Automated external defibrillator electrode size and termination of ventricular fibrillation in out-of-hospital cardiac arrest.

Smaller electrodes allow more options for design of automated external defibrillator (AED) user interfaces. However, previous studies employing monophasic-waveform defibrillators found that smaller electrode sizes have lower defibrillation shock success rates. We hypothesize that, for impedance-compensated, biphasic truncated exponential (BTE) shocks, smaller electrodes increase transthoracic impedance (TTI) but do not adversely affect defibrillation success rates. METHODS AND RESULTS: In this prospective before-and-after clinical study, Amsterdam police and firefighters used AEDs with BTE waveforms: an AED with larger electrodes in 2016-2017 (113 cm2), and an AED with smaller electrodes in 2017-2020 (65 cm2). We analyzed 157 and 178 patient cases with an initial shockable rhythm where the larger and smaller electrodes were used, respectively. A single 200-J shock terminated ventricular fibrillation (VF) in 86% of patients treated with large electrodes and 89% of patients treated with smaller electrodes. Small electrodes had a non-inferior first shock defibrillation success rate compared to large electrodes, with a difference of 3% (95% CI: -3% -9%) with the lower confidence limit remaining above the defined non-inferiority threshold. TTI was significantly higher for the smaller electrodes (median: 100 Ω) compared to the larger electrodes (median: 88 Ω) (p < 0.001). CONCLUSIONS: For AEDs with impedance-compensating BTE waveforms, TTI was higher for smaller electrodes than the large electrode electrodes. Overall defibrillation shock success for AEDs with smaller electrodes was non-inferior to the AEDs with larger electrodes.

To transport or to terminate resuscitation on-site. What factors influence EMS decisions in patients without ROSC? A mixed-methods study.

BACKGROUND: If a patient in out-of-hospital cardiac arrest (OHCA) does not achieve return of spontaneous circulation (ROSC) despite advanced life support, emergency medical services can decide to either transport the patient with ongoing CPR or terminate resuscitation on scene. PURPOSE: To determine differences between patients without ROSC to be transported vs. terminated on scene and explore medical and nonmedical factors that contribute to the decision-making of paramedics on scene. METHODS: Mixed-methods approach combining quantitative and qualitative data. Quantitative data on all-cause OHCA patients without ROSC on scene, between January 1, 2012, and December 31, 2016, in the Amsterdam Resuscitation Study database, were analyzed to find factors associated with decision to transport. Qualitative data was collected by performing 16 semi-structured interviews with paramedics from the study region, transcribed and coded to identify themes regarding OHCA decision-making on the scene. RESULTS: In the quantitative Utstein dataset, of 5870 OHCA patients, 3190 (54%) patients did not achieve ROSC on scene. In a multivariable model, age (OR 0.98), public location (OR 2.70), bystander witnessed (OR 1.65), EMS witnessed (OR 9.03), and first rhythm VF/VT (OR 11.22) or PEA (OR 2.34), were independently associated with transport with ongoing CPR. The proportion of variance explained by the model was only 0.36. With the qualitative method, four main themes were identified: patient-related factors, local circumstances, paramedic-related factors, and the structure of the organization. CONCLUSION: In patients without ROSC on scene, besides known resuscitation characteristics, the decision to transport a patient is largely determined by non-protocollized factors.

Management of first responder programmes for out-of-hospital cardiac arrest during the COVID-19 pandemic in Europe.

