Ocular sonography shows good diagnostic test accuracy for detecting raised ICP compared to CT: specifically, high sensitivity for ruling out raised ICP in a low-risk group and high specificity for ruling in raised ICP in a high-risk group. This noninvasive point-of-care method could lead to rapid interventions for raised ICP, assist centers without CT, and monitor patients during transport or as part of a protocol to reduce CT use.

Introduction Dizziness is a common complaint presented in the emergency department (ED). A subset of these patients will present with acute vestibular syndrome (AVS). AVS is a clinical syndrome defined by the presence of vertigo, nystagmus, head motion intolerance, ataxia, and nausea/vomiting. These symptoms are most often due to benign vestibular neuritis; however, they can be a sign of a dangerous central cause, i.e., vertebrobasilar stroke. The Head Impulse test, Nystagmus, Test of Skew (HINTS) examination has been proposed as a bedside test for frontline clinicians to rule out stroke in those presenting with AVS. Our objective was to assess the diagnostic accuracy of the HINTS examination to rule out a central cause of vertigo in an adult population presenting to the ED with AVS. Our aim was to assess the diagnostic accuracy when performed by emergency physicians versus neurologists. Methods We searched PubMed, Medline, Embase, the Cochrane database, and relevant conference abstracts from 2009 to September 2019 and performed hand searches. No restrictions for language or study type were imposed. Prospective studies with patients presenting with AVS using criterion standard of computed tomography and/or magnetic resonance imaging were selected for review. Two independent reviewers extracted data from relevant studies. Studies were combined if low clinical and statistical heterogeneity was present. Study quality was assessed using the QUADAS‐2 tool. Random effects meta‐analysis was performed using RevMan 5 and SAS 9.3. Results A total of five studies with 617 participants met the inclusion criteria. The mean (±SD) study length was 5.3 (±3.3) years. Prevalence of vertebrobasilar stroke ranged 9.3% to 44% (mean ± SD = 39.1% ± 17.1%). The most common diagnoses were vertebrobasilar stroke (mean ± SD = 34.8% ± 17.1%), peripheral cause (mean ± SD = 30.9% ± 16%), and intracerebral hemorrhage (mean ± SD = 2.2% ± 0.5%). The HINTS examination, when performed by neurologists, had a sensitivity of 96.7% (95% CI = 93.1% to 98.5%, I2 = 0%) and specificity of 94.8% (95% CI = 91% to 97.1%, I2 = 0%). When performed by a cohort of physicians including both emergency physicians (board certified) and neurologists (fellowship trained in neurootology or vascular neurology) the sensitivity was 83% (95% CI = 63% to 95%) and specificity was 44% (95% CI = 36% to 51%). Conclusions The HINTS examination, when used in isolation by emergency physicians, has not been shown to be sufficiently accurate to rule out a stroke in those presenting with AVS.

Introduction The HINTS exam is a series of bedside ocular motor tests designed to distinguish between central and peripheral causes of dizziness in patients with continuous dizziness, nystagmus, and gait unsteadiness. Previous studies, where the HINTS exam was performed by trained specialists, have shown excellent diagnostic accuracy. Our objective was to assess the diagnostic accuracy of the HINTS exam as performed by emergency physicians on patients presenting to the emergency department (ED) with a primary complaint of vertigo or dizziness. Methods A retrospective cohort study was performed using data from patients who presented to a tertiary care ED between September 2014 and March 2018 with a primary complaint of vertigo or dizziness. Patient characteristics of those who received the HINTS exam were assessed along with sensitivity and specificity of the test to rule out a central cause of stroke. Results A total of 2,309 patients met criteria for inclusion in the study. Physician uptake of the HINTS exam was high, with 450 (19.5%) dizzy patients receiving all or part of the HINTS. A large majority of patients (96.9%) did not meet criteria for receiving the test as described in validation studies; most often this was because patients lacked documentation of nystagmus or described their symptoms as intermittent. In addition, many patients received both HINTS and Dix‐Hallpike exams, which are intended for use in mutually exclusive patient populations. In no case was dizziness due to a central cause identified using the HINTS exam. Conclusions Our results suggest that despite widespread use of the HINTS exam in our ED, its diagnostic value in that setting was limited. The test was frequently used in patients who did not meet criteria to receive the HINTS exam (i.e., continuous vertigo, nystagmus, and unsteady gait). Additional training of emergency physicians may be required to improve test sensitivity and specificity.

