Association of prehospital hypotension depth and dose with survival following out-of-hospital cardiac arrest

A retrospective 'target trial emulation' comparing amiodarone and lidocaine for adult out-of-hospital cardiac arrest resuscitation

OBJECTIVE

The administration of amiodarone or lidocaine is recommended during the resuscitation of out-of-hospital cardiac arrest (OHCA) patients presenting with defibrillation-refractory or recurrent ventricular fibrillation or ventricular tachycardia. Our objective was to use 'target trial emulation' methodology to compare the outcomes of patients who received amiodarone or lidocaine during resuscitation.

METHODS

Adult, non-traumatic OHCA patients in the ESO Data Collaborative 2018-2023 datasets who experienced OHCA prior to EMS arrival, presented with a shockable rhythm, and received amiodarone or lidocaine during resuscitation were evaluated for inclusion. We used propensity score matching (PSM) to investigate the association between antiarrhythmic and outcomes. Return of spontaneous circulation (ROSC) was the primary outcome. Secondary outcomes included the number of post-drug defibrillations and survival to hospital discharge.

RESULTS

After application of exclusion criteria, 23,263 patients from 1,707 EMS agencies were eligible for analysis. Prior to PSM, 6,010/20,284 (29.6%) of the patients who received amiodarone and 1,071/2,979 (35.9%) of the patients who received lidocaine achieved prehospital ROSC. Following PSM, lidocaine administration was associated with greater odds of prehospital ROSC (36.0 vs. 30.4%; aOR: 1.29 [1.16, 1.44], n = 2,976 matched pairs). Lidocaine administration was also associated with fewer post-drug defibrillations (median: 2 [0-4] vs. 2 [0-6], mean: 3.3 vs. 3.9, p < 0.01, n = 2,976 pairs), and greater odds of survival to discharge (35.1 vs. 25.7%; OR: 1.54 [1.19, 2.00], n = 538 pairs).

CONCLUSION

Our 'target trial emulation' suggested that lidocaine was associated with greater odds of prehospital ROSC in comparison to amiodarone when administered during resuscitation from shock refractory or recurrent VF/VT.

Advancing a machine learning-based decision support tool for pre-hospital assessment of dyspnoea by emergency medical service clinicians: a retrospective observational study

BACKGROUND

In Sweden with about 10 million inhabitants, there are about one million primary ambulance missions every year. Among them, around 10% are assessed by Emergency Medical Service (EMS) clinicians with the primary symptom of dyspnoea. The risk of death among these patients has been reported to be remarkably high, at 11,1% and 13,2%. The aim was to develop a Machine Learning (ML) model to provide support in assessing patients in pre-hospital settings and to compare them with established triage tools.

METHODS

This was a retrospective observational study including 6,354 patients who called the Swedish emergency telephone number (112) between January and December 2017. Patients presenting with the main symptom of dyspnoea were included which were recruited from two EMS organisations in Göteborg and Södra Älvsborg. Serious Adverse Event (SAE) was used as outcome, defined as any of the following:1) death within 30 days after call for an ambulance, 2) a final diagnosis defined as time-sensitive, 3) admitted to intensive care unit, or 4) readmission within 72 h and admitted to hospital receiving a final time-sensitive diagnosis. Logistic regression, LASSO logistic regression and gradient boosting were compared to the Rapid Emergency Triage and Treatment System for Adults (RETTS-A) and National Early Warning Score2 (NEWS2) with respect to discrimination and calibration of predictions. Eighty percent (80%) of the data was used for model development and 20% for model validation.

RESULTS

All ML models showed better performance than RETTS-A and NEWS2 with respect to all evaluated performance metrics. The gradient boosting algorithm had the overall best performance, with excellent calibration of the predictions, and consistently showed higher sensitivity to detect SAE than the other methods. The ROC AUC on test data increased from 0.73 (95% CI 0.70-0.76) with RETTS-A to 0.81 (95% CI 0.78-0.84) using gradient boosting.

CONCLUSIONS

Among 6,354 ambulance missions caused by patients suffering from dyspnoea, an ML method using gradient boosting demonstrated excellent performance for predicting SAE, with substantial improvement over the more established methods RETTS-A and NEWS2.

