Search tips
Search criteria

Results 1-25 (45)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
more »
1.  Clinical characteristics associated with adverse events in patients with exacerbation of chronic obstructive pulmonary disease: a prospective cohort study 
To assist physicians with difficult decisions about hospital admission for patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) presenting in the emergency department, we sought to identify clinical characteristics associated with serious adverse events.
We conducted this prospective cohort study in 6 large Canadian academic emergency departments. Patients were assessed for standardized clinical variables and then followed for serious adverse events, defined as death, intubation, admission to a monitored unit or new visit to the emergency department requiring admission.
We enrolled 945 patients, of whom 354 (37.5%) were admitted to hospital. Of 74 (7.8%) patients with a subsequent serious adverse event, 36 (49%) had not been admitted after the initial emergency visit. Multivariable modelling identified 5 variables that were independently associated with adverse events: prior intubation, initial heart rate ≥ 110/minute, being too ill to do a walk test, hemoglobin < 100 g/L and urea ≥ 12 mmol/L. A preliminary risk scale incorporating these and 5 other clinical variables produced risk categories ranging from 2.2% for a score of 0 to 91.4% for a score of 10. Using a risk score of 2 or higher as a threshold for admission would capture all patients with a predicted risk of adverse events of 7.2% or higher, while only slightly increasing admission rates, from 37.5% to 43.2%.
In Canada, many patients with COPD suffer a serious adverse event or death after being discharged home from the emergency department. We identified high-risk characteristics and developed a preliminary risk scale that, once validated, could be used to stratify the likelihood of poor outcomes and to enable rational and safe admission decisions.
PMCID: PMC3971051  PMID: 24549125
2.  Time trends in intracranial bleeding associated with direct oral anticoagulants: a 5-year cohort study 
CMAJ Open  2015;3(4):E432-E437.
Over the past 5 years, dabigatran, rivaroxaban and apixaban were approved for stroke prevention. Phase III studies have shown a lower risk of intracranial bleeding with these direct oral anticoagulants than with warfarin; however, there is a lack of real-life data to validate this. We analyzed time trends in atraumatic intracranial bleeding from 2009 to 2013 among patients prescribed oral anticoagulants and those not prescribed oral anticoagulants.
We used ICD-10-CA (enhanced Canadian version of the 10th revision of the International Statistical Classification of Diseases and Related Health Problems) codes to identify all patients with atraumatic intracranial bleeding who presented to our neurosurgical centre (serving a population of more than 1.2 million). Trained researchers extracted data on anticoagulant medications used in the week before diagnosis of the intracranial bleed. Provincial prescription data for oral anticoagulants were obtained from IMS Brogan CompuScript Market Dynamics. The primary outcome was the time trend in incident intracranial bleeds associated with oral anticoagulation during the period 2009-2013. The secondary outcomes were the time trend in intracranial bleeds not associated with oral anticoagulation and the provincial prescribing patterns for oral anticoagulants during the same period.
A total of 2050 patients presented with atraumatic intracranial bleeds during the study period. Of the 371 (18%) prescribed an anticoagulant in the week before presentation, 335 were prescribed an oral anticoagulant. There was an increasing time trend in intracranial bleeding associated with oral anticoagulants (p = 0.009; 6 additional events per year) and in intracranial bleeding not associated with oral anticoagulation (p = 0.06). During 2013, prescriptions for warfarin decreased to 70% of all oral anticoagulant prescriptions in the province, whereas those for dabigatran and rivaroxaban increased to 17% and 12%, respectively.
We observed increasing time trends in intracranial bleeding, both associated with and not associated with oral anticoagulants, over the study period. Although aggregate provincial data showed increased prescribing of oral anticoagulants, other more likely explanations for our findings include an aging population or increasing frailty.
PMCID: PMC4701652  PMID: 26770966
3.  What is the Role of Chest Compression Depth during Out-of-Hospital Cardiac Arrest Resuscitation? 
Critical Care Medicine  2012;40(4):1192-1198.
The 2010 international guidelines for CPR recently recommended an increase in the minimum compression depth from 38 to 50 mm, although there are limited human data to support this. We sought to study patterns of CPR compression depth and their associations with patient outcomes in out-of-hospital cardiac arrest (OOHCA) cases treated by the 2005 guideline standards.
Methods and Results
We studied emergency medical services treated OOHCA patients from the Resuscitation Outcomes Consortium Epistry - Cardiac Arrest for whom electronic CPR compression depth data were available, from May 2006 to June 2009. We calculated anterior chest wall depression in millimeters and the period of active CPR (chest compression fraction) for each minute of CPR. We controlled for covariates including compression rate and calculated adjusted odds ratios for any return of spontaneous circulation (ROSC), 1-day survival, and hospital discharge.
We included 1,029 adult patients from 7 U.S. and Canadian cities with these characteristics: mean age 68 years; male 62 %; bystander witnessed 40%; bystander CPR 37%; initial rhythms - VF/VT 24%, PEA 16%, asystole 48%, other non-shockable 12%; outcomes - ROSC 26%, 1-day survival 18%, discharge 5%. For all patients, median compression rate was 106 per minute, median compression fraction 0.65, and median compression depth 37.3 mm with 52.8% of cases having depth < 38 mm and 91.6% having depth < 50 mm. We found an inverse association between depth and compression rate (P<0.001). Adjusted odds ratios for all depth measures (mean values, categories, and in range) showed strong trends towards better outcomes with increased depth for all three survival measures.
We found suboptimal compression depth in half of patients by 2005 guideline standards and almost all by 2010 standards, as well as an inverse association between compression depth and rate. We found a strong association between survival outcomes and increased compression depth but no clear evidence to support or refute the 2010 recommendations of > 50 mm. While compression depth is an important component of CPR and should be measured routinely, the most effective depth is currently unknown.
PMCID: PMC3307954  PMID: 22202708
cardiac arrest; cardiopulmonary resuscitation; compression depth; emergency medical services
4.  Early Coronary Angiography and Induced Hypothermia are Associated with Survival and Functional Recovery after Out-of-Hospital Cardiac Arrest 
Resuscitation  2014;85(5):657-663.
