Clinical outcomes following out-of-hospital cardiac arrest: The minute-by-minute impact of bystander cardiopulmonary resuscitation.

AIMS: The time-dependent prognostic role of bystander cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) patients has not been described with great precision, especially for neurologic outcomes. Our objective was to assess the association between bystander CPR, emergency medical service (EMS) response time, and OHCA patients' outcomes. METHODS: This cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registries. Bystander-witnessed adult OHCA treated by EMS were included. The primary outcome was survival to hospital discharge and secondary outcome was survival with a good neurologic outcome (modified Rankin scale 0-2). Multivariable logistic regression models were used to assess the associations and interactions between bystander CPR, EMS response time and clinical outcomes. RESULTS: Out of 229,637 patients, 41,012 were included (18,867 [46.0%] without bystander CPR and 22,145 [54.0%] with bystander CPR). Bystander CPR was independently associated with higher survival (adjusted odds ratio [AOR] = 1.70 [95%CI 1.61-1.80]) and survival with a good neurologic outcome (AOR = 1.87 [95%CI 1.70-2.06]), while longer EMS response times were independently associated with lower survival to hospital discharge (each additional minute of EMS response time: AOR = 0.92 [95%CI 0.91-0.93], p < 0.001) and lower survival with a good neurologic outcome (AOR = 0.88 [95%CI 0.86-0.89], p < 0.001). There was no interaction between bystander CPR and EMS response time's association with survival (p = 0.12) and neurologic outcomes (p = 0.65). CONCLUSIONS: Although bystander CPR is associated with an immediate increase in odds of survival and of good neurologic outcome for OHCA patients, it does not influence the negative association between longer EMS response time and survival and good neurologic outcome.

Association of Initial Pulseless Electrical Activity Heart Rate and Clinical Outcomes following Adult Non-Traumatic Out-of-Hospital Cardiac Arrest.

OBJECTIVE: Studies evaluating the prognostic value of the pulseless electrical activity (PEA) heart rate in out-of-hospital cardiac arrest (OHCA) patients have reported conflicting results. The objective of this study was to evaluate the association between the initial PEA heart rate and favorable clinical outcomes for OHCA patients. METHODS: The present post-hoc cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registry Version 3, which included OHCA patients in seven US and three Canadian sites from April 2011 to June 2015. The primary outcome was survival to hospital discharge and the secondary outcome was survival with a good functional outcome. For the primary analysis, the patients were separated into eight groups according to their first rhythms and PEA heart rates: (1) initial PEA heart rate of 1-20 beats per minute (bpm); (2) 21-40 bpm; (3) 41-60 bpm; (4) 61-80 bpm; (5) 81-100 bpm; (6) 101-120 bpm; (7) over 120 bpm; (8) initial shockable rhythm (reference category). Multivariable logistic regression models were used to assess the associations of interest. RESULTS: We identified 17,675 patients (PEA: 7,089 [40.1%]; initial shockable rhythm: 10,797 [59.9%]). Patients with initial PEA electrical frequencies ≤100 bpm were less likely to survive to hospital discharge than patients with initial shockable rhythms (1-20 bpm: adjusted odds ratio [AOR] = 0.15 [95%CI 0.11-0.21]; 21-40 bpm: AOR = 0.21 [0.18-0.25]; 41-60 bpm: AOR = 0.30 [0.25-0.36]; 61-80 bpm: AOR = 0.37 [0.28-0.49]; 81-100 bpm: AOR = 0.55 [0.41-0.65]). However, there were no statistical outcome differences between PEA patients with initial electrical frequencies of >100 bpm and patients with initial shockable rhythms (101-120 bpm: AOR = 0.65 [95%CI 0.42-1.01]; >120 bpm: AOR = 0.72 [95%CI 0.37-1.39]). Similar results were observed for survival with good functional outcomes (101-120 bpm: AOR = 0.60 [95%CI 0.31-1.15]; >120 bpm: AOR = 1.08 [95%CI 0.50-2.28]). CONCLUSIONS: We observed a good association between higher initial PEA electrical frequency and favorable clinical outcomes for OHCA patients. As there is no significant difference in outcomes between patients with initial PEA heart rates of more than 100 bpm and those with initial shockable rhythms, we can hypothesize that these patients could be considered in the same prognostic category.

