Guidelines for STEMI.
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Angioplasty, Balloon↗
Biomedical subjects
Laurie J Morrison
Publications and source records attributed to Laurie J Morrison.
Out-of-hospital cardiac arrest rectilinear biphasic to monophasic damped sine defibrillation waveforms with advanced life support intervention trial (ORBIT).
BACKGROUND: Although biphasic defibrillation waveforms appear to be superior to monophasic waveforms in terminating VF, their relative benefits in out-of-hospital resuscitation are incompletely understood. Prior comparisons of defibrillation waveform efficacy in out-of-hospital cardiac arrest (OHCA) are confined to patients presenting in a shockable rhythm and resuscitated by first responder (basic life support). This effectiveness study compared monophasic and biphasic defibrillation waveform for conversion of ventricular arrhythmias in all OHCA treated with advance life support (ALS). METHODS AND RESULTS: This prospective randomized controlled trial compared the rectilinear biphasic (RLB) waveform with the monophasic damped sine (MDS) waveform, using step-up energy levels. The study enrolled OHCA patients requiring at least one shock delivered by ALS providers, regardless of initial presenting rhythm. Shock success was defined as conversion at 5s to organized rhythm after one to three escalating shocks. We report efficacy results for the cohort of patients treated by ALS paramedics who presented with an initially shockable rhythm who had not received a shock from a first responder (MDS: n=83; RLB: n=86). Shock success within the first three ascending energy shocks for RLB (120, 150, 200J) was superior to MDS (200, 300, 360J) for patients initially presenting in a shockable rhythm (52% versus 34%, p=0.01). First shock conversion was 23% and12%, for RLB and MDS, respectively (p=0.07). There were no significant differences in return of spontaneous circulation (47% versus 47%), survival to 24h (31% versus 27%), and survival to discharge (9% versus 7%). Mean 24h survival rates of bystander witnessed events showed differences between waveforms in the early circulatory phase at 4-10 min post event (mean (S.D.) RLB 0.45 (0.07) versus MDS 0.31 (0.06), p=0.0002) and demonstrated decline as time to first shock increased to 20 min. CONCLUSION: Shock success to an organized rhythm comparing step-up protocol for energy settings demonstrated the RLB waveform was superior to MDS in ALS treatment of OHCA. Survival rates for both waveforms are consistent with current theories on the circulatory and metabolic phases of out-of-hospital cardiac arrest.
Adult↗
Responses to written notification during out-of-hospital care trials using waiver of informed consent.
BACKGROUND: Resuscitation research has been allowed to proceed using waiver of consent when compliance with guidelines is assured. In these circumstances, institutional review boards (IRBs) may request notification of enrolled patients. OBJECTIVES: To describe the notification process developed with IRB feedback and implemented in two out-of-hospital randomized controlled trials (RCTs) in a large urban setting. METHODS: This was a descriptive review of two RCTs recruiting a total of 620 patients: the Out-of-hospital Cardiac Arrest Rectilinear Biphasic to Monophasic Damped Sine Defibrillation Waveforms with Advanced Life Support Intervention Trial (ORBIT), which compared rectilinear biphasic and monophasic damped sine waveform for out-of-hospital cardiac arrest, and the Prehospital Pacing versus Conventional Treatment Effectiveness Trial (PrePACE), which compared dopamine and transcutaneous pacing for unstable bradycardia. RESULTS: The ORBIT study enrolled 538 patients. In 44 (8%) patients, contact information could not be obtained. Notification was attempted for 494 (92%) patients; 48 (10%) letters were returned to sender. Researchers were contacted by telephone regarding 37 (8%) subjects: 16 (43%) requested information, 14 (38%) responded positively, and one (3%) did not return follow-up calls. Overall, two (0.4%) were withdrawn from the study. The PrePACE study enrolled 82 subjects. Contact information was unavailable for one (1%). For the remaining 81 patients, four (5%) letters were returned to sender. Researchers were contacted regarding ten (13%) subjects: seven (70%) requested information, two (20%) responded positively, and one (10%) did not return follow-up calls. No patient was withdrawn from the study. CONCLUSIONS: Contact information may be difficult to obtain for up to 20% of out-of-hospital critical patients. In 8% to 13% of cases, patients or designates contacted researchers; most feedback was positive. Frequently, non-study-related information was requested, consuming significant resources. Using this method, fewer than 1% of patients were withdrawn from the studies.
Aged↗
Emergency department overcrowding and ambulance transport delays for patients with chest pain.