Background Acute aortic syndrome (AAS) is a time‐sensitive and difficult‐to‐diagnose aortic emergency. The American Heart Association (AHA) proposed the acute aortic dissection detection risk score (ADD‐RS) as a means to reduce miss rate and improve time to diagnosis. Previous validation studies were performed in a high prevalence population of patients. We do not know how the rule will perform in a lower‐prevalence population. This is important because application of a rule with low specificity would increase imaging rates and complications. Our goal was to assess if the diagnostic accuracy of the score would be maintained in a low‐prevalence population that we are attempting to risk stratify in the emergency department (ED). Methods Retrospective cohort of patients age 18 years old and older who presented to two tertiary care EDs from January 1, 2015, to December 31, 2015, and underwent a computed tomographic angiography to rule out AAS. Two trained reviewers extracted data using a standardized data collection form. AAS was defined according to accepted radiologic standards. The components of the AHA risk score were defined a priori. Agreement was measured using kappa statistic. Sensitivity, specificity, and positive and negative likelihood ratios with 95% confidence intervals (CIs) were calculated. Analysis was performed using SAS 9.4 University Edition. Results A total 370 patients underwent computed tomography for suspected AAS. Chief presenting symptoms were chest pain (207, 58%), back pain (26, 7%), abdominal pain (32, 8.6%), syncope (7, 2.6%), and symptoms of stroke (6, 1.6%). AAS was finally diagnosed in 12 (3.2%) patients: five (1.4%) type A aortic dissection, four (1%) type B aortic dissection, two (0.5%) an aortic intramural hematoma, no penetrating aortic ulcer, and one a ruptured abdominal aortic aneurysm. The presence of one or more ADD risk markers (ADD‐RS ≥ 1) was associated with a sensitivity of 100% (95% CI = 73.5%–100%) and a specificity of 12.3% (95% CI = 9.1%–16.2%) for the diagnosis of AAS. The negative likelihood ratio was 0 and the positive likelihood ratio was 1.14 (95% CI = 1.1–1.2). Conclusions Our study confirms that in North America the prevalence of AAS in those undergoing advanced imaging is low. The ADD‐RS in this population has a low specificity. A lack of defined inclusion criteria and a low specificity limits the application of this rule in practice.

: Therapeutic, IV.

Objectives A simple bedside test, the Dix-Hallpike test (DHT), can reliably diagnose benign paroxysmal positional vertigo (BPPV) in patients with acute onset dizziness or vertigo. We evaluated patterns of DHT use by emergency physicians in patients presenting with dizziness and vertigo. Our objective was to assess the frequency and clinically appropriate use of the DHT in an emergency department. Methods A health records review was performed using data from patients who presented to a tertiary care emergency department between September 2014 and March 2018 with a primary complaint of vertigo or dizziness. Patient records were reviewed for documentation of symptoms consistent with BPPV and DHT usage. Results A total of 2309 patients met inclusion criteria. Of all dizzy patients who had complete documentation of signs and symptoms consistent with BPPV, 53% were assessed with a DHT. Of 469 patients who received a DHT, 134 (29%) of tests were done on patients who had documentation of at least one characteristic that was inconsistent with a diagnosis of BPPV. Eight patients who received a DHT were ultimately diagnosed with a central cause for their vertigo. Conclusions The DHT is both underutilized and frequently applied to patients whose symptoms are not consistent with BPPV. This may result in prolonged patient discomfort and increased resource utilization, as well as increasing the risk of misdiagnosing central vertigo. Keywords Vertigo • BPPV • Dix-Hallpike RésuméObjectifs Un simple test de chevet, le test de Dix-Hallpike (DHT), peut diagnostiquer de manière fiable le vertige positionnel paroxystique bénin (VPPB) chez les patients présentant des étourdissements ou des vertiges d'apparition aiguë. Nous avons évalué les modèles d'utilisation de la DHT par les médecins d'urgence chez les patients présentant des étourdissements et

