Lawrence D Sherman

• Professor (Associate) at University of Washington

Background: Quantitative measures of the ventricular fibrillation (VF) electrocardiogram (ECG) such as Amplitude Spectrum Area (AMSA) assess myocardial physiology and predict cardiac arrest outcomes, offering the potential to guide resuscitation care. Guidelines recommend minimally-interrupted chest compressions (CCs) during resuscitation, but CCs...

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...

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. Thus the potential use of waveform measures is limited by the need to pause CPR. We sought to ch...

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...

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 four-second ECG frames in isola...

Background: During resuscitation of cardiac arrest victims a variety of information in electronic format is recorded as part of the documentation of the patient care contact and in order to be provided for case review for quality improvement. Such review requires considerable effort and resources. There is also the problem of interobserver effects...

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. We evaluated 390 persons treated by emergency providers following out-of-hospital ventricular fibrilla...

Introduction: Methods to identify appropriate treatments for the various stages of ventricular fibrillation (VF) involve differentiating groups of subjects who will respond to defibrillation with return of spontaneous circulation (ROSC) and those who require other therapies (e.g., CPR, drugs) prior to defibrillation. The use of quantitative wavefo...

There are few if any real-time physiologic measures that currently provide feedback during resuscitation from cardiac arrest. Such measures could be used to guide therapy not simply based on process guidelines but on the physiologic response of the patient from moment to moment. To this end, we applied an existing technology - quantitative waveform...

Some patients presenting with nonshockable cardiac arrest rhythms will subsequently manifest ventricular fibrillation. Their prognosis remains poor despite transition to a shockable rhythm. Quantitative waveform measures assess the electrophysiologic status of the fibrillating heart and predict outcome. To use waveform measures to compare those who...

Background: Cardiocerebral resuscitation (CCR) is reportedly superior to cardiopulmonary resuscitation (CPR) for primary cardiac arrest in the prehospital setting. This study was done using a swine model of prolonged ventricular fibrillation (VF) to quantify the effect of the emergency medical services component of CCR with intraosseous access (CC...

Quantitative measures of the ventricular fibrillation (VF) electrocardiogram (ECG) have been correlated with the success of rescue shocks, making them ideal measures for guiding resuscitative interventions. Correlation of intramyocardial energy stores with the change in quantitative VF ECG measures would provide mechanistic insight into their utili...

Hypothermia has been shown to improve survival and neurological outcomes for ventricular fibrillation (VF) cardiac arrest. The electrophysiological mechanisms of hypothermia are not well-understood, nor are the effects of beginning cooling during the resuscitation. We hypothesized that inducing hypothermia prior to the onset of VF would slow the de...

Background: The Logarithm of the Absolute Correlations (LAC) is a measure which estimates VF duration based on the fractal dimension of the waveform. We hypothesized that the LAC measures the underlying physiology of the myocardium and would enable identification of those who would have return of spontaneous circulation (ROSC) in response to the in...

Background: Analysis of the ECG has been shown to be useful to estimate the duration of VF in swine and the probability of successful defibrillation in animals and in patients. We use four methods to analyze the waveform: the logarithm of the absolute correlations (LAC): the median slope (MS): the angular velocity (AV): the amplitude spectrum area...

Endogenous adenosine (ADO) is cardioprotective during ischemia and its myocardial concentration increases during untreated ventricular fibrillation (VF). We have previously shown that ADO A1 receptor (ADOA1R) antagonism hastens the time-dependent decay in VF waveform morphology during the circulatory phase of cardiac arrest. To determine the effect...

An impedance threshold device (ITD) has been designed to enhance circulation during CPR. A recent study suggests that the ITD does not improve hemodynamics and that it may actually worsen outcomes. We sought to independently assess the effect of the ITD on coronary perfusion pressure (CPP) and passive ventilation (PaCO(2) and PaO(2)) during standar...

Background: Measures of the ventricular fibrillation (VF) waveform may enable better allocation of cardiac arrest treatment by discriminating which patients should receive immediate defibrillation versus alternate therapies such as CPR. We derive a new measure based on the 'roughness' of the VF waveform, the Logarithm of the Absolute Correlations...

Introduction: Most animal studies of ventricular fibrillation (VF) waveform characteristics involve healthy animals with VF initiated by electric shock. However, clinical VF is usually the result of ischemia. The waveform characteristics in these two types of VF may differ. The angular velocity (AV), frequency ratio (FR) and median frequency (MF)...

