Survival After Intra-Arrest Transport vs On-Scene Cardiopulmonary Resuscitation in Children

Importance

For pediatric out-of-hospital cardiac arrest (OHCA), emergency medical services (EMS) may elect to transport to the hospital during active cardiopulmonary resuscitation (CPR) (ie, intra-arrest transport) or to continue on-scene CPR for the entirety of the resuscitative effort. The comparative effectiveness of these strategies is unclear.

Objective

To evaluate the association between intra-arrest transport compared with continued on-scene CPR and survival after pediatric OHCA, and to determine whether this association differs based on the timing of intra-arrest transport.

Design, Setting, and Participants

This cohort study included pediatric patients aged younger than 18 years with EMS-treated OHCA between December 1, 2005 and June 30, 2015. Data were collected from the Resuscitation Outcomes Consortium Epidemiologic Registry, a prospective 10-site OHCA registry in the US and Canada. Data analysis was performed from May 2022 to February 2024.

Exposures

Intra-arrest transport, defined as an initiation of transport prior to the return of spontaneous circulation, and the interval between EMS arrival and intra-arrest transport.

Main Outcomes and Measures

The primary outcome was survival to hospital discharge. Patients who underwent intra-arrest transport at any given minute after EMS arrival were compared with patients who were at risk of undergoing intra-arrest transport within the same minute using time-dependent propensity scores calculated from patient demographics, arrest characteristics, and EMS interventions. We examined subgroups based on age (<1 year vs ≥1 year).

Results

Of 2854 eligible pediatric patients (median [IQR] age, 1 [0-9] years); 1691 males [59.3%]) who experienced OHCA between December 2005 and June 2015, 1892 children (66.3%) were treated with intra-arrest transport and 962 children (33.7%) received continued on-scene CPR. The median (IQR) time between EMS arrival and intra-arrest transport was 15 (9-22) minutes. In the propensity score-matched cohort (3680 matched cases), there was no significant difference in survival to hospital discharge between the intra-arrest transport group and the continued on-scene CPR group (87 of 1840 patients [4.7%] vs 95 of 1840 patients [5.2%]; risk ratio [RR], 0.81 [95% CI, 0.59-1.10]). Survival to hospital discharge was not modified by the timing of intra-arrest transport (P value for the interaction between intra-arrest transport and time to matching = .10). Among patients aged younger than 1 year, intra-arrest transport was associated with lower survival to hospital discharge (RR, 0.52; 95% CI, 0.33-0.83) but there was no association for children aged 1 year or older (RR, 1.22; 95% CI, 0.77-1.93).

Conclusions and Relevance

In this cohort study of a North American OHCA registry, intra-arrest transport compared with continued on-scene CPR was not associated with survival to hospital discharge among children with OHCA. However, intra-arrest transport was associated with a lower likelihood of survival to hospital discharge among children aged younger than 1 year.

Risk Prediction in Male Adolescents With Congenital Long QT Syndrome: Implications for Sex-Specific Risk Stratification in Potassium Channel-Mediated Long QT Syndrome

BACKGROUND

Sex-specific risk management may improve outcomes in congenital long QT syndrome (LQTS). We recently developed a prediction score for cardiac events (CEs) and life-threatening events (LTEs) in postadolescent women with LQTS. In the present study, we aimed to develop personalized risk estimates for the burden of CEs and LTEs in male adolescents with potassium channel-mediated LQTS.

METHODS AND RESULTS

The prognostic model was derived from the LQTS Registry headquartered in Rochester, NY, comprising 611 LQT1 or LQT2 male adolescents from age 10 through 20 years, using the following variables: genotype/mutation location, QTc-specific thresholds, history of syncope, and β-blocker therapy. Anderson-Gill modeling was performed for the end point of CE burden (total number of syncope, aborted cardiac arrest, and appropriate defibrillator shocks). The applicability of the CE prediction model was tested for the end point of the first LTE (excluding syncope and adding sudden cardiac death) using Cox modeling. A total of 270 CEs occurred during follow-up. The genotype-phenotype risk prediction model identified low-, intermediate-, and high-risk groups, comprising 74%, 14%, and 12% of the study population, respectively. Compared with the low-risk group, high-risk male subjects experienced a pronounced 5.2-fold increased risk of recurrent CEs (P<0.001), whereas intermediate-risk patients had a 2.1-fold (P=0.004) increased risk . At age 20 years, the low-, intermediate-, and high-risk adolescent male patients had on average 0.3, 0.6, and 1.4 CEs per person, respectively. Corresponding 10-year adjusted probabilities for a first LTE were 2%, 6%, and 8%.

CONCLUSIONS

Personalized genotype-phenotype risk estimates can be used to guide sex-specific management in male adolescents with potassium channel-mediated LQTS.

Pediatric Out-of-Hospital Cardiac Arrest: The Role of the Telecommunicator in Recognition of Cardiac Arrest and Delivery of Bystander Cardiopulmonary Resuscitation

BACKGROUND

Telecommunicator CPR (T-CPR), whereby emergency dispatch facilitates cardiac arrest recognition and coaches CPR over the telephone, is an important strategy to increase early recognition and bystander CPR in adult out-of-hospital cardiac arrest (OHCA). Little is known about this treatment strategy in the pediatric population. We investigated the role of T-CPR and related performance among pediatric OHCA.

METHODS AND RESULTS

This study was a retrospective cohort investigation of OHCA among individuals <18 years in King County, Washington, from April 1, 2013, to December 31, 2019. We reviewed the 911 audio recordings to determine if and how bystander CPR was delivered (unassisted or T-CPR), key time intervals in recognition of arrest, and key components of T-CPR delivery. Of the 185 eligible pediatric OHCAs, 23% (n=43) had bystander CPR initiated unassisted, 59% (n=109) required T-CPR, and 18% (n=33) did not receive CPR before emergency medical services arrival. Among all cases, cardiac arrest was recognized by the telecommunicator in 89% (n=165). Among those receiving T-CPR, the median (interquartile range) interval from start of call to OHCA recognition was 59 seconds (38-87) and first CPR intervention was 115 seconds (94-162). When stratified by age (≤8 versus >8), the older age group was less likely to receive CPR before emergency medical services arrival (88% versus 69%, P=0.002). For those receiving T-CPR, bystanders spent a median of 207 seconds (133-270) performing CPR. The median compression rate was 93 per minute (82-107) among those receiving T-CPR.

CONCLUSIONS

T-CPR is an important strategy to increase early recognition and early CPR among pediatric OHCA.

Overdose and mortality risk following a non-fatal opioid overdose treated by Emergency Medical Services in King County, Washington

BACKGROUND

Emergency Medical Services (EMS) agencies respond to hundreds of thousands of acute overdose events each year. We conducted a retrospective cohort study of EMS patients who survived a prior opioid overdose in 2019-2021 in King County, Washington.

METHODS

A novel record linkage algorithm was applied to EMS electronic health records and the state vital statistics registry to identify repeat overdoses and deaths that occurred up to 3 years following the index opioid overdose. We measured overdose incidence rates and applied survival analysis techniques to assess all-cause and overdose-specific mortality risks.

RESULTS

In the year following the index opioid overdose, the overdose (fatal or non-fatal) incidence rate was 23.3 per 100 person-year, overdose mortality rate was 2.7 per 100 person-year, and all-cause mortality rate was 5.2 per 100 person-year in this cohort of overdose survivors (n=4234). Overdose incidence was highest in the first 30 days following the index overdose (43 opioid overdoses and 4 fatal overdoses per 1000 person-months), declined precipitously, and then plateaued from the third month onwards (10-15 opioid overdoses and 1-2 fatal overdoses per 1000 person-months). Overdose incidence rates, measured at 30 days, were highest among overdose survivors who were young, male, and experienced a low severity index opioid overdose, but these differences diminished when measured at 12 months.

CONCLUSIONS

Among EMS patients who survived an opioid overdose, the risk of subsequent overdose is high, especially in the weeks following the index opioid overdose. Non-fatal overdose may represent a pivotal time to connect patients with harm-reduction, treatment, and other support services.

Association of small adult ventilation bags with return of spontaneous circulation in out of hospital cardiac arrest

INTRODUCTION

Little is known about the impact of tidal volumes delivered by emergency medical services (EMS) to adult patients with out-of-hospital cardiac arrest (OHCA). A large urban EMS system changed from standard adult ventilation bags to small adult bags. We hypothesized that the incidence of return of spontaneous circulation (ROSC) at the end of EMS care would increase after this change.

METHODS

We performed a retrospective analysis evaluating adults treated with advanced airway placement for nontraumatic OHCA between January 1, 2015 and December 31, 2021. We compared rates of ROSC, ventilation rate, and mean end tidal carbon dioxide (ETCO2) by minute before and after the smaller ventilation bag implementation using linear and logistic regression.

