Jacques Lee

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.

Prediction of Heart Failure Mortality in Emergent Care: A Cohort Study

BACKGROUND Heart failure contributes to millions of emergency department (ED) visits, but hospitalization-versus-discharge decisions are often not accompanied by prognostic risk quantification. OBJECTIVE To derive and validate a model for acute heart failure mortality applicable in the ED. DESIGN Clinical data abstraction with development of a broadly applicable multivariate risk index for 7-day death using initial vital signs, clinical and presentation features, and readily available laboratory tests. SETTING Multicenter study of 86 hospitals in Ontario, Canada. PATIENTS Population-based random sample of 12 591 patients presenting to the ED from 2004 to 2007. MEASUREMENTS Death within 7 days of presentation. RESULTS In the derivation cohort (n = 7433; mean age, 75.4 years [SD, 11.4]; 51.5% men), mortality risk increased with higher triage heart rate (adjusted odds ratio [OR], 1.15 [95% CI, 1.03 to 1.30] per 10 beats/min) and creatinine concentration (OR, 1.35 [CI, 1.14 to 1.60] per 1 mg/dL [88.4 µmol/L]), and lower triage systolic blood pressure (OR, 1.52 [CI, 1.31 to 1.77] per 20 mm Hg) and initial oxygen saturation (OR, 1.16 [CI, 1.01 to 1.33] per 5%). Nonnormal serum troponin levels (OR, 2.75 [CI, 1.86 to 4.07]) were associated with increased mortality risk. Areas under the receiver-operating characteristic curves of the multivariate model were 0.805 for the derivation data set (bootstrap-corrected, 0.811) and 0.826 for validation data set (n = 5158; mean age, 75.7 years [SD, 11.4]; 51.6% men). In the derivation cohort, a multivariate index score stratified 7-day mortality with rates of 0.3%, 0.3%, 0.7%, and 1.9% in quintiles 1 to 4, respectively. Mortality rates in the 2 highest risk groups were 3.5% and 8.2% in deciles 9 and 10, respectively. LIMITATION Left ventricular ejection fraction was not included in the model. CONCLUSION A multivariate index comprising routinely collected variables stratified mortality risk with high discrimination in a broad group of patients with acute heart failure presenting to the ED. PRIMARY FUNDING SOURCE Canadian Institutes of Health Research.

Implementation of the Canadian C-Spine Rule: prospective 12 centre cluster randomised trial

Objective To evaluate the effectiveness of an active strategy to implement the validated Canadian C-Spine Rule into multiple emergency departments. Design Matched pair cluster randomised trial. Setting University and community emergency departments in Canada. Participants 11 824 alert and stable adults presenting with blunt trauma to the head or neck at one of 12 hospitals. Interventions Six hospitals were randomly allocated to the intervention and six to the control. At the intervention sites, active strategies were used to implement the Canadian C-Spine Rule, including education, policy, and real time reminders on radiology requisitions. No specific intervention was introduced to alter the behaviour of doctors requesting cervical spine imaging at the control sites. Main outcome measure Diagnostic imaging rate of the cervical spine during two 12 month before and after periods. Results Patients were balanced between control and intervention sites. From the before to the after periods, the intervention group showed a relative reduction in cervical spine imaging of 12.8% (95% confidence interval 9% to 16%; 61.7% v 53.3%; P=0.01) and the control group a relative increase of 12.5% (7% to 18%; 52.8% v 58.9%; P=0.03). These changes were significant when both groups were compared (P<0.001). No fractures were missed and no adverse outcomes occurred. Conclusions Implementation of the Canadian C-Spine Rule led to a significant decrease in imaging without injuries being missed or patient morbidity. Final imaging rates were much lower at intervention sites than at most US hospitals. Widespread implementation of this rule could lead to reduced healthcare costs and more efficient patient flow in busy emergency departments worldwide. Trial registration Clinical trials NCT00290875.

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.

Comparison of the 20-hour intravenous and 72-hour oral acetylcysteine protocols for the treatment of acute acetaminophen poisoning.

