Underlying reasons for sex difference in survival following out-of-hospital cardiac arrest: a mediation analysis.

AIMS: Previous studies have indicated a poorer survival among women following out-of-hospital cardiac arrest (OHCA), but the mechanisms explaining this difference remain largely uncertain.This study aimed to assess the survival after OHCA among women and men and explore the role of potential mediators, such as resuscitation characteristics, prior comorbidity, and socioeconomic factors. METHODS AND RESULTS: This was a population-based cohort study including emergency medical service-treated OHCA reported to the Swedish Registry for Cardiopulmonary Resuscitation in 2010-2020, linked to nationwide Swedish healthcare registries. The relative risks (RR) of 30-day survival were compared among women and men, and a mediation analysis was performed to investigate the importance of potential mediators. Total of 43 226 OHCAs were included, of which 14 249 (33.0%) were women. Women were older and had a lower proportion of shockable initial rhythm. The crude 30-day survival among women was 6.2% compared to 10.7% for men [RR 0.58, 95% confidence interval (CI) = 0.54-0.62]. Stepwise adjustment for shockable initial rhythm attenuated the association to RR 0.85 (95% CI = 0.79-0.91). Further adjustments for age and resuscitation factors attenuated the survival difference to null (RR 0.98; 95% CI = 0.92-1.05). Mediation analysis showed that shockable initial rhythm explained ∼50% of the negative association of female sex on survival. Older age and lower disposable income were the second and third most important variables, respectively. CONCLUSION: Women have a lower crude 30-day survival following OHCA compared to men. The poor prognosis is largely explained by a lower proportion of shockable initial rhythm, older age at presentation, and lower income.

Aetiology and predictors of outcome in non-shockable in-hospital cardiac arrest: A retrospective cohort study from the Swedish Registry for Cardiopulmonary Resuscitation.

BACKGROUND: Non-shockable in-hospital cardiac arrest (IHCA) is a condition with diverse aetiology, predictive factors, and outcome. This study aimed to compare IHCA with initial asystole or pulseless electrical activity (PEA), focusing specifically on their aetiologies and the significance of predictive factors. METHODS: Using the Swedish Registry of Cardiopulmonary Resuscitation, adult non-shockable IHCA cases from 2018 to 2022 (n = 5788) were analysed. Exposure was initial rhythm, while survival to hospital discharge was the primary outcome. A random forest model with 28 variables was used to generate permutation-based variable importance for outcome prediction. RESULTS: Overall, 60% of patients (n = 3486) were male and the median age was 75 years (IQR 67-81). The most frequent arrest location (46%) was on general wards. Comorbidities were present in 79% of cases and the most prevalent comorbidity was heart failure (33%). Initial rhythm was PEA in 47% (n = 2702) of patients, and asystole in 53% (n = 3086). The most frequent aetiologies in both PEA and asystole were cardiac ischemia (24% vs. 19%, absolute difference [AD]: 5.4%; 95% confidence interval [CI] 3.0% to 7.7%), and respiratory failure (14% vs. 13%, no significant difference). Survival was higher in asystole (24%) than in PEA (17%) (AD: 7.3%; 95% CI 5.2% to 9.4%). Cardiopulmonary resuscitation (CPR) durations were longer in PEA, 18 vs 15 min (AD 4.9 min, 95% CI 4.0-5.9 min). The duration of CPR was the single most important predictor of survival across all subgroup and sensitivity analyses. Aetiology ranked as the second most important predictor in most analyses, except in the asystole subgroup where responsiveness at cardiac arrest team arrival took precedence. CONCLUSIONS: In this nationwide registry study of non-shockable IHCA comparing asystole to PEA, cardiac ischemia and respiratory failure were the predominant aetiologies. Duration of CPR was the most important predictor of survival, followed by aetiology. Asystole was associated with higher survival compared to PEA, possibly due to shorter CPR durations and a larger proportion of reversible aetiologies.

Survival in Out-of-Hospital Cardiac Arrest After Standard Cardiopulmonary Resuscitation or Chest Compressions Only Before Arrival of Emergency Medical Services: Nationwide Study During Three Guideline Periods.