The rate and effect of coronary interventions and induced hypothermia after out-of-hospital cardiac arrest (OHCA) are unknown. We measured the association of early (≤24 hours after arrival) coronary angiography, reperfusion, and induced hypothermia with favorable outcome after OHCA.
We performed a secondary analysis of a multicenter clinical trial (NCT00394706) conducted between 2007 and 2009 in 10 North American regions. Subjects were adults (≥ 18 years) hospitalized after OHCA with pulses sustained ≥ 60 minutes. We measured the association of early coronary catheterization, percutaneous coronary intervention, fibrinolysis, and induced hypothermia with survival to hospital discharge with favorable functional status (modified Rankin Score ≤3).
From 16,875 OHCA subjects, 3,981 (23.6%) arrived at 151 hospitals with sustained pulses. 1,317 (33.1%) survived to hospital discharge, with 1,006 (25.3%) favorable outcomes. Rates of early coronary catheterization (19.2%), coronary reperfusion (17.7%) or induced hypothermia (39.3%) varied between hospitals, and were higher in hospitals treating more subjects per year. Odds of survival and favorable outcome increased with hospital volume (per 5 subjects/year OR 1.06; 95%CI: 1.04–1.08 and OR 1.06; 95%CI: 1.04, 1.08, respectively). Survival and favorable outcome were independently associated with early coronary angiography (OR 1.69; 95%CI 1.06–2.70 and OR 1.87; 95%CI 1.15–3.04), coronary reperfusion (OR 1.94; 95%CI 1.34–2.82 and OR 2.14; 95%CI 1.46–3.14), and induced hypothermia (OR 1.36; 95%CI 1.01–1.83 and OR 1.42; 95%CI 1.04–1.94).
Early coronary intervention and induced hypothermia are associated with favorable outcome and are more frequent in hospitals that treat higher numbers of OHCA subjects per year.
PMCID: PMC4117649  PMID: 24412161
5.  Multicentre prospective validation of use of the Canadian C-Spine Rule by triage nurses in the emergency department 
The Canadian C-Spine Rule for imaging of the cervical spine was developed for use by physicians. We believe that nurses in the emergency department could use this rule to clinically clear the cervical spine. We prospectively evaluated the accuracy, reliability and acceptability of the Canadian C-Spine Rule when used by nurses.
We conducted this three-year prospective cohort study in six Canadian emergency departments. The study involved adult trauma patients who were alert and whose condition was stable. We provided two hours of training to 191 triage nurses. The nurses then assessed patients using the Canadian C-Spine Rule, including determination of neck tenderness and range of motion, reapplied immobilization and completed a data form.
Of the 3633 study patients, 42 (1.2%) had clinically important injuries of the cervical spine. The kappa value for interobserver assessments of 498 patients with the Canadian C-Spine Rule was 0.78. We calculated sensitivity of 100.0% (95% confidence interval [CI] 91.0%–100.0%) and specificity of 43.4% (95% CI 42.0%–45.0%) for the Canadian C-Spine Rule as interpreted by the investigators. The nurses classified patients with a sensitivity of 90.2% (95% CI 76.0%–95.0%) and a specificity of 43.9% (95% CI 42.0%–46.0%). Early in the study, nurses failed to identify four cases of injury, despite the presence of clear high-risk factors. None of these patients suffered sequelae, and after retraining there were no further missed cases. We estimated that for 40.7% of patients, the cervical spine could be cleared clinically by nurses. Nurses reported discomfort in applying the Canadian C-Spine Rule in only 4.8% of cases.
Use of the Canadian C-Spine Rule by nurses was accurate, reliable and clinically acceptable. Widespread implementation by nurses throughout Canada and elsewhere would diminish patient discomfort and improve patient flow in overcrowded emergency departments.
PMCID: PMC2917929  PMID: 20457772
6.  Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study 
Objectives To describe the findings in cerebrospinal fluid from patients with acute headache that could distinguish subarachnoid hemorrhage from the effects of a traumatic lumbar puncture.
Design A substudy of a prospective multicenter cohort study.
Setting 12 Canadian academic emergency departments, from November 2000 to December 2009.
Participants Alert patients aged over 15 with an acute non-traumatic headache who underwent lumbar puncture to rule out subarachnoid hemorrhage.
Main outcome measure Aneurysmal subarachnoid hemorrhage requiring intervention or resulting in death.
Results Of the 1739 patients enrolled, 641 (36.9%) had abnormal results on cerebrospinal fluid analysis with >1×106/L red blood cells in the final tube of cerebrospinal fluid and/or xanthochromia in one or more tubes. There were 15 (0.9%) patients with aneurysmal subarachnoid hemorrhage based on abnormal results of a lumbar puncture. The presence of fewer than 2000×106/L red blood cells in addition to no xanthochromia excluded the diagnosis of aneurysmal subarachnoid hemorrhage, with a sensitivity of 100% (95% confidence interval 74.7% to 100%) and specificity of 91.2% (88.6% to 93.3%).
Conclusion No xanthochromia and red blood cell count <2000×106/L reasonably excludes the diagnosis of aneurysmal subarachnoid hemorrhage. Most patients with acute headache who meet this cut off will need no further investigations and aneurysmal subarachnoid hemorrhage can be excluded as a cause of their headache.
PMCID: PMC4353280  PMID: 25694274
7.  Resuscitation Outcomes Consortium (ROC) PRIMED Cardiac Arrest Trial Methods Part 2: Rationale and Methodology for “Analyze Later” Protocol 
Resuscitation  2008;78(2):186-195.
The primary objective of the trial is to compare survival to hospital discharge with Modified Rankin Score (MRS) ≤3 between a strategy that prioritizes a specified period of CPR before rhythm analysis (Analyze Later) versus a strategy of minimal CPR followed by early rhythm analysis (Analyze Early) in patients with out-of-hospital cardiac arrest.
Cluster randomized trial with cluster units defined by geographic region, or monitor/defibrillator machine.
Adults treated by Emergency Medical Service (EMS) providers for non-traumatic out-of-hospital cardiac arrest not witnessed by EMS.
