This year Boston Emergency Medical Services (BEMS), the Center for Cardiovascular Health Services Research in the Division of Clinical Care Research at New England Medical Center (NEMC) and Boston Medical Center’s Emergency Medicine Research Division embarked upon a research trial to test the impact of 12-lead electrocardiograms (EKGs) enhanced with predictive instruments in the pre-hospital setting. Although 12-lead EKGs are not new to Boston EMS, the use of predictive instruments in the paramedic’s decision tree was innovative. The TIPI-5-EMS Trial's (Time Insensitive Predictive Instrument) principal investigators are Dr. Harry Selker from NEMC and Dr. Peter Moyer from BUMC and Medical Director of BEMS. This research project had its origins here in the Boston emergency medical community in 1980 with a computer program designed by Dr. Michael Pozen, an early pioneer in the use of predictive instruments as well as one of the founding physicians of the first Boston EMS paramedic training program in 1979.

The technology is testing the prehospital use of 12-lead EKGs enhanced by the predictions of the Acute Cardiac Ischemia Time-Insensitive Predictive Instrument (ACI-TIPI) and the Thrombolytic Predictive Instrument (TPI).  In the field, when BEMS Paramedics determine that a patient requires an EKG, by random allocation the electrocardiograph will print a standard EKG or a standard EKG plus predictions of the ACI-TIPI, and of the TPI if the patient is a coronary reperfusion candidate. The trial is sponsored by the National Institutes of Health National Library of Medicine, National Heart Lung Blood Institute, and the National Heart Attack Alert Program.

The ACI-TIPI and TPI are ECG-based “predictive instruments” that provide clinicians with probabilities of cardiac outcomes for a given patient, based on clinical and ECG features. These 0-100% predictions, printed on the ECG, are intended to supplement not replace clinician judgment, much as the probability of rain supplements evaluation of the weather. For patients considered for possible cardiac problems, standard electrocardiograph software can generate the ACI-TIPI 0-100% probability that a patient is having acute cardiac ischemia (ACI: i.e. either acute myocardial infarction [AMI] or unstable angina pectoris) based on age, sex, chest pain status, and ECG measurements. Also, if ST elevation of AMI is detected, identifying a possible coronary reperfusion candidate, the TPI program is automatically activated.

Boston EMS paramedics attended a 4-hour training, which included an introduction to predictive instruments, review of cardiac anatomy and physiology, 12-lead EKG interpretation in acute cardiac ischemia, and practical training on the application and data collection methods to be utilized in the TIPI trial. During this training session instructors made clear that these measurements are meant to supplement not replace the paramedic’s clinical judgment in the field. The 7-week study ran from January 6 through February 25, 2002. 12-lead EKGs recorded in the field were captured for data collection by utilizing the memory and modem transfer capabilities of the Medtronic Physio-Control monitors issued to paramedic units. Download connection sites were established at the 10 participating hospital emergency departments as well as Paramedic base stations using analog phone lines. A central computer networked to BEMS research coordinator provided collection and data storage. Patient care reports (PCRs), dispatch information, EKGs and ACI-TIPI and TPI data were compiled by the clinical research center for analysis.  Analyses for the TIPI-5-EMS Trial will be completed within the next few months; however, this trial is a pilot study and a definitive answer will likely not be available until the national study is completed. 

Where can you go to find out more about ACI-TIPI or the TIPI-5-EMS Trial? Questions and comments are welcome at the BMC research office. Please call (617) 414-4560 or email Boston EMS Paramedic John Doyle, coordinator of the study.