BACKGROUND: In out-of-hospital cardiac arrest, chest compression-only cardiopulmonary resuscitation (CO-CPR) has emerged as an alternative to standard CPR (S-CPR), using both chest compressions and rescue breaths. Since 2010, CPR guidelines recommend CO-CPR for both untrained bystanders and trained bystanders unwilling to perform rescue breaths. The aim of this study was to describe changes in the rate and type of CPR performed before the arrival of emergency medical services (EMS) during 3 consecutive guideline periods in correlation to 30-day survival. METHODS: All bystander-witnessed out-of-hospital cardiac arrests reported to the Swedish register for cardiopulmonary resuscitation in 2000 to 2017 were included. Nonwitnessed, EMS-witnessed, and rescue breath-only CPR cases were excluded. Patients were categorized as receivers of no CPR (NO-CPR), S-CPR, or CO-CPR before EMS arrival. Guideline periods 2000 to 2005, 2006 to 2010, and 2011 to 2017 were used for comparisons over time. The primary outcome was 30-day survival. RESULTS: A total of 30 445 patients were included. The proportions of patients receiving CPR before EMS arrival changed from 40.8% in the first time period to 58.8% in the second period, and to 68.2% in the last period. S-CPR changed from 35.4% to 44.8% to 38.1%, and CO-CPR changed from 5.4% to 14.0% to 30.1%, respectively. Thirty-day survival changed from 3.9% to 6.0% to 7.1% in the NO-CPR group, from 9.4% to 12.5% to 16.2% in the S-CPR group, and from 8.0% to 11.5% to 14.3% in the CO-CPR group. For all time periods combined, the adjusted odds ratio for 30-day survival was 2.6 (95% CI, 2.4-2.9) for S-CPR and 2.0 (95% CI, 1.8-2.3) for CO-CPR, in comparison with NO-CPR. S-CPR was superior to CO-CPR (adjusted odds ratio, 1.2; 95% CI, 1.1-1.4). CONCLUSIONS: In this nationwide study of out-of-hospital cardiac arrest during 3 periods of different CPR guidelines, there was an almost a 2-fold higher rate of CPR before EMS arrival and a concomitant 6-fold higher rate of CO-CPR over time. Any type of CPR was associated with doubled survival rates in comparison with NO-CPR. These findings support continuous endorsement of CO-CPR as an option in future CPR guidelines because it is associated with higher CPR rates and overall survival in out-of-hospital cardiac arrest.

Early cardiopulmonary resuscitation in out-of-hospital cardiac arrest.

BACKGROUND: Three million people in Sweden are trained in cardiopulmonary resuscitation (CPR). Whether this training increases the frequency of bystander CPR or the survival rate among persons who have out-of-hospital cardiac arrests has been questioned. METHODS: We analyzed a total of 30,381 out-of-hospital cardiac arrests witnessed in Sweden from January 1, 1990, through December 31, 2011, to determine whether CPR was performed before the arrival of emergency medical services (EMS) and whether early CPR was correlated with survival. RESULTS: CPR was performed before the arrival of EMS in 15,512 cases (51.1%) and was not performed before the arrival of EMS in 14,869 cases (48.9%). The 30-day survival rate was 10.5% when CPR was performed before EMS arrival versus 4.0% when CPR was not performed before EMS arrival (P<0.001). When adjustment was made for a propensity score (which included the variables of age, sex, location of cardiac arrest, cause of cardiac arrest, initial cardiac rhythm, EMS response time, time from collapse to call for EMS, and year of event), CPR before the arrival of EMS was associated with an increased 30-day survival rate (odds ratio, 2.15; 95% confidence interval, 1.88 to 2.45). When the time to defibrillation in patients who were found to be in ventricular fibrillation was included in the propensity score, the results were similar. The positive correlation between early CPR and survival rate remained stable over the course of the study period. An association was also observed between the time from collapse to the start of CPR and the 30-day survival rate. CONCLUSIONS: CPR performed before EMS arrival was associated with a 30-day survival rate after an out-of-hospital cardiac arrest that was more than twice as high as that associated with no CPR before EMS arrival. (Funded by the Laerdal Foundation for Acute Medicine and others.).

Mobile-phone dispatch of laypersons for CPR in out-of-hospital cardiac arrest.