Accuracy of the Initial Rhythm to Predict a Short No-Flow Time in Out-of-Hospital Cardiac Arrest.

OBJECTIVES: The no-flow time (NFT) can help establish prognosis in out-of-hospital cardiac arrest (OHCA) patients. It is often used as a selection criterion for extracorporeal resuscitation. In patients with an unwitnessed OHCA for whom the NFT is unknown, the initial rhythm has been proposed to identify those more likely to have had a short NFT. Our objective was to determine the predictive accuracy of an initial shockable rhythm for an NFT of 5 minutes or less (NFT ≤ 5). DESIGN: Retrospective analysis of prospectively collected data. SETTING: Prehospital OHCA in eight U.S. and three Canadian sites. PATIENTS: A total of 28,139 adult patients with a witnessed nontraumatic OHCA were included, of whom 11,228 (39.9%) experienced an emergency medical service-witnessed OHCA (NFT = 0), 695 (2.7%) had a bystander-witnessed OHCA, and an NFT less than or equal to 5, and 16,216 (57.6%) with a bystander-witnessed OHCA and an NFT greater than 5. INTERVENTIONS: Sensitivity, specificity, and likelihood ratios of an initial shockable rhythm to identify patients with an NFT less than or equal to 5 minutes. MEASUREMENTS AND MAIN RESULTS: The sensitivity of an initial shockable rhythm to identify patients with an NFT less than or equal to 5 was poor (25% [95% CI, 25-26]), but specificity was moderate (70% [95% CI, 69-71]). The positive and likelihood ratios were inverted (negative accuracy) (positive likelihood ratio, 0.76 [95% CI, 0.74-0.79]; negative likelihood ratio, 1.12 [95% CI, 1.10-1.12]). Including only patients with a bystander-witnessed OHCA improved the sensitivity to 48% (95% CI, 45-52), the positive likelihood ratio to 1.45 (95% CI, 1.33-1.58), and the negative likelihood ratio to 0.77 (95% CI, 0.72-0.83), while slightly lowering the specificity to 67% (95% CI, 66-67). CONCLUSIONS: Our analysis demonstrated that the presence of a shockable rhythm at the time of initial assessment was poorly sensitive and only moderately specific for OHCA patients with a short NFT. The initial rhythm, therefore, should not be used as a surrogate for NFT in clinical decision-making.

Prospective Evaluation of a Two-Scale Protocol for Prehospital Large Vessel Occlusion Detection.

Background and purposes: Stroke severity scales may expedite prehospital large vessel occlusion (LVO) stroke detection, but few are validated for paramedic use. We evaluated the feasibility of introducing the Cincinnati Stroke Triage Assessment Tool (C-STAT) in the field and its capacity to detect LVO stroke.Methods: We performed a prospective paramedic-based study assessing C-STAT in the field on patients currently redirected to two comprehensive stroke centers (CSC), based on a Cincinnati Prehospital Stroke Scale (CPSS) score of 3/3. C-STAT was administered by on-site paramedics with telephone guidance from trained centralized clinical support paramedics.Results: Between October 2018 and November 2019, C-STAT scores were obtained in 188/218 (86.2%) patients, among which 118/188 (62.8%) were positive. Paramedics reported performing the C-STAT in less than 5 minutes on 170/188 (90.4%) patients and noted no difficulties administering the scale in 151/188 (80.3%). A positive C-STAT identified 51/68 (75%) LVO strokes in the cohort, demonstrating a 43% (95% CI: 38%-48%) positive and 76% (95% CI: 66%-83%) negative predictive value for LVO stroke diagnosis. In a cohort of 100 patients with CPSS 3/3, requiring a positive C-STAT for redirection would decrease CSC patient volume by 37 but miss 9 of 36 LVO strokes.Conclusion: Prehospital administration of the C-STAT was feasible, using a model of minimal paramedic training and real-time telephone guidance. A protocol based on both a CPSS 3/3 and a positive C-STAT would decrease CSC redirected patient volume by one-third but would miss one-quarter of LVO strokes when compared to a CPSS-based protocol.