RESULTS

Of the 1,994 patients included, 1,331 (67%) were treated with a small adult bag. ROSC at the end of EMS care was lower in the small bag cohort than the large bag cohort, 33% vs 40% (p = 0.003). After adjustment, small bag use was associated with lower odds of ROSC at the end of EMS care [OR 0.74, 95% CI 0.61 - 0.91]. Ventilation rates did not differ between cohorts. ETCO2 values were lower in the large bag cohort (33.2 ± 17.2 mmHg vs. 36.9 ± 19.2 mmHg, p < 0.01).

CONCLUSION

Use of a small adult bag during OHCA was associated with lower odds of ROSC at the end of EMS care. The effects on acid base status, hemodynamics, and delivered minute ventilation remain unclear and warrant additional study.

Presentation and Outcomes of Adults With Overdose-Related Out-of-Hospital Cardiac Arrest

Importance

Drug overdose (OD) is a public health challenge and an important cause of out-of-hospital cardiac arrest (OHCA). Existing studies evaluating OD-related OHCA (OD-OHCA) either aggregate all drugs or focus on opioids. The epidemiology, presentation, and outcomes of drug-specific OHCA are largely unknown.

Objective

To evaluate the temporal pattern, clinical presentation, care, and outcomes of adult patients with OHCA overall and according to the drug-specific profile.

Design, Setting, and Participants

This cohort study of adults with OHCA in King County Washington was conducted between January 1, 2015, and December 31, 2021. Etiology of OHCA was determined using emergency medical service, hospital, and medical examiner records. Etiology was classified as non-OD OHCA or OD-OHCA, with drug-specific profiles categorized as (1) opioid without stimulant, (2) stimulant without opioid, (3) opioid and stimulant, or (4) all other nonstimulant, nonopioid drugs. Statistical analysis was performed on July 1, 2023.

Exposure

Out-of-hospital cardiac arrest.

Main Outcomes and Measures

The primary outcome was survival to hospital discharge. The secondary outcome was survival with favorable functional status defined by Cerebral Performance Category 1 or 2 based on review of the hospital record.

Results

In this cohort study, there were 6790 adult patients with emergency medical services-treated OHCA from a US metropolitan system. During the 7-year study period, there were 702 patients with OD-OHCA (median age, 41 years [IQR, 29-53 years]; 64% male [n = 450] and 36% female [n = 252]) and 6088 patients with non-OD OHCA (median age, 66 years [IQR, 56-77 years]; 65% male [n = 3944] and 35% female [n = 2144]). The incidence of OD-OHCA increased from 5.2 (95% CI, 3.8-6.6) per 100 000 person-years in 2015 to 13.0 (95% CI, 10.9-15.1) per 100 000 person-years in 2021 (P < .001 for trend), whereas there was no significant temporal change in the incidence of non-OD OHCA (P = .30). OD-OHCA were more likely to be unwitnessed (66% [460 of 702] vs 41% [2515 of 6088]) and less likely to be shockable (8% [56 of 702] vs 25% [1529 of 6088]) compared with non-OD OHCA. Unadjusted survival was not different (20% [138 of 702] for OD vs 18% [1095 of 6088] for non-OD). When stratified by drug profile, combined opioid-stimulant OHCA demonstrated the greatest relative increase in incidence. Presentation and outcomes differed by drug profile. Patients with stimulant-only OHCA were more likely to have a shockable rhythm (24% [31 of 129]) compared with patients with opioid-only OHCA (4% [11 of 295]) or patients with combined stimulant-opioid OHCA 5% [10 of 205]), and they were more likely to have a witnessed arrest (50% [64 of 129]) compared with patients with OHCA due to other drugs (19% [14 of 73]) or patients with combined stimulant-opioid OHCA (23% [48 of 205]). Patients with a combined opioid-stimulant OHCA had the lowest survival to hospital discharge (10% [21 of 205]) compared with patients with stimulant-only OHCA (22% [29 of 129]) or patients with OHCA due to other drugs (26% [19 of 73]), a difference that persisted after multivariable adjustment.

Conclusions and Relevance

In a population-based cohort study, the incidence of OD-OHCA increased significantly from 2015 to 2021, with the greatest increase observed among patients with a combined stimulant-opioid OHCA. Presentation and outcome differed according to the drug-specific profile. The combination of increasing incidence and lower survival among among patients with a opioid-stimulant OHCA supports prevention and treatment initiatives that consider the drug-specific profile.

Acute SARS-CoV-2 Infection and Incidence and Outcomes of Out-of-Hospital Cardiac Arrest

Importance

Little is known about how COVID-19 affects the incidence or outcomes of out-of-hospital cardiac arrest (OHCA), and it is possible that more generalized factors beyond SARS-CoV-2 infection are primarily responsible for changes in OHCA incidence and outcome.

Objective

To assess whether COVID-19 is associated with OHCA incidence and outcomes.

Design, Setting, and Participants

This retrospective cohort study was conducted in Seattle and King County, Washington. Participants included persons aged 18 years or older with nontraumatic OHCA attended by emergency medical services (EMS) between January 1, 2018, and December 31, 2021. Data analysis was performed from November 2022 to March 2023.

Exposures

Prepandemic (2018-2019) and pandemic (2020-2021) periods and SARS-CoV-2 infection.

Main Outcomes and Measures

The primary outcomes were OHCA incidence and patient outcomes (ie, survival to hospital discharge). Mediation analysis was used to determine the percentage change in OHCA incidence and outcomes between prepandemic and pandemic periods that was attributable to acute SARS-CoV-2 infection vs conventional Utstein elements related to OHCA circumstances (ie, witness status and OHCA location) and resuscitation care (ie, bystander cardiopulmonary resuscitation, early defibrillation, and EMS response intervals).

Results

There were a total of 13 081 patients with OHCA (7102 dead upon EMS arrival and 5979 EMS treated). Among EMS-treated patients, the median (IQR) age was 64.0 (51.0-75.0) years, 3864 (64.6%) were male, and 1027 (17.2%) survived to hospital discharge. The total number of patients with OHCA increased by 19.0% (from 5963 in the prepandemic period to 7118 in the pandemic period), corresponding to an incidence increase from 168.8 to 195.3 events per 100 000 person-years. Of EMS-treated patients with OHCA during the pandemic period, 194 (6.2%) were acutely infected with SARS-CoV-2 compared with 7 of 191 EMS-attended but untreated patients with OHCA (3.7%). In time-series correlation analysis, there was a positive correlation between community SARS-CoV-2 incidence and overall OHCA incidence (r = 0.27; P = .01), as well as OHCA incidence with acute SARS-CoV-2 infection (r = 0.43; P < .001). The survival rate during the pandemic period was lower than that in the prepandemic period (483 patients [15.4%] vs 544 patients [19.2%]). During the pandemic, those with OHCA and acute SARS-CoV-2 infection had lower likelihood of survival compared with those without acute infection (12 patients [6.2%] vs 471 patients [16.0%]). SARS-CoV-2 infection itself accounted for 18.5% of the pandemic survival decline, whereas Utstein elements mediated 68.2% of the survival decline.

Conclusions and Relevance

In this cohort study of COVID-19 and OHCA, a substantial proportion of the higher OHCA incidence and lower survival during the pandemic was not directly due to SARS-CoV-2 infection but indirect factors that challenged OHCA prevention and treatment.

THE COMPENSATORY RESERVE INDEX FOR PREDICTING HEMORRHAGIC SHOCK IN PREHOSPITAL TRAUMA

ABSTRACT

Background: The compensatory reserve index (CRI) is a noninvasive, continuous measure designed to detect intravascular volume loss. CRI is derived from the pulse oximetry waveform and reflects the proportion of physiologic reserve remaining before clinical hemodynamic decompensation. Methods: In this prospective, observational, prehospital cohort study, we measured CRI in injured patients transported by emergency medical services (EMS) to a single Level I trauma center. We determined whether the rolling average of CRI values over 60 s (CRI trend [CRI-T]) predicts in-hospital diagnosis of hemorrhagic shock, defined as blood product administration in the prehospital setting or within 4 h of hospital arrival. We hypothesized that lower CRI-T values would be associated with an increased likelihood of hemorrhagic shock and better predict hemorrhagic shock than prehospital vital signs. Results: Prehospital CRI was collected on 696 adult trauma patients, 21% of whom met our definition of hemorrhagic shock. The minimum CRI-T was 0.14 (interquartile range [IQR], 0.08-0.31) in those with hemorrhagic shock and 0.31 (IQR 0.15-0.50) in those without ( P = <0.0001). The positive likelihood ratio of a CRI-T value <0.2 predicting hemorrhagic shock was 1.85 (95% confidence interval [CI], 1.55-2.22). The area under the ROC curve (AUC) for the minimum CRI-T predicting hemorrhagic shock was 0.65 (95% CI, 0.60-0.70), which outperformed initial prehospital HR (0.56; 95% CI, 0.50-0.62) but underperformed EMS systolic blood pressure and shock index (0.74; 95% CI, 0.70-0.79 and 0.72; 95% CI, 0.67-0.77, respectively). Conclusions: Low prehospital CRI-T predicts blood product transfusion by EMS or within 4 hours of hospital arrival but is less prognostic than EMS blood pressure or shock index. The evaluated version of CRI may be useful in an austere setting at identifying injured patients that require the most significant medical resources. CRI may be improved with noise filtering to attenuate the effects of vibration and patient movement.