BACKGROUND: Cardiopulmonary resuscitation (CPR) performed by bystanders is associated with increased survival rates among persons with out-of-hospital cardiac arrest. We investigated whether rates of bystander-initiated CPR could be increased with the use of a mobile-phone positioning system that could instantly locate mobile-phone users and dispatch lay volunteers who were trained in CPR to a patient nearby with out-of-hospital cardiac arrest. METHODS: We conducted a blinded, randomized, controlled trial in Stockholm from April 2012 through December 2013. A mobile-phone positioning system that was activated when ambulance, fire, and police services were dispatched was used to locate trained volunteers who were within 500 m of patients with out-of-hospital cardiac arrest; volunteers were then dispatched to the patients (the intervention group) or not dispatched to them (the control group). The primary outcome was bystander-initiated CPR before the arrival of ambulance, fire, and police services. RESULTS: A total of 5989 lay volunteers who were trained in CPR were recruited initially, and overall 9828 were recruited during the study. The mobile-phone positioning system was activated in 667 out-of-hospital cardiac arrests: 46% (306 patients) in the intervention group and 54% (361 patients) in the control group. The rate of bystander-initiated CPR was 62% (188 of 305 patients) in the intervention group and 48% (172 of 360 patients) in the control group (absolute difference for intervention vs. control, 14 percentage points; 95% confidence interval, 6 to 21; P<0.001). CONCLUSIONS: A mobile-phone positioning system to dispatch lay volunteers who were trained in CPR was associated with significantly increased rates of bystander-initiated CPR among persons with out-of-hospital cardiac arrest. (Funded by the Swedish Heart-Lung Foundation and Stockholm County; ClinicalTrials.gov number, NCT01789554.).

Association of postsystolic shortening on stress echocardiography and significant coronary artery stenosis: A single-centre retrospective cohort study.

BACKGROUND: Postsystolic shortening (PSS) is one of the proposed quantitative measures to predict myocardial ischaemia in the stress echocardiographic (SE) evaluation. It is previously known that hypo-/akinesia (HA) correlates well with coronary stenosis. However, some patients undergoing SE only present with PSS, and their risk of significant coronary stenosis is less clear. This study aimed to evaluate the association between PSS and significant coronary stenosis compared with HA. METHODS: This was a retrospective cohort study at the hospital of S:t Görans, Stockholm, Sweden. All patients who underwent SE to investigate inducible ischaemia between 1 January 2018 and 15 October 2021 were eligible for inclusion. Exclusion criteria were normal SE and inconclusive test. Pathological SE were divided into two groups, patients with HA and those with PSS. Outcome was significant coronary artery stenosis visualized by invasive coronary angiography. RESULTS: The final study population consisted of 108 patients (73 PSS, 35 HA). The presence of HA was associated with a higher risk of significant stenosis compared to those with PSS (63% vs. 23%, p < 0.001). This relationship was observed among males (p < 0.001), but not among females (p = 0.133). Nonsignificant stenosis trended to be more common among patients with PSS (21% vs. 6%, p = 0.053) CONCLUSIONS: The finding of PSS without HA was associated with a lower risk of significant coronary stenosis than HA. However, patients with PSS still often had nonsignificant coronary stenosis and PSS in the evaluation for nonobstructive coronary artery disease (CAD) should be further investigated.

Outline and validation of a new dispatcher-assisted cardiopulmonary resuscitation educational bundle using the Delphi method.

Aim: Dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is time-dependent. To date, evidence-based training programmes for dispatchers are lacking. This study aimed to reach expert consensus on an educational bundle content for dispatchers to provide DA-CPR using the Delphi method. Method: An educational bundle was created by the Swedish Resuscitation Council consisting of three parts: e-learning on DA-CPR, basic life support training and audit of emergency out-of-hospital cardiac arrest calls. Thereafter, a two-round modified Delphi study was conducted between November 2022 and March 2023; 37 experts with broad clinical and/or scientific knowledge of DA-CPR were invited. In the first round, the experts participated in the e-learning module and answered a questionnaire with 13 closed and open questions, whereafter the e-learning part of the bundle was revised. In the second round, the revised e-learning part was evaluated using Likert scores (20 items). The predefined consensus level was set at 80%. Results: Delphi rounds one and two were assessed by 20 and 18 of the invited experts, respectively. In round one, 18 experts (18 of 20, 90%) stated that they did not miss any content in the programme. In round two, the scale-level content validity index based on the average method (S-CVI/AVE, 0.99) and scale-level content validity index based on universal agreement (S-CVI/UA, 0.85) exceeded the threshold level of 80%. Conclusion: Expert consensus on the educational bundle content was reached using the Delphi method. Further work is required to evaluate its effect in real-world out-of-hospital cardiac arrest calls.

Compression-Only or Standard Cardiopulmonary Resuscitation for Trained Laypersons in Out-of-Hospital Cardiac Arrest: A Nationwide Randomized Trial in Sweden.