Electrical rhythm degeneration in adults with out-of-hospital cardiac arrest according to the no-flow and bystander low-flow time.

AIMS: For out-of-hospital cardiac arrest (OHCA) patients, the influence of the delay before the initiation of resuscitation, termed the no-flow time (NFT), and duration of bystander-only resuscitation low-flow time (BLFT) on the type of electrical rhythm observed has not been well described. The objective of this study is to determine the relationship between NFT, BLFT and the likelihood of a shockable rhythm over time. METHODS: Using a North American prospective registry (2005-2015; mostly urban settings), we selected adult (18 years and over) patients who experienced a witnessed OHCA from a suspected cardiac etiology. Patients with an emergency medical services witnessed OHCA were only included in sensitivity analyses. The association between the NFT, BLFT and the presence of a shockable rhythm was evaluated using a multivariable logistic regression adjusting for the registry version, age, sex, and public location. RESULTS: A total of 229,632 patients were logged in the registry, 50,957 of whom were included. Of these, 17,704 (34.7%) had an initial shockable rhythm. After the first minute, a significant decrease over time in the occurrence of shockable rhythm is observed but is slower when bystander cardiopulmonary resuscitation (CPR) is provided (each supplemental minute of BLFT: adjusted odds ratio = 0.95, 95 %CI = 0.94-0.95; each supplemental minute of NFT: adjusted odds ratio = 0.91, 95 %CI = 0.90-0.91]). CONCLUSIONS: In this large observational study, we were able to demonstrate that longer NFT were associated with lower odds of shockable presenting rhythms. Bystander CPR significantly mitigates the degradation of shockable rhythms over time, strengthening the need to improve bystander CPR rates around the world.

Can a Shockable Initial Rhythm Identify Out-of-Hospital Cardiac Arrest Patients with a Short No-flow Time?

AIMS: Initial shockable rhythms may be a marker of shorter duration between collapse and initiation of cardiopulmonary resuscitation, known as no-flow time (NFT), for patients suffering an out-of-hospital cardiac arrest (OHCA). Eligibility for extracorporeal resuscitation is conditional on a short NFT. Patients with an unwitnessed OHCA could be candidate for extracorporeal resuscitation despite uncertain NFT if an initial shockable rhythm is a reliable stand-in. Herein, we sought to describe the sensitivity and specificity of an initial shockable rhythm for predicting a NFT of five minutes or less. METHODS: Using a registry of OHCA in Montreal, Canada, adult patients who experienced a witnessed non-traumatic OHCA, but who did not receive bystander cardiopulmonary resuscitation, were included. The sensitivity and specificity of an initial shockable rhythm for predicting a NFT of five minute or less were calculated. The association between the NFT and the presence of a shockable rhythm was evaluated using a multivariable logistic regression. RESULTS: A total of 2450 patients were included, of whom 863 (35%) had an initial shockable rhythm and 1085 (44%) a NFT of five minutes or less. The sensitivity of an initial shockable rhythm to predict a NFT of five minutes or less was 36% (95% confidence interval [95%CI] 33-39), specificity was 66% (95%CI 63-68), the positive likelihood ratio was 1.05 (95%CI 0.94-1.17) and the negative likelihood ratio of 0.97 (95%CI 0.92-1.03). The probabilities of observing a shockable rhythm stayed stable up to 15 minutes, while the probabilities of observing a PEA lowered rapidly initially. Longer NFT were associated with lower odds of observing an initial shockable rhythm (adjusted odds ratio = 0.97 [95%CI 0.94-0.99], p = 0.012). CONCLUSIONS: An initial shockable rhythm is a poor predictor of a short NFT, despite there being an association between the NFT and the presence of a shockable rhythm.

