Søren Viereck

The Effects of Public Access Defibrillation on Survival After Out-of-Hospital Cardiac Arrest: A Systematic Review of Observational Studies

Background: Despite recent advances, the average survival after out-of-hospital cardiac arrest (OHCA) remains <10%. Early defibrillation by an automated external defibrillator is the most important intervention for patients with OHCA, showing survival proportions >50%. Accordingly, placement of automated external defibrillators in the community as part of a public access defibrillation program (PAD) is recommended by international guidelines. However, different strategies have been proposed on how exactly to increase and make use of publicly available automated external defibrillators. This systematic review aimed to evaluate the effect of PAD and the different PAD strategies on survival after OHCA. Methods: PubMed, Embase, and the Cochrane Library were systematically searched on August 31, 2015 for observational studies reporting survival to hospital discharge in OHCA patients where an automated external defibrillator had been used by nonemergency medical services. PAD was divided into 3 groups according to who applied the defibrillator: nondispatched lay first responders, professional first responders (firefighters/police) dispatched by the Emergency Medical Dispatch Center (EMDC), or lay first responders dispatched by the EMDC. Results: A total of 41 studies were included; 18 reported PAD by nondispatched lay first responders, 20 reported PAD by EMDC-dispatched professional first responders (firefighters/police), and 3 reported both. We identified no qualified studies reporting survival after PAD by EMDC-dispatched lay first responders. The overall survival to hospital discharge after OHCA treated with PAD showed a median survival of 40.0% (range, 9.1–83.3). Defibrillation by nondispatched lay first responders was associated with the highest survival with a median survival of 53.0% (range, 26.0–72.0), whereas defibrillation by EMDC-dispatched professional first responders (firefighters/police) was associated with a median survival of 28.6% (range, 9.0–76.0). A meta-analysis of the different survival outcomes could not be performed because of the large heterogeneity of the included studies. Conclusions: This systematic review showed a median overall survival of 40% for patients with OHCA treated by PAD. Defibrillation by nondispatched lay first responders was found to correlate with the highest impact on survival in comparison with EMDC-dispatched professional first responders. PAD by EMDC-dispatched lay first responders could be a promising strategy, but evidence is lacking.

Evaluation of pre-hospital transport time of stroke patients to thrombolytic treatment

BackgroundEffective treatment of stroke is time dependent. Pre-hospital management is an important link in reducing the time from occurrence of stroke symptoms to effective treatment. The aim of this study was to evaluate time used by emergency medical services (EMS) for stroke patients during a five-year period in order to identify potential delays and evaluate the reorganization of EMS in Copenhagen in 2009.MethodsWe performed a retrospective analysis of ambulance records from stroke patients suitable for thrombolysis from 1 January 2006 to 7 July 2011. We noted response time from dispatch of the ambulance to arrival at the scene, on-scene time and transport time to the hospital—in total, alarm-to-door time. In addition, we noted baseline characteristics.ResultsWe reviewed 481 records (58% male, median age 66 years). The median (IQR) alarm-to-door time in minutes was 41 (33–52), of which 18 (12–24) minutes were spent on scene. Response time was reduced from the period before to the period after reorganization (7 vs. 5 minutes, p <0.001). In a linear multiple regression model, higher patient age and longer distance to the hospital correlated with significantly longer transportation time (p <0.001).ConclusionsThis study shows an unchanged alarm-to-door time of 41 minutes over a five-year period. Response time, but not total alarm-to-door time, was reduced during the five years. On-scene time constituted nearly half of the total alarm-to-door time and is thus a point of focus for improvement.

Preoperative Risk Factors for Conversion of Laparoscopic Cholecystectomy to Open Surgery - A Systematic Review and Meta-Analysis of Observational Studies.