AIM: First responder (FR) programmes dispatch professional FRs (police and/or firefighters) or citizen responders to perform cardiopulmonary resuscitation (CPR) and use automated external defibrillators (AED) in out-of-hospital cardiac arrest (OHCA). We aimed to describe management of FR-programmes across Europe in response to the Coronavirus Disease 2019 (COVID-19) pandemic. METHODS: In June 2020, we conducted a cross-sectional survey sent to OHCA registry representatives in 18 European countries with active FR-programmes. The survey was administered by e-mail and included questions regarding management of both citizen responder and FR-programmes. A follow-up question was conducted in October 2020 assessing management during a potential "second wave" of COVID-19. RESULTS: All representatives responded (response rate = 100%). Fourteen regions dispatched citizen responders and 17 regions dispatched professional FRs (9 regions dispatched both). Responses were post-hoc divided into three categories: FR activation continued unchanged, FR activation continued with restrictions, or FR activation temporarily paused. For citizen responders, regions either temporarily paused activation (n = 7, 50.0%) or continued activation with restrictions (n = 7, 50.0%). The most common restriction was to omit rescue breaths and perform compression-only CPR. For professional FRs, nine regions continued activation with restrictions (52.9%) and five regions (29.4%) continued activation unchanged, but with personal protective equipment available for the professional FRs. In three regions (17.6%), activation of professional FRs temporarily paused. CONCLUSION: Most regions changed management of FR-programmes in response to the COVID-19 pandemic. Studies are needed to investigate the consequences of pausing or restricting FR-programmes for bystander CPR and AED use, and how this may impact patient outcome.

Analyzing the heart rhythm during chest compressions: Performance and clinical value of a new AED algorithm.

PURPOSE: Automated external defibrillators (AED) prompt the rescuer to stop chest compressions (CC) for ECG analysis during out-of-hospital cardiac arrest (OHCA). We assessed the diagnostic accuracy and clinical benefit of a new AED algorithm (cprINSIGHT), which analyzes ECG and impedance signals during CC, allowing rhythm analysis with ongoing chest compressions. METHODS: Amsterdam Police and Fire Fighters used a conventional AED in 2016-2017 (control) and an AED with cprINSIGHT in 2018-2019 (intervention). In the intervention AED, cprINSIGHT was activated after the first (conventional) analysis. This algorithm classified the rhythm as "shockable" (S) and "non-shockable" (NS), or "pause needed". Sensitivity for S, specificity for NS with 90% lower confidence limit (LCL), chest compression fractions (CCF) and pre-shock pause were compared between control and intervention cases accounting for multiple observations per patient. RESULTS: Data from 465 control and 425 intervention cases were analyzed. cprINSIGHT reached a decision during CC in 70% of analyses. Sensitivity of the intervention AED was 96%, (LCL 93%) and specificity was 98% (LCL 97%), both not significantly different from control. Intervention cases had a shorter median pre-shock pause compared to control cases (8 s vs 22 s, p < 0.001) and higher median CCF (86% vs 80%, P < 0.001). CONCLUSION: AEDs with cprINSIGHT analyzed the ECG during chest compressions in 70% of analyses with 96% sensitivity and 98% specificity when it made a S or a NS decision. Compared to conventional AEDs, cprINSIGHT leads to a significantly shorter pre-shock pause and a significant increase in CCF.

Time to Return of Spontaneous Circulation and Survival: When to Transport in out-of-Hospital Cardiac Arrest?

BACKGROUND: In out-of-hospital cardiac arrest (OHCA), 10-50% of patients have return of spontaneous circulation (ROSC) before hospital arrival. It is important to investigate the relation between time-to-ROSC and survival to determine the optimal timing of transport to the hospital in patients without ROSC. Methods: We analyzed data of OHCA patients with a presumed cardiac cause (excluding traumatic and other obvious non-cardiac causes) and ROSC before hospital arrival from the Amsterdam Resuscitation Study (ARREST) database. ROSC included those patients whose ROSC was persistent or transient before or during transport, lasting ≥1 min. Of these data, we analyzed the association between the time of emergency medical services (EMS) arrival until ROSC (time-to-ROSC) and 30-day survival. Results: Of 3632 OHCA patients with attempted resuscitation, 810 patients with prehospital ROSC were included. Of these, 332 (41%) survived 30 days. Survivors had a significant shorter time-to-ROSC compared to non-survivors of median 5 min (IQR 2,10) vs. median 12 min (IQR 9,17) (p < 0.001). Of the survivors, 90% achieved ROSC within 15 min compared to 22 min of non-survivors. In a multivariable model adjusted for known system determinants time-to-ROSC per minute was significantly associated with 30-day survival (OR 0.89; 95%CI 0.86-0.91). A ROC curve showed 8 min as the time-to-ROSC with the best test performance (sensitivity of 0.72 and specificity of 0.77). Conclusion: In OHCA patients with prehospital ROSC survival significantly decreases with increasing time-to-ROSC. Of all patients, 90% of survivors had achieved ROSC within the first 15 min of EMS resuscitation. The optimal time for the decision to transport is between 8 and 15 min after EMS arrival.