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.

Impact of the direct transfer to percutaneous coronary intervention-capable hospitals on survival to hospital discharge for patients with out-of-hospital cardiac arrest.

AIMS: Patients suffering from out-of-hospital cardiac arrest (OHCA) are frequently transported to the closest hospital. Percutaneous coronary intervention (PCI) is often indicated following OHCA. This study's primary objective was to determine the association between being transported to a PCI-capable hospital and survival to discharge for patients with OHCA. The additional delay to hospital arrival which could offset a potential increase in survival associated with being transported to a PCI-capable center was also evaluated. METHODS: This study used a registry of OHCA in Montreal, Canada. Adult patients transported to a hospital following a non-traumatic OHCA were included. Hospitals were dichotomized based on whether PCI was available on-site or not. The effect of hospital type on survival to discharge was assessed using a multivariable logistic regression. The added prehospital delay which could offset the increase in survival associated with being transported to a PCI-capable center was calculated using that regression. RESULTS: A total of 4922 patients were included, of whom 2389 (48%) were transported to a PCI-capable hospital and 2533 (52%) to a non-PCI-capable hospital. There was an association between being transported to a PCI-capable center and survival to discharge (adjusted odds ratio = 1.60 [95% confidence interval 1.25-2.05], p < .001). Increasing the delay from call to hospital arrival by 14.0 min would offset the potential benefit of being transported to a PCI-capable center. CONCLUSIONS: It could be advantageous to redirect patients suffering from OHCA patients to PCI-capable centers if the resulting expected delay is of less than 14 min.

Is Distance to the Nearest Registered Public Automated Defibrillator Associated with the Probability of Bystander Shock for Victims of Out-of-Hospital Cardiac Arrest?

Introduction Rapid access to defibrillation is a key element in the management of out-of-hospital cardiac arrests (OHCAs). Public automated external defibrillators (PAEDs) are becoming increasingly available, but little information exists regarding the relation between the proximity to the arrest and their usage in urban areas. METHODS: This study is a retrospective, observational, cross-sectional analysis of non-traumatic OHCA during a 24-month period in the greater Montreal area (Quebec, Canada). Using logistic regression, bystander shock odds are described with regards to distance from the OHCA scene to the nearest PAED, adjusted for prehospital care arrival delay and time of day, and stratifying for type of location. RESULTS: Out of a total of 2,443 OHCA victims identified, 77 (3%) received bystander PAED shock, 622 (26%) occurred out-of-home, and 743 (30%) occurred during business hours. When controlling for time (business hours versus other hours) and minimum response delay for prehospital care arrival, a marginal negative association was found between bystander shock and distance to the nearest PAED in logged meters (aOR=0.80; CI, 0.64-0.99) for out-of-home cardiac arrests. No significant association was found between distance and bystander shock for at-home arrests. Out-of-home victims had significantly higher odds of receiving bystander shock up to 175 meters of distance to a PAED inclusively (aOR=2.52; CI, 1.07-5.89). CONCLUSION: For out-of-home cardiac arrests, proximity to a PAED was associated with bystander shock in the greater Montreal area. Strategies aiming to increase accessibility and use of these life-saving devices could further expand this advantage by assisting bystanders in rapidly locating nearby PAEDs. Neves Briard J , de Montigny L , Ross D , de Champlain F , Segal E . Is distance to the nearest registered public automated defibrillator associated with the probability of bystander shock for victims of out-of-hospital cardiac arrest? Prehosp Disaster Med. 2018;33(2):153-159.