BACKGROUND: The ongoing TANGO2 (Telephone Assisted CPR. AN evaluation of efficacy amonGst cOmpression only and standard CPR) trial is designed to evaluate whether compression-only cardiopulmonary resuscitation (CPR) by trained laypersons is noninferior to standard CPR in adult out-of-hospital cardiac arrest. This pilot study assesses feasibility, safety, and intermediate clinical outcomes as part of the larger TANGO2 survival trial. METHODS: Emergency medical dispatch calls of suspected out-of-hospital cardiac arrest were screened for inclusion at 18 dispatch centers in Sweden between January 1, 2017, and March 12, 2020. Inclusion criteria were witnessed event, bystander on the scene with previous CPR training, age above 18 years of age, and no signs of trauma, pregnancy, or intoxication. Cases were randomized 1:1 at the dispatch center to either instructions to perform compression-only CPR (intervention) or instructions to perform standard CPR (control). Feasibility included evaluation of inclusion, randomization, and adherence to protocol. Safety measures were time to emergency medical service dispatch CPR instructions, and to start of CPR, intermediate clinical outcome was defined as 1-day survival. RESULTS: Of 11 838 calls of suspected out-of-hospital cardiac arrest screened for inclusion, 2168 were randomized and 1250 (57.7%) were out-of-hospital cardiac arrests treated by the emergency medical service. Of these, 640 were assigned to intervention and 610 to control. Crossover from intervention to control occurred in 16.3% and from control to intervention in 18.5%. The median time from emergency call to ambulance dispatch was 1 minute and 36 s (interquartile range, 1.1-2.2) in the intervention group and 1 minute and 30 s (interquartile range, 1.1-2.2) in the control group. Survival to 1 day was 28.6% versus 28.4% (P=0.984) for intervention and control, respectively. CONCLUSIONS: In this national randomized pilot trial, compression-only CPR versus standard CPR by trained laypersons was feasible. No differences in safety measures or short-term survival were found between the 2 strategies. Efforts to reduce crossover are important and may strengthen the ongoing main trial that will assess differences in long-term survival. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02401633.

Effects of a volunteer responder system for out-of-hospital cardiac arrest in areas of different population density - A retrospective cohort study.

BACKGROUND: Volunteer responder dispatch to nearby out-of-hospital cardiac arrests using a smartphone application can increase the proportion of patients receiving cardiopulmonary resuscitation. It is unknown how population density is related to the efficacy of a volunteer responder system. This study aimed to compare the response time of volunteer responders and EMS dispatched to suspected OHCAs in areas of different population density. METHODS: A total of 2630 suspected OHCAs in Stockholm County during 2018-2020 where at least one dispatched volunteer responder reached the patient were identified through the HeartRunner™ application database. Study outcome was the proportion of cases where volunteer responders arrived at the scene before EMS, as well as the difference in time between the arrival of volunteer responders and EMS. RESULTS: Volunteer responders arrived before EMS in 68% of examined cases (n = 1613). Higher population density was associated with a lower proportion of cases where volunteer responders arrived at the scene before EMS. Time on scene before arrival of EMS was highest in areas of low population density and averaged 4:07 (mm:ss). Response time was significantly shorter for volunteer responders compared to EMS across all population density groups at 4:47 vs 8:11 (mm:ss) (p < 0.001); the largest difference in response time was found in low population density areas. CONCLUSION: Volunteer responders have significantly shorter response time than EMS regardless of population density, with the greatest difference in low population density areas. Although their impact on clinical outcome remains unknown, the benefits of dispatching volunteer responders to OHCAs may be greatest in rural areas.

Swedish emergency medical dispatch centres' ability to answer emergency medical calls and dispatch an ambulance in response to out-of-hospital cardiac arrest calls in accordance with the American Heart Association performance goals: An observational study.