Instantaneous amplitude: Association of ventricular fibrillation waveform measures at time of shock with outcome in out-of-hospital cardiac arrest

BACKGROUND

Prompt defibrillation is key to successful resuscitation from ventricular fibrillation out-of-hospital cardiac arrest (VF-OHCA). Preliminary evidence suggests that the timing of shock relative to the amplitude of the VF ECG waveform may affect the likelihood of resuscitation. We investigated whether the VF waveform amplitude at the time of shock (instantaneous amplitude) predicts outcome independent of other validated waveform measures.

METHODS

We conducted a retrospective study of VF-OHCA patients ≥18 old. We evaluated three VF waveform measures for each shock: instantaneous amplitude at the time of shock, and maximum amplitude and amplitude spectrum area (AMSA) over a 3-s window preceding the shock. Linear mixed-effects modeling was used to determine whether instantaneous amplitude was associated with shock-specific return of organized rhythm (ROR) or return of spontaneous circulation (ROSC) independent of maximum amplitude or AMSA.

RESULTS

The 566 eligible patients received 1513 shocks, resulting in ROR of 62.0% (938/1513) and ROSC of 22.3% (337/1513). In unadjusted regression, an interquartile increase in instantaneous amplitude was associated with ROR (Odds ratio [OR] [95% confidence interval] = 1.27 [1.11-1.45]) and ROSC (OR = 1.27 [1.14-1.42]). However, instantaneous amplitude was not associated with ROR (OR = 1.13 [0.97-1.30]) after accounting for maximum amplitude, nor with ROR (OR = 1.00 [0.87-1.15]) or ROSC (OR = 1.05 [0.93-1.18]) after accounting for AMSA. By contrast, AMSA and maximum amplitude remained independently associated with ROR and ROSC.

CONCLUSIONS

We did not observe an independent association between instantaneous amplitude and shock-specific outcomes. Efforts to time shock to the maximal amplitude of the VF waveform are unlikely to affect resuscitation outcome.

Prediction of Shock-Refractory Ventricular Fibrillation During Resuscitation of Out-of-Hospital Cardiac Arrest

BACKGROUND

Out-of-hospital cardiac arrest due to shock-refractory ventricular fibrillation (VF) is associated with relatively poor survival. The ability to predict refractory VF (requiring ≥3 shocks) in advance of repeated shock failure could enable preemptive targeted interventions aimed at improving outcome, such as earlier administration of antiarrhythmics, reconsideration of epinephrine use or dosage, changes in shock delivery strategy, or expedited invasive treatments.

METHODS

We conducted a cohort study of VF out-of-hospital cardiac arrest to develop an ECG-based algorithm to predict patients with refractory VF. Patients with available defibrillator recordings were randomized 80%/20% into training/test groups. A random forest classifier applied to 3-s ECG segments immediately before and 1 minute after the initial shock during cardiopulmonary resuscitation was used to predict the need for ≥3 shocks based on singular value decompositions of ECG wavelet transforms. Performance was quantified by area under the receiver operating characteristic curve.

RESULTS

Of 1376 patients with VF out-of-hospital cardiac arrest, 311 (23%) were female, 864 (63%) experienced refractory VF, and 591 (43%) achieved functional neurological survival. Total shock count was associated with decreasing likelihood of functional neurological survival, with a relative risk of 0.95 (95% CI, 0.93-0.97) for each successive shock (P<0.001). In the 275 test patients, the area under the receiver operating characteristic curve for predicting refractory VF was 0.85 (95% CI, 0.79-0.89), with specificity of 91%, sensitivity of 63%, and a positive likelihood ratio of 6.7.

CONCLUSIONS

A machine learning algorithm using ECGs surrounding the initial shock predicts patients likely to experience refractory VF, and could enable rescuers to preemptively target interventions to potentially improve resuscitation outcome.

Title: Age, sex, and survival following ventricular fibrillation cardiac arrest: a mechanistic evaluation of the ECG waveform: Short title: Age, sex, and survival via VF waveform in OHCA

BACKGROUND

Studies of outcome differences by sex in out-of-hospital cardiac arrest (OHCA) have produced mixed results that may depend on age, a potential surrogate for menopausal status.

OBJECTIVE

We used quantitative measures of ventricular fibrillation (VF) waveforms - indicators of the myocardium's physiology - to assess whether survival differences according to sex and age group may be mediated via a biologic mechanism.

METHODS

We conducted a cohort study of VF-OHCA in a metropolitan EMS system. We used multivariable logistic regression to assess the association of survival to hospital discharge with sex and age group (<55, ≥55 years). We determined the proportion of outcome difference mediated by VF waveform measures: VitalityScore and amplitude spectrum area (AMSA).

RESULTS

Among 1526 VF-OHCA patients, the average age was 62 years, and 29% were female. Overall, younger women were more likely to survive than younger men (survival 67% vs 54%, p=0.02), while survival among older women and older men did not differ (40% vs 44%, p=0.3). Adjusting for Utstein characteristics, women <55 compared to men <55 had greater odds of survival to hospital discharge (OR=1.93, 95% CI 1.23-3.09), an association not observed between the ≥55 groups. Waveform measures were more favorable among women and mediated some of the beneficial association between female sex and survival among those <55 years: 47% for VitalityScore and 25% for AMSA.

CONCLUSIONS

Women <55 years were more likely to survive than men <55 years following VF-OHCA. The biologic mechanism represented by VF waveform mediated some, though not all, of the outcome difference.

Burnout and Workplace Incivility Among Emergency Medical Services Practitioners: A Preliminary Report

OBJECTIVE

Burnout has detrimental consequences for health care organizations, clinicians, and the quality of care that patients receive. Prior work suggests that workplace incivility (negative interpersonal acts) contributes to burnout. While workplace incivility is linked to EMS practitioner job dissatisfaction, absenteeism, and planned attrition, the relationship between workplace incivility and burnout has not been evaluated among EMS practitioners. This study aimed to characterize the prevalence and association of burnout and workplace incivility among EMS practitioners.

METHODS

A cross-sectional survey of EMS personnel in King County, Washington was performed in January to March of 2021 with burnout as the primary outcome and workplace incivility as a secondary outcome. Multivariable logistic regression was used to evaluate associations between outcomes and EMS practitioner factors that included age, sex, race/ethnicity, years of EMS experience, and current job role.

RESULTS

835 completed surveys were received (response rate 25%). The prevalence of burnout was 39.2%. Women were more likely to have burnout than men (59.3% vs. 33.7%, aOR 2.2, 95% CI 1.3-3.7). Workplace incivility was experienced weekly by 32.1% of respondents, with women more likely to experience incivility compared to men (41.9% vs. 27.2%, aOR 2.0, 95% CI 1.2-3.3). Respondents who experienced frequent workplace incivility were more likely to have burnout than those who did not experience frequent incivility (61.9% vs. 38.1%, OR 4.0, 95% CI 3.0-5.5).

CONCLUSIONS

The prevalence of burnout and workplace incivility were concerning among EMS practitioners, with women more likely to experience both compared to men. EMS practitioners who experienced frequent workplace incivility were also more likely to have burnout than those who did not experience frequent incivility.

Continuous Assessment of Ventricular Fibrillation Prognostic Status during CPR: Implications for Resuscitation

BACKGROUND

Ventricular fibrillation (VF) waveform measures reflect myocardial physiologic status. Continuous assessment of VF prognosis using such measures could guide resuscitation, but has not been possible due to CPR artifact in the ECG. A recently-validated VF measure (termed VitalityScore), which estimates the probability (0-100%) of return-of-rhythm (ROR) after shock, can assess VF during CPR, suggesting potential for continuous application during resuscitation.

OBJECTIVE

We evaluated VF using VitalityScore to characterize VF prognostic status continuously during resuscitation.

METHODS

We characterized VF using VitalityScore during 60 seconds of CPR and 10 seconds of subsequent pre-shock CPR interruption in patients with out-of-hospital VF arrest. VitalityScore utility was quantified using area under the receiver operating characteristic curve (AUC). VitalityScore trends over time were estimated using mixed-effects models, and associations between trends and ROR were evaluated using logistic models. A sensitivity analysis characterized VF during protracted (100-second) periods of CPR.

RESULTS

We evaluated 724 VF episodes among 434 patients. After an initial decline from 0-8 seconds following VF onset, VitalityScore increased slightly during CPR from 8-60 seconds (slope: 0.18 %/min). During the first 10 seconds of subsequent pre-shock CPR interruption, VitalityScore declined (slope: -14 %/min). VitalityScore predicted ROR throughout CPR with AUCs 0.73-0.75. Individual VitalityScore trends during 8-60 seconds of CPR were marginally associated with subsequent ROR (adjusted odds ratio for interquartile slope change (OR)=1.10, p=0.21), and became significant with protracted (≥100 seconds) CPR duration (OR=1.28, p=0.006).