Potential impact of a prehospital redirection system for refractory cardiac arrest.

AIM: A change in prehospital redirection practice could potentially increase the proportion of E-CPR eligible patients with out-of-hospital cardiac arrest (OHCA) transported to extracorporeal cardiopulmonary resuscitation (E-CPR) capable centers. The objective of this study was to quantify this potential increase of E-CPR candidates transported to E-CPR capable centers. METHODS: Adults with non-traumatic OHCA refractory to 15min of resuscitation were selected from a registry of adult OHCA collected between 2010 and 2015 in Montreal, Canada. Using this cohort, three simulation scenarios allowing prehospital redirection to E-CPR centers were created. Stringent eligibility criteria for E-CPR and redirection for E-CPR (e.g. age <60years old, initial shockable rhythm) were used in the first scenario, intermediate eligibility criteria (e.g. age <65years old, at least one shock given) in the second scenario and inclusive eligibility criteria (e.g. age <70years old, initial rhythm ≠ asystole) in the third scenario. All three scenarios were contrasted with equivalent scenarios in which patients were transported to the closest hospital. Proportions were compared using McNemar's test. RESULTS: The proportion of E-CPR eligible patients transported to E-CPR capable centers increased in each scenario (stringent criteria: 48 [24.5%] vs 155 patients [79.1%], p<0.001; intermediate criteria: 81 [29.6%] vs 262 patients [95.6%], p<0.001; inclusive criteria: 238 [23.9%] vs 981 patients [98.5%], p<0.001). CONCLUSIONS: A prehospital redirection system could significantly increase the number of patients with refractory OHCA transported to E-CPR capable centers, thus increasing their access to this potentially life-saving procedure, provided allocated resources are planned accordingly.

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.

Outcomes of Patients With ST-Elevation Myocardial Infarction Receiving and Not Receiving Reperfusion Therapy: The Importance of Examining All Patients.

BACKGROUND: Hospitals treating patients with ST-elevation myocardial infarction (STEMI) may show good results with reperfusion treatment (fibrinolysis or primary percutaneous coronary intervention [PPCI]), but a comprehensive evaluation should factor in outcomes of patients with STEMI who do not receive reperfusion. We compared outcomes of patients receiving and not receiving reperfusion within a complete system of STEMI care by hospital type: PPCI centres, fibrinolysis centres, centres that only transfer for PPCI, and centres providing a mix of fibrinolysis and PPCI transfer. METHODS: All patients presenting to 82 Quebec hospitals with characteristic symptoms, a final diagnosis of acute myocardial infarction, and core-laboratory confirmed STEMI over two 6-month periods were studied. RESULTS: Of the total 3731 patients with STEMI, 2918 (78.2%) received reperfusion treatment (81% PPCI, 19% fibrinolysis); 813 (21.8%) did not. For reperfusion-treated patients, 30-day mortality was 5.4% in PPCI centres, 5.4% in fibrinolysis centres, 6.9% in transfer PPCI centres, and 6.0% in mixed centres (P = 0.55). For untreated patients, 30-day mortality was 15.7% (PPCI centres), 16.1% (fibrinolysis centres), 21.8% (transfer PPCI), and 24.6% (mixed) (P = 0.08). Adjusted mortality odds ratios for all patients were 1.00 (PPCI centres), 1.50 (95% CI: 0.97-2.32; fibrinolysis centres), 1.30 (0.95-1.78; transfer PPCI centres), and 1.58 (1.09-2.29; mixed centres). PPCI was within recommended delays in 35.4%, 11.9%, and 1.2% of PPCI, transfer, and mixed centres, respectively. CONCLUSIONS: Mixed centres had the highest crude and adjusted all-patient 30-day STEMI mortality. Relatively good outcomes of reperfusion-treated patients, despite long treatment delays, can misrepresent overall performance if untreated patients are not examined.