Background: Preoperative risk factors for the conversion of laparoscopic cholecystectomy to open surgery have been identified, but never been explored systematically. Our objective was to systematically present the evidence of preoperative risk factors for conversion of laparoscopic cholecystectomy to open surgery. Methods: PubMed and Embase were searched systematically in March 2014. Observational studies evaluating preoperative risk factors for conversion of laparoscopic cholecystectomy to open surgery in patients with gallstone disease were included. The outcome variables extracted were patient demographics, medical history, severity of gallstone disease, and preoperative laboratory values. Results: A total of 1,393 studies were screened for eligibility. We found 32 studies, including 460,995 patients operated with laparoscopic cholecystectomy, eligible for the systematic review. Of these, 10 studies were suitable for 7 meta-analyses on age, gender, body mass index, previous abdominal surgery, severity of disease, white blood cell count, and gallbladder wall thickness. Conclusions: A gallbladder wall thicker than 4-5 mm, a contracted gallbladder, age above 60 or 65, male gender, and acute cholecystitis were risk factors for the conversion of laparoscopic cholecystectomy to open surgery. Furthermore, there was no association between diabetes mellitus or white blood cell count and conversion to open surgery.

Recognition of out-of-hospital cardiac arrest during emergency calls — a systematic review of observational studies

BackgroundThe medical dispatcher plays an essential role as part of the first link in the Chain of Survival, by recognising the out-of-hospital cardiac arrest (OHCA) during the emergency call, dispatching the appropriate first responder or emergency medical services response, performing dispatcher assisted cardiopulmonary resuscitation, and referring to the nearest automated external defibrillator. The objective of this systematic review was to evaluate and compare studies reporting recognition of OHCA patients during emergency calls.MethodsThis systematic review was reported in compliance with the PRISMA guidelines. We systematically searched MEDLINE, Embase and the Cochrane Library on 4 November 2015. Observational studies, reporting the proportion of clinically confirmed OHCAs that was recognised during the emergency call, were included. Two authors independently screened abstracts and full-text articles for inclusion. Data were extracted and the risk of bias within studies was assessed using the QUADAS-2 tool for quality assessment of diagnostic accuracy studies.ResultsA total of 3,180 abstracts were screened for eligibility and 53 publications were assessed in full-text. We identified 16 studies including 6,955 patients that fulfilled the criteria for inclusion in the systematic review. The studies reported recognition of OHCA with a median sensitivity of 73.9% (range: 14.1–96.9%). The selection of study population and the definition of “recognised OHCA” (threshold for positive test) varied greatly between the studies, resulting in high risk of bias. Heterogeneity in the studies precluded meta-analysis.ConclusionAmong the 16 included studies, we found a median sensitivity for OHCA recognition of 73.9% (range: 14.1–96.9%). However, great heterogeneity between study populations and in the definition of “recognised OHCA”, lead to insufficient comparability of results. Uniform and transparent reporting is required to ensure comparability and development towards best practice.

Recognition of out-of-hospital cardiac arrest by medical dispatchers in emergency medical dispatch centres in two countries

INTRODUCTION Survival after out-of-hospital cardiac arrest (OHCA) remains low. Early recognition by emergency medical dispatchers is essential for an effective chain of actions, leading to early cardiopulmonary resuscitation, use of an automated external defibrillator and rapid dispatching of the emergency medical services. AIM To analyse and compare the accuracy of OHCA recognition by medical dispatchers in two countries. METHOD An observational register-based study collecting data from national cardiac arrest registers in Denmark and Sweden during a six-month period in 2013. Data were analysed in two steps; registry data were merged with electronically registered emergency call data from the emergency medical dispatch centres in the two regions. Cases with missing or non-OHCA dispatch codes were analysed further by auditing emergency call recordings using a uniform data collection template. RESULTS The sensitivity for recognition of OHCA was 40.9% (95% CI: 37.1-44.7%) in the Capital Region of Denmark and 78.4% (95% CI: 73.2-83.0%) in the Skåne Region in Sweden (p<0.001). With additional data from the emergency call recordings, the sensitivity was 80.7% (95% CI: 77.7-84.3%) and 86.0% (95% CI: 81.3-89.8%) for the two regions (p=0.06). The majority of the non-recognised OHCA were dispatched with the highest priority. CONCLUSION The accuracy of OHCA recognition was high and comparable. We identified large differences in data registration practices despite the use of similar dispatch tools. This raises a discussion of definitions and transparency in general in scientific reporting of OHCA recognition, which is essential if used as quality indicator in emergency medical services.

