Identifying Features of a System of Practice to Inform a Contemporary Competency Framework for Paramedics in Canada.

INTRODUCTION: Paramedic practice is highly variable, occurs in diverse contexts, and involves the assessment and management of a range of presentations of varying acuity across the lifespan. As a result, attempts to define paramedic practice have been challenging and incomplete. This has led to inaccurate or under-representations of practice that can ultimately affect education, assessment, and the delivery of care. In this study, we outline our efforts to better identify, explore, and represent professional practice when developing a national competency framework for paramedics in Canada. METHODS: We used a systems-thinking approach to identify the settings, contexts, features, and influences on paramedic practice in Canada. This approach makes use of the role and influence of system features at the microsystem, mesosystem, exosystem, macrosystem, supra-macrosystem, and chronosystem levels in ways that can provide new insights. We used methods such as rich pictures, diagramming, and systems mapping to explore relationships between these contexts and features. FINDINGS: When we examine the system of practice in paramedicine, multiple layers become evident and within them we start to see details of features that ought to be considered in any future competency development work. Our exploration of the system highlights that paramedic practice considers the person receiving care, caregivers, and paramedics. It involves collaboration within co-located and dispersed teams that are composed of other health and social care professionals, public safety personnel, and others. Practice is enacted across varying geographical, cultural, social, and technical contexts and is subject to multiple levels of policy, regulatory, and legislative influence. CONCLUSION: Using a systems-thinking approach, we developed a detailed systems map of paramedic practice in Canada. This map can be used to inform the initial stages of a more representative, comprehensive, and contemporary national competency framework for paramedics in Canada.

Derivation and validation of the Montreal prehospital ST-elevation myocardial infarction activation rule.

BACKGROUND: Prehospital ECGs (phECGs) are the main screening tool used by paramedics to identify ST elevation myocardial infarction (STEMI). In the absence of telemetry or personnel trained in ECG interpretation, paramedics must rely on computerized interpretation of phECGs, which suffer from an elevated false-positive (FP) rate, impairing reliable early activation of reperfusion centers by Emergency Medical Services. OBJECTIVE: Develop a clinical prediction rule to reduce the frequency of FPs for STEMI in prehospital patients. METHODS: This was a retrospective analysis of prehospital patients with a computer interpretation of '***ACUTE MI***' on phECG. We used logistic regression analysis to identify the independent variables for derivation of the rule. Once derived, we validated the rule on a distinct cohort of consecutive phECGs. RESULTS: Among the 654 cases in the derivation cohort, 46.2% were FP STEMIs. Four elements emerged as independent FP predictors: HR ≥ 120, no ongoing chest pain, no interpretable ST-segments in a lead, and presence of baseline wander or pacemaker spikes. In the derivation cohort this rule decreased FPs to 15.1% of the total cohort, while labelling 13.8% of STEMI cases as false-negatives (FNs). In the validation cohort (386 phECGs, 41.7% FPs), the rule decreased FPs down to 8.0%, while 25.9% were FN. CONCLUSION: Use of computer interpretation alone leads to a high STEMI FP rate. A clinical prediction rule based upon four elements available to paramedics can substantially lower the proportion of FPs. This clinical prediction rule should be incorporated into the decision for prehospital activation of the cardiac catheterization laboratory.

Prehospital Nitroglycerin in Tachycardic Chest Pain Patients: A Risk for Hypotension or Not?

BACKGROUND: The American Heart Association guidelines (AHA) guidelines list tachycardia as a contraindication for the administration of nitroglycerin (NTG), despite limited evidence of adverse events. We sought to determine whether NTG administered for chest pain was a predictor of hypotension (systolic blood pressure <90 mmHg) in patients with tachycardia, compared to patients without tachycardia (50≥ heart rate ≤100). METHODS: We performed a retrospective cohort study using patient care reports completed by basic life support (BLS) providers in a large urban Canadian EMS system for the period 2010-2012. We used logistic regression to test the association between post-NTG hypotension and tachycardia, independent of pre-NTG blood pressure, age, sex, and comorbidities. Using identical models, we tested four secondary outcomes (drop in blood pressure, reduced consciousness, bradycardia, and cardiac arrest). RESULTS: The cohort included 10,308 patients who were administered NTG by BLS in the prehospital setting; 2,057 (20%) of patients were tachycardic before NTG administration. Hypotension occurred in 320 of all patients (3.1%): 239 without tachycardia (2.9%) and 81 with tachycardia (3.9%). Compared to non-tachycardic patients, tachycardic patients showed increased adjusted odds of hypotension (AOR: 1.60; 95% CI: 1.23-2.08) or of a drop in blood pressure of 30mm Hg or greater (AOR: 1.11; CI: 1.00-1.24). Tachycardia was associated with decreased odds of bradycardia (OR: 0.33; CI: 0.17-0.64). We did not find a significant association between tachycardia and either post-NTG reduced level of consciousness or cardiac arrest. We did find a strong, significant association between pre-NTG blood pressure and post-NTG hypotension (AOR for units of 10mmHg: 0.64; CI: 0.61-0.69). CONCLUSION: Hypotension following prehospital administration of NTG was infrequent in patients with chest pain. However, while the absolute risk of NTG-induced hypotension was low, patients with pre-NTG tachycardia had a significant increase in the relative risk of hypotension. In addition, hypotension occurred most frequently in patients presenting with a lower pre-NTG blood pressure, which may prove to be a more discriminating basis for future guidelines. EMS medical directors should review BLS chest pain protocols to weigh the benefits of NTG administration against its risks.

Prehospital Nitroglycerin Safety in Inferior ST Elevation Myocardial Infarction.

Patients with inferior ST elevation myocardial infarction (STEMI), associated with right ventricular infarction, are thought to be at higher risk of developing hypotension when administered nitroglycerin (NTG). However, current basic life support (BLS) protocols do not differentiate location of STEMI prior to NTG administration. We sought to determine if NTG administration is more likely to be associated with hypotension (systolic blood pressure < 90 mmHg) in inferior STEMI compared to non-inferior STEMI. We conducted a retrospective chart review of prehospital patients with chest pain of suspected cardiac origin and computer-interpreted prehospital ECGs indicating "ACUTE MI." We included all local STEMI cases identified as part of our STEMI registry. Univariate analysis was used to compare differences in proportions of hypotension and drop in systolic blood pressure ≥ 30 mmHg after nitroglycerin administration between patients with inferior wall STEMI and those with STEMI in another region (non-inferior). Multiple variable logistic regression analysis was also used to assess the study outcomes while controlling for various factors. Over a 29-month period, we identified 1,466 STEMI cases. Of those, 821 (56.0%) received NTG. We excluded 16 cases because of missing data. Hypotension occurred post NTG in 38/466 inferior STEMIs and 30/339 non-inferior STEMIs, 8.2% vs. 8.9%, p = 0.73. A drop in systolic blood pressure ≥ 30 mmHg post NTG occurred in 23.4% of inferior STEMIs and 23.9% of non-inferior STEMIs, p = 0.87. Interrater agreement for chart review of the primary outcome was excellent (κ = 0.94). NTG administration to patients with chest pain and inferior STEMI on their computer-interpreted electrocardiogram is not associated with a higher rate of hypotension compared to patients with STEMI in other territories. Computer interpretation of inferior STEMI cannot be used as the sole predictor for patients who may be at higher risk for hypotension following NTG administration.