Ottawa cardiac arrest and brain hemorrhage studies to be presented at international conference

May 18, 2006

Two scientists from the Ottawa Hospital Research Institute were selected to give plenary lectures at the at the Society for Academic Emergency Medicine Annual Meeting in San Francisco on May 18th. Dr. Ian Stiell will present new results that may improve the use of Automated External Defibrillation (AED) devices, which are being increasingly made available in public places to assist in resuscitating cardiac arrest victims. Also, Dr. Jeffrey Perry will present a protocol he has developed to improve diagnosis of subarachnoid brain hemorrhages among severe headache patients arriving in the emergency department. Both scientists are also professors at the University of Ottawa, and physicians at The Ottawa Hospital. For more information, please see the following press releases issued by the Society for Academic Emergency Medicine:

Best Settings for Biphasic Automated Defibrillators Investigated
San Francisco, May 18, 2006 -- As the use of automated external defibrillation (AED) devices outside of hospital settings increases, the scientific medical community has not agreed on the optimal energy levels for initial and subsequent biphasic shocks. A study presented at the 2006 Society for Academic Emergency Medicine Annual Meeting, May 18-21, 2006 in San Francisco investigated both fixed and escalating biphasic energy regimes for out-of-hospital cardiac arrest.

In a randomized, controlled trial, emergency medical services (EMS) personnel or firefighters in three cities used preprogrammed LIFEPAK® 500 biphasic AED devices to treat 221 patients in sudden cardiac arrest, with 114 receiving fixed levels of 150-150-150 joules (FIXED) and 107 receiving escalating levels of 200-300-360 joules (ESC). The energy being delivered was unknown to the firefighters.

The patients had a mean age of 66 years and were 80 percent male. The event was witnessed in 64 percent of the cases and 24 percent of the patients received CPR from bystanders. Outcomes included conversion (return of QRS complexes within 60 sec), termination (removal of ventricular fibrillation (VF) for at least 5 seconds), survival, and evidence of harm.

For first shocks, the rates of termination and conversion were similar for the two regimens. For subsequent shocks, however, the rates of both termination and conversion were higher for the escalating than the fixed energy regimen. The study did not demonstrate a difference in other outcomes between the two regimens but was not powered to do so.

This is the first randomized trial to compare fixed and escalating biphasic energy regimens, and it found more successful termination of VF and conversion to an organized rhythm for secondary shocks with the escalating regimen. A much larger trial will be necessary to determine whether these differences in electrical outcomes translate to a difference in survival.

The study, “A Randomized Controlled Trial of Fixed Versus Escalating Energy Levels for Defibrillation,” was presented by Ian G Stiell MD. His co-authors are Robert Walker, Lisa Nesbitt MBA, Fred Chapman, Donna Cousineau RN, James Christenson MD, Paul Bradford MD, Sunil Sookram MD, Ross Berringer MD, Paula Lank, and George A Wells PhD. This paper will be presented at the 2006 SAEM Annual Meeting, May 18-21, 2006, San Francisco, CA on Thursday, May 18, in the Plenary Session beginning at 8:00 AM in Salon 9 of the San Francisco Marriott. Abstracts of the papers presented are published in the May issue of the official journal of the SAEM, Academic Emergency Medicine.

A Simple Protocol Avoids Unnecessary Invasive Procedures
San Francisco, May 18, 2006 -- When a patient comes to the emergency room with a severe headache, this may be a sign of a Subarachnoid Hemorrhage (SAH), an extremely serious condition caused by a bleeding brain aneurysm. On the other hand, there may be less threatening explanations for the pain. Until now, there has been no way to rule out the more serious condition and a series of tests involving some risk to the patient would have had to be done.

In a paper presented at the 2006 Society for Academic Emergency Medicine Annual Meeting, May 18-21, 2006 in San Francisco, a group of Canadian researchers reported on their investigation of a protocol which could minimize invasive testing. In a study conducted at 6 university Emergency Departments involving nearly 2000 patients, 80% underwent head computed tomography (CT), 45% received lumbar puncture (LP, i.e. a spinal tap), 83% had either CT and/or LP, and 6.4% had a final diagnosis of SAH.

By using 4 simple clinical observations, the authors were able to predict whether a patient was at high risk for SAH. For example, of those who arrived by ambulance, 57% were later diagnosed with SAH, while only 17% of those who arrived by ambulance did not have SAH. Vomiting was a symptom in 58% of the patients with SAH and only in 26% of those without SAH. A diastolic blood pressure ≥100mmHg or age ≥45 were also strong predictors of SAH.
By using these simple observations, the authors developed a clinical rule that any patient showing 1 or more of these symptoms would then be a candidate for further investigation, via CT and/or LP. This rule would identify all the patients with SAH, while reducing the investigation rate to 66%.

According to Jeffrey Perry, MD, “While we do not recommend an immediate change in management until after a validation study is complete, this study will have a tremendous impact on patient care. It will improve our ability to determine which patients require investigations for their headache and which ones just need pain control without costly and invasive testing.”

The presentation is “A Clinical Decision Rule to Safely Rule-Out Subarachnoid Hemorrhage in Acute Headache Patients in the Emergency Department” by Jeffrey J Perry MD. Dr. Perry’s coauthors are Ian G Stiell MD, George A Wells PhD, Melodie Mortensen RN, Marco Sivilotti MD, Michael Bullard MD, Cheryl Symington RN, Howard Lesiuk MD, Jacques S Lee MD, Mary A Eisenhauer MD, Lorne Wiesenfeld MD, and Joseph Caytak MD. Dr. Perry is an emergency medicine physician at The Ottawa Hospital, a scientist at the Ottawa Hospital Research Institute, and an assistant professor at the University of Ottawa.
This paper will be presented at the 2006 SAEM Annual Meeting, May 18-21, 2006, San Francisco, CA on Thursday, May 18, in the Plenary Session beginning at 8:00 AMin Salon 9 of the San Francisco Marriott. Abstracts of the papers presented are published in the May issue of the official journal of the SAEM, Academic Emergency Medicine.

About The Society for Academic Emergency Medicine
The Society for Academic Emergency Medicine (SAEM) is a national non-profit organization of over 6,000 academic emergency physicians, emergency medicine residents and medical students. SAEM's mission is to improve patient care by advancing research and education in emergency medicine. SAEM's vision is to promote ready access to quality emergency care for all patients, to advance emergency medicine as an academic and clinical discipline, and to maintain the highest professional standards as clinicians, teachers, and researchers. The SAEM Annual Meeting attracts approximately 2,000 medical students, residents and academic emergency physicians. It provides the largest forum for the presentation of original research in the specialty of Emergency Medicine.

About Academic Emergency Medicine
The SAEM's official journal, Academic Emergency Medicine, is published by Elsevier. Established in 1994, Academic Emergency Medicine is a monthly peer-reviewed journal that publishes material relevant to the practice, education, and investigation of emergency medicine, and reaches a wide audience of emergency care practitioners and educators. Each issue contains a broad range of topics relevant to the improvement of emergency, urgent or critical care of the acutely ill or injured patient. Regular features include original research, preliminary reports, education & practice and annotated literature.

About Elsevier
Elsevier is a world-leading publisher of scientific, technical and medical information products and services. Working in partnership with the global science and health communities, Elsevier’s 7,000 employees in over 70 offices worldwide publish more than 2,000 journals and 1,900 new books per year, in addition to offering a suite of innovative electronic products, such as ScienceDirect, MD Consult, Scopus, bibliographic databases, and online reference works.