AIM: To investigate the ability of Swedish Emergency Medical Dispatch Centres (EMDCs) to answer medical emergency calls and dispatch an ambulance for out-of-hospital cardiac arrest (OHCA) in accordance with the American Heart Association (AHA) performance goals in a 1-step (call connected directly to the EMDC) and a 2-step (call transferred to regional EMDC) procedure over 10 years, and to assess whether delays may be associated with 30-day survival. METHOD: Observational data from the Swedish Registry for Cardiopulmonary Resuscitation and EMDC. RESULTS: A total of 9,174,940 medical calls were answered (1-step). The median answer delay was 7.3 s (interquartile range [IQR], 3.6-14.5 s). Furthermore, 594,008 calls (6.1%) were transferred in a 2-step procedure, with a median answer delay of 39 s (IQR, 30-53 s). A total of 45,367 cases (0.5%, 1-step) were registered as OHCA, with a median answer delay of 7.2 s (IQR, 3.6-14.1 s) (AHA high-performance goal, 10 s). For 1-step procedure, no difference in 30-day survival was found regarding answer delay. For OHCA (1-step), an ambulance was dispatched after a median of 111.9 s (IQR, 81.7-159.9 s). Thirty-day survival was 10.8% (n = 664) when an ambulance was dispatched within 70 s (AHA high-performance) versus 9.3% (n = 2174) > 100 s (AHA acceptable) (p = 0.0013). Outcome data in the 2-step procedure was unobtainable. CONCLUSION: The majority of calls were answered within the AHA performance goals. When an ambulance was dispatched within the AHA high-performance standard in response to OHCA calls, survival was higher compared with calls when dispatch was delayed.

Effect of Smartphone Dispatch of Volunteer Responders on Automated External Defibrillators and Out-of-Hospital Cardiac Arrests: The SAMBA Randomized Clinical Trial.

Importance: Smartphone dispatch of volunteer responders to nearby out-of-hospital cardiac arrests (OHCAs) has emerged in several emergency medical services, but no randomized clinical trials have evaluated the effect on bystander use of automated external defibrillators (AEDs). Objective: To evaluate if bystander AED use could be increased by smartphone-aided dispatch of lay volunteer responders with instructions to collect nearby AEDs compared with instructions to go directly to patients with OHCAs to start cardiopulmonary resuscitation (CPR). Design, Setting, and Participants: This randomized clinical trial assessed a system for smartphone dispatch of volunteer responders to individuals experiencing OHCAs that was triggered at emergency dispatch centers in response to suspected OHCAs and randomized 1:1. The study was conducted in 2 main Swedish regions: Stockholm and Västra Götaland between December 2018 and January 2020. At study start, there were 3123 AEDs in Stockholm and 3195 in Västra Götaland and 24 493 volunteer responders in Stockholm and 19 117 in Västra Götaland. All OHCAs in which the volunteer responder system was activated by dispatchers were included. Excluded were patients with no OHCAs, those with OHCAs not treated by the emergency medical services, and those with OHCAs witnessed by the emergency medical services. Interventions: Volunteer responders were alerted through the volunteer responder system smartphone application and received map-aided instructions to retrieve nearest available public AEDs on their way to the OHCAs. The control arm included volunteer responders who were instructed to go directly to the OHCAs to perform CPR. Main Outcomes and Measures: Overall bystander AED attachment, including those attached by volunteer responders and lay volunteers who did not use the smartphone application. Results: Volunteer responders were activated for 947 patients with OHCAs. Of those, 461 were randomized to the intervention group (median [IQR] age of patients, 73 [61-81] years; 295 male patients [65.3%]) and 486 were randomized to the control group (median [IQR] age of patients, 73 [63-82] years; 312 male patients [65.3%]). Primary outcome of AED attachment occurred in 61 patients (13.2%) in the intervention arm vs 46 patients (9.5%) in the control arm (difference, 3.8% [95% CI, -0.3% to 7.9%]; P = .08). The majority of AEDs were attached by lay volunteers who were not using the smartphone application (37 in intervention arm, 28 in control). There were no significant differences in secondary outcomes. Among the volunteer responders using the application, crossover was 11% and compliance to instructions was 31%. Volunteer responders attached 38% (41 of 107) of all AEDs and provided 45% (16 of 36) of all defibrillations and 43% (293 of 666) of all CPR. Conclusions and Relevance: In this study, smartphone dispatch of volunteer responders to OHCAs to retrieve nearby AEDs vs instructions to directly perform CPR did not significantly increase volunteer AED use. High baseline AED attachement rate and crossover may explain why the difference was not significant. Trial Registration: ClinicalTrials.gov Identifier: NCT02992873.

Adult cardiac arrest in the emergency department - A Swedish cohort study.