CONCLUSION

VF prognostic status can be continuously evaluated during resuscitation, a development that could translate to patient-specific resuscitation strategies.

Analysis of Epinephrine Dose, Targeted Temperature Management, and Neurologic and Survival Outcomes Among Adults With Out-of-Hospital Cardiac Arrest

IMPORTANCE

Epinephrine improves return of spontaneous circulation after out-of-hospital cardiac arrest (OHCA). These beneficial cardiac effects do not directly translate to better neurologic outcomes, possibly because of epinephrine-induced microvascular effects that produce critical brain ischemia.

OBJECTIVE

To examine whether targeted temperature management (TTM) modifies the adverse association between increasing prehospital epinephrine dose and neurologically favorable survival.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study assessed 14 612 adults from Seattle and King County, Washington, with nontraumatic OHCA between January 1, 2008, and December 31, 2018, and included those who achieved return of spontaneous circulation and were unconscious at hospital admission. Data analysis was performed from April 2021 to May 2022.

EXPOSURES

Epinephrine dose and TTM during prehospital resuscitation.

MAIN OUTCOMES AND MEASURES

Favorable neurologic survival (Cerebral Performance Category [CPC] 1 or 2) and survival to hospital discharge.

RESULTS

Of the 14 612 assessed adults, 5253 (median age, 63 years; IQR, 51-74 years; 3460 [65.8%] male) were eligible for the study. The median epinephrine dose was 2.0 mg (IQR, 1.0-3.0 mg); 3052 patients (58.1%) received TTM. In all, 1889 patients (36.0%) survived with CPC 1 to 2, and 2177 (41.4%) survived to discharge. Increasing doses of epinephrine were associated with a decreasing likelihood of CPC 1 to 2 (odds ratio [OR], 0.46; 95% CI 0.42-0.50 for each additional milligram of epinephrine) and survival (OR, 0.47; 95% CI, 0.43-0.51). The dose-dependent epinephrine association was modified by TTM. After adjusting for Utstein covariates, TTM was associated with a relative stepwise improvement in odds of CPC 1 to 2 (interaction OR, 1.36; 95% CI, 1.22-1.51) and survival (interaction OR, 1.37; 95% CI, 1.24-1.51). A significant interaction was also observed when the analysis was stratified according to initial rhythm among shockable OHCA and nonshockable OHCA (shockable interaction OR, 1.20; 95% CI, 1.04-1.39; and nonshockable interaction OR, 1.24, 95% CI, 1.07-1.45).

CONCLUSIONS AND RELEVANCE

This cohort study found an interaction between TTM and epinephrine dose such that the beneficial association of TTM increased with increasing epinephrine dose, suggesting that TTM may attenuate the adverse effects of higher-dose epinephrine.

Investigating the Airway Opening Index during Cardiopulmonary Resuscitation

INTRODUCTION

Chest compressions during CPR induce oscillations in capnography (E_TCO₂) waveforms. Studies suggest E_TCO₂ oscillation characteristics are associated with intrathoracic airflow dependent on airway patency. Oscillations can be quantified by the Airway Opening Index (AOI). We sought to evaluate multiple methods of computing AOI and their association with return of spontaneous circulation (ROSC).

METHODS

We conducted a retrospective study of 307 out-of-hospital cardiac arrest (OHCA) cases in Seattle, WA during 2019. E_TCO₂ and chest impedance waveforms were annotated for the presence of intubation and CPR. We developed four methods for computing AOI based on peak E_TCO₂ and the oscillations in E_TCO₂ during CCs (ΔE_TCO₂). We examined the feasibility of automating ΔE_TCO₂ and AOI calculation and evaluated differences in AOI across the methods using nonparametric testing (p=0.05).

RESULTS

Median [interquartile range] AOI across all cases using Methods 1-4 was 28.0% [17.9-45.5%], 20.6% [13.0-36.6%], 18.3% [11.4-30.4%], and 22.4% [12.8-38.5%], respectively (p<0.001). Cases with ROSC had a higher median AOI than those without ROSC across all methods, though not statistically significant. Cases with ROSC had a significantly higher median [interquartile range] ΔE_TCO₂ of 7.3 mmHg [4.5-13.6 mmHg] compared to those without ROSC (4.8 mmHg [2.6-9.1 mmHg], p<0.001).

CONCLUSION

We calculated AOI using four proposed methods resulting in significantly different AOI. Additionally, AOI and ΔE_TCO₂ were larger in cases achieving ROSC. Further investigation is required to characterize AOI's ability to predict OHCA outcomes, and whether this information can improve resuscitation care.

A pilot evaluation of respiratory mechanics during prehospital manual ventilation

INTRODUCTION

Respiratory mechanics, such as tidal volume (V_T) and inspiratory pressures, may affect outcome in hospitalized patients with respiratory failure. Little is known about respiratory mechanics in the prehospital setting.

METHODS

In this prospective, pilot investigation of patients receiving prehospital advanced airway placement, paramedics applied a device to measure respiratory mechanics. We evaluated tidal volume (V_T) per predicted body weight (V_TPBW) to determine the proportion of breaths within the lung-protective range of 4-10 mL/kg per PBW overall, according to ventilation bag volume (large versus small) and cardiac arrest status (active CPR, post-ROSC, non-arrest).

RESULTS

Over 16-months, 7371 post-intubation breaths were measured in 54 patients, 32 patients with cardiac arrest and 22 with other conditions. Paramedics ventilated 19 patients with a small bag and 35 patients with a large bag. Overall, mean V_T was 435 mL (95% CI 403, 467); V_TPBW was 7.0 mL/kg (95% CI 6.4, 7.6) with 75% within the lung-protective range. Mean V_TPBW and peak pressure differed according to arrest status (absolute difference -0.36 mL/kg and 32 cmH₂O for active CPR compared to post-ROSC), though not according to bag size.

CONCLUSIONS

We observed that measuring respiratory mechanics in the prehospital setting was feasible. Tidal volumes were generally delivered within a safe range. Respiratory mechanics varied most significantly with active CPR with lower V_TPBW and higher peak pressures, though did not seem to be affected by bag size. Future work might examine the relationship between respiratory mechanics and outcomes, which may identify opportunities to improve clinical outcomes.

Sex Hormones and Repolarization Dynamics during the Menstrual Cycle in Women with Congenital Long QT Syndrome

BACKGROUND

Women with congenital long QT syndrome (LQTS) experience increased cardiac events risk after the onset of adolescence, perhaps stemming from the known modulating effects of sex hormones on the cardiac potassium channels.

OBJECTIVE

We hypothesized that the effect of sex hormones on cardiac ion channel function may modify ECG parameters associated with the propensity for ventricular tachyarrhythmias during the menstrual cycle in women with LQTS.

METHODS

We prospectively enrolled 65 women with congenital LQTS (LQT1 [N=24], LQT2 [N=20]) and unaffected female relatives [N=21]. Subjects underwent three 7-day ECG recordings during their menstrual cycles. Simultaneous saliva testing of sex hormone levels was obtained on the first day of each 7-day ECG recording cycle.

RESULTS

Mean age was 35±8 years, without a significant difference among the groups. In LQT2 women, linear mixed effects models showed significant inverse correlations of QTc with progesterone (p<0.001), and the progesterone to estradiol ratio (p<0.001). Inverse relationships of the RR interval with estradiol levels (p=0.003) and of the T-wave duration with testosterone levels (p=0.014) were also observed in women with LQT2. In contrast, no significant associations were observed between ECG parameters and sex hormone levels the women with LQT1 women or the unaffected relatives.

CONCLUSIONS

This is the first study to prospectively assess correlations between repolarization dynamics and sex hormone levels during the menstrual cycle in women with congenital LQTS. Our findings show genotype-specific unique QTc dynamics during the menstrual cycle that may affect the propensity for ventricular tachyarrhythmia in women with LQTS, particularly LQT2 women.

Machine learning and feature engineering for predicting pulse presence during chest compressions

Current resuscitation protocols require pausing chest compressions during cardiopulmonary resuscitation (CPR) to check for a pulse. However, pausing CPR when a patient is pulseless can worsen patient outcomes. Our objective was to design and evaluate an ECG-based algorithm that predicts pulse presence with or without CPR. We evaluated 383 patients being treated for out-of-hospital cardiac arrest with real-time ECG, impedance and audio recordings. Paired ECG segments having an organized rhythm immediately preceding a pulse check (during CPR) and during the pulse check (without CPR) were extracted. Patients were randomly divided into 60% training and 40% test groups. From training data, we developed an algorithm to predict the clinical pulse presence based on the wavelet transform of the bandpass-filtered ECG. Principal component analysis was used to reduce dimensionality, and we then trained a linear discriminant model using three principal component modes as input features. Overall, 38% (351/912) of checks had a spontaneous pulse. AUCs for predicting pulse presence with and without CPR on test data were 0.84 (95% CI (0.80, 0.88)) and 0.89 (95% CI (0.86, 0.92)), respectively. This ECG-based algorithm demonstrates potential to improve resuscitation by predicting the presence of a spontaneous pulse without pausing CPR with moderate accuracy.