OBJECTIVE: Emergency department overcrowding sometimes results in diversion of ambulances to other locations. We sought to determine the resulting prehospital delays for cardiac patients. METHODS: Data on consecutive patients with chest pain who were transported to Toronto hospitals by ambulance were obtained for a 4-month period in 1997 and a 4-month period in 1999, which represented periods of low and high emergency department overcrowding respectively. Multivariate analyses were used to model 90th percentile system response (initiation of 9-1-1 call to arrival on scene), on-scene (arrival on scene to departure from scene) and transport (departure from scene to arrival at hospital) intervals. Predictor variables were study period (1997 or 1999), day of the week, time of day, geographic location of the patient, dispatch priority, case severity, return priority and number of other patients with chest pain transported within 2 hours of the index transport. RESULTS: A total of 3609 patients (mean age 66.3 years, 50.3% female) who met the study criteria were transported by ambulance during the 2 study periods. There were no significant differences in patient characteristics between the 2 periods, despite the fact that more patients were transported during the second period (p < 0.001). The 90th percentile system response interval increased by 11.3% from the first to the second period (9.7 v. 10.8 min, p < 0.001), whereas the on-scene interval decreased by 8.2% (28.0 v. 25.7 min, p < 0.001). The longest delay was in the transport interval, which increased by 28.4% from 1997 to 1999 (13.4 v. 17.2 min, p < 0.001). In multivariate analyses, the study period (1997 v. 1999) remained a significant predictor of longer transport interval (p < 0.001) and total prehospital interval (p = 0.004). INTERPRETATION: An increase in overcrowding in emergency departments was associated with a substantial increase in the system response interval and the ambulance transport interval for patients with chest pain.
Adult↗
Emergency department contributors to ambulance diversion: a quantitative analysis.
STUDY OBJECTIVE: We determine the relationship between physician, nursing, and patient factors on emergency department use of ambulance diversion. METHODS: Data were collected at 1 ED in Toronto, Ontario, Canada, on the duration of ambulance diversion during consecutive 8-hour intervals from January to December 1999 (intervals=1,095). By using time series methods, the association between ambulance diversion and nurse hours, physician on duty, and boarded patients was determined. Covariates included patient volume, assessment time, and boarding time. RESULTS: A total of 37,999 patients were treated in the ED over the study period (2% major trauma, 16% ambulance arrivals, and 22% admitted). Nurse hours per interval averaged 60. A mean of 3.2 admitted patients were boarded in the ED each interval. For admitted patients, the time from registration to admission order and from admission order to ED departure averaged 5.2 and 3.5 hours, respectively. There was no ambulance diversion during 170 (15.5%) intervals, whereas 17 (1.5%) intervals were continuously on diversion. In time series analyses, ambulance diversion increased with the number of admitted patients boarded in the ED (6.2 minutes per patient; 95% confidence interval [CI] 2.6 to 9.8 minutes), the number admitted per interval (4.6 minutes per patient; 95% CI 0.1 to 9.1 minutes), assessment time (9.9 minutes per hour; 95% CI 3.3 to 16.5 minutes), and boarding time (11.3 minutes per hour; 95% CI 5.6 to 17.0 minutes). Thirteen of 15 emergency physicians were not associated with ambulance diversion, 1 was associated with reduced use (-36.3 minutes; 95% CI -65.2 to -7.5 minutes), and 1 was associated with increased use (47.6 minutes; 95% CI 4.5 to 90.6 minutes). ED nurse hours were not associated with diversion. Ambulance-delivered patient volume was associated with diversion (5.2 minutes per patient; 95% CI 2.7 to 7.8 minutes), but walk-in patients and patients with major trauma were not. CONCLUSION: Admitted patients in the ED are important determinants of ambulance diversion, whereas nurse hours and most emergency physicians are not. Reducing the volume of walk-in patients is unlikely to lessen the use of diversion.
Ambulances↗
Evaluating paramedic comfort with field pronouncement: development and validation of an outcome measure.
OBJECTIVES: Interventions designed to improve cardiac resuscitation and the quality of field pronouncement need to consider outcomes on paramedic providers. The authors developed and evaluated the reliability and validity of a survey instrument measuring paramedic comfort with field pronouncement. METHODS: A mail survey of 120 paramedics (EMT-Ps) was performed using the Modified Dillman survey methodology. Questions were sorted for analysis into subgroups assessing psychological comfort and technical skills. Sixty-five respondents were retested within two weeks. RESULTS: The overall response rate was 96% (115). Respondents had an average age of 36 years (SD +/- 5), with 5.2 years (SD +/- 3.8) of out-of-hospital experience as an EMT-P, and were involved in a median of ten field pronouncements annually (range = 2-60). The face and content validity of the survey instrument was consistent with a content matrix derived by a focus group. The Cronbach's alpha for the survey instrument was 0.91. The retest response rate was 76% (46). The test-retest reliability coefficient was 0.84. CONCLUSIONS: This survey is a valid and reliable instrument for measuring the paramedic psychological comfort with field pronouncement. The high response rate and intrareliability support its generalizability. This outcome measure may be helpful in evaluating the psychological impact of changes to emergency medical services (EMS) policy with respect to termination of resuscitation promoted by the National Association of EMS Physicians.
