Perfusing Rhythm Research Articles

Feasibility of HEMS performed prehospital extracorporeal-cardiopulmonary resuscitation in paediatric cardiac arrests; two case reports

IntroductionA broad range of pathophysiologic conditions can lead to cardiopulmonary arrest in children. Some of these children suffer from refractory cardiac arrest, not responding to basic and advanced life support. Extracorporeal-Cardiopulmonary Resuscitation (E-CPR) might be a life-saving option for this group. Currently this therapy is only performed in-hospital, often necessitating long transport times, thereby negatively impacting eligibility and chances of survival. We present the first two cases of prehospital E-CPR in children performed by regular Helicopter Emergency Medical Services (HEMS).Case presentationsThe first patient was a previously healthy 7 year old boy who was feeling unwell for a couple of days due to influenza. His course deteriorated into a witnessed collapse. Direct bystander CPR and subsequent ambulance advanced life support was unsuccessful in establishing a perfusing rhythm. While doing chest compressions, the patient was seen moving both his arms and making spontaneous breathing efforts. Echocardiography however revealed a severe left ventricular impairment (near standstill). The second patient was a 15 year old girl, known with bronchial asthma and poor medication compliance. She suffered yet another asthmatic attack, so severe that she progressed into cardiac arrest in front of the attending ambulance and HEMS crews. Despite maximum bronchodilator therapy, intubation and the exclusion of tension pneumothoraxes and dynamic hyperinflation, no cardiac output was achieved.InterventionAfter consultation with the nearest paediatric E-CPR facilities, both patients were on-scene cannulated by regular HEMS. The femoral artery and vein were cannulated (15-17Fr and 21Fr respectively) under direct ultrasound guidance using an out-of-plane Seldinger approach. Extracorporeal Life Support flow of 2.1 and 3.8 l/min was established in 20 and 16 min respectively (including preparation and cannulation). Both patients were transported uneventfully to the nearest paediatric intensive care with spontaneous breathing efforts and reactive pupils during transport.ConclusionThis case-series shows that a properly trained regular HEMS crew of only two health care professionals (doctor and flight nurse) can establish E-CPR on-scene in (older) children. Ambulance transport with ongoing CPR is challenging, even more so in children since transportation times tend to be longer compared to adults and automatic chest compression devices are often unsuitable and/or unapproved for children. Prehospital cannulation of susceptible E-CPR candidates has the potential to reduce low-flow time and offer E-CPR therapy to a wider group of children suffering refractory cardiac arrest.

Amplitude of spectral area of ventricular fibrillation as a guide for low energy defibrillation level in patients with out-of-hospital cardiac arrest

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The optimal energy level for shock in biphasic waveform defibrillation represents a significant knowledge gap. Different energy regimens have been trialed; however, a selection criterion which may help in adopting one approach over another has never been identified. Choosing the maximum energy may be an option but current-induced myocardial damage should not be neglected and an effort to tailor energy delivery is desirable. Purpose To assess whether amplitude spectral area (AMSA) of VF can guide the dose-regimens of defibrillation in out-of-hospital cardiac arrest (OHCA) patients. Methods This is a multicenter study based on the data from some of the largest OHCA registers in Europe, which enrolled 830 OHCA patients who received at least one shock during advanced resuscitation. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 and LIFEPAK 12/15 monitors/defibrillators and by using a 2-second-pre-shock ECG interval. Results Among 830 OHCAs, 2135 shocks were delivered from a minimum energy level of 150 J to a maximum of 360 J. The AMSA values of efficacious shocks delivered at 150 J were higher compared to those of efficacious shock at 360 J [13.1 (IQR 10.2-17.1) vs 11.8 (IQR 8.3-15.2) HzxmV; p<0.01). In a multivariate analysis corrected for time to each shock, sex, age, amiodarone administration and study center, AMSA values, and not the dose of the shock energy, was significantly associated with the probability of shock success [OR 5.8, (95%CI 4.7-7.3); p< 0.01]. By dividing the total shocks into three tertiles based on AMSA values (T1: 0.8-6.9 Hz×mV; T2: 6.9-11.8 Hz×mV; T3: 11.8-63.2 Hz×mV), the rate of shock success at low energy was significantly higher in the tertile with highest AMSA values (T3: 38% vs T2: 15% vs T1: 5%; p<0.01). Particularly in T3, low energy was more effective than high energy shocks (38% vs 23%, p < 0.001). Conclusion This is the first study to identify a datapoint to guide decision-making with regards to defibrillation with lower energy levels. AMSA could indeed guide the selection of energy levels in order to optimize efficaciousness in restoring a perfusing rhythm while minimizing the contribution to myocardial dysfunction.

