01). CONCLUSION Most EMS providers are knowledgeable about the symptoms of stroke but are unaware of the therapeutic window for thrombolysis and the recommended avoidance of prehospital blood pressure reduction. In addition, further education is needed regarding TIAs.

MATHEMATICALDETERMINATION OFEXTERNALDEFIBRILLATORSNEEDED ATMASSGATHERINGS

Objective. To develop a mathematical formula that assists in determining the number of automated external defibrillators (AEDs) needed at sites of mass gatherings. Methods. Twenty (10 male, 10 female) healthy volunteers (equally divided between age groups 21–30 and 31–40 years) responded to mock cardiac arrests in a sports stadium. Seven different first-responder scenarios were simulated (ascending and descending three separate stairway slopes (22°, 39°, and 69°), as well as a response across a horizontal (0°) surface. To assess the impact of spectator congestion, the same volunteers conducted each scenario in an empty and full stadium. The quantitative relationship between time and distance was then plotted for each situation. Using the quantitative relationship, the area a first responder can cover in a specified time was calculated. Results. The formula for the total number of AEDs needed in a stadium (or other mass gathering site) can be expressed as follows: Total AEDs = [A1/(Ds1 × Dh1)] + [A2/(Ds2 × Dh2)] + [A3/(Ds3 × Dh3)] where A1, A2, and A3 represent the total areas of a stadium with a slight, moderate, or steep stairway slope, respectively; Ds1, Ds2, and Ds3 represent the stairway distance a first responder must ascend or descend for each slope; and Dh1, Dh2, and Dh3 are the horizontal distances a responder can run in the time remaining. Conclusion. Given a medical directors targeted response times and goals, the optimal number of AEDs required at a mass gathering can be calculated using time versus distance relationships. Future studies should evaluate the impact of the mathematically derived optimal number of AEDs at mass gatherings.