Incidence, Mechanism, and Outcomes of On-Plane Versus Off-Plane Cardiac Arrest in Air Travelers

Background Air travel affords an opportunity to evaluate resuscitation performance and outcome in a setting where automated external defibrillators (AEDs) are readily available. Methods and Results The study cohort included people aged ≥18 years with out of hospital cardiac arrest (OHCA) traveling through Seattle-Tacoma International Airport between January 1, 2004 and December 31, 2019 treated by emergency medical services (EMS). The primary outcomes were pre-EMS therapies (cardiopulmonary resuscitation, application of AED), return of spontaneous circulation, and survival to hospital discharge. Over the 16-year study period, there were 143 OHCA occurring before EMS arrival, 34 (24%) on-plane and 109 (76%) off-plane. Cardiac etiology (81%) was the most common mechanism of arrest. The majority of arrests were bystander-witnessed and presented with a shockable rhythm; these characteristics were more common in off-plane OHCA compared with on-plane (witnessed: 89% versus 74% and shockable: 72% versus 50%). Pre-EMS therapies including cardiopulmonary resuscitation and AED application were common regardless of arrest location. Compared with on-plane OHCA, off-plane OHCA was associated with greater rates of return of spontaneous circulation (68% versus 44%) and 3-fold higher rate of survival to hospital discharge (44% versus 15%). All survivors of on-plane OHCA had AED application with defibrillation before EMS arrival. Conclusions When applied to air travel volumes, we estimate 350 air travel-associated OHCA occur in the United States and 2000 OHCA worldwide each year, nearly a quarter of which happen on-plane. These events are survivable when early arrest interventions including rapid arrest recognition, AED application, and CPR are deployed.

Emergency medical services employing intra-arrest transport less frequently for out-of-hospital cardiac arrest have higher survival and favorable neurological outcomes

BACKGROUND

There is substantial regional variation in out-of-hospital cardiac arrest (OHCA) survival. We investigated whether regional emergency medical services (EMS) intra-arrest transport (IAT) practices are associated with patient outcomes.

METHODS

We performed a secondary analysis of a multi-center North American clinical trial dataset, which enrolled EMS-treated adult OHCA cases from 49 regional population-based clusters. The exposure of interest was regional-level intra-arrest transport (IAT), calculated as the proportion of cases in each cluster transported to hospital prior to return of spontaneous circulation, examined as quartiles and as a continuous variable. Multilevel mixed-effects logistic regression modeling estimated the association between regional IAT with survival to hospital discharge and favorable neurologic status (modified Rankin Scale ≤ 3) at hospital discharge.

RESULTS

Of 26,148 subjects (median age 68 years; 36% female; 23% shockable initial rhythm) 2424 (9.3%), survived to hospital discharge and 1993 (7.6%) had favourable neurological outcomes. Across regional clusters, IAT ranged from 0.84% to 75% (quartiles <6.2%, 6.2-19.6%, 19.6-30.4%, and ≥30.4%). For each quartile, 13.3%, 7.9%, 7.4%, and 4.8% survived, and 10.4%, 7.8%, 7.4%, and 4.8% had favourable neurological status. Regional IAT (per 10% change) was associated with decreased probability of survival (AOR 0.86, 95% CI 0.82-0.91) and favorable neurological outcome (AOR 0.80, 95% CI 0.76-0.85).

CONCLUSION

Treatment within a region that utilizes IAT less frequently was associated with improved clinical outcomes at hospital discharge. These findings may account for some of the known regional variation in OHCA outcomes.

Use of oral contraceptives in women with congenital long QT syndrome

BACKGROUND

Use of oral contraceptives (OCs) may modulate the clinical course of women with congenital long QT syndrome (LQTS). The safety of OC use by sex hormone content has not been assessed in women with LQTS.

OBJECTIVE

We aimed to evaluate the association of OCs with the risk of cardiac events (CEs) in women with LQTS.

METHODS

Beginning in 2010, information on menarche onset, OC use, pregnancy, and menopause were obtained from women enrolled in the Rochester LQTS Registry. Type of OC was categorized as progestin-only, estrogen-only, or combined (estrogen/progestin). Andersen-Gill multivariate modeling was used to evaluate the association of time-dependent OC use with the burden of CE (total number of syncope, aborted cardiac arrest, and LQTS-related sudden cardiac death) from menarche onset through 40 years. Findings were adjusted for genotype, corrected QT duration, and time-dependent β-blocker therapy.

RESULTS

A total of 1659 women with LQTS followed through March 2021, of whom 370 (22%) were treated with an OC. During a cumulative follow-up of 35,797 years, there were a total of 2027 CE. Multivariate analysis showed that progestin-only OC was associated with a pronounced 2.8-fold (P = .01) increased risk of CEs in women who did not receive β-blocker therapy, while β-blockers were highly protective during progestin-only OC treatment (hazard ratio 0.22; P = .01; P = .006 for β-blocker-by-OC interaction). The risk associated with OC use without concomitant β-blocker treatment was pronounced in women with LQTS type 2.

CONCLUSION

Our findings suggest that progestin-only OC should not be administered in women with LQTS without concomitant β-blocker therapy. OCs should be used with caution in women with LQTS type 2.

Risk Prediction in Women With Congenital Long QT Syndrome

Background

We aimed to provide personalized risk estimates for cardiac events (CEs) and life‐threatening events in women with either type 1 or type 2 long QT.

Methods and Results

The prognostic model was derived from the Rochester Long QT Syndrome Registry, comprising 767 women with type 1 long QT (n=404) and type 2 long QT (n=363) from age 15 through 60 years. The risk prediction model included the following variables: genotype/mutation location, QTc‐specific thresholds, history of syncope, and β‐blocker therapy. A model was developed with the end point of CEs (syncope, aborted cardiac arrest, or long QT syndrome–related sudden cardiac death), and was applied with the end point of life‐threatening events (aborted cardiac arrest, sudden cardiac death, or appropriate defibrillator shocks). External validation was performed with data from the Mayo Clinic Genetic Heart Rhythm Clinic (N=467; type 1 long QT [n=286] and type 2 long QT [n=181]). The cumulative follow‐up duration among the 767 enrolled women was 22 243 patient‐years, during which 323 patients (42%) experienced ≥1 CE. Based on genotype‐phenotype data, we identified 3 risk groups with 10‐year projected rates of CEs ranging from 15%, 29%, to 51%. The corresponding 10‐year projected rates of life‐threatening events were 2%, 5%, and 14%. C statistics for the prediction model for the 2 respective end points were 0.68 (95% CI 0.65–0.71) and 0.71 (95% CI 0.66–0.76). Corresponding C statistics for the model in the external validation Mayo Clinic cohort were 0.65 (95% CI 0.60–0.70) and 0.77 (95% CI 0.70–0.84).

Conclusions

This is the first risk prediction model that provides absolute risk estimates for CEs and life‐threatening events in women with type 1 or type 2 long QT based on personalized genotype‐phenotype data. The projected risk estimates can be used to guide female‐specific management in long QT syndrome.

Prehospital tourniquet use: An evaluation of community application and outcome

BACKGROUND

There is substantial investment in layperson and first responder training involving tourniquet use for hemorrhage control. Little is known however about prehospital tourniquet application, field conversion, or outcomes in the civilian setting. We describe the experience of a metropolitan region with prehospital tourniquet application.

METHODS

We conducted a retrospective cohort study characterizing prehospital tourniquet use treated by emergency medical services (EMS) in King County, Washington, from January 2018 to June 2019. Emergency medical services and hospital records were abstracted for demographics, injury mechanism, tourniquet details, clinical care, and outcomes. We evaluated the incidence of tourniquet application, who applied the device (EMS, law enforcement, or layperson), and subsequent course.

RESULTS

A total of 168 patients received tourniquet application, an incidence of 5.1 per 100,000 person-years and 3.48 per 1,000 EMS responses for trauma. Tourniquets were applied for penetrating trauma (64%), blunt trauma (30%), and bleeding ateriovenous fistulas (7%). A subset was critically ill: 13% had systolic blood pressures of <90 mm Hg, 8% had Glasgow Coma Scale score of <13, and 3% had cardiac arrest. Among initial applications, 48% were placed by law enforcement, 33% by laypersons, and 18% by EMS. Among tourniquets applied by layperson or law enforcement (n = 137), EMS relied solely on the original tourniquet in 45% (n = 61), placed a second tourniquet in 20% (n = 28), and removed the tourniquet without replacement in 35% (n = 48). Overall, 24% required massive transfusion, 59% underwent urgent surgery, and 21% required vascular surgery. Mortality was 3% (n = 4). At hospital discharge, the tourniquet limb was fully functional in 81%, partially functional in 10%, and nonfunctional in 9%; decreased function was not attributed to tourniquet application.