EMS systems participating in the Resuscitation Outcomes Consortium and agreeing to cluster randomization to the Analyze Later versus Analyze Early intervention in a crossover fashion.
Sample Size
Based on a two-sided significance level of 0.05, a maximum of 13,239 evaluable patients will allow statistical power of 0.996 to detect a hypothesized improvement in the probability of survival to discharge with MRS ≤ 3 rate from 5.41% after Analyze Early to 7.45% after Analyze Later (2.04% absolute increase in primary outcome).
If this trial demonstrates a significant improvement in survival with a strategy of Analyze Later, it is estimated that 4,000 premature deaths from cardiac arrest would be averted annually in North America alone.
PMCID: PMC2614111  PMID: 18487004
prehospital; cardiac arrest; CPR; defibrillation
8.  Severe Traumatic Injury 
Annals of surgery  2010;252(1):149-157.
The public health implications of regional variation in incidence and outcome of severe traumatic injury remain to be analyzed. The objective of this study was to determine whether the incidence and outcome associated with severe traumatic injury differs across geographic regions of North America.
A prospective, observational study was conducted of the Resuscitation Outcomes Consortium of all patients in 9 North American sites (6 US and 3 Canadian) sustaining severe traumatic injury from April 1, 2006 to March 31, 2007 followed to hospital discharge. Eligible patients were assessed by organized emergency medical services, and had field-based physiologic criteria including systolic blood pressure ≤90 mm Hg, Glasgow Coma Scale score ≤12, respiratory rate <10 or >29 per minute, advanced airway procedure, or traumatic death in the field. Census data were used to determine rates adjusted for age and sex. The main outcome measures were incidence rate, mortality rate, case fatality rate, and survival to discharge for patients sustaining severe traumatic injury assessed by EMS.
The total catchment population of 20.5 million yielded 7080 cases of severe traumatic injury. Median age was 36 years and 67% were male. The median incidence of EMS-assessed severe traumatic injury per 100,000 population across sites was 37.4 (interquartile range [IQR] = 24.6 – 69.6); survival ranged from 39.8% to 80.8%, with a median of 64.5% (IQR = 55.5–78.4). About 942 cases were pronounced dead at the scene and 5857 patients were transported to hospital; 4477 (63.2%) were discharged alive. The median incidence of severe trauma due to a blunt mechanism, transported to hospital, was 25.8 (IQR = 13.1–44.3); survival ranged from 52.6% to 87.3%, with a median of 78.0% (IQR = 68.4–83.5). The median incidence of severe penetrating trauma, transported to hospital, was 2.6 (IQR = 1.5–10.4); survival ranged from 37.5% to 84.7%, with a median of 67.5% (IQR = 54.1–75.9). All P values for differences across sites for incidence and survival were <0.001.
In this study involving 9 geographic regions in North America, there were significant and important regional differences in severe traumatic injury, incidence, and outcome. These differences were sustained for patients with either isolated blunt or penetrating injury mechanisms.
PMCID: PMC4153828  PMID: 20531005
9.  Acute Isolated Dysarthria Is Associated with a High Risk of Stroke 
Cerebrovascular Diseases Extra  2014;4(2):182-185.
Isolated dysarthria is an uncommon presentation of transient ischemic attack (TIA)/minor stroke and has a broad differential diagnosis. There is little information in the literature about how often this presentation is confirmed to be a TIA/stroke, and therefore there is debate about the risk of subsequent vascular events. Given the uncertain prognosis, it is unclear how to best manage patients presenting to the emergency department (ED) with isolated dysarthria. The objective of this study was to prospectively identify and follow a cohort of patients presenting to EDs with isolated dysarthria in order to explore their natural history and risk of recurrent cerebrovascular events. Specifically, we sought to determine early outcomes of individuals with this nonspecific and atypical presentation in order to appropriately expedite their management.
Patients with isolated dysarthria having presented to 8 Canadian EDs between October 2006 and April 2009 were analyzed as part of a prospective multicenter cohort study of patients with acute neurological symptoms as assessed by emergency physicians. The study inclusion criteria were age ≥18 years, a normal level of consciousness, and a symptom onset <1 week prior to presentation without an established nonvascular etiology. The primary outcome was a subsequent stroke within 90 days of the index visit. The secondary outcomes were the rate of TIA, myocardial infarction, and death. Isolated dysarthria was defined as slurring with imprecise articulation but without evidence of language dysfunction. The overall rate of stroke in this cohort was compared with that predicted by the median ABCD2 score for this group.
Between 2006 and 2009, 1,528 patients were enrolled and had a 90-day follow-up. Of these, 43 patients presented with isolated acute-onset dysarthria (2.8%). Recurrent stroke occurred in 6/43 (14.0%) within 90 days of enrollment. The predicted maximal 90-day stroke rate was 9.8% (based on a median ABCD2 score of 5 for the isolated dysarthria cohort). After adjusting for covariates, isolated dysarthria independently predicted stroke within 90 days (aOR: 3.96; 95% CI: 1.3-11.9; p = 0.014).
The isolated dysarthria cohort carried a recurrent stroke risk comparable to that predicted by the median ABCD2 scores. Although isolated dysarthria is a nonspecific and uncommon clinical presentation of TIA, these findings support the need to view it first and foremost as a vascular presentation until proven otherwise and to manage such patients as if they were at high risk of stroke in accordance with established high-risk TIA guidelines.
PMCID: PMC4176400  PMID: 25298772
Stroke; Transient ischemic attack; Risk stratification; Outcome; Dysarthria
10.  Theory of planned behaviour can help understand processes underlying the use of two emergency medicine diagnostic imaging rules 
Clinical decision rules (CDRs) can be an effective tool for knowledge translation in emergency medicine, but their implementation is often a challenge. This study examined whether the Theory of Planned Behaviour (TPB) could help explain the inconsistent results between the successful Canadian C-Spine Rule (CCR) implementation study and unsuccessful Canadian CT Head Rule (CCHR) implementation study. Both rules are aimed at improving the accuracy and efficiency of emergency department radiography use in clinical contexts that exhibit enormous inefficiency at the present time. The rules were prospectively derived and validated using the same methodology demonstrating high sensitivity and reliability. The rules subsequently underwent parallel implementations at 12 Canadian hospitals, yet only the CCR was observed to significantly reduce radiography ordering rates, while the CCHR failed to have any significant impact at all. The drastically different results are unlikely to be the result of differences in implementation strategies or the decision rules.