BACKGROUND: Cardiac arrests occurring in emergency departments (ED) represent 10-20% of all in-hospital cardiac arrests (IHCA). Yet few studies have examined the characteristics and outcomes of IHCA occurring in the ED. The aim was to describe this population in a nationwide registry covering all EDs in Sweden. METHODS: Patients ≥18 years with an IHCA in the ED reported to the Swedish Registry for Cardio-Pulmonary Resuscitation (SRCR) during 2007-2018 were included. Descriptive statistics were calculated. RESULTS: We identified 2,604 (10 % of all IHCA in SRCR) ED arrests; 902 (35%) survived to hospital discharge and 672 (75%) had good neurological outcomes (Cerebral Performance Category 1-2). The national incidence rate 2016-2018 was 1.6 (range 1.60-1.70) cardiac arrests per 10,000 ED visits. Over 90% were witnessed and 26% had a shockable first rhythm. Three presumed aetiologies together explained half of the cases; myocardial ischaemia (30%, n = 789), primary arrhythmia (12%, n = 327) and respiratory insufficiency (10%, n = 265). At a subset of ED arrest at Karolinska University Hospital, half of the cardiac arrests occurred within one hour from arrival to the ED. CONCLUSION: About 10% of all IHCA occurs in ED, however, from an ED perspective it is a rare event. Cardiac arrests in the ED generally occur within an hour from arrival to the ED. One in three survive to discharge from hospital and the majority of survivors have a good neurological outcome.

Association between type of bystander cardiopulmonary resuscitation and survival in out-of-hospital cardiac arrest: A machine learning study.

Aim: In the event of an out of hospital cardiac arrest (OHCA) it is recommended for a sole untrained bystander to perform compression only CPR (CO-CPR). However, it remains unknown if CO-CPR is inferior to standard CPR (S-CPR), including both compressions and ventilation, in terms of survival. One could speculate that due to the current pandemic, bystanders may be more hesitant performing mouth-to-mouth ventilation. The aim of this study is to assess the association between type of bystander CPR and survival in OHCA. Methods: This study included all patients with a bystander treated OHCA between year 2015-2019 in ages 18-100 using The Swedish Registry for Cardiopulmonary Resuscitation (SRCR). We compared CO-CPR to S-CPR in terms of 30-day survival using a propensity score approach based on machine learning adjusting for a large number of covariates. Results: A total of 13,481 patients were included (5,293 with S-CPR and 8,188 with CO-CPR). The matched subgroup consisted of 2994 cases in each group.Gradient boosting were the best models with regards to predictive accuracy (for type of bystander CPR) and covariate balance. The difference between S-CPR and CO-CPR in all 30 models computed on covariate adjustment and 1-to-1 matching were non-significant. In the 30 weighted models, three comparisons (S-CPR vs. CO-CPR) were significant in terms of improved survival; odds ratio for men was 1.21 (99% confidence interval (CI) 1.02-1.43; Average treatment effect (ATE)); for patients ≥73 years 1.57 (99% CI 1.17-2.12) for Average treatment effect on treated (ATT) and 1.63 (99% CI 1.18-2.25) for ATE. Remaining 27 models showed no differences. No significances remain after adjustment for multiple testing. Conclusion: We found no significant differences between S-CPR and CO-CPR in terms of survival, supporting current recommendations for untrained bystanders regarding CO-CPR.

Dual dispatch early defibrillation in out-of-hospital cardiac arrest: the SALSA-pilot.

AIMS: Out-of-hospital cardiac arrest (OHCA) is a major public health problem. The objective of this study is to explore the effects of a dual dispatch early defibrillation programme. METHODS AND RESULTS: In this pilot study, automated external defibrillators (AEDs) were provided to all 43 fire stations in Stockholm during 2005. Fire-fighters were dispatched in parallel with traditional emergency medical responders (EMS) to all suspected cases of OHCA. Additionally, 65 larger public venues were equipped with AEDs. All 863 OHCA from December 2005 to December 2006 were included during the intervention, whereas all 657 OHCA from 2004 served as historical controls. Among dual dispatches, fire-fighters assisted with cardiopulmonary resuscitation (CPR) in 94% of the cases and arrived first on scene in 36%. The median time from call to arrival of first responder decreased from 7.5 min during the control period to 7.1 min during the intervention (P = 0.004). The proportion of patients in shockable rhythm remained unchanged. The proportion of patients alive 1 month after OHCA rose from 4.4 to 6.8% [adjusted odds ratio (OR): 1.6; 95% confidence interval (CI): 0.9-2.9]. One-month survival in witnessed cases rose from 5.7 to 9.7% (adjusted OR: 2.0; 95% CI: 1.1-3.7). Survival after OHCA in the rest of Sweden (Stockholm excluded) declined from 8.3 to 6.6% during the corresponding time period (unadjusted OR: 0.8; 95% CI: 0.6-1.0). Only three OHCA occurred at public venues equipped with AEDs. CONCLUSION: An introduction of a dual dispatch early defibrillation programme in Stockholm has shortened response times and is likely to have improved survival in patients with OHCA, especially in the group of witnessed cardiac arrests. The increase in survival is believed to be associated with improved CPR and shortened time intervals.