CONCLUSION

The high rate of application, need for urgent hospital intervention in a subset, and low incidence of apparent complication suggest that efforts to increase access and early tourniquet use can provide public health benefit.

LEVEL OF EVIDENCE

Therapeutic, level IV.

A method to predict ventricular fibrillation shock outcome during chest compressions

BACKGROUND

Out-of-hospital ventricular fibrillation (VF) cardiac arrest is a leading cause of death. Quantitative analysis of the VF electrocardiogram (ECG) can predict patient outcomes and could potentially enable a patient-specific, guided approach to resuscitation. However, VF analysis during resuscitation is confounded by cardiopulmonary resuscitation (CPR) artifact in the ECG, challenging continuous application to guide therapy throughout resuscitation. We therefore sought to design a method to predict VF shock outcomes during CPR.

METHODS

Study data included 4577 5-s VF segments collected during and without CPR prior to defibrillation attempts in N = 1151 arrest patients. Using training data (460 patients), an algorithm was designed to predict the VF shock outcomes of defibrillation success (return of organized ventricular rhythm) and functional survival (Cerebral Performance Category 1-2). The algorithm was designed with variable-frequency notch filters to reduce CPR artifact in the ECG based on real-time chest compression rate. Ten ECG features and three dichotomous patient characteristics were developed to predict outcomes. These variables were combined using support vector machines and logistic regression. Algorithm performance was evaluated by area under the receiver operating characteristic curve (AUC) to predict outcomes in validation data (691 patients).

RESULTS

AUC (95% Confidence Interval) for predicting defibrillation success was 0.74 (0.71-0.77) during CPR and 0.77 (0.74-0.79) without CPR. AUC for predicting functional survival was 0.75 (0.72-0.78) during CPR and 0.76 (0.74-0.79) without CPR.

CONCLUSION

A novel algorithm predicted defibrillation success and functional survival during ongoing CPR following VF arrest, providing a potential proof-of-concept towards real-time guidance of resuscitation therapy.

Occupational exposures and programmatic response to COVID-19 pandemic: an emergency medical services experience

Rigorous assessment of occupational COVID-19 risk and personal protective equipment (PPE) use is not well-described. We evaluated 9-1-1 emergency medical services (EMS) encounters for patients with COVID-19 to assess occupational exposure, programmatic strategies to reduce exposure and PPE use. We conducted a retrospective cohort investigation of laboratory-confirmed patients with COVID-19 in King County, Washington, USA, who received 9-1-1 EMS responses from 14 February 2020 to 26 March 2020. We reviewed dispatch, EMS and public health surveillance records to evaluate the temporal relationship between exposure and programmatic changes to EMS operations designed to identify high-risk patients, protect the workforce and conserve PPE. There were 274 EMS encounters for 220 unique COVID-19 patients involving 700 unique EMS providers with 988 EMS person-encounters. Use of 'full' PPE including mask (surgical or N95), eye protection, gown and gloves (MEGG) was 67%. There were 151 person-exposures among 129 individuals, who required 981 quarantine days. Of the 700 EMS providers, 3 (0.4%) tested positive within 14 days of encounter, though these positive tests were not attributed to occupational exposure from inadequate PPE. Programmatic changes were associated with a temporal reduction in exposures. When stratified at the study encounters midpoint, 94% (142/151) of exposures occurred during the first 137 EMS encounters compared with 6% (9/151) during the second 137 EMS encounters (p<0.01). By the investigation's final week, EMS deployed MEGG PPE in 34% (3579/10 468) of all EMS person-encounters. Less than 0.5% of EMS providers experienced COVID-19 illness within 14 days of occupational encounter. Programmatic strategies were associated with a reduction in exposures, while achieving a measured use of PPE.

Outcome by Sex in Patients With Long QT Syndrome With an Implantable Cardioverter Defibrillator

Background

Sex differences in outcome have been reported in patients with congenital long QT syndrome. We aimed to report on the incidence of time‐dependent life‐threatening events in male and female patients with long QT syndrome with an implantable cardioverter defibrillator (ICD).

Methods and Results

A total of 60 patients with long QT syndrome received an ICD for primary or secondary prevention indications. Life‐threatening events were evaluated from the date of ICD implant and included ICD shocks for ventricular tachycardia, ventricular fibrillation, or death. ICDs were implanted in 219 women (mean age 38±13 years), 46 girls (12±5 years), 55 men (43±17 years), and 40 boys (11±4 years). Mean follow‐up post‐ICD implantation was 14±6 years for females and 12±6 years for males. At 15 years of follow‐up, the cumulative probability of life‐threatening events was 27% in females and 34% in males (log‐rank P=0.26 for the overall difference). In the multivariable Cox model, sex was not associated with significant differences in risk first appropriate ICD shock (hazard ratio, 0.83 female versus male; 95% CI, 0.52–1.34; P=0.47). Results were similar when stratified by age and by genotype: long QT syndrome type 1 (LQT1), long QT syndrome type 2 (LQT2), and long QT syndrome type 3 (LQT3). Incidence of inappropriate ICD shocks was higher in males versus females (4.2 versus 2.7 episodes per 100 patient‐years; P=0.018), predominantly attributed to atrial fibrillation. The first shock did not terminate ventricular tachycardia/ventricular fibrillation in 48% of females and 62% of males (P=0.25).

Conclusions

In patients with long QT syndrome with an ICD, the risk and rate of life‐threatening events did not significantly differ between males and females regardless of ICD indications or genotype. In a substantial proportion of patients with long QT syndrome, first shock did not terminate ventricular tachycardia/ventricular fibrillation.

Secondary prevention of sudden cardiac death

The prevention and treatment of sudden cardiac death (SCD) remains a significant public health challenge. For patients with a history of sudden death attributable to ventricular arrhythmia, implantable cardioverter-defibrillator (ICD) therapy is a mainstay of treatment, although these patients remain at high risk for recurrent ventricular arrhythmia and defibrillator therapies. In this review, we summarize landmark clinical trials evaluating the efficacy of ICD therapy in secondary prevention patients, review clinical outcomes including mode of death in survivors of SCD, and highlight the role for systematic diagnostic evaluation. We additionally discuss the invasive electrophysiological management of these patients, including ICD selection and programming as well as the role and timing of antiarrhythmic drug therapy and catheter ablation. Finally, we frame future challenges and needs to advance the care for secondary prevention patients.

Epidemiology of Covid-19 in a Long-Term Care Facility in King County, Washington

BACKGROUND

Long-term care facilities are high-risk settings for severe outcomes from outbreaks of Covid-19, owing to both the advanced age and frequent chronic underlying health conditions of the residents and the movement of health care personnel among facilities in a region.

METHODS

After identification on February 28, 2020, of a confirmed case of Covid-19 in a skilled nursing facility in King County, Washington, Public Health-Seattle and King County, aided by the Centers for Disease Control and Prevention, launched a case investigation, contact tracing, quarantine of exposed persons, isolation of confirmed and suspected cases, and on-site enhancement of infection prevention and control.

RESULTS

As of March 18, a total of 167 confirmed cases of Covid-19 affecting 101 residents, 50 health care personnel, and 16 visitors were found to be epidemiologically linked to the facility. Most cases among residents included respiratory illness consistent with Covid-19; however, in 7 residents no symptoms were documented. Hospitalization rates for facility residents, visitors, and staff were 54.5%, 50.0%, and 6.0%, respectively. The case fatality rate for residents was 33.7% (34 of 101). As of March 18, a total of 30 long-term care facilities with at least one confirmed case of Covid-19 had been identified in King County.

CONCLUSIONS

In the context of rapidly escalating Covid-19 outbreaks, proactive steps by long-term care facilities to identify and exclude potentially infected staff and visitors, actively monitor for potentially infected patients, and implement appropriate infection prevention and control measures are needed to prevent the introduction of Covid-19.

Causes of Chest Compression Interruptions During Out-of-Hospital Cardiac Arrest Resuscitation

Background

Interruptions in chest compressions contribute to poor outcomes in out‐of‐hospital cardiac arrest. The objective of this retrospective observational cohort study was to characterize the frequency, reasons, and duration of interruptions in chest compressions and to determine if interruptions changed over time.

Methods and Results

All out‐of‐hospital cardiac arrests treated by the Seattle Fire Department (Seattle, WA, United States) from 2007 to 2016 with capture of recordings from automated external defibrillators and manual defibrillators were included. Compression interruptions >1 second were classified into categories using audio recordings. Among the 3601 eligible out‐of‐hospital cardiac arrests, we analyzed 74 584 minutes, identifying 30 043 pauses that accounted for 6621 minutes (8.9% of total resuscitation duration). The median total interruption duration per case decreased from 115 seconds in 2007 to 72 seconds in 2016 (P<0.0001). Median individual interruption duration decreased from 14 seconds in 2007 to 7 seconds in 2016 (P<0.0001). Among interruptions >10 seconds, median interruption duration decreased from 20 seconds in 2007 to 16 seconds in 2016 (P<0.0001). Cardiac rhythm analysis accounted for most compression interruptions. Manual ECG rhythm analysis and pulse checks accounted for 41.6% of all interruption time (median individual interruption, 8 seconds), automated external defibrillator rhythm analysis for 13.7% (median, 17 seconds), and manual rhythm analysis and shock delivery for 8.0% (median, 9 seconds).