The difficult medical emergency call: A register-based study of predictors and outcomes

BackgroundPre-hospital emergency care requires proper categorization of emergency calls and assessment of emergency priority levels by the medical dispatchers. We investigated predictors for emergency call categorization as “unclear problem” in contrast to “symptom-specific” categories and the effect of categorization on mortality.MethodsRegister-based study in a 2-year period based on emergency call data from the emergency medical dispatch center in Copenhagen combined with nationwide register data. Logistic regression analysis (N = 78,040 individuals) was used for identification of predictors of emergency call categorization as “unclear problem”. Poisson regression analysis (N = 97,293 calls) was used for examining the effect of categorization as “unclear problem” on mortality.Results“Unclear problem” was the registered category in 18% of calls. Significant predictors for “unclear problem” categorization were: age (odds ratio (OR) 1.34 for age group 76+ versus 18–30 years), ethnicity (OR 1.27 for non-Danish vs. Danish), day of week (OR 0.92 for weekend vs. weekday), and time of day (OR 0.79 for night vs. day). Emergency call categorization had no effect on mortality for emergency priority level A calls, incidence rate ratio (IRR) 0.99 (95% confidence interval (CI) 0.90–1.09). For emergency priority level B calls, an association was observed, IRR 1.26 (95% CI 1.18–1.36).DiscussionsThe results shed light on the complexity of emergency call handling, but also implicate a need for further improvement. Educational interventions at the dispatch centers may improve the call handling, but also the underlying supportive tools are modifiable. The higher mortality rate for patients with emergency priority level B calls with “unclear problem categorization” could imply lowering the threshold for dispatching a high level ambulance response when the call is considered unclear. On the other hand a “benefit of the doubt” approach could hinder the adequate response to other patients in need for an ambulance as there is an increasing demand and limited resources for ambulance services.ConclusionsAge, ethnicity, day of week and time of day were significant predictors of emergency call categorization as “unclear problem”. “Unclear problem” categorization was not associated with mortality for emergency priority level A calls, but a higher mortality was observed for emergency priority level B calls.

The challenges and possibilities of public access defibrillation

Out‐of‐hospital cardiac arrest (OHCA) is a major health problem that affects approximately four hundred and thousand patients annually in the United States alone. It is a major challenge for the emergency medical system as decreased survival rates are directly proportional to the time delay from collapse to defibrillation. Historically, defibrillation has only been performed by physicians and in‐hospital. With the development of automated external defibrillators (AEDs), rapid defibrillation by nonmedical professionals and subsequently by trained or untrained lay bystanders has become possible. Much hope has been put to the concept of Public Access Defibrillation with a massive dissemination of public available AEDs throughout most Western countries. Accordingly, current guidelines recommend that AEDs should be deployed in places with a high likelihood of OHCA. Despite these efforts, AED use is in most settings anecdotal with little effect on overall OHCA survival. The major reasons for low use of public AEDs are that most OHCAs take place outside high incidence sites of cardiac arrest and that most OHCAs take place in residential settings, currently defined as not suitable for Public Access Defibrillation. However, the use of new technology for identification and recruitment of lay bystanders and nearby AEDs to the scene of the cardiac arrest as well as new methods for strategic AED placement redefines and challenges the current concept and definitions of Public Access Defibrillation. Existing evidence of Public Access Defibrillation and knowledge gaps and future directions to improve outcomes for OHCA are discussed. In addition, a new definition of the different levels of Public Access Defibrillation is offered as well as new strategies for increasing AED use in the society.

Effect of bystander CPR initiation prior to the emergency call on ROSC and 30 day survival—An evaluation of 548 emergency calls