Rationale and development of a prehospital goal-directed bundle of care to prevent rearrest after return of spontaneous circulation

In patients with out-of-hospital cardiac arrest (OHCA) who attain return of spontaneous circulation (ROSC), rearrest while in the prehospital setting represents a significant barrier to survival. To date, there are limited data to guide prehospital emergency medical services (EMS) management immediately following successful resuscitation resulting in ROSC and prior to handoff in the emergency department. Post-ROSC care encompasses a multifaceted approach including hemodynamic optimization, airway management, oxygenation, and ventilation. We sought to develop an evidenced-based, goal-directed bundle of care targeting specified vital parameters in the immediate post-ROSC period, with the goal of decreasing the incidence of rearrest and improving survival outcomes. Here, we describe the rationale and development of this goal-directed bundle of care, which will be adopted by several EMS agencies within California. We convened a group of EMS experts, including EMS Medical Directors, quality improvement officers, data managers, educators, EMS clinicians, emergency medicine clinicians, and resuscitation researchers to develop a goal-directed bundle of care to be applied in the field during the period immediately following ROSC. This care bundle includes guidance for prehospital personnel on recognition of impending rearrest, hemodynamic optimization, ventilatory strategies, airway management, and diagnosis of underlying causes prior to the initiation of transport.

Management of Patients With Cardiac Arrest Requiring Interfacility Transport: A Scientific Statement From the American Heart Association

People who experience out-of-hospital cardiac arrest often require care at a regional center for continued treatment after resuscitation, but many do not initially present to the hospital where they will be admitted. For patients who require interfacility transport after cardiac arrest, the decision to transfer between centers is complex and often based on individual clinical characteristics, resources at the presenting hospital, and available transport resources. Once the decision has been made to transfer a patient after cardiac arrest, there is little direct guidance on how best to provide interfacility transport. Accepting centers depend on transferring emergency departments and emergency medical services professionals to make important and nuanced decisions about postresuscitation care that may determine the efficacy of future treatments. The consequences of early care are greater when transport delays occur, which is common in rural areas or due to inclement weather. Challenges of providing interfacility transfer services for patients who have experienced cardiac arrest include varying expertise of clinicians, differing resources available to them, and nonstandardized communication between transferring and receiving centers. Although many aspects of care are insufficiently studied to determine implications for specific out-of-hospital treatment on outcomes, a general approach of maintaining otherwise recommended postresuscitation care during interfacility transfer is reasonable. This includes close attention to airway, vascular access, ventilator management, sedation, cardiopulmonary monitoring, antiarrhythmic treatments, blood pressure control, temperature control, and metabolic management. Patient stability for transfer, equity and inclusion, and communication also must be considered. Many of these aspects can be delivered by protocol-driven care.

Prehospital Post-Resuscitation Vital Sign Phenotypes are Associated with Outcomes Following Out-of-Hospital Cardiac Arrest

OBJECTIVES

The use of machine learning to identify patient 'clusters' using post-return of spontaneous circulation (ROSC) vital signs may facilitate the identification of patient subgroups at high risk of rearrest and mortality. Our objective was to use k-means clustering to identify post-ROSC vital sign clusters and determine whether these clusters were associated with rearrest and mortality.

METHODS

The ESO Data Collaborative 2018-2022 datasets were used for this study. We included adult, non-traumatic OHCA patients with >2 post-ROSC vital sign sets. Patients were excluded if they had an EMS-witnessed OHCA or were encountered during an interfacility transfer. Unsupervised (k-means) clustering was performed using minimum, maximum, and delta (last minus first) systolic blood pressure (BP), heart rate, SpO2, shock index, and pulse pressure. The assessed outcomes were mortality and rearrest. To explore the association between rearrest, mortality, and cluster, multivariable logistic regression modeling was used.

RESULTS

Within our cohort of 12,320 patients, five clusters were identified. Patients in cluster 1 were hypertensive, patients in cluster 2 were normotensive, patients in cluster 3 were hypotensive and tachycardic (n = 2164; 17.6%), patients in cluster 4 were hypoxemic and exhibited increasing systolic BP, and patients in cluster 5 were severely hypoxemic and exhibited a declining systolic BP. The overall proportion of patients who experienced mortality stratified by cluster was 63.4% (c1), 68.1% (c2), 78.8% (c3), 84.8% (c4), and 86.6% (c5). In comparison to the cluster with the lowest mortality (c1), each other cluster was associated with greater odds of mortality and rearrest.

CONCLUSIONS

Unsupervised k-means clustering yielded 5 post-ROSC vital sign clusters that were associated with rearrest and mortality.

A retrospective, multi-agency 'target trial emulation' for the comparison of post-resuscitation epinephrine to norepinephrine

INTRODUCTION

Epinephrine and norepinephrine are the two most commonly used prehospital vasopressors in the United States. Prior studies have suggested that use of a post-ROSC epinephrine infusion may be associated with increased rearrest and mortality in comparison to use of norepinephrine. We used target trial emulation methodology to compare the rates of rearrest and mortality between the groups of OHCA patients receiving these vasopressors in the prehospital setting.