STUDY OBJECTIVE To compare outcomes after acute acetaminophen poisoning in 2 large cohorts of patients treated with either the 20-hour intravenous or 72-hour oral acetylcysteine protocol. METHODS We conducted a retrospective cohort study with historical control comparing patients treated with one of 2 acetylcysteine regimens. Data for the 20-hour group were obtained from a medical record review of patients on whom the 20-hour intravenous protocol was initiated in Canadian hospitals from 1980 to 2005. The 72-hour group consisted of a historical cohort of patients treated in US hospitals with the 72-hour oral protocol from 1976 to 1985. The primary outcome was hepatotoxicity (aminotransferase levels >1,000 IU/L). RESULTS Of the 4,048 patients analyzed, 2,086 were in the 20-hour group and 1,962 were in the 72-hour group. The incidence of hepatotoxicity was 13.9% in the 20-hour group and 15.8% in the 72-hour group (-1.9% absolute difference; 95% confidence interval [CI] -4.2 to 0.3). The relative risk of hepatotoxicity was lower in the 20-hour group when acetylcysteine was initiated within 12 hours of ingestion. The relative risk was lower in the 72-hour group when acetylcysteine was initiated later than 18 hours after ingestion. There was no significant risk difference between groups when acetylcysteine treatment was started 12 to 18 hours after ingestion. One patient in the 20-hour group received a liver transplant and died because of acetaminophen toxicity compared with no liver transplants and 3 deaths in the 72-hour group. Anaphylactoid reactions to intravenous acetylcysteine were reported in 148 of 2,086 patients (7.1%; 95% CI 6.1% to 8.3%). This study is limited by comparison of 2 separate data sets from different countries and study years. CONCLUSION The risk of hepatotoxicity differed between the 20-hour and 72-hour protocols according to the time to initiation of acetylcysteine. It favored the 20-hour protocol for patients presenting early and favored the 72-hour protocol for patients presenting late after acute acetaminophen overdose.

The influence of triage systems and triage scores on timeliness of ED analgesic administration

OBJECTIVES The aim of the study was to examine the association between triage scoring systems and triage priority scores on time to initial emergency department (ED) analgesic administration. METHODS An observational, multicenter, prospective, cohort study was conducted at 20 US and Canadian EDs. Centers from the United States used the Emergency Severity Index triage system or 1 of 3 unvalidated triage systems. Canadian centers used the Canadian Triage and Acuity Scale. Patients aged 8 years or older who presented to the ED with a chief complaint of moderate to severe pain (>3 on a 10-point numerical rating scale) and who were ultimately discharged home were eligible for study enrollment. Triage score, triage system, pain rating on arrival, and time of initial analgesic administration were recorded. RESULTS Among 842 enrolled subjects, 506 (60%) received an analgesic while in the ED. Lower-acuity patients consistently waited longer for analgesics. On multivariate modeling, presenting pain intensity, total time spent in the ED, white ethnicity, and triage system were associated with time to initial analgesic administration. Emergency departments using the Canadian Triage and Acuity Scale triage system exhibited the lowest rates of analgesic use and displayed longer median times to initial analgesic administration. CONCLUSIONS Although there were some differences between triage systems, all sites and systems demonstrated unacceptably long times to analgesic provision. Many patients with moderate to severe pain received no analgesic during their ED stay. Future studies should examine whether ED overcrowding impacts timeliness of analgesic administration and identify specific strategies to improve pain management practices in this challenging environment.

Community-associated methicillin-resistant Staphylococcus aureus: prevalence in skin and soft tissue infections at emergency departments in the Greater Toronto Area and associated risk factors.