Introduction: Induced hypothermia has been shown to improve survival and neurologic outcomes for ventricular fibrillation (VF) cardiac arrest. Clinical studies have not begun inducing hypothermia until after return of spontaneous circulation (ROSC). The effects of cooling during the resuscitation are not well-studied. Hypothesis: We hypothesized th...

Background: Ventricular fibrillation (VF) is highly energy-wasteful, producing no perfusion. High-energy phosphates (HEPs) deplete rapidly during VF, adding to metabolic/ischemic stress and adversely affecting VF. We have shown that the scaling exponent (ScE) of the VF waveform predicts rescue shock outcome and can be used to guide decision-making...

Background: Endogenous adenosine (ADO) is known to be cardioprotective during acute myocardial ischemia. Coronary sinus ADO concentration has recently been shown to increase nearly 13-fold over baseline levels after 5 min of untreated ventricular fibrillation (VF). The role of ADO in VF has never been previously examined. The objective of this stu...

CPR prior to defibrillation improves survival from prolonged ventricular fibrillation (VF) by over 10%, based on recent studies. Waveform analysis could identify those patients with VF of over 5 to 7-min duration who should receive CPR first. A method based on the changes in the Fourier-derived frequency spectrum over time could improve the ability...

The scaling exponent (ScE) of the ventricular fibrillation (VF) waveform correlates with duration of VF and predicts defibrillation outcome. We compared 4 therapeutic approaches to the treatment of VF of various durations. Seventy-two swine (19.5 to 25.7 kg) were randomly assigned to 1 of 9 groups (n=8 each). VF was induced and left untreated until...

Ventricular fibrillation (VF) is a leading cause of sudden death. Electrical defibrillation is the primary modality of treatment, but evidence is accumulating that its use in the late stage of VF prior to providing ventilation, chest compressions and the administration of appropriate medication is detrimental. In VF of <5 min duration a 'shock firs...

we compared time-dependent rescue shock success when delivered immediately, to defibrillation preceded by 3 min of CPR, with and without high dose epinephrine (HDE) in a swine model of prolonged ventricular fibrillation (VF). Our hypotheses were that pretreatment with CPR and HDE would produce higher rates of successful first-shock defibrillation a...

Survival decreases with duration of ventricular fibrillation, and it is possible that failed rescue shocks increase myocardial damage. Structure in the ECG signal during ventricular fibrillation can be quantified by using the scaling exponent, a dimensionless measure that correlates with ventricular fibrillation duration. This study examined whethe...

Objective: Mathematical analyses of ventricular fibrillation (VF) have resulted in the derivation of a measure termed the scaling exponent (ScE) that characterizes the duration of VF and probability of defibrillation success. The purpose of this study was to compare the effects of biphasic defibrillation waveform (BDW) and monophasic defibrillatio...

Background: -Defibrillator shocks often fail to terminate ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OOHCA), and repeated failed shocks can worsen the subsequent response to therapy. Because the VF waveform changes with increasing duration of VF, it is possible that ECG analyses could estimate the preshock likelihood of defib...

Objectives: The characteristics of the ventricular fibrillation (VF) waveform may influence treatment decisions and the likelihood of therapeutic success. However, assessment of VF as being fine or coarse and the distinction between fine VF and asystole are largely subjective. The authors sought to determine the level of agreement among physicians...

The characteristics of the ventricular fibrillation (VF) waveform may influence treatment decisions and the likelihood of therapeutic success. However, assessment of VF as being fine or coarse and the distinction between fine VF and asystole are largely subjective. The authors sought to determine the level of agreement among physicians for interpre...

Electrocardiographic recordings of ventricular fibrillation (VF) appear chaotic. Previous attempts to characterize the chaotic nature of VF have relied on peak-to-peak intervals [Witkowski et al., Phys. Rev. Lett. 1995;75(6):1230-3; Garfinkel et al., J. Clin. Investig. 1997;99(2):305-314; Hastings et al., Proc. Natl. Acad. Sci. USA 1996;93:10495-9]...

Ventricular fibrillation (VF) is the most common arrhythmia causing sudden cardiac death. However, the likelihood of successful defibrillation declines with increasing duration of VF. Because the morphology of the electrocardiogram (ECG) waveform during VF also changes with time, this study examined a new measure that describes the VF waveform and...