Clinical Profiles Related to Timing of Death, Including In-Hospital Deaths Before Admission, in Patients With ST-Elevation Myocardial Infarction.

Patients with ST-elevation myocardial infarction (STEMI) who die in hospital before inpatient admission are generally not included in clinical studies and registries, and the clinical profiles of patients who die earlier versus later are not well defined. We aimed to characterize all patients with STEMI who arrived at emergency departments in the province of Quebec (Canada) based on inpatient admission status and when they died. All patients who presented with symptoms and core laboratory-confirmed STEMI or left bundle branch block during 6 months in 82 hospitals in Quebec were included. Death certificates were used to identify nonadmitted deaths. Of the 2017 patients with STEMI, 340 (16.9%) died within 1 year. Of the latter, 63 (18.5%) were nonadmitted deaths (group A), 179 (52.6%) were deaths after admission but within 30 days (group B), and 98 (28.8%) were deaths after 30 days to 1 year (group C). Group A was younger and most often hemodynamically unstable, followed for both features by B then C. Earliest presentation from symptom onset and most frequent ambulance use were found in group A, followed by B, then C. Presenting electrocardiogram (ECG) features were most severe in A, then B, then C (more arrhythmias, more anterior STEMI, more leads with ST elevation, and higher ST elevation). Patients who died earliest had the least frequency of previous myocardial infarction, coronary revascularization, vascular disease, and heart failure, and the least noncardiac co-morbidity. In conclusion, patients with STEMI dying in hospital before inpatient admission contributed substantially to overall STEMI mortality. Although dying patients who presented earlier had severer presenting clinical profiles, they were paradoxically younger and had less co-morbidity. Previous co-morbidities may favor adaptive protective mechanisms on initial presentation with STEMI.

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.

Effect of the use of ambulance-based thrombolysis on time to thrombolysis in acute ischemic stroke: a randomized clinical trial.

UNLABELLED: Article chosen Ebinger M, Winter B, Wendt M, et al. Effect of the use of ambulance-based thrombolysis on time to thrombolysis in acute ischemic stroke: a randomized clinical trial. JAMA 2014;311(16):1622-31. Clinical question Does prehospital thrombolysis in specialized ambulances reduce delay to thrombolysis in acute ischemic stroke? OBJECTIVE: To determine the effect of prehospital thrombolysis for acute ischemic stroke administered in specialized ambulances on delay in thrombolytic administration, thrombolysis rate, post-thrombolysis intracerebral hemorrhage, and 7-day mortality.

Cervical Spine Motion during Transfer and Stabilization Techniques.

Abstract Objectives. To compare paramedics' ability to minimize cervical spine motion during patient transfer onto a vacuum mattress with two stabilization techniques (head squeeze vs. trap squeeze) and two transfer methods (log roll with one assistant (LR2) vs. 3 assistants (LR4)). Methods. We used a crossover design to minimize bias. Each lead paramedic performed 10 LR2 transfers and 10 LR4 transfers. For each of the 10 LR2 and 10 LR4 transfers, the lead paramedic stabilized the cervical spine using the head squeeze technique five times and the trap squeeze technique five times. We randomized the order of the stabilization techniques and LR2/LR4 across lead paramedics to avoid a practice or fatigue effect with repeated trials. We measured relative cervical spine motion between the head and trunk using inertial measurement units placed on the forehead and sternum. Results. On average, total motion was 3.9° less with three assistants compared to one assistant (p = 0.0002), and 2.8° less with the trap squeeze compared to the head squeeze (p = 0.002). There was no interaction between the transfer method and stabilization technique. When examining specific motions in the six directions, the trap squeeze generally produced less lateral flexion and rotation motion but allowed more extension. Examining within paramedic differences, some paramedics were clearly more proficient with the trap squeeze technique and others were clearly more proficient with the head squeeze technique. Conclusion. Paramedics performing a log roll with three assistants created less motion compared to a log roll with only one assistant, and using the trap squeeze stabilization technique resulted in less motion than the head squeeze technique but the clinical relevance of the magnitude remains unclear. However, large individual differences suggest future paramedic training should incorporate both best evidence practice as well as recognition that there may be individual differences between paramedics.