Physicians at the 12 participating Canadian hospitals were randomized to CCR or CCHR TPB surveys that were administered during the baseline phases of the implementation studies, before any intervention had taken place. The collected baseline survey data were linked to concurrent baseline physician and patient-specific imaging data, and subsequently analyzed using mixed effects linear and logistic models.
A total of 223 of the 378 eligible physicians randomized to a TPB survey completed their assigned baseline survey (CCR: 122 of 181; CCHR: 101 of 197). Attitudes were significantly associated with intention in both settings (CCR: ß = 0.40; CCHR: ß = 0.30), as were subjective norms (CCR: ß = 0.26; CCHR: ß = 0.73). Intention was significantly associated with actual image ordering for CCR (OR = 1.79), but not CCHR.
The TPB can be used to better understand processes underlying use of CDRs. TPB constructs were significantly associated with intention to perform both imaging behaviours, but intention was only associated with actual behaviour for CCR, suggesting that constructs outside of the TPB framework may need to be considered when seeking to understand use of CDRs.
Electronic supplementary material
The online version of this article (doi:10.1186/s13012-014-0088-x) contains supplementary material, which is available to authorized users.
PMCID: PMC4243777  PMID: 25099167
Clinical decision rules; Canadian C-Spine Rule; Canadian CT-Head Rule; Theory of planned behaviour; Emergency physicians; Implementation study
11.  Risk stratification of adult emergency department syncope patients to predict short-term serious outcomes after discharge (RiSEDS) study 
While Canadian ED physicians discharge most syncope patients with no specific further follow-up, approximately 5% will suffer serious outcomes after ED discharge. The goal of this study is to prospectively identify risk factors and to derive a clinical decision tool to accurately predict those at risk for serious outcomes after ED discharge within 30 days.
We will conduct a prospective cohort study at 6 Canadian EDs to include adults with syncope and exclude patients with loss of consciousness > 5 minutes, mental status changes from baseline, obvious witnessed seizure, or head trauma prior to syncope. Emergency physicians will collect standardized clinical variables including historical features, physical findings, and results of immediately available tests (blood, ECG, and ED cardiac monitoring) prior to ED discharge/hospital admission. A second emergency physician will evaluate approximately 10% of study patients for interobserver agreement calculation of predictor variables. The primary outcome will be a composite serious outcome occurring within 30 days of ED discharge and includes three distinct categories: serious adverse events (death, arrhythmia); identification of serious underlying disease (structural heart disease, aortic dissection, pulmonary embolism, severe pulmonary hypertension, subarachnoid hemorrhage, significant hemorrhage, myocardial infarction); or procedures to treat the cause of syncope. The secondary outcome will be any of the above serious outcomes either suspected or those occurring in the ED. A blinded Adjudication Committee will confirm all serious outcomes. Univariate analysis will be performed to compare the predictor variables in patients with and without primary outcome. Variables with p-values <0.2 and kappa values ≥0.60 will be selected for stepwise logistic regression to identify the risk factors and to develop the clinical decision tool. We will enroll 5,000 patients (with 125 positive for primary outcome) for robust identification of risk factors and clinical decision tool development.
Once successfully developed, this tool will accurately risk-stratify adult syncope patients; however, validation and implementation will still be required. This program of research should lead to standardized care of syncope patients, and improve patient safety.
PMCID: PMC4003802  PMID: 24629180
Syncope; Serious outcomes; Prognosis; Arrhythmia; Emergency department; Management
12.  Resuscitation Outcomes Consortium (ROC) PRIMED Cardiac Arrest Trial Methods, Part 1: Rationale and Methodology for the Impedance Threshold Device (ITD) Protocol 
Resuscitation  2008;78(2):179-185.
The primary aim of this study is to compare survival to hospital discharge with a modified Rankin score (MRS) ≤3 between standard cardiopulmonary resuscitation (CPR) plus an active impedance threshold device (ITD) versus standard CPR plus a sham ITD in patients with out-of-hospital cardiac arrest. Secondary aims are to compare functional status and depression at discharge and at 3 and 6 months post discharge in survivors.
Materials and Methods
Prospective, double-blind, randomized, controlled, clinical trial.
Patients with non-traumatic out-of-hospital cardiac arrest treated by emergency medical services (EMS) providers.
EMS systems participating in the Resuscitation Outcomes Consortium.
Sample Size
Based on a one-sided significance level of 0.025, power = 0.90, a survival with MRS ≤ 3 to discharge rate of 5.33% with standard CPR and sham ITD, and two interim analyses, a maximum of 14,742 evaluable patients are needed to detect a 6.69% survival with MRS ≤ 3 to discharge with standard CPR and active ITD (1.36% absolute survival difference).
If the ITD demonstrates the hypothesized improvement in survival, it is estimated that2,700 deaths from cardiac arrest per year would be averted in North America alone.
PMCID: PMC3797446  PMID: 18487005
Cardiac arrest; sudden death; impedance threshold device; CPR
13.  A Critical Assessment of the Out-of-Hospital Trauma Triage Guidelines for Physiologic Abnormality 
The Journal of trauma  2010;68(2):452-462.
It remains unclear whether the American College of Surgeons Committee on Trauma (ACSCOT) “step 1” field physiologic criteria could be further restricted without substantially sacrificing sensitivity. We assessed whether more restrictive physiologic criteria would improve the specificity of this triage step without missing high-risk patients.