European first responder systems and differences in return of spontaneous circulation and survival after out-of-hospital cardiac arrest: A study of registry cohorts.

BACKGROUND: In Europe, survival-rates after out-of-hospital cardiac arrest (OHCA) vary widely between regions. Whether a system dispatching First Responders (FRs; main FR-types: firefighters, police officers, citizen-responders) is present or not may be associated with survival-rates. This study aimed to assess the association between having a dispatched FR-system and rates of return of spontaneous circulation (ROSC) and survival across Europe. METHODS: Results of an inventory of dispatched FR-systems for OHCA in Europe were combined with aggregate ROSC and survival data from the EuReCa-TWO study and additionally collected data. Regression analysis (weighted on number of patients included per region) was performed to study the association between having a dispatched FR-system and ROSC and survival-rates to hospital discharge in the total population and in patients with shockable initial rhythm, witnessed OHCA and bystander cardiopulmonary resuscitation (CPR; Utstein comparator group). For regions without a dispatched FR-system, the theoretical survival-rate if a dispatched FR-system would have existed was estimated. FINDINGS: We included 27 European regions. There were 15,859 OHCAs in the total group and 2,326 OHCAs in the Utstein comparator group. Aggregate ROSC and survival-rates were significantly higher in regions with an FR-system compared to regions without (ROSC: 36% [95%CI 35%-37%] vs. 24% [95%CI 23%-25%]; P<0.001; survival in total population [N=15.859]: 13% [95%CI 12%-15%] vs. 5% [95%CI 4%-6%]; P<0.001; survival in Utstein comparator group [N=2326]: 33% [95%CI 30%-36%] vs. 18% [95%CI 16%-20%]; P<0.001), and in regions with more than one FR-type compared to regions with only one FR-type. All main FR-types were associated with higher survival-rates (all P<0.050). INTERPRETATION: European regions with dispatched FRs showed higher ROSC and survival-rates than regions without. FUNDING: This project/work has received funding from the European Union's Horizon 2020 research and innovation programme under acronym ESCAPE-NET, registered under grant agreement No 733381 (IO, HLT and MTB) and the European Union's COST programme under acronym PARQ, registered under grant agreement No CA19137 (IO, DC, HLT, MTB). HLT and MTB were supported by a grant from the Netherlands CardioVascular Research Initiative, Dutch Heart Foundation, Dutch Federation of University Medical Centres, Netherlands Organization for Health Research and Development, Royal Netherlands Academy of Sciences - CVON2017-15 RESCUED (HLT), and CVON2018-30 Predict2 (HLT and MTB).

Occurrence of shockable rhythm in out-of-hospital cardiac arrest over time: A report from the COSTA group.