Adult↗
Emergency department gridlock and out-of-hospital delays for cardiac patients.
OBJECTIVES: To determine the effect of simultaneous ambulance diversion at multiple emergency departments (EDs) (gridlock) on transport delays for patients with chest pain. METHODS: Retrospective data on consecutive ambulance patients with chest pain and the diversion status of EDs in Toronto were obtained from January 1998 to December 1999. Gridlock was calculated separately for the four city quadrants as the daily duration of episodes where all EDs in the quadrant were simultaneously diverting ambulances. The primary outcome was 90th percentile ambulance transport interval (scene departure to hospital arrival). RESULTS: Eleven thousand four hundred patients were included (mean age 67 years; female 51%; severity of illness: moderate to life-threatening 89%). Gridlock occurred an average of 1.1 hour/day, and 3,060 patients were transported on days when it occurred. Ninetieth percentile transport interval was 15.5 minutes (95% CI = 15.3 to 15.9) for patients not exposed to gridlock vs. 17.4 minutes (95% CI = 16.8 to 17.8) for patients who were exposed to gridlock. In multivariate analyses, gridlock was associated with both transport and total out-of-hospital interval delays (0.2 min/hour, 95% CI = 0.1 to 0.4 and 0.2 min/hour, 95% CI = 0.04 to 0.4, respectively). Delays were similar regardless of patient severity of illness (p = 0.5). Age (0.8 min/10 years, 95% CI = 0.5 to 1), female gender (1.9 min, 95% CI = 1.3 to 2.6), advanced care paramedics (5.3 min, 95% CI = 4.4 to 6.3), and snowfall (0.8 min/cm, 95% CI = 0.2 to 1.5) were also independently associated with delays. CONCLUSIONS: Ambulance diversion was associated with delays in out-of-hospital ambulance transport for chest pain patients, but only when it resulted in gridlock. The magnitude of the out-of-hospital delay was the same regardless of the patient's severity of illness.
Ambulances↗
Subcutaneous glucagon may be better than oral glucose for prehospital treatment of symptomatic hypoglycemia.
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Administration, Oral↗
Defining the outcome measures for out-of-hospital trials in acute pulmonary edema.
OBJECTIVE: Comparing studies of the effectiveness of out-of-hospital interventions in acute pulmonary edema (APE) is difficult due to the diversity of outcome measures used in the literature. The objective of this study was to define a set of clinically relevant outcome measures for future out-of-hospital trials in APE. METHODS: A Medline search and hand-search of bibliographies was undertaken to develop a list of APE outcome measures. A survey was mailed to a sample of 227 Canadian emergency physicians using the Dillman methodology, requesting that respondents select clinically relevant outcome measures from this list and rank them by importance. A selection frequency of >or=70% and a median ranking score were used to determine relevant outcome measures. RESULTS: The Medline and bibliography search identified 21 APE outcome measures. The survey response rate was 71%. Outcome measures selected most frequently were heart rate, respiratory rate, respiratory distress scale, subjective dyspnea scale, out-of-hospital intubation, emergency department (ED) intubation, survival to discharge, and out-of-hospital mortality. The median ranking score identified a similar set of measures: heart rate, respiratory rate, respiratory distress scale, subjective dyspnea scale, out-of-hospital intubation rate, and ED intubation rate. There was no significant difference in outcome selection between physicians who worked in communities with and without advanced out-of-hospital care. CONCLUSIONS: Clinically relevant out-of-hospital APE outcome measures were identified and endorsed by a representative survey of Canadian emergency physicians. Clinicians appear to favor short-term and non-mortality outcomes for out-of-hospital interventions. The use of this set of APE outcome measures may improve the design and comparability of future out-of-hospital trials.
Emergency Medical Services↗
Derivation of a termination-of-resuscitation guideline for emergency medical technicians using automated external defibrillators.