We analyzed an out-of-hospital, consecutive patient, prospective cohort of injured adults ≥15 years collected from December 1, 2005, to February 28, 2007, by 237 emergency medical service agencies transporting to 207 acute care hospitals in 11 sites across the United States and Canada. Patients were included based on ACSCOT field decision scheme physiologic criteria systolic blood pressure ≤90, respiratory rate <10 or >29 breaths/min, Glasgow Coma Scale score ≤12, or field intubation. Seven field physiologic variables and four additional demographic and mechanism variables were included in the analysis. The composite outcome was mortality (field or in-hospital) or hospital length of stay >2 days.
Of 7,127 injured persons, 6,259 had complete outcome information and were included in the analysis. There were 3,631 (58.0%) persons with death or LOS >2 days. Using only physiologic measures, the derived rule included advanced airway intervention, shock index >1.4, Glasgow Coma Scale <11, and pulse oximetry <93%. Rule validation demonstrated sensitivity 72% (95% confidence interval: 70%–74%) and specificity 69% (95% confidence interval: 67%–72%). Inclusion of demographic and mechanism variables did not significantly improve performance measures.
We were unable to omit or further restrict any ACSCOT step 1 physiologic measures in a decision rule practical for field use without missing high-risk trauma patients.
PMCID: PMC3785297  PMID: 20154558
Trauma; Physiologic; Emergency medical services; Out-of-hospital; Triage
14.  The Impact of Increased Chest Compression Fraction on Return of Spontaneous Circulation for Out-of-Hospital Cardiac Arrest Patients not in Ventricular Fibrillation 
Resuscitation  2011;82(12):1501-1507.
Greater chest compression fraction (CCF, or proportion of CPR time spent providing compressions) is associated with better survival for out-of-hospital cardiac arrest OOHCA) patients in ventricular fibrillation (VF). We evaluated the effect of CCF on return of spontaneous circulation (ROSC) in OOHCA patients with non-VF ECG rhythms in the Resuscitation Outcomes Consortium Epistry.
This prospective cohort study included OOHCA patients if: not witnessed by EMS, no automated external defibrillator (AED) shock prior to EMS arrival, received > 1 minute of CPR with CPR process measures available, and initial non-VF rhythm. We reviewed the first minutes of electronic CPR records following defibrillator application, measuring the proportion of compressions/min during the resuscitation.
Demographics of 2,103 adult patients from 10 U.S. and Canadian centers were: mean age 67.8; male 61.2%; public location 10.6%; bystander witnessed 32.9%; bystander CPR 35.4%; median interval from 911 to defibrillator turned on 8min:27sec; initial rhythm asystole 64.0%, PEA 28.0%, other non-shockable 8.0%; median compression rate 110/min; median CCF 71%; ROSC 24.2%; survival to hospital discharge 2.0%. The estimated linear effect on adjusted odds ratio with 95% confidence interval (OR; 95%CI) of ROSC for each 10% increase in CCF was (1.05; 0.99, 1.12). Adjusted (OR; 95%CI) of ROSC for each CCF category were: 0–40% reference group); 41–60% (1.14; 0.72, 1.81); 61–80% (1.42; 0.92, 2.20); and 81–100% (1.48; 0.94, 2.32).
This is the first study to demonstrate that increased CCF among non-VF OOHCA patients is associated with a trend toward increased likelihood of ROSC.
PMCID: PMC3215827  PMID: 21763252
cardiopulmonary resuscitation; heart arrest; resuscitation
15.  Early versus Later Rhythm Analysis in Patients with Out-of-Hospital Cardiac Arrest 
The New England journal of medicine  2011;365(9):787-797.
In a departure from the previous strategy of immediate defibrillation, the 2005 resuscitation guidelines from the American Heart Association–International Liaison Committee on Resuscitation suggested that emergency medical service (EMS) personnel could provide 2 minutes of cardiopulmonary resuscitation (CPR) before the first analysis of cardiac rhythm. We compared the strategy of a brief period of CPR with early analysis of rhythm with the strategy of a longer period of CPR with delayed analysis of rhythm.
We conducted a cluster-randomized trial involving adults with out-of-hospital cardiac arrest at 10 Resuscitation Outcomes Consortium sites in the United States and Canada. Patients in the early-analysis group were assigned to receive 30 to 60 seconds of EMS-administered CPR and those in the later-analysis group were assigned to receive 180 seconds of CPR, before the initial electrocardiographic analysis. The primary outcome was survival to hospital discharge with satisfactory functional status (a modified Rankin scale score of ≤3, on a scale of 0 to 6, with higher scores indicating greater disability).
We included 9933 patients, of whom 5290 were assigned to early analysis of cardiac rhythm and 4643 to later analysis. A total of 273 patients (5.9%) in the later-analysis group and 310 patients (5.9%) in the early-analysis group met the criteria for the primary outcome, with a cluster-adjusted difference of −0.2 percentage points (95% confidence interval, −1.1 to 0.7; P = 0.59). Analyses of the data with adjustment for confounding factors, as well as subgroup analyses, also showed no survival benefit for either study group.
Among patients who had an out-of-hospital cardiac arrest, we found no difference in the outcomes with a brief period, as compared with a longer period, of EMS-administered CPR before the first analysis of cardiac rhythm. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED number, NCT00394706.)
PMCID: PMC3181067  PMID: 21879896
16.  A Trial of an Impedance Threshold Device in Out-of-Hospital Cardiac Arrest 
The New England journal of medicine  2011;365(9):798-806.
The impedance threshold device (ITD) is designed to enhance venous return and cardiac output during cardiopulmonary resuscitation (CPR) by increasing the degree of negative intrathoracic pressure. Previous studies have suggested that the use of an ITD during CPR may improve survival rates after cardiac arrest.
We compared the use of an active ITD with that of a sham ITD in patients with out-of-hospital cardiac arrest who underwent standard CPR at 10 sites in the United States and Canada. Patients, investigators, study coordinators, and all care providers were unaware of the treatment assignments. The primary outcome was survival to hospital discharge with satisfactory function (i.e., a score of ≤3 on the modified Rankin scale, which ranges from 0 to 6, with higher scores indicating greater disability).