Comparison of outcomes of ambulance users and nonusers in ST elevation myocardial infarction.

In a systematic province-wide evaluation of care and outcomes of ST elevation myocardial infarction (STEMI), we sought to examine whether a previously documented association between ambulance use and outcome remains after control for clinical risk factors. All 82 acute care hospitals in Quebec (Canada) that treated at least 30 acute myocardial infarctions annually participated in a 6-month evaluation in 2008 to 2009. Medical record librarians abstracted hospital chart data for consecutive patients with a discharge diagnosis of myocardial infarction who presented with characteristic symptoms and met a priori study criteria for STEMI. Linkage to administrative databases provided outcome data (to 1 year) and co-morbidities. Of 1,956 patients, 1,222 (62.5%) arrived by ambulance. Compared with nonusers of an ambulance, users were older, more often women, and more likely to have co-morbidities, low systolic pressure, abnormal heart rate, and a higher Thrombolysis In Myocardial Infarction risk index at presentation. Ambulance users were less likely to receive fibrinolysis or to be sent for primary angioplasty (78.5% vs 83.2% for nonusers, p = 0.01), although if they did, treatment delays were shorter (p <0.001). The 1-year mortality rate was 18.7% versus 7.1% for nonusers (p <0.001). Greater mortality persisted after adjusting for presenting risk factors, co-morbidities, reperfusion treatment, and symptom duration (hazard ratio 1.56, 95% confidence interval 1.30 to 1.87). In conclusion, ambulance users with STEMI were older and sicker than nonusers. Mortality of users was substantially greater after adjustment for clinical risk factors, although they received faster reperfusion treatment overall.

Impact of ECG findings and process-of-care characteristics on the likelihood of not receiving reperfusion therapy in patients with ST-elevation myocardial infarction: results of a field evaluation.

BACKGROUND: Many patients with ST-elevation myocardial infarction (STEMI) do not receive reperfusion therapy and are known to have poorer outcomes. We aimed to perform the first population-level, integrated analysis of clinical, ECG and hospital characteristics associated with non-receipt of reperfusion therapy in patients with STEMI. METHODS AND RESULTS: This systematic evaluation of STEMI care in 82 hospitals in Quebec included all patients with a discharge diagnosis of myocardial infarction, presenting with characteristic symptoms and an ECG showing STEMI as attested by at least one of two study cardiologists or left bundle branch block (LBBB). Excluding LBBB, an ECG was considered a definite STEMI diagnosis if both cardiologists scored 'certain STEMI' and ambiguous if one scored 'uncertain' or 'not STEMI'. Centers were classified according to accessibility to primary percutaneous coronary intervention (PPCI): 1) on-site PPCI; 2) routine transfer for PPCI; 3) varying mix of PPCI transfer and on-site fibrinolysis; and 4) routine on-site fibrinolysis. Of 3730 STEMI/LBBB patients, 812 (21.8%) did not receive reperfusion therapy. In multivariate analysis, likelihood of no reperfusion therapy was a function of PPCI accessibility (odds ratio [OR] for fibrinolysis versus PPCI centers = 3.1; 95% CI: 2.2-4.4), presence of LBBB (OR = 24.1; 95% CI: 17.8-32.9) and an ECG ambiguous for STEMI (OR = 4.1; 95% CI: 3.3-5.1). When the ECG was ambiguous, likelihood of no reperfusion therapy was highest in hospitals most distant from PPCI centers. CONCLUSIONS: ECG diagnostic ambiguity, LBBB and PPCI accessibility are important predictors of not receiving reperfusion therapy, suggesting opportunities for improving outcomes.