METHODS

Adult (18-80 years of age) non-traumatic OHCA patients in the 2018-2022 ESO Data Collaborative datasets with a documented post-ROSC norepinephrine or epinephrine infusion were included in this study. Logistic regression modeling was used to evaluate the association between vasopressor agent and outcome using two sets of covariables. The first set of covariables included standard Utstein factors, the dispatch to ROSC interval, the ROSC to vasopressor interval, and the follow-up interval. The second set added prehospital systolic blood pressure and SpO2 values. Kaplan-Meier time-to-event analysis was also conducted and the vasopressor groups were compared using a multivariable Cox regression model.

RESULTS

Overall, 1,893 patients treated by 309 EMS agencies were eligible for analysis. 1,010 (53.4%) received an epinephrine infusion and 883 (46.7%) received a norepinephrine infusion as their initial vasopressor. Adjusted analyses did not discover an association between vasopressor agent and rearrest (aOR: 0.93 [0.72, 1.21]) or mortality (aOR: 1.00 [0.59, 1.69]).

CONCLUSIONS

In this multi-agency target trial emulation, the use of a post-resuscitation epinephrine infusion was not associated with increased odds of rearrest in comparison to the use of a norepinephrine infusion.

A Guide to the Use of Vasopressors and Inotropes for Patients in Shock

Shock is a life-threatening circulatory failure that results in inadequate tissue perfusion and oxygenation. Vasopressors and inotropes are vasoactive medications that are vital in increasing systemic vascular resistance and cardiac contractility, respectively, in patients presenting with shock. To be well versed in using these agents is an important skill to have in the critical care setting where patients can frequently exhibit symptoms of shock. In this review, we will discuss the pathophysiological mechanisms of shock and evaluate the current evidence behind the management of shock with an emphasis on vasopressors and inotropes.

Retrospective Comparison of Upper and Lower Extremity Intraosseous Access During Out-of-Hospital Cardiac Arrest Resuscitation

OBJECTIVE

Intraosseous (IO) access is frequently utilized during the resuscitation of out-of-hospital cardiac arrest (OHCA) patients. Due to proximity to the heart and differential flow rates, the anatomical site of IO access may impact patient outcomes. Using a large dataset, we aimed to compare the outcomes of OHCA patients who received upper or lower extremity IO access during resuscitation.

METHODS

The ESO Data Collaborative public use research datasets were used for this retrospective study. All adult (≥18 years of age) OHCA patients with successful IO access in an upper or lower extremity were evaluated for inclusion. Patients were excluded if they had intravenous (IV) access prior to IO access, or if they had a Do Not Resuscitate order documented. Our primary outcome was return of spontaneous circulation (ROSC). Secondary outcomes included survival to discharge and survival to discharge to home. Mixed-effects multivariable logistic regression models adjusted for age, sex, etiology, witnessed status, pre-first responder cardiopulmonary resuscitation (CPR), initial electrocardiogram (ECG) rhythm, location [private/residential, public, or assisted living/institutional], and response time in addition to the primary airway management strategy (endotracheal intubation, supraglottic device, surgical airway, no advanced airway) were used to compare the outcomes of patients with upper extremity IO access to the outcomes of patients with lower extremity IO access.

RESULTS

After application of exclusion criteria, 155,884 patients who received IO access during resuscitation remained (76% lower extremity, 24% upper extremity). Upper extremity IO access was associated with greater adjusted odds of ROSC (1.11 [1.08, 1.15]), and this finding was consistent across multiple patient subgroups. Secondary analyses suggested that upper extremity access was associated with increased survival to discharge (1.18 [1.00, 1.39]) and survival to discharge to home (1.23 [1.02, 1.48]) in comparison to lower extremity IO access.

CONCLUSION

In this large prehospital dataset, upper extremity IO access was associated with a small increase in the odds of ROSC in comparison to lower extremity IO access. These data support the need for prospective investigation of the ideal IO access site during OHCA resuscitation.

The association of clinical, treatment, and demographic characteristics with rearrest in a national dataset

INTRODUCTION

Following initial resuscitation from out-of-hospital cardiac arrest, rearrest frequently occurs and has been associated with adverse outcomes. We aimed to identify clinical, treatment, and demographic characteristics associated with prehospital rearrest at the encounter and agency levels.

METHODS

Adult non-traumatic cardiac arrest patients who achieved ROSC following EMS resuscitation in the 2018-2021 ESO annual datasets were included in this study. Patients were excluded if they had a documented DNR/POLST or achieved ROSC after bystander CPR only. Rearrest was defined as post-ROSC CPR initiation, administration of ≥ 1 milligram of adrenaline, defibrillation, or a documented non-perfusing rhythm on arrival at the receiving hospital. Multivariable logistic regression modeling was used to evaluate the association between rearrest and case characteristics. Linear regression modeling was used to evaluate the association between agency-level factors (ROSC rate, scene time, and scene termination rate), and rearrest rate.