Of 8718 patients included in the analysis, 4345 were randomly assigned to treatment with a sham ITD and 4373 to treatment with an active device. A total of 260 patients (6.0%) in the sham-ITD group and 254 patients (5.8%) in the active-ITD group met the primary outcome (risk difference adjusted for sequential monitoring, −0.1 percentage points; 95% confidence interval, −1.1 to 0.8; P = 0.71). There were also no significant differences in the secondary outcomes, including rates of return of spontaneous circulation on arrival at the emergency department, survival to hospital admission, and survival to hospital discharge.
Use of the ITD did not significantly improve survival with satisfactory function among patients with out-of-hospital cardiac arrest receiving standard CPR. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED number, NCT00394706.)
PMCID: PMC3204381  PMID: 21879897
17.  Out-of-hospital Hypertonic Resuscitation After Traumatic Hypovolemic Shock 
Annals of surgery  2011;253(3):431-441.
To determine whether out-of-hospital administration of hypertonic fluids would improve survival after severe injury with hemorrhagic shock.
Hypertonic fluids have potential benefit in the resuscitation of severely injured patients because of rapid restoration of tissue perfusion, with a smaller volume, and modulation of the inflammatory response, to reduce subsequent organ injury.
Multicenter, randomized, blinded clinical trial, May 2006 to August 2008, 114 emergency medical services agencies in North America within the Resuscitation Outcomes Consortium. Inclusion criteria: injured patients, age ≥ 15 years with hypovolemic shock (systolic blood pressure ≤ 70 mm Hg or systolic blood pressure 71–90 mm Hg with heart rate ≥ 108 beats per minute). Initial resuscitation fluid, 250 mL of either 7.5% saline per 6% dextran 70 (hypertonic saline/dextran, HSD), 7.5% saline (hypertonic saline, HS), or 0.9% saline (normal saline, NS) administered by out-of-hospital providers. Primary outcome was 28-day survival. On the recommendation of the data and safety monitoring board, the study was stopped early (23% of proposed sample size) for futility and potential safety concern.
A total of 853 treated patients were enrolled, among whom 62% were with blunt trauma, 38% with penetrating. There was no difference in 28-day survival—HSD: 74.5% (0.1; 95% confidence interval [CI], −7.5 to 7.8); HS: 73.0% (−1.4; 95% CI, −8.7–6.0); and NS: 74.4%, P = 0.91. There was a higher mortality for the postrandomization subgroup of patients who did not receive blood transfusions in the first 24 hours, who received hypertonic fluids compared to NS [28-day mortality—HSD: 10% (5.2; 95% CI, 0.4–10.1); HS: 12.2% (7.4; 95% CI, 2.5–12.2); and NS: 4.8%, P < 0.01].
Among injured patients with hypovolemic shock, initial resuscitation fluid treatment with either HS or HSD compared with NS, did not result in superior 28-day survival. However, interpretation of these findings is limited by the early stopping of the trial.
PMCID: PMC3232054  PMID: 21178763
18.  Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study 
Objective To measure the sensitivity of modern third generation computed tomography in emergency patients being evaluated for possible subarachnoid haemorrhage, especially when carried out within six hours of headache onset.
Design Prospective cohort study.
Setting 11 tertiary care emergency departments across Canada, 2000-9.
Participants Neurologically intact adults with a new acute headache peaking in intensity within one hour of onset in whom a computed tomography was ordered by the treating physician to rule out subarachnoid haemorrhage.
Main outcome measures Subarachnoid haemorrhage was defined by any of subarachnoid blood on computed tomography, xanthochromia in cerebrospinal fluid, or any red blood cells in final tube of cerebrospinal fluid collected with positive results on cerebral angiography.
Results Of the 3132 patients enrolled (mean age 45.1, 2571 (82.1%) with worst headache ever), 240 had subarachnoid haemorrhage (7.7%). The sensitivity of computed tomography overall for subarachnoid haemorrhage was 92.9% (95% confidence interval 89.0% to 95.5%), the specificity was 100% (99.9% to 100%), the negative predictive value was 99.4% (99.1% to 99.6%), and the positive predictive value was 100% (98.3% to 100%). For the 953 patients scanned within six hours of headache onset, all 121 patients with subarachnoid haemorrhage were identified by computed tomography, yielding a sensitivity of 100% (97.0% to 100.0%), specificity of 100% (99.5% to 100%), negative predictive value of 100% (99.5% to 100%), and positive predictive value of 100% (96.9% to 100%).
Conclusion Modern third generation computed tomography is extremely sensitive in identifying subarachnoid haemorrhage when it is carried out within six hours of headache onset and interpreted by a qualified radiologist.
PMCID: PMC3138338  PMID: 21768192
19.  Prospective validation of the ABCD2 score for patients in the emergency department with transient ischemic attack 
The ABCD2 score (Age, Blood pressure, Clinical features, Duration of symptoms and Diabetes) is used to identify patients having a transient ischemic attack who are at high risk for imminent stroke. However, despite its widespread implementation, the ABCD2 score has not yet been prospectively validated. We assessed the accuracy of the ABCD2 score for predicting stroke at 7 (primary outcome) and 90 days.
This prospective cohort study enrolled adults from eight Canadian emergency departments who had received a diagnosis of transient ischemic attack. Physicians completed data forms with the ABCD2 score before disposition. The outcome criterion, stroke, was established by a treating neurologist or by an Adjudication Committee. We calculated the sensitivity and specificity for predicting stroke 7 and 90 days after visiting the emergency department using the original “high-risk” cutpoint of an ABCD2 score of more than 5, and the American Heart Association recommendation of a score of more than 2.
We enrolled 2056 patients (mean age 68.0 yr, 1046 (50.9%) women) who had a rate of stroke of 1.8% at 7 days and 3.2% at 90 days. An ABCD2 score of more than 5 had a sensitivity of 31.6% (95% confidence interval [CI] 19.1–47.5) for stroke at 7 days and 29.2% (95% CI 19.6–41.2) for stroke at 90 days. An ABCD2 score of more than 2 resulted in sensitivity of 94.7% (95% CI 82.7–98.5) for stroke at 7 days with a specificity of 12.5% (95% CI 11.2–14.1). The accuracy of the ABCD2 score as calculated by either the enrolling physician (area under the curve 0.56; 95% CI 0.47–0.65) or the coordinating centre (area under the curve 0.65; 95% CI 0.57–0.73) was poor.