OBJECTIVES: To determine the association between characteristics of cardiac arrest and survival to hospital discharge following failed resuscitation by defibrillation-trained emergency medical technicians (EMT-Ds), and to propose an out-of-hospital termination-of-resuscitation (TOR) guideline for EMT-Ds. METHODS: A 22-month retrospective review of 700 out-of-hospital primary cardiac arrest patients in a large emergency medical services (EMS) system who received exclusively EMT-D care. RESULTS: Seven hundred primary cardiac arrest patients were identified. Follow-up was obtained in 662 cases (94.6%). Of these, 36 (5.4%) achieved a return of spontaneous circulation (ROSC) prior to transport. Among the 626 patients who failed to achieve ROSC at any time, two (0.3%) survived to discharge. Multivariate analysis showed that ROSC at any time had the strongest association with survival [odds ratio (OR) 45.5; 95% confidence interval (95% CI) = 8.5 to 243.7]. A shock prior to transport (OR 6.9; 95% CI = 1.2 to 40.3) and cardiac arrest witnessed by EMS personnel (OR 4.4; 95% CI = 1.0 to 18.5) were also independently associated with survival. These variables were incorporated into a TOR guideline. The guideline was 100% sensitive (95% CI = 99.1 to 100) in identifying survivors and had 100% negative predictive value (95% CI = 75.3 to 100) for identifying nonsurvivors of out-of-hospital cardiac arrest in the study population. CONCLUSIONS: In this EMS system, cardiac arrest patients may be considered for out-of-hospital TOR following EMT-D resuscitation attempts when there has been no ROSC, no shock has been given, and the arrest was not witnessed by EMS personnel. These guidelines require prospective validation.
Advanced Cardiac Life Support↗
Predictive validity of the Global Assessment Form used in a final-year undergraduate rotation in emergency medicine.
OBJECTIVES: To determine whether the predictive validity of Global Assessment Form (GAF) knowledge subdomain marks exceeds that of the overall GAF marks with respect to written examination marks for an undergraduate rotation in emergency medicine, and to determine the interdependence between subdomain marks on the GAF. METHODS: Final-year clinical clerks completing a four-week rotation through the emergency departments of a university teaching center were evaluated using both a ten-subdomain GAF for clinical performance and an independent written examination. The GAF and examination marks were prospectively obtained for clinical clerks over a two-year period. Pearson correlations were calculated between examination marks and both the GAF knowledge subdomain and the GAF overall mark. Olkin's Z score was calculated to determine the significance of the difference between correlations. Interdependencies between subdomains of the GAF were calculated using an alpha coefficient and inter-item correlations. RESULTS: Data sets were reviewed for 347 clinical clerks. Nine sets of data were excluded (incomplete evaluations); 338 sets were analyzed. Means for overall clinical mark and examination mark were 80.11% (SD = 4.375) and 81 (SD = 7.66). Among subdomains, knowledge had the highest correlation with the examination mark (0.19). Overall clinical marks had lower correlation with the examination marks (0.169); the difference was not significant (Olkin's Z = 0.40). The correlation of the examination marks with the average marks of all subdomains excluding knowledge was even lower (0.12). The tenitem alpha for the GAF was 0.92. CONCLUSIONS: Clinical GAF assessments of knowledge, as measured by written examination, do not appear to be any more predictive than overall clinical impression. There is substantial consistency between subdomain scores, suggesting that assessors are not effectively discriminating between them when assigning marks.
Academic Medical Centers↗
Measuring the EMS patient access time interval and the impact of responding to high-rise buildings.
OBJECTIVES: To measure the patient access time interval and characterize its contribution to the total emergency medical services (EMS) response time interval; to compare the patient access time intervals for patients located three or more floors above ground with those less than three floors above or below ground, and specifically in the apartment subgroup; and to identify barriers that significantly impede EMS access to patients in high-rise apartments. METHODS: An observational study of all patients treated by an emergency medical technician paramedics (EMT-P) crew was conducted using a trained independent observer to collect time intervals and identify potential barriers to access. RESULTS: Of 118 observed calls, 25 (21%) originated from patients three or more floors above ground. The overall median and 90th percentile (95% confidence interval) patient access time intervals were 1.61 (1.27, 1.91) and 3.47 (3.08, 4.05) minutes, respectively. The median interval was 2.73 (2.22, 3.03) minutes among calls from patients located three or more stories above ground compared with 1.25 (1.07, 1.55) minutes among those at lower levels. The patient access time interval represented 23.5% of the total EMS response time interval among calls originating less than three floors above or below ground and 32.2% of those located three or more stories above ground. The most frequently encountered barriers to access included security code entry requirements, lack of directional signs, and inability to fit the stretcher into the elevator. CONCLUSIONS: The patient access time interval is significantly long and represents a substantial component of the total EMS response time interval, especially among ambulance calls originating three or more floors above ground. A number of barriers appear to contribute to delayed paramedic access.
Ambulances↗