CJEM Articles: John Trickett

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  • Underuse of prehospital strategies to reduce time to reperfusion for ST-elevation myocardial infarction patients in 5 Canadian provinces
    September 2009 11 5
    Andrew Travers, Dug Andrusiek, Jack V. Tu, John Trickett, Linda Donovan, Lucy J. Boothroyd, Marian J. Vermeulen, Michael J. Schull, Samuel Vaillancourt, Sunil Sookram

    Objective: Timely reperfusion therapy for ST-elevation myocardial infarction (STEMI) is an important determinant of outcome, yet targets for time to treatment are frequently unmet in North America. Prehospital strategies can reduce time to reperfusion. We sought to determine the extent to which emergency medical services (EMS) use these strategies in Canada.
    Methods: We carried out a cross-sectional survey in 2007 of ground EMS operators in British Columbia, Alberta, Ontario, Quebec and Nova Scotia. We focused on the use of 4 prehospital strategies: 1) 12-lead electrocardiogram (ECG), 2) routine expedited emergency department (ED) transfer of STEMI patients (from a referring ED to a percutaneous coronary intervention [PCI] centre), 3) prehospital bypass (ambulance bypass of local EDs to transport patients directly to PCI centres) and 4) prehospital fibrinolysis.
    Results: Ninety-seven ambulance operators were surveyed, representing 15 681 paramedics serving 97% of the combined provincial populations. Of the operators surveyed, 68% (95% confidence interval [CI] 59%-77%) had ambulances equipped with 12-lead ECGs, ranging from 40% in Quebec to 100% in Alberta and Nova Scotia. Overall, 47% (95% CI 46%-48%) of paramedics were trained in ECG acquisition and 40% (95% CI 39%-41%) were trained in ECG interpretation. Only 18% (95% CI 10%-25%) of operators had prehospital bypass protocols; 45% (95% CI 35%-55%) had protocols for expedited ED transfer. Prehospital fibrinolysis was available only in Alberta. All EMS operators in British Columbia, Alberta and Nova Scotia used at least 1 of the 4 prehospital strategies, and one-third of operators in Ontario and Quebec used 0 of 4. In major urban centres, at least 1 of the 3 prehospital strategies 12-lead ECG acquisition, bypass or expedited transfer was used, but there was considerable variation within and across provinces.
    Conclusion: The implementation of widely recommended prehospital STEMI strategies varies substantially across the 5 provinces studied, and relatively simple existing technologies, such as prehospital ECGs, are underused in many regions. Substantial improvements in prehospital services and better integration with hospital-based care will be necessary in many regions of Canada if optimal times to reperfusion, and associated outcomes, are to be achieved.

  • Diagnostic performance and potential clinical impact of advanced care paramedic interpretation of ST-segment elevation myocardial infarction in the field
    November 2006 8 6
    Ian Stiell, Irene Watpool, John Trickett, Justin Maloney, Michel R. Le May, Michel Ruest, Richard Dionne, Richard F. Davies, Sheila Ryan

    Objectives: Most studies of pre-hospital management of ST-elevation myocardial infarction (STEMI) have involved physicians accompanying the ambulance crew, or electrocardiogram (ECG) transmission to a physician at the base hospital. We sought to determine if Advanced Care Paramedics (ACPs) could accurately identify STEMI on the pre-hospital ECG and contribute to strategies that shorten time to reperfusion.

    Methods: A STEMI tool was developed to: 1) measure the accuracy of the ACPs at diagnosing STEMI; and 2) determine the potential time saved if ACPs were to independently administer thrombolytic therapy. Using registry data, we subsequently estimated the time saved by initiating thrombolytic therapy in the field compared with in-hospital administration by a physician.

    Results: Between August 2003 and July 2004, a correct diagnosis of STEMI on the pre-hospital ECG was confirmed in 63 patients. The performance of the ACPs in identifying STEMI on the ECG resulted in a sensitivity of 95% (95% confidence interval [CI] 86%-99%), a specificity of 96% (95% CI 94%-98%), a positive predictive value (PPV) of 82% (95% CI 71%-90%), and a negative predictive value (NPV) of 99% (95% CI 97%-100%). ACP performance for appropriately using thrombolytic therapy resulted in a sensitivity of 92% (95% CI 78%-98%), a specificity of 97% (95% CI 94%-98%), a PPV of 73% (95% CI 59%-85%) and an NPV of 99% (95% CI 97%-100%). We estimated that the median time saved by ACP administration of thrombolytic therapy would have been 44 minutes.

    Conclusions: ACPs can be trained to accurately interpret the pre-hospital ECG for the diagnosis of STEMI. These results are important for the design of regional integrated programs aimed at reducing delays to reperfusion.