This multicentre prospective study involving patients in emergency departments with transient ischemic attack found the ABCD2 score to be inaccurate, at any cut-point, as a predictor of imminent stroke. Furthermore, the ABCD2 score of more than 2 that is recommended by the American Heart Association is nonspecific.
PMCID: PMC3134721  PMID: 21646462
20.  Increased survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry - Cardiac Arrest 
Resuscitation  2010;81(7):826-830.
Out of hospital cardiac arrest (OHCA) is common and lethal. It has been suggested that OHCA witnessed by EMS providers is a predictor of survival because advanced help is immediately available. We examined EMS witnessed OHCA from the Resuscitation Outcomes Consortium (ROC) to determine the effect of EMS witnessed vs. bystander witnessed and unwitnessed OHCA.
Data were analyzed from a prospective, population-based cohort study in 10 U.S. and Canadian ROC sites. Individuals with non-traumatic OHCA treated 04/01/06 – 03/31/07 by EMS providers with defibrillation or chest compressions were included. Cases were grouped into EMS-witnessed, bystander witnessed, and unwitnessed and further stratified for bystander CPR. Multiple logistic regressions evaluated the odds ratio (OR) for survival to discharge relative to the EMS-witnessed group after adjusting for age, sex, public/private location of collapse, ROC site, and initial ECG rhythm. Of 9,991 OHCA, 1022 (10.2%) of EMS-witnessed, 3,369 (33.7%) bystander witnessed, and 5,600 (56.1%) unwitnessed.
The most common initial rhythm in the EMS-witnessed group was PEA which was higher than in the bystander- and unwitnessed groups (p<0.001). The adjusted OR (95% CI) of survival compared to the EMS-witnessed group was 0.41, (0.36, 0.46) in bystander witnessed with bystander CPR, 0.37, (0.33, 0.43) in bystander witnessed without bystander CPR, 0.17 (0.14, 0.20) in unwitnessed with bystander CPR and 0.21 (0.18, 0.24) in unwitnessed cases without bystander CPR.
Immediate application of prehospital care for OHCA may improve survival. Efforts should be made to educate patients to access 9-1-1 for prodromal symptoms.
PMCID: PMC2893256  PMID: 20403656
Prehospital; CPR; Bystander; Return of spontaneous circulation; ROSC
21.  Effect of real-time feedback during cardiopulmonary resuscitation outside hospital: prospective, cluster-randomised trial 
Objective To investigate whether real-time audio and visual feedback during cardiopulmonary resuscitation outside hospital increases the proportion of subjects who achieved prehospital return of spontaneous circulation.
Design A cluster-randomised trial.
Subjects 1586 people having cardiac arrest outside hospital in whom resuscitation was attempted by emergency medical services (771 procedures without feedback, 815 with feedback).
Setting Emergency medical services from three sites within the Resuscitation Outcomes Consortium in the United States and Canada.
Intervention Real-time audio and visual feedback on cardiopulmonary resuscitation (CPR) provided by the monitor-defibrillator.
Main outcome measure Prehospital return of spontaneous circulation after CPR.
Results Baseline patient and emergency medical service characteristics did not differ between groups. Emergency medical services muted the audible feedback in 14% of cases during the period with feedback. Compared with CPR clusters lacking feedback, clusters assigned to feedback were associated with increased proportion of time in which chest compressions were provided (64% v 66%, cluster-adjusted difference 1.9 (95% CI 0.4 to 3.4)), increased compression depth (38 v 40 mm, adjusted difference 1.6 (0.5 to 2.7)), and decreased proportion of compressions with incomplete release (15% v 10%, adjusted difference −3.4 (−5.2 to −1.5)). However, frequency of prehospital return of spontaneous circulation did not differ according to feedback status (45% v 44%, adjusted difference 0.1% (−4.4% to 4.6%)), nor did the presence of a pulse at hospital arrival (32% v 32%, adjusted difference −0.8 (−4.9 to 3.4)), survival to discharge (12% v 11%, adjusted difference −1.5 (−3.9 to 0.9)), or awake at hospital discharge (10% v 10%, adjusted difference −0.2 (−2.5 to 2.1)).
Conclusions Real-time visual and audible feedback during CPR altered performance to more closely conform with guidelines. However, these changes in CPR performance were not associated with improvements in return of spontaneous circulation or other clinical outcomes.
Trial Registration Clinical Trials NCT00539539
PMCID: PMC3033623  PMID: 21296838
22.  Survival Increases with CPR by Emergency Medical Services Before Defibrillation of Out-of-Hospital Ventricular Fibrillation or Ventricular Tachycardia: Observations from the Resuscitation Outcomes Consortium 
Resuscitation  2009;81(2):155.
Immediate defibrillation is the traditional approach to resuscitation of cardiac arrest due to ventricular fibrillation or tachycardia (VF/VT). Delaying defibrillation to provide chest compressions may improve survival. We examined the effect of the duration of Emergency Medical Services (EMS) cardiopulmonary resuscitation (CPR) prior to first defibrillation on survival in patients with out-of-hospital VF/VT.
Materials and Methods
From a prospective multi-center observational registry of EMS-treated out-of-hospital cardiac arrest, we identified 1,638 EMS-treated cardiac arrests with first recorded rhythm VF/VT or “shockable” and complete data for analysis. Survival to hospital discharge was determined as a function of EMS CPR duration prior to first shock.