OBJECTIVE Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), which is caused primarily by the Canadian methicillin-resistant Staphylococcus aureus-10 (CMRSA-10) strain (also known as the USA300 strain) has emerged rapidly in the United States and is now emerging in Canada. We assessed the prevalence, risk factors, microbiological characteristics and outcomes of CA-MRSA in patients with purulent skin and soft tissue infections (SSTIs) presenting to emergency departments (EDs) in the Greater Toronto Area. METHODS Patients with Staphylococcus aureus SSTIs who presented to 7 EDs between Mar. 1 and Jun. 30, 2007, were eligible for inclusion in this study. Antimicrobial susceptibilities and molecular characteristics of MRSA strains were identified. Demographic, risk factor and clinical data were collected through telephone interviews. RESULTS MRSA was isolated from 58 (19%) of 299 eligible patients. CMRSA-10 was identified at 6 of the 7 study sites and accounted for 29 (50%) of all cases of MRSA. Telephone interviews were completed for 161 of the eligible patients. Individuals with CMRSA-10 were younger (median 34 v. 63 yr, p = 0.002), less likely to report recent antibiotic use (22% v. 67%, p = 0.046) or health care-related risk factors (33% v. 72%, p = 0.097) and more likely to report community-related risk factors (56% v. 6%, p = 0.008) than patients with other MRSA strains. CMRSA-10 SSTIs were treated with incision and drainage (1 patient), antibiotic therapy (3 patients) or both (5 patients), and all resolved. CMRSA-10 isolates were susceptible to clindamycin, tetracycline and trimethoprim-sulfamethoxazole. CONCLUSION CA-MRSA is a significant cause of SSTIs in the Greater Toronto Area, and can affect patients without known community-related risk factors. The changing epidemiology of CA-MRSA necessitates further surveillance to inform prevention strategies and empiric treatment guidelines.

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.

Emergency department length of stay for patients requiring mechanical ventilation: a prospective observational study

BackgroundRecommendations for acceptable emergency department (ED) length of stay (LOS) vary internationally with ≤ 8 h generally considered acceptable. Protracted ED LOS may place critically ill patients requiring mechanical ventilation at increased risk of adverse events as most EDs are not resourced for longitudinal delivery of critical care. Our objective was to quantify the ED LOS for mechanically ventilated patients (invasive and/or non-invasive ventilation [NIV]) and to explore patient and system level predictors of prolonged ED LOS. Additionally, we aimed to describe delivery and monitoring of ventilation in the ED.MethodsProspective observational study of ED LOS for all patients receiving mechanical ventilation at four metropolitan EDs in Toronto, Canada over two six-month periods in 2009 and 2010.ResultsWe identified 618 mechanically ventilated patients which represented 0.5% (95% CI 0.4%–0.5%) of all ED visits. Of these, 484 (78.3%) received invasive ventilation, 118 (19.1%) received NIV; 16 received both during the ED stay. Median Kaplan-Meier estimated duration of ED stay for all patients was 6.4 h (IQR 2.8–14.6). Patients with trauma diagnoses had a shorter median (IQR) LOS, 2.5 h (1.3–5.1), compared to ventilated patients with non-trauma diagnoses, 8.5 h (3.3–14.0) (p <0.001). Patients requiring NIV had a longer ED stay (16.6 h, 8.2–27.9) compared to those receiving invasive ventilation exclusively (4.6 h, 2.2–11.1) and patients receiving both (15.4 h, 6.4–32.6) (p <0.001). Longer ED LOS was associated with ED site and lower priority triage scores. Shorter ED LOS was associated with intubation at another ED prior to transfer.ConclusionsWhile patients requiring mechanical ventilation represent a small proportion of overall ED visits these critically ill patients frequently experienced prolonged ED stay especially those treated with NIV, assigned lower priority triage scores at ED presentation, and non-trauma patients.

Predictors of emergency service use in adolescents and adults with autism spectrum disorder living with family

Introduction The use of emergency services among adolescents and adults with autism spectrum disorder (ASD) transitioning into adult health services has not been well described. Objectives To describe emergency service use including emergency departments (EDs), paramedics, and police involvement among adolescents and adults with ASD and to examine predictors of using emergency services. Methods Caregivers of 396 adolescents and adults with ASD were recruited through autism advocacy agencies and support programmes in Ontario to complete a survey about their childs health service use. Surveys were completed online, by mail and over the phone between December 2010 and October 2012. Parents were asked to describe their childs emergency service use and provide information about potential predictive factors including predisposing, enabling and clinical need variables. Results According to parents, 13% of their children with ASD used at least one emergency service in a 2-month period. Sedation or restraints were used 23% of the time. A combination of need and enabling variables predicted emergency service use with previous ED use in the last year (OR 3.4, 95% CI 1.7 to 6.8), a history of hurting others (OR 2.3, 95% 1.2 CI to 4.7) and having no structured daytime activities (OR 3.2, 95% CI 1.4 to 7.0) being the strongest multivariate predictors in the model. Conclusions Patients with ASD and their families are likely to engage with paramedics or police or visit the ED. Further education and support to families and emergency clinicians are needed to improve and, when possible, prevent such occurrences.