Real-time cerebral oximetry and outcomes during out-of-hospital resuscitation.

Background: Anoxic brain injury is a common mode of death following out-of-hospital cardiac arrest (OHCA). We assessed the course of regional cerebral oxygen saturation (rSO) during resuscitation to understand its association with return of spontaneous circulation (ROSC) and functional survival.

Methods: We conducted a prospective observational investigation of OHCA patients treated by Emergency Medical Services (EMS) in a suburban community.

Implications of an individualized resuscitation strategy using continuous rhythm and physiologic status assessment during ongoing CPR.

Background: Prior studies have proposed defibrillator biosignal algorithms which characterize cardiac arrest rhythm and physiologic status. We evaluated whether a novel, individualized resuscitation strategy that integrates multiple ECG and impedance-based algorithms could reduce CPR interruptions and better align rescuer actions with patient-specific physiology.

Methods: In a retrospective cohort of ventricular fibrillation out-of-hospital cardiac arrests, observed rescuer actions (rhythm analysis, shock delivery, pulse checks, and drug therapy) were compared to hypothetical actions recommended by the proposed individualized strategy.

Classifying Race in Out-of-Hospital Cardiac Arrest and Potential Disparities: A Retrospective Cohort Study.

Background: Although racial disparities have been described in resuscitation, little is known about potential bias in race classification of out-of-hospital cardiac arrest (OHCA).

Methods: We conducted a retrospective cohort study of adults treated by emergency medical services (EMS) for nontraumatic OHCA in King County, WA between January 1, 2018, and December 31, 2021. We assessed agreement using κ and evaluated patterns of missingness between EMS-assessed race versus comprehensive race classification from hospital and death records.

Age, sex, and survival following ventricular fibrillation cardiac arrest: A mechanistic evaluation of the ECG waveform.

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.

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.

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.

Racial Disparity in Oxygen Saturation Measurements by Pulse Oximetry: Evidence and Implications.

The pulse oximeter is a ubiquitous clinical tool used to estimate blood oxygen concentrations. However, decreased accuracy of pulse oximetry in patients with dark skin tones has been demonstrated since as early as 1985. Most commonly, pulse oximeters may overestimate the true oxygen saturation in individuals with dark skin tones, leading to higher rates of occult hypoxemia (i.

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.

Investigating the Airway Opening Index during cardiopulmonary resuscitation.

Introduction: Chest compressions during CPR induce oscillations in capnography (ECO) waveforms. Studies suggest ECO oscillation characteristics are associated with intrathoracic airflow dependent on airway patency. Oscillations can be quantified by the Airway Opening Index (AOI).

A method for continuous rhythm classification and early detection of ventricular fibrillation during CPR.

Aim: We developed a method which continuously classifies the ECG rhythm during CPR in order to guide clinical care.

Methods: We conducted a retrospective study of 432 patients treated following out-of-hospital cardiac arrest. Continuous ECG sequences from two-minute CPR cycles were extracted from defibrillator recordings and further divided into five-second clips.

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.

Insights From the Ventricular Fibrillation Waveform Into the Mechanism of Survival Benefit From Bystander Cardiopulmonary Resuscitation.

Background The mechanism by which bystander cardiopulmonary resuscitation (CPR) improves survival following out-of-hospital cardiac arrest is unclear. We hypothesized that ventricular fibrillation (VF) waveform measures, as surrogates of myocardial physiology, mediate the relationship between bystander CPR and survival. Methods and Results We performed a retrospective cohort study of adult, bystander-witnessed patients with out-of-hospital cardiac arrest with an initial rhythm of VF who were treated by a metropolitan emergency medical services system from 2005 to 2018.

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.

Electrocardiogram-based pulse prediction during cardiopulmonary resuscitation.

Objective: Resuscitation requires CPR interruptions every 2 min to assess rhythm and pulse status. We developed a method to predict real-time pulse status in organized rhythm ECG segments with and without CPR artifact.