Compared to the reference group of first EMS CPR duration ≤ 45 seconds, the odds of survival was greater among patients who received between 46 seconds to 195 seconds of EMS CPR before first shock (46 to 75 seconds odds ratio [OR] 1.15, 95% confidence interval [CI] 0.71-1.87; 76 to 105 seconds, OR 1.37, 95% CI 0.80-2.35; 106 to 135 seconds, OR 1.53, 95% CI 0.96-2.45; 136 to 165 seconds, OR 1.24, 95% CI 0.71-2.15; 166 to 195 seconds, OR 1.47, 95% CI 0.85-2.52). The benefit of EMS CPR before defibrillation was reduced when the duration of CPR exceeded 195 seconds (196 to 225 seconds, OR 0.95, 95% CI 0.47-1.81; 226 to 255 seconds, OR 0.91, 95% CI 0.46-1.79; 256 to 285 seconds, OR 0.46, 95% CI 0.17-1.29; 286 to 315 seconds, OR 1.29, 95% CI 0.59-2.85). An optimal EMS CPR duration was not identified and no duration achieved statistical significance.
In this observational analysis of VF/VT arrest, between 46 and 195 seconds of EMS CPR prior to defibrillation was weakly associated with improved survival compared to ≤ 45 seconds. Randomized trials are needed to confirm the optimal duration of EMS CPR prior to defibrillation and to assess the impact of first CPR duration on all initial rhythms.
PMCID: PMC2814939  PMID: 19969407
Cardiopulmonary resuscitation; heart arrest; defibrillation; registries; survival
23.  Evaluation of the safety of C-spine clearance by paramedics: design and methodology 
Canadian Emergency Medical Services annually transport 1.3 million patients with potential neck injuries to local emergency departments. Less than 1% of those patients have a c-spine fracture and even less (0.5%) have a spinal cord injury. Most injuries occur before the arrival of paramedics, not during transport to the hospital, yet most patients are transported in ambulances immobilized. They stay fully immobilized until a bed is available, or until physician assessment and/or X-rays are complete. The prolonged immobilization is often unnecessary and adds to the burden of already overtaxed emergency medical services systems and crowded emergency departments.
The goal of this study is to evaluate the safety and potential impact of an active strategy that allows paramedics to assess very low-risk trauma patients using a validated clinical decision rule, the Canadian C-Spine Rule, in order to determine the need for immobilization during transport to the emergency department.
This cohort study will be conducted in Ottawa, Canada with one emergency medical service. Paramedics with this service participated in an earlier validation study of the Canadian C-Spine Rule. Three thousand consecutive, alert, stable adult trauma patients with a potential c-spine injury will be enrolled in the study and evaluated using the Canadian C-Spine Rule to determine the need for immobilization. The outcomes that will be assessed include measures of safety (numbers of missed fractures and serious adverse outcomes), measures of clinical impact (proportion of patients transported without immobilization, key time intervals) and performance of the Rule.
Approximately 40% of all very low-risk trauma patients could be transported safely, without c-spine immobilization, if paramedics were empowered to make clinical decisions using the Canadian C-Spine Rule. This safety study is an essential step before allowing all paramedics across Canada to selectively immobilize trauma victims before transport. Once safety and potential impact are established, we intend to implement a multi-centre study to study actual impact.
Trial Registration NCT01188447
PMCID: PMC3040719  PMID: 21284880
24.  Admissions to Canadian hospitals for acute asthma: A prospective, multicentre study 
Asthma exacerbations constitute one of the most common causes of emergency department (ED) attendance in most developed countries. While severe asthma often requires hospitalization, variability in admission practices has been observed.
To describe the factors associated with admission to Canadian hospitals for acute asthma after ED treatment.
Subjects 18 to 55 years of age treated for acute asthma in 20 Canadian EDs prospectively underwent a structured ED interview (n=695) and telephone interview two weeks later.
The median age of the patients was 30 years, and the majority were women (62.8%). The admission rate was 13.1% (95% CI 10.7% to 15.8%). Admitted patients were older, more often receiving oral or inhaled corticosteroids at presentation, and more frequently receiving systemic corticosteroids and magnesium sulphate in the ED. Similar proportions received beta-2 agonists and/or ipratropium bromide within 1 h of arrival. On multivariable analyses, factors associated with admission included age, previous admission in the past two years, more than eight beta-2 agonist puffs in the past 24 h, a Canadian Triage and Acuity Score of 1 to 2, a respiratory rate of greater than 22 breaths/min and an oxygen saturation of less than 95%.
The admission rate for acute asthma from these Canadian EDs was lower than reported in other North American studies. The present study provides insight into practical factors associated with admission for acute asthma and highlights the importance of history and asthma severity markers on ED decision making. Further efforts to standardize ED management and expedite admission decision-making appear warranted.
PMCID: PMC2866213  PMID: 20186368
Admissions; Asthma; Emergency department; Exacerbations; Severity
25.  High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study 
Objective To identify high risk clinical characteristics for subarachnoid haemorrhage in neurologically intact patients with headache.
Design Multicentre prospective cohort study over five years.
Setting Six university affiliated tertiary care teaching hospitals in Canada. Data collected from November 2000 until November 2005.
Participants Neurologically intact adults with a non-traumatic headache peaking within an hour.
Main outcome measures Subarachnoid haemorrhage, as defined by any of subarachnoid haemorrhage on computed tomography of the head, xanthochromia in the cerebrospinal fluid, or red blood cells in the final sample of cerebrospinal fluid with positive results on angiography. Physicians completed data collection forms before investigations.
Results In the 1999 patients enrolled there were 130 cases of subarachnoid haemorrhage. Mean (range) age was 43.4 (16-93), 1207 (60.4%) were women, and 1546 (78.5%) reported that it was the worst headache of their life. Thirteen of the variables collected on history and three on examination were reliable and associated with subarachnoid haemorrhage. We used recursive partitioning with different combinations of these variables to create three clinical decisions rules. All had 100% (95% confidence interval 97.1% to 100.0%) sensitivity with specificities from 28.4% to 38.8%. Use of any one of these rules would have lowered rates of investigation (computed tomography, lumbar puncture, or both) from the current 82.9% to between 63.7% and 73.5%.
Conclusion Clinical characteristics can be predictive for subarachnoid haemorrhage. Practical and sensitive clinical decision rules can be used in patients with a headache peaking within an hour. Further study of these proposed decision rules, including prospective validation, could allow clinicians to be more selective and accurate when investigating patients with headache.
PMCID: PMC2966872  PMID: 21030443

Results 1-25 (45)