Survival after dispatcher-assisted cardiopulmonary resuscitation in out-of-hospital cardiac arrest.

AIM: Strategies to increase provision of bystander CPR include mass education of laypersons. Additionally, programs directed at emergency dispatchers to provide CPR instructions during emergency calls to untrained bystanders have emerged. The aim of this study was to evaluate the association between dispatcher-assisted CPR (DA- CPR) and 30-day survival compared with no CPR or spontaneously initiated CPR by lay bystanders prior to emergency medical services in out of hospital cardiac arrest (OHCA). METHODS: Nationwide observational cohort study including all consecutive lay bystander witnessed OHCAs reported to the Swedish Register for Cardiopulmonary Resuscitation in 2010-2017. Exposure was categorized as: no CPR (NO-CPR), DA-CPR and spontaneously initiated CPR (SP-CPR) prior to EMS arrival. Propensity-score matched cohorts were used for comparison between groups. Main Outcome was 30-day survival. RESULTS: A total of 15 471 patients were included and distributed as follows: NO-CPR 6440 (41.6%), DA-CPR 4793 (31.0%) and SP-CPR 4238 (27.4%). Survival rates to 30 days were 7.1%, 13.0% and 18.3%, respectively. In propensity-score matched analysis (DA-CPR as reference), NO-CPR was associated with lower survival (conditional OR 0.61, 95% CI 0.52-0.72) and SP-CPR was associated with higher survival (conditional OR 1.21 (95% CI 1.05-1.39). CONCLUSIONS: DA-CPR was associated with a higher survival compared with NO-CPR. However, DA-CPR was associated with a lower survival compared with SP-CPR. These results reinforce the vital role of DA-CPR, although continuous efforts to disseminate CPR training must be considered a top priority if survival after out of hospital cardiac arrest is to continue to increase.

Improved survival after out-of-hospital cardiac arrest is associated with an increase in proportion of emergency crew--witnessed cases and bystander cardiopulmonary resuscitation.

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is a major public health problem. We sought to describe changes in 1-month survival after OHCA in patients given cardiopulmonary resuscitation (CPR) during the last 14 years in Sweden. METHODS AND RESULTS: All patients experiencing OHCA in whom CPR was attempted between 1992 and 2005 and who were reported to the Swedish Cardiac Arrest Register were included in the study. In all, 38,646 patients were included in this survey. The proportion of patients who were admitted alive to a hospital increased from 15.3% in 1992 to 21.7% in 2005 (P for trend <0.0001). The corresponding values for patients being alive after 1 month were 4.8% and 7.3%, respectively (P for trend <0.0001). The increase in 1-month survival was particularly evident among patients found with a shockable rhythm (increase from 12.7% in 1992 to 22.3% in 2005; P for trend <0.0001). The corresponding figures for patients found with a nonshockable rhythm were 1.2% in 1992 and 2.3% in 2005 (P for trend=0.044). Factors that potentially contributed to the improved survival rate were an increase in emergency medical crew-witnessed cases from 9% in 1992 to 15% in 2005 (P for trend <0.0001) and, to a lesser degree, an increase in bystander CPR from 31% in 1992 to 50% in 2005 (P for trend <0.0001). After adjustment for potential risk factors, the increase in survival remained significant. CONCLUSIONS: We found a significant increase in survival after OHCA in Sweden over the last 14 years. The increase was particularly marked among patients found with a shockable rhythm and was associated with an increase in the proportion of crew-witnessed cases and, to a lesser degree, an increase in the performance of bystander CPR.

A smartphone application for dispatch of lay responders to out-of-hospital cardiac arrests.