cute aortic syndrome (AAS) is a life-threatening emergency, accounting for 1/2000 presentations of acute chest or back pain to the emergency department. 1 It is a clinical spectrum of diagnoses including aortic dissection, intramural hematoma and penetrating atherosclerotic ulcer at any location along the aorta. 1 The incidence of AAS is about 3 per 100 000 persons. 2,3 Many physicians do not consider AAS in their initial differential diagnosis, which is in part why 25% of patients with AAS are not diagnosed with the condition until 24 hours after presenting to the emergency department. 4 Prognosis is most favourable when patients are treated early, while they are clinically stable. Mortality follows a linear increase with diagnostic delay and can be as high as 2% per hour of delay. 5 The misdiagnosis rate during the initial emergency department visit for AAS (i.e., patient admitted for an alternative diagnosis and later diagnosed as AAS; discharged from the emergency department and presenting again with a diagnosis of AAS; or diagnosed on postmortem examination) is estimated to be as high as 38%. 4,6-16 Patients with suspected AAS are typically investigated with electrocardiogram (ECG)-gated contrast-enhanced computed tomography (CT). 2 Current use of this investigation in patients with a clinical suspicion for AAS is inefficient. 17,18 The unnecessary use of CT leads to a direct increase in health care costs but also an increase in contrast-associated complications (e.g., allergic reactions), increased length of emergency department stay or incidental findings requiring further follow-up, additional im aging and increased stress or anxiety for the patient. 17 Use of CT in a low-prevalence population can result in an increase in false-positives, which can lead to further testing, unnecessary transfer and even surgical intervention. 19 There are 2 high-quality guidelines related to the diagnosis of AAS, from the American Heart Association (2010) and the European Society of Cardiology (2014). 20,21 However, there is still considerable variation in how clinicians investigate for AAS in Canada. 17 This variation is likely multifactorial but may be a result of lack of key stakeholder involvement in the development of the guidelines or the difference in threshold for investigation within the Canadian health care system. 22,23 The aims of this guideline are to update the available guideline recommendations with current evidence; include key stakeholders to allow interpretation of the evidence in context of values and preferences; and make practice recommendations that are applicable to the Canadian health care system. The full guideline, including supplemental documents, is available at Appendix 1

Survival following out-of-hospital cardiac arrest (OHCA) remains low, typically less than 10%. Bystander cardiopulmonary resuscitation (CPR) and bystander-AED use have been shown to improve survival by up to fourfold in individual studies. Numerous community-based interventions have been implemented worldwide in an effort to enhance rates of bystander-CPR, bystander-AED use, and improve OHCA survival. This systematic review and meta-analysis aims to evaluate the effect of such interventions on OHCA outcomes. Medline and Embase were systematically searched from inception through July 2021 for studies describing the implementation and effect of one or more community-based interventions targeting OHCA outcomes. Two reviewers screened articles, extracted data, and evaluated study quality using the Newcastle–Ottawa Scale. For each outcome, data were pooled using random-effects meta-analysis. Of the 2481 studies identified, 16 met inclusion criteria. All included studies were observational. They reported a total of 1,081,040 OHCAs across 11 countries. The most common interventions included community-based CPR training (n = 12), community-based AED training (n = 9), and dispatcher-assisted CPR (n = 8). Health system interventions (hospital or paramedical services) were also described in 11 of the included studies. Evidence certainty among all outcomes was low or very low according to GRADE criteria. On meta-analysis, community-based interventions with and without health system interventions were consistently associated with improved OCHA outcomes: rates of bystander-CPR, bystander-AED use, survival, and survival with a favorable neurological outcome. Bystander CPR—14 studies showed a significant increase in post-intervention bystander-CPR rates (n = 285 752; OR 2.26 [1.74, 2.94]; I2 = 99%, and bystander AED use (n = 37 882; OR 2.08 [1.44, 3.01]; I2 = 54%) and durvival—10 studies, pooling survival to hospital discharge and survival to 30 days (n = 79 206; OR 1.59 [1.20, 2.10]; I2 = 95%. The results provide foundational support for the efficacy of community-based interventions in enhancing OHCA outcomes. These findings inform our recommendation that communities, regions, and countries should implement community-based interventions in their pre-hospital strategy for OHCA. Further research is needed to identify which specific intervention types are most effective.