BACKGROUND This study aimed at evaluating if time for initiation of bystander cardiopulmonary resuscitation (CPR) - prior to the emergency call (CPRprior) versus during the emergency call following dispatcher-assisted CPR (CPRduring) - was associated with return of spontaneous circulation (ROSC) and 30-day survival. The secondary aim was to identify predictors of CPRprior. METHODS This observational study evaluated out-of-hospital cardiac arrests (OHCA) occurring in the Capital Region of Denmark from 01.01.2013 to 31.12.2013. OHCAs were linked to emergency medical dispatch centre records and corresponding emergency calls were evaluated. Multivariable logistic regression analyses were applied to evaluate the association between time for initiation of bystander CPR, ROSC, and 30-day survival. Univariable logistic regression analyses were applied to identify predictors of CPRprior. RESULTS The study included 548 emergency calls for OHCA patients receiving bystander CPR, 34.9% (n=191) in the CPRprior group and 65.1% (n=357) in the CPRduring group. Multivariable analyses showed no difference in ROSC (OR=0.88, 95% CI: 0.56-1.38) or 30-day survival (OR=1.14, 95% CI: 0.68-1.92) between CPRprior and CPRduring. Predictors positively associated with CPRprior included witnessed OHCA and healthcare professional bystanders. Predictors negatively associated with CPRprior included residential location, solitary bystanders, and bystanders related to the patient. CONCLUSIONS The majority of bystander CPR (65%) was initiated during the emergency call, following dispatcher-assisted CPR instructions. Whether bystander CPR was initiated prior to emergency call versus during the emergency call following dispatcher-assisted CPR was not associated with ROSC or 30-day survival. Dispatcher-assisted CPR was especially beneficial for the initiation of bystander CPR in residential areas.

Danish first aid books compliance with the new evidence-based non-resuscitative first aid guidelines

BackgroundThe European Resuscitation Council (ERC) released new guidelines on resuscitation in 2015. For the first time, the guidelines included a separate chapter on first aid for laypersons. We analysed the current major Danish national first aid books to identify potential inconsistencies between the current books and the new evidence-based first aid guidelines.MethodsWe identified first aid books from all the first aid courses offered by major Danish suppliers. Based on the new ERC first aid guidelines, we developed a checklist of 26 items within 16 different categories to assess the content; this checklist was adapted following the principle of mutually exclusive and collectively exhaustive questioning. To assess the agreement between four raters, Fleiss’ kappa test was used. Items that did not reach an acceptable kappa score were excluded.ResultsWe evaluated 10 first aid books used for first aid courses and published between 2009 and 2015. The content of the books complied with the new in 38% of the answers.In 12 of the 26 items, there was less than 50% consistency. These items include proximal pressure points and elevation of extremities for the control of bleeding, use of cervical collars, treatment for an open chest wound, burn dressing, dental avulsion, passive leg raising, administration of bronchodilators, adrenaline, and aspirin.ConclusionsDanish course material showed significant inconsistencies with the new evidence-based first aid guidelines. The new knowledge from the evidence-based guidelines should be incorporated into revised and updated first aid course material.

Different defibrillation strategies in survivors after out-of-hospital cardiac arrest

Background In the last decade, there has been a rapid increase in the dissemination of automated external defibrillators (AEDs) for prehospital defibrillation of out-of-hospital cardiac arrest patients. The aim of this study was to study the association between different defibrillation strategies on survival rates over time in Copenhagen, Stockholm, Western Sweden and Amsterdam, and the hypothesis was that non-EMS defibrillation increased over time and was associated with increased survival. Methods We performed a retrospective analysis of four prospectively collected cohorts of out-of-hospital cardiac arrest patients between 2008 and 2013. Emergency medical service (EMS)-witnessed arrests were excluded. Results A total of 22 453 out-of-hospital cardiac arrest patients with known survival status were identified, of whom 2957 (13%) survived at least 30 days postresuscitation. Of all survivors with a known defibrillation status, 2289 (81%) were defibrillated, 1349 (59%) were defibrillated by EMS, 454 (20%) were defibrillated by a first responder AED and 429 (19%) were defibrillated by an onsite AED and 57 (2%) were unknown. The percentage of survivors defibrillated by first responder AEDs (from 13% in 2008 to 26% in 2013, p<0.001 for trend) and onsite AEDs (from 14% in 2008 to 30% in 2013, p<0.001 for trend) increased. The increased use of these non-EMS AEDs was associated with the increase in survival rate of patients with a shockable initial rhythm. Conclusion Survivors of out-of-hospital cardiac arrest are increasingly defibrillated by non-EMS AEDs. This increase is primarily due to a large increase in the use of onsite AEDs as well as an increase in first-responder defibrillation over time. Non-EMS defibrillation accounted for at least part of the increase in survival rate of patients with a shockable initial rhythm.