BACKGROUND: Prior research suggests that the proportion of a shockable initial rhythm in out-of-hospital cardiac arrest (OHCA) declined during the last decades. This study aims to investigate if this decline is still ongoing and explore the relationship between location of OHCA and proportion of a shockable initial rhythm as initial rhythm. METHODS: We calculated the proportion of patients with a shockable initial rhythm between 2006-2015 using pooled data from the COSTA-group (Copenhagen, Oslo, Stockholm, Amsterdam). Analyses were stratified according to location of OHCA (residential vs. public). RESULTS: A total of 19,054 OHCA cases were included. Overall, the total proportion of cases with a shockable initial rhythm decreased from 42% to 37% (P < 0.01) from 2006 to 2015. When stratified according to location, the proportion of cases with a shockable initial rhythm decreased for OHCAs at a residential location (34% to 27%; P = 0.03), while the proportion of a shockable initial rhythm was stable among OHCAs in public locations (59%-57%; P = 0.2). During the last years of the study period (2011-2015), the overall proportion of a shockable initial rhythm remained stable (38%-37%; P = 0.45); this was observed for both residential and public OHCA. CONCLUSION: We found a decline in the proportion of patients with a shockable initial rhythm in OHCAs at a residential location; this decline levelled off during the second half of the study period (2011-2015). In public locations, we observed no decline in shockable initial rhythm over time.

Transfer of essential AED information to treating hospital (TREAT).

BACKGROUND: Defibrillation in out-of-hospital cardiac arrest (OHCA) is increasingly performed by using an Automated External Defibrillator (AED). Therefore presence of a shockable rhythm is recurrently only documented by the AED. However, AED-information is rarely available to the treating physician. PURPOSE: To determine (1) how often a shockable rhythm was recorded only in the AED; (2) if so, how often information that a shockable rhythm had been present reached the physician. METHODS: Data on OHCA patients with (presumed) cardiac cause with an AED connected in the years 2012-2014 (Study period 1) and 2016 (Study period 2) in the Amsterdam Resuscitation Study (ARREST) database were collected. We determined how often only the AED had defibrillated. In these patients, we retrospectively analyzed EMS run sheets and hospital discharge letters to determine if a shockable rhythm and/or AED use was correctly noted. In Study period 2, we prospectively contacted the physicians to study whether AED defibrillation was known. RESULTS: In Study period 1, of 2840 OHCA CPR attempts with (presumed) cardiac cause, 1521 (54%) patients had a shockable rhythm, with 356 patients (13%) receiving AED defibrillation only. Of these patients, 11 hospital discharge letters (4%) contained no information about a shockable rhythm. In Study period 2, 125/1128 patients (11%) received AED defibrillation only; of these, in two cases the shockable rhythm was unknown by the physician. CONCLUSION: In 11-13% of OHCAs, a shockable rhythm is only seen on the AED-ECG. Adequate transfer to the physician of vital AED-information is essential but not always accomplished.

Time of on-scene resuscitation in out of-hospital cardiac arrest patients transported without return of spontaneous circulation.

BACKGROUND: In out-of-hospital cardiac arrest (OHCA), return of spontaneous circulation (ROSC) on scene occurs only in a minority of patients. The optimal duration of resuscitation on scene before transport with ongoing cardiopulmonary resuscitation (CPR) is unknown. PURPOSE: To determine the time of resuscitation on scene ('time on scene') and survival in patients transported with ongoing CPR in the Netherlands. METHODS: Data on OHCA patients (>18 years) without ROSC on scene, where resuscitation was started between January 1, 2012 and December 31, 2016 in the Amsterdam Resuscitation Study (ARREST) database were analyzed. Time on scene was related to 30-day survival. RESULTS: Of the 5871 OHCA patients where resuscitation was started, 2437 did not achieve ROSC on scene. Of these, 655 patients were transported with ongoing CPR and 606 (93%) had complete rhythm data. At the moment of transport, 199 (33%) patients had a shockable rhythm, 299 (49%) pulseless electrical activity (PEA) and 108 (18%) asystole as rhythm. Twenty-nine patients (4%) were alive at 30 days. Patients who survived 30 days had a higher proportion of a shockable first monitored rhythm (89% vs. 52%, p < 0.001). Survivors had a significantly shorter time on scene (20 min vs. 26 min, p = 0.004), with the highest survival rate (8%) in patients transported within 20 min. In a multivariable model time on scene (OR 0.94; 95%CI 0.89-0.99) was independently associated with 30-day survival. CONCLUSION: In OHCA patients transported with ongoing CPR the survival rate significantly declines when time on scene increases.