Conclusions

Median duration of chest compression interruptions decreased by half from 2007 to 2016, indicating that care teams can significantly improve performance. Reducing compression interruptions is an evidence‐based benchmark that provides a modifiable process quality improvement goal.

A Method to Detect Presence of Chest Compressions During Resuscitation Using Transthoracic Impedance

OBJECTIVE

Interruptions in chest compressions during treatment of out-of-hospital cardiac arrest are associated with lower likelihood of successful resuscitation. Real-time automated detection of chest compressions may improve CPR administration during resuscitation, and could facilitate application of next-generation ECG algorithms that employ different parameters depending on compression state. In contrast to accelerometer sensors, transthoracic impedance (TTI) is commonly acquired by defibrillators. We sought to develop and evaluate the performance of a TTI-based algorithm to automatically detect chest compressions.

METHODS

Five-second TTI segments were collected from patients with out-of-hospital cardiac arrest treated by one of four defibrillator models. Segments with and without chest compressions were collected prior to each of the first four defibrillation shocks (when available) from each case. Patients were divided randomly into 40% training and 60% validation groups. From the training segments, we identified spectral and time-domain features of the TTI associated with compressions. We used logistic regression to predict compression state from these features. Performance was measured by sensitivity and specificity in the validation set. The relationship between performance and TTI segment length was also evaluated.

RESULTS

The algorithm was trained using 1859 segments from 460 training patients. Validation sensitivity and specificity were >98% using 2727 segments from 691 validation patients. Validation performance was significantly reduced using segments shorter than 3.2 s.

CONCLUSIONS

A novel method can reliably detect the presence of chest compressions using TTI. These results suggest potential to provide real-time feedback in order to improve CPR performance or facilitate next-generation ECG rhythm algorithms during resuscitation.

Survival After Intravenous Versus Intraosseous Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Shock-Refractory Cardiac Arrest

BACKGROUND

Antiarrhythmic drugs have not proven to significantly improve overall survival after out-of-hospital cardiac arrest from shock-refractory ventricular fibrillation/pulseless ventricular tachycardia. How this might be influenced by the route of drug administration is not known.

METHODS

In this prespecified analysis of a randomized, placebo-controlled clinical trial, we compared the differences in survival to hospital discharge in adults with shock-refractory ventricular fibrillation/pulseless ventricular tachycardia out-of-hospital cardiac arrest who were randomly assigned by emergency medical services personnel to an antiarrhythmic drug versus placebo in the ALPS trial (Resuscitation Outcomes Consortium Amiodarone, Lidocaine or Placebo Study), when stratified by the intravenous versus intraosseous route of administration.

RESULTS

Of 3019 randomly assigned patients with a known vascular access site, 2358 received ALPS drugs intravenously and 661 patients by the intraosseous route. Intraosseous and intravenous groups differed in sex, time-to-emergency medical services arrival, and some cardiopulmonary resuscitation characteristics, but were similar in others, including time-to-intravenous/intrasosseous drug receipt. Overall hospital discharge survival was 23%. In comparison with placebo, discharge survival was significantly higher in recipients of intravenous amiodarone (adjusted risk ratio, 1.26 [95% CI, 1.06-1.50]; adjusted absolute survival difference, 5.5% [95% CI, 1.5-9.5]) and intravenous lidocaine (adjusted risk ratio, 1.21 [95% CI, 1.02-1.45]; adjusted absolute survival difference, 4.7% [95% CI, 0.7-8.8]); but not in recipients of intraosseous amiodarone (adjusted risk ratio, 0.94 [95% CI, 0.66-1.32]) or intraosseous lidocaine (adjusted risk ratio, 1.03 [95% CI, 0.74-1.44]). Survival to hospital admission also increased significantly when drugs were given intravenously but not intraosseously, and favored improved neurological outcome at discharge. There were no outcome differences between intravenous and intraosseous placebo, indicating that the access route itself did not demarcate patients with poor prognosis. The study was underpowered to assess intravenous/intraosseous drug interactions, which were not statistically significant.

CONCLUSIONS

We found no significant effect modification by drug administration route for amiodarone or lidocaine in comparison with placebo during out-of-hospital cardiac arrest. However, point estimates for the effects of both drugs in comparison with placebo were significantly greater for the intravenous than for the intraosseous route across virtually all outcomes and beneficial only for the intravenous route. Given that the study was underpowered to statistically assess interactions, these findings signal the potential importance of the drug administration route during resuscitation that merits further investigation.

Association of Bystander and First-Responder Efforts and Outcomes According to Sex: Results From the North Carolina HeartRescue Statewide Quality Improvement Initiative

Background

The Institute of Medicine has called for actions to understand and target sex‐related differences in care and outcomes for out‐of‐hospital cardiac arrest patients. We assessed changes in bystander and first‐responder interventions and outcomes for males versus females after statewide efforts to improve cardiac arrest care.

Methods and Results

We identified out‐of‐hospital cardiac arrests from North Carolina (2010–2014) through the CARES (Cardiac Arrest Registry to Enhance Survival) registry. Outcomes for men versus women were examined through multivariable logistic regression analyses adjusted for (1) nonmodifiable factors (age, witnessed status, and initial heart rhythm) and (2) nonmodifiable plus modifiable factors (bystander cardiopulmonary resuscitation and defibrillation before emergency medical services), including interactions between sex and time (ie, year and year²). Of 8100 patients, 38.1% were women. From 2010 to 2014, there was an increase in bystander cardiopulmonary resuscitation (men, 40.5%–50.6%; women, 35.3%–51.8%; P for each <0.0001) and in the combination of bystander cardiopulmonary resuscitation and first‐responder defibrillation (men, 15.8%–23.0%, P=0.007; women, 8.5%–23.7%, P=0.004). From 2010 to 2014, the unadjusted predicted probability of favorable neurologic outcome was higher and increased more for men (men, from 6.5% [95% confidence interval (CI), 5.1–8.0] to 9.7% [95% CI, 8.1–11.3]; women, from 6.3% [95% CI, 4.4–8.3] to 7.4% [95% CI, 5.5–9.3%]); while adjusted for nonmodifiable factors, it was slightly higher but with a nonsignificant increase for women (from 9.2% [95% CI, 6.8–11.8] to 10.2% [95% CI, 8.0–12.5]; men, from 5.8% [95% CI, 4.6–7.0] to 8.4% [95% CI, 7.1–9.7]). Adding bystander cardiopulmonary resuscitation and defibrillation before EMS (modifiable factors) did not substantially change the results.

Conclusions

Bystander and first‐responder interventions increased for men and women, but outcomes improved significantly only for men. Additional strategies may be necessary to improve survival among female cardiac arrest patients.

The acute respiratory distress syndrome after out-of-hospital cardiac arrest: Incidence, risk factors, and outcomes

OBJECTIVE

To define the incidence of the acute respiratory distress syndrome (ARDS) following out-of-hospital cardiac arrest (OHCA) and characterize its impact on outcome.

METHODS

This was a retrospective cohort study conducted at two urban, tertiary, academic hospitals from 2007 to 2014. We included adults with non-traumatic OHCA and survived for ≥48 h. Patients who received mechanical ventilation for ≥24 h, had 2 consecutive arterial blood gases with a ratio of the partial pressure of oxygen to the fraction of inspired oxygen ≤300, and bilateral radiographic opacities within 48 h of hospital admission were defined as having ARDS. We examined the associations between ARDS and outcome using multivariable analyses and performed sensitivity analyses excluding patients with evidence of cardiac dysfunction.

RESULTS

Of 978 OHCA patients transported to the study hospitals, 600 were mechanically ventilated and survived ≥48 h. A total of 287 (48%, 95% CI 44-52%) met criteria for ARDS within 48 h of admission. There were no differences in demographics, OHCA etiology, or cardiac rhythm according to ARDS status. Patients with ARDS had higher hospital mortality, longer ICU stays, more ventilator days, and were less likely to survive with full neurologic recovery. Upon excluding patients with cardiac dysfunction, the incidence of ARDS was unchanged.

CONCLUSION

Nearly half of initial OHCA survivors develop ARDS within 48 h of hospital admission. ARDS was associated with poor outcome and increased resource utilization. OHCA should be considered among the traditional ARDS risk factors.

Ventricular Fibrillation Waveform Analysis During Chest Compressions to Predict Survival From Cardiac Arrest

BACKGROUND

Quantitative measures of the ventricular fibrillation (VF) ECG waveform can assess myocardial physiology and predict cardiac arrest outcomes, making these measures a candidate to help guide resuscitation. Chest compressions are typically paused for waveform measure calculation because compressions cause ECG artifact. However, such pauses contradict resuscitation guideline recommendations to minimize cardiopulmonary resuscitation interruptions. We evaluated a comprehensive group of VF measures with and without ongoing compressions to determine their performance under both conditions for predicting functionally-intact survival, the study's primary outcome.