RESULTS

Among the 53,027 cases included, 16,116 (30.4%) experienced rearrest. Factors including longer response intervals, longer 'low-flow' intervals, unwitnessed OHCA, and a lack of bystander CPR were associated with rearrest. Among agencies that treated ≥ 30 patients with outcome data, the agency-level rate of rearrest was inversely associated with agency-level rate of survival to discharge to home (R2 = -0.393, p < 0.001).

CONCLUSIONS

This multiagency retrospective study found that factors associated with increased ischaemic burden following OHCA were associated with rearrest. Agency-level rearrest frequency was inversely associated with agency-level survival to home. Interventions that decrease the burden of ischemia sustained by OHCA patients may decrease the rate of rearrest and increase survival.

The Association of Combined Prehospital Hypotension and Hypoxia with Outcomes following Out-of-Hospital Cardiac Arrest Resuscitation

BACKGROUND

Prehospital post-resuscitation hypotension and hypoxia have been associated with adverse outcomes in the context of out-of-hospital cardiac arrest (OHCA). We aimed to investigate the association between clinical outcomes and post-resuscitation hypoxia alone, hypotension alone, and combined hypoxia and hypotension.

METHODS

We used the 2018-2021 ESO annual datasets to conduct this study. All EMS-treated non-traumatic OHCA patients who had a documented prehospital return of spontaneous circulation (ROSC) and two or more SpO2 readings and systolic blood pressures recorded were evaluated for inclusion. Patients who were less than 18 years of age, pregnant, had a do-not-resuscitate order or similar, achieved ROSC after bystander CPR only, or had an EMS-witnessed cardiac arrest were excluded. Multivariable logistic regression adjusted for standard Utstein factors and highest prehospital Glasgow Coma Scale (GCS) score was used to investigate the association between hypoxia, hypotension, and outcomes.

RESULTS

We analyzed data for 17,943 patients, of whom 3,979 had hospital disposition data. Hypotension and hypoxia were not documented in 1,343 (33.8%) patients, 1,144 (28.8%) had only hypoxia documented, 507 (12.7%) had only hypotension documented, and 985 (24.8%) had both hypoxia and hypotension documented. In comparison to patients who did not have documented hypotension or hypoxia, patients who had documented hypoxia (aOR: 1.76 [1.38, 2.24]), documented hypotension (aOR: 3.00 [2.15, 4.18]), and documented hypoxia and hypotension combined (aOR: 4.87 [3.63, 6.53]) had significantly increased mortality. The relationship between mortality and vital sign abnormalities (hypoxia and hypotension > hypotension > hypoxia) was observed in every evaluated subgroup.

CONCLUSIONS

In this large dataset, hypotension and hypoxia were independently associated with mortality both alone and in combination. Compared to patients without documented hypotension and hypoxia, patients with documented hypotension and hypoxia had nearly five-fold greater odds of mortality.

The association of the post-resuscitation on-scene interval and patient outcomes after out-of-hospital cardiac arrest

BACKGROUND

After resuscitation from out-of-hospital cardiac arrest (OHCA) by Emergency Medical Services (EMS), the amount of time that should be dedicated to pre-transport stabilization is unclear. We examined whether the time spent on-scene after return of spontaneous circulation (ROSC) was associated with patient outcomes.

METHODS

We examined consecutive adult EMS-treated OHCAs from the British Columbia Cardiac Arrest registry (January 1/2019-June 1/2021) that had on-scene ROSC (sustained to scene departure). The primary outcome was favourable neurological outcome (Cerebral Performance Category ≤ 2) at hospital discharge; secondary outcomes were re-arrest during transport and hospital-discharge survival. Using adjusted logistic regression models, we estimated the association between the post-resuscitation on-scene interval (divided into quartiles) and outcomes.

RESULTS

Of 1653 cases, 611 (37%) survived to hospital discharge, and 523 (32%) had favourable neurological outcomes. The median post-resuscitation on-scene interval was 18.8 minutes (IQR:13.0-25.5). Compared to the first post-resuscitation on-scene interval quartile, neither the second (adjusted odds ratio [AOR] 1.19; 95% CI 0.72-1.98), third (AOR 1.10; 95% CI 0.67-1.81), nor fourth (AOR 1.54; 95% CI 0.93-2.56) quartiles were associated with favourable neurological outcomes; however, the fourth quartile was associated with a greater odds of hospital-discharge survival (AOR 1.73; 95% CI 1.05-2.85), and both the third (AOR 0.40; 95% CI 0.22-0.72) and fourth (AOR 0.44;95% CI 0.24-0.81) quartiles were associated with a lower odds of intra-transport re-arrest.

CONCLUSION

Among resuscitated OHCAs, increased post-resuscitation on-scene time was not associated with improved neurological outcomes, but was associated with improved survival to hospital discharge and decreased intra-transport re-arrest.