Methods: The study cohort included patients who received attempted resuscitation following ventricular fibrillation arrest.

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.

The association of chronic health status and survival following ventricular fibrillation cardiac arrest: Investigation of a primary myocardial mechanism.

Introduction: Quantitative waveform measures are a surrogate of the acute physiological status of the myocardium and predict survival following ventricular fibrillation out-of-hospital cardiac arrest (OHCA). We investigated whether the amplitude spectrum area (AMSA) waveform measure mediates the adverse relationship between increasing burden of chronic health conditions and lower likelihood of survival.

Methods: We performed a cohort investigation of persons > = 18 years who suffered ventricular fibrillation OHCA between 2008-2015 in a metropolitan emergency medical service (EMS) system.

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.

Rhythm profiles and survival after out-of-hospital ventricular fibrillation cardiac arrest.

Objective: Treatment: protocols for cardiac arrest rely upon rhythm analyses performed at two-minute intervals, neglecting possible rhythm changes during the intervening period of CPR. Our objective was to describe rhythm profiles (patterns of rhythm transitions during two-minute CPR cycles) following attempted defibrillation and to assess their relationship to survival.

Methods: The study included out-of-hospital cardiac arrest cases presenting with ventricular fibrillation from 2011 to 2015.

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.

Ventricular fibrillation waveform measures and the etiology of cardiac arrest.

Background: Early determination of the acute etiology of cardiac arrest could help guide resuscitation or post-resuscitation care. In experimental studies, quantitative measures of the ventricular fibrillation waveform distinguish ischemic from non-ischemic etiology.

Methods: We investigated whether waveform measures distinguished arrest etiology among adults treated by EMS for out-of-hospital ventricular fibrillation between January 1, 2006-December 31, 2014.

Short ECG segments predict defibrillation outcome using quantitative waveform measures.

Aim: Quantitative waveform measures of the ventricular fibrillation (VF) electrocardiogram (ECG) predict defibrillation outcome. Calculation requires an ECG epoch without chest compression artifact. However, pauses in CPR can adversely affect survival.

An accurate method for real-time chest compression detection from the impedance signal.

Objective: Real-time feedback improves CPR performance. Chest compression data may be obtained from an accelerometer/force sensor, but the impedance signal would serve as a less costly, universally available alternative. The objective is to assess the performance of a method which detects the presence/absence of chest compressions and derives CPR quality metrics from the impedance signal in real-time at 1s intervals without any latency period.

Adaptive rhythm sequencing: A method for dynamic rhythm classification during CPR.

Objective: The accuracy of methods that classify the cardiac rhythm despite CPR artifact could potentially be improved by utilizing continuous ECG data. Our objective is to compare three approaches which use identical ECG features and differ only in their degree of temporal integration: (1) static classification, which analyzes 4-s ECG frames in isolation; (2) "best-of-three averaging," which takes the average of three consecutive static classifications successively; and (3) "adaptive rhythm sequencing," which uses hidden Markov models to model ECG segments as rhythm sequences.

Methods: Defibrillator recordings from 95 out-of-hospital cardiac arrests were divided into training and test sets.

Cardiopulmonary resuscitation duty cycle in out-of-hospital cardiac arrest.

Background: Duty cycle is the portion of time spent in compression relative to total time of the compression-decompression cycle. Guidelines recommend a 50% duty cycle based largely on animal investigation. We undertook a descriptive evaluation of duty cycle in human resuscitation, and whether duty cycle correlates with other CPR measures.

Course of quantitative ventricular fibrillation waveform measure and outcome following out-of-hospital cardiac arrest.

Background: Quantitative measures of the ventricular fibrillation waveform at the outset of resuscitation are associated with survival. However, little is known about the course of these measures during resuscitation and how this course is related to outcome.

Objective: The purpose of this study was to determine how waveform measures change over the course of resuscitation and whether these changes might be used to guide resuscitation.