METHODS

Five-second VF ECG segments were collected with and without chest compressions before 2755 defibrillation shocks from 1151 out-of-hospital cardiac arrest patients. Twenty-four individual measures and 3 combination measures were implemented. Measures were optimized to predict functionally-intact survival (Cerebral Performance Category score ≤2) using 460 training cases, and their performance evaluated using 691 independent test cases.

RESULTS

Measures predicted functionally-intact survival on test data with an area under the receiver operating characteristic curve ranging from 0.56 to 0.75 (median, 0.73) without chest compressions and from 0.53 to 0.75 (median, 0.69) with compressions ( P<0.001 for difference). Of all measures evaluated, the support vector machine model ranked highest both without chest compressions (area under the receiver operating characteristic curve, 0.75; 95% CI, 0.73-0.78) and with compressions (area under the receiver operating characteristic curve, 0.75; 95% CI, 0.72-0.78; P=0.75 for difference).

CONCLUSIONS

VF waveform measures predict functionally-intact survival when calculated during chest compressions, but prognostic performance is generally reduced compared with compression-free analysis. However, support vector machine models exhibited similar performance with and without compressions while also achieving the highest area under the receiver operating characteristic curve. Such machine learning models may, therefore, offer means to guide resuscitation during uninterrupted cardiopulmonary resuscitation.

Prehospital Care and Emergency Department Door-to-Antibiotic Time in Sepsis

RATIONALE

Early antibiotics improve outcomes for patients with sepsis. Factors influencing antibiotic timing in emergency department (ED) sepsis remain unclear.

OBJECTIVES

Determine the relationship between prehospital level of care of patients with sepsis and ED door-to-antibiotic time.

METHODS

This retrospective cohort study comprised patients admitted from the community to an academic ED June 2009 to February 2015 with fluid-refractory sepsis or septic shock. Transfer patients and those whose antibiotics began before ED arrival or after ED discharge were excluded. We used multivariable regression to evaluate the association between the time from ED arrival to antibiotic initiation and prehospital level of care, defined as the highest level of emergency medical services received: none, basic life support (BLS) ambulance, or advanced life support (ALS) ambulance. We measured variation in this association when hypotension was or was not present by ED arrival.

RESULTS

Among 361 community-dwelling patients with sepsis, the level of prehospital care correlated with illness severity. ALS-treated patients received antibiotics faster than patients who did not receive prehospital care (median, 103 [interquartile range, 75 to 135] vs. 144 [98 to 251] minutes, respectively) or BLS-only patients (168 [100-250] minutes; P < 0.001 for each pairwise comparison with ALS). This pattern persisted after multivariable adjustment, where ALS care (-43 min; 95% confidence interval [CI], -84 to -2; P = 0.033) but not BLS-only care (-4 min; 95% CI, -41 to +34; P = 0.97) was associated with less antibiotic delay compared with no prehospital care. ALS-treated patients more frequently received antibiotics within 3 hours of ED arrival (91%) compared with walk-in patients (62%; adjusted odds ratio, 3.11; 95% CI, 1.20 to 8.03; P = 0.015) or BLS-treated patients (56%; adjusted odds ratio, 4.51; 95% CI, 1.89 to 11.35; P < 0.001). ALS-treated patients started antibiotics faster than walk-in patients in the absence of hypotension by ED arrival (-41 min; 95% CI, -110 to -13; P = 0.009) but not when hypotension was present (+25 min; 95% CI, -43 to +92; P = 0.66).

CONCLUSIONS

Prehospital ALS but not BLS-only care was associated with faster antibiotic initiation for patients with sepsis without hypotension. Process redesign for non-ALS patients may improve antibiotic timeliness for ED sepsis.

Impact of Regionalization of ST-Segment–Elevation Myocardial Infarction Care on Treatment Times and Outcomes for Emergency Medical Services–Transported Patients Presenting to Hospitals With Percutaneous Coronary Intervention

Background:

Regional variations in reperfusion times and mortality in patients with ST-segment–elevation myocardial infarction are influenced by differences in coordinating care between emergency medical services (EMS) and hospitals. Building on the Accelerator-1 Project, we hypothesized that time to reperfusion could be further reduced with enhanced regional efforts.

Methods:

Between April 2015 and March 2017, we worked with 12 metropolitan regions across the United States with 132 percutaneous coronary intervention–capable hospitals and 946 EMS agencies. Data were collected in the ACTION (Acute Coronary Treatment and Intervention Outcomes Network)-Get With The Guidelines Registry for quarterly Mission: Lifeline reports. The primary end point was the change in the proportion of EMS-transported patients with first medical contact to device time ≤90 minutes from baseline to final quarter. We also compared treatment times and mortality with patients treated in hospitals not participating in the project during the corresponding time period.

Results:

During the study period, 10 730 patients were transported to percutaneous coronary intervention–capable hospitals, including 974 in the baseline quarter and 972 in the final quarter who met inclusion criteria. Median age was 61 years; 27% were women, 6% had cardiac arrest, and 6% had shock on admission; 10% were black, 12% were Latino, and 10% were uninsured. By the end of the intervention, all process measures reflecting coordination between EMS and hospitals had improved, including the proportion of patients with a first medical contact to device time of ≤90 minutes (67%–74%; P <0.002), a first medical contact to device time to catheterization laboratory activation of ≤20 minutes (38%–56%; P <0.0001), and emergency department dwell time of ≤20 minutes (33%–43%; P <0.0001). Of the 12 regions, 9 regions reduced first medical contact to device time, and 8 met or exceeded the national goal of 75% of patients treated in ≤90 minutes. Improvements in treatment times corresponded with a significant reduction in mortality (in-hospital death, 4.4%–2.3%; P =0.001) that was not apparent in hospitals not participating in the project during the same time period.

Conclusions:

Organization of care among EMS and hospitals in 12 regions was associated with significant reductions in time to reperfusion in patients with ST-segment–elevation myocardial infarction as well as in in-hospital mortality. These findings support a more intensive regional approach to emergency care for patients with ST-segment–elevation myocardial infarction.

Multistate 5-Year Initiative to Improve Care for Out-of-Hospital Cardiac Arrest: Primary Results From the HeartRescue Project

Background

The HeartRescue Project is a multistate public health initiative focused on establishing statewide out‐of‐hospital cardiac arrest (OHCA) systems of care to improve case capture and OHCA care in the community, by emergency medical services (EMS), and at hospital level.

Methods and Results

From 2011 to 2015 in the 5 original HeartRescue states, all adults with EMS–treated OHCA due to a presumed cardiac cause were included. In an adult population of 32.8 million, a total of 64 988 OHCAs—including 10 046 patients with a bystander‐witnessed OHCA with a shockable rhythm—were treated by 330 EMS agencies. From 2011 to 2015, the case‐capture rate for all‐rhythm OHCA increased from an estimated 39.0% (n=6762) to 89.2% (n=16 103; P<0.001 for trend). Overall survival to hospital discharge was 11.4% for all rhythms and 34.0% in the subgroup with bystander‐witnessed OHCA with a shockable rhythm. We observed modest temporal increases in bystander cardiopulmonary resuscitation (41.8–43.5%, P<0.001 for trend) and bystander automated external defibrillator application (3.2–5.6%, P<0.001 for trend) in the all‐rhythm group, although there were no temporal changes in survival. There were marked all‐rhythm survival differences across the 5 states (8.0–16.1%, P<0.001) and across participating EMS agencies (2.7–26.5%, P<0.001).

Conclusions

In the initial 5 years, the HeartRescue Project developed a population‐based OHCA registry and improved statewide case‐capture rates and some processes of care, although there were no early temporal changes in survival. The observed survival variation across states and EMS systems presents a future challenge to elucidate the characteristics of high‐performing systems with the goal of improving OHCA care and survival.

Ventricular fibrillation waveform measures combined with prior shock outcome predict defibrillation success during cardiopulmonary resuscitation

AIM

Amplitude Spectrum Area (AMSA) and Median Slope (MS) are ventricular fibrillation (VF) waveform measures that predict defibrillation shock success. Cardiopulmonary resuscitation (CPR) obscures electrocardiograms and must be paused for analysis. Studies suggest waveform measures better predict subsequent shock success when combined with prior shock success. We determined whether this relationship applies during CPR.

METHODS

AMSA and MS were calculated from 5-second pre-shock segments with and without CPR, and compared to logistic models combining each measure with prior return of organized rhythm (ROR).

RESULTS

VF segments from 692 patients were analyzed during CPR before 1372 shocks and without CPR before 1283 shocks. Combining waveform measures with prior ROR increased areas under receiver operating characteristic curves for AMSA/MS with CPR (0.66/0.68 to 0.73/0.74, p<0.001) and without CPR (0.71/0.72 to 0.76/0.76, p<0.001).

CONCLUSIONS

Prior ROR improves prediction of shock success during CPR, and may enable waveform measure calculation without chest compression pauses.