BACKGROUND: Dispatch of lay volunteers trained in cardiopulmonary resuscitation (CPR) and equipped with automated external defibrillators (AEDs) may improve survival in cases of out-of-hospital cardiac arrest (OHCA). The aim of this study was to investigate the functionality and performance of a smartphone application for locating and alerting nearby trained laymen/women in cases of OHCA. METHODS: A system using a smartphone application activated by Emergency Dispatch Centres was used to locate and alert laymen/women to nearby suspected OHCAs. Lay responders were instructed either to perform CPR or collect a nearby AED. An online survey was carried out among the responders. RESULTS: From February to August 2016, the system was activated in 685 cases of suspected OHCA. Among these, 224 cases were Emergency Medical Services (EMSs)-treated OHCAs (33%). EMS-witnessed cases (n = 11) and cases with missing survey data (n = 15) were excluded. In the remaining 198 OHCAs, lay responders arrived at the scene in 116 cases (58%), and prior to EMSs in 51 cases (26%). An AED was attached in 17 cases (9%) and 4 (2%) were defibrillated. Lay responders performed CPR in 54 cases (27%). Median distance to the OHCA was 560 m (IQR 332-860 m), and 1280 m (IQR 748-1776 m) via AED pick-up. The survey-answering rate was 82%. CONCLUSION: A smartphone application can be used to alert CPR-trained lay volunteers to OHCAs for CPR. Further improvements are needed to shorten the time to defibrillation before EMS arrival.

The survival benefit of dual dispatch of EMS and fire-fighters in out-of-hospital cardiac arrest may differ depending on population density--a prospective cohort study.

BACKGROUND: Outcome after out-of-hospital cardiac arrest (OHCA) varies between contexts. Dual dispatching of fire-fighters or police in addition to emergency medical services (EMS) has the potential to increase survival, but the effect in urban vs. rural areas is unknown. The aim of this study was to determine the effects of dual dispatching on response times and outcome in regions with different population density. METHODS AND RESULTS: The study design was a prospective cohort study of EMS-treated OHCAs from 2004 (historical controls, only EMS dispatch) and 2006-2009 (intervention, dual dispatch of EMS and fire-fighters), with data on exact geographical coordinates. Patients were divided into four subgroups depending on population density: rural (<250 persons/km2), suburban (250-2999/km2), urban (3000-5999/km2) and downtown (≥6000/km2). Totally, 2513 OHCAs were included (historical controls, n=571 and intervention, n=1942). Median time to arrival of first unit shortened significantly in all subgroups, ranging from 0.8 to 3.2 min, with the main time gain in the rural area. There were significant differences in 30-day survival between the historical controls vs. the intervention group in the suburban population (3.1% vs. 7.0%, p=0.02) and in downtown (4.1 vs. 14.6, p=0.04). In the urban population the difference was 2.7 vs. 6.9% (p=0.06) and in the rural population (4.7 vs. 5.3, p=0.82). CONCLUSIONS: Dual dispatch of fire-fighters and EMS in OHCA significantly reduced response times in all studied regions. The 30-day survival increased significantly in the downtown and suburban populations, while a limited impact was seen in the rural areas.

Survival after Public Access Defibrillation in Stockholm, Sweden--A striking success.

BACKGROUND: In Stockholm, a first responder system and a Public Access Defibrillation (PAD) program has been implemented. Additionally, the number of "unregulated" public Automated External Defibrillators (AEDs) sold "over-the-counter" has increased. The aim of this study was to evaluate the impact on survival from different defibrillation strategies in cases of out-of-hospital cardiac arrest (OHCA) available for PAD. DESIGN: Retrospective study of all OHCAs in Stockholm, 2006-2012. Witnessed OHCAs occurring outside home with cardiac origin and ventricular fibrillation were considered subjects for PAD. The sites within the PAD program increased from 60 to 135 while the number of unregulated AEDs outside the PAD program increased from 178 to 5016. Of 6532 OHCAs, 7% (n = 474) were defined as subjects for PAD. Of these, 69% (n = 326) were defibrillated by the EMS, 11% (n = 53) by first responders and 16% (n =7 4) by public AEDs. Survival to one month was 31% (n = 101) for cases defibrillated by the EMS, 42% (n = 22) when defibrillated by first responders and 70% (n = 52) when defibrillated by a public AED. The AEDs within the PAD program constituted 2.6% of all public AEDs and were used in 28% (n = 21) of cases when a public AED was used. CONCLUSIONS: In OHCAs available for PAD, 70% of patients survived if a public AED was used. Both the structured AED program as well as the spread of unregulated AEDs was associated with very high survival rates, but the structured approach was more efficient in relation to the number of AEDs used.