Intra-Cardiac Arrest Use of Stellate Ganglion Block for Refractory Ventricular Tachycardia

BackgroundRefractory ventricular dysrhythmia, or electrical storm, is a cardiac condition consisting of three or more episodes of ventricular dysrhythmia resistant to treatment within a 24-hour period. These dysrhythmias carry high morbidity and mortality if not diagnosed and abated promptly. When traditional resuscitative algorithms fail to return a patient to a perfusing rhythm, providers need to consider other, more novel techniques to terminate these dangerous dysrhythmias. One approach is the use of a stellate ganglion block, which has been documented in the literature only a handful of times for its resuscitative use in cardiac arrest. Case SeriesThis case series details two cases from an urban emergency department (ED) in a large metropolitan city, where the use of ultrasound-guided stellate ganglion blocks during cardiac arrest provided successful ablation of the tachydysrhythmia. The first case involves a patient who went into cardiac arrest while in the ED and was found to be in refractory pulseless ventricular tachycardiawhile. The second case describes a patient who went into a witnessed out-of-hospital cardiac arrest while with emergency medical services. Why Should an Emergency Physician Be Aware of This?The stellate ganglion block is a procedure currently being used as a treatment modality for a variety of neurologic, psychological, and cardiac conditions. This intervention may provide a viable and lifesaving option for emergency physicians to adopt when traditional resuscitative algorithms fail to break resistant ventricular tachydysrhythmias.

Common Injury Patterns in Trauma Patients Arriving in Extremis.

Resuscitative thoracotomy (RT) may be utilized to obtain a perfusing rhythm, but identifying and treating bleeding immediately after successful RT is mandatory for survival. Trauma surgeons must be able to manage all injuries in these cases as there will likely not be enough time to obtain specialty consultation or to use endovascular management. We sought to determine common injuries in patients arriving in extremis and the injuries that require operative management. A retrospective review was conducted of all patients who underwent a RT at a high-volume Level 1 trauma center from 2010 to 2020. Those who had an autopsy report or lived to discharge were included in the study. High-grade cardiac, high-grade liver injuries, and pelvic fractures are commonly seen when trauma patients arrive in extremis and often require hemorrhage control. Trauma surgeons must be able to manage such injuries as obtaining specialty consultation or using endovascular therapy is not feasible.

Risk factors and outcomes of sudden cardiac arrest in pediatric heart transplant recipients

Sudden cardiac arrest (SCA) is a prevailing cause of mortality after pediatric heart transplant (HT) but remains understudied. We analyzed the incidence, outcomes, and risk factors for SCA at our center. Retrospective review of all pediatric HT patients at our center from January 1, 2009 to January 1, 2021. SCA was defined as an abrupt loss of cardiac function requiring cardiopulmonary resuscitation and/or mechanical circulatory support (MCS). Events that occurred in the setting of limited resuscitative wishes, or while on MCS were excluded. Patient characteristics and risk factors were analyzed. Fourteen of 254 (6%) experienced SCA at a median of 3 (1, 4) years post-HT. Seven (50%) events occurred out-of-hospital. Eleven (79%) died from their initial event, 2 (18%) after failure to separate from extracorporeal membrane (ECMO). In univariate analysis, black race, younger donor age, prior acute cellular rejection (ACR) episode, pacemaker and/or ICD in place, and pre-mortem diagnosis of allograft vasculopathy were associated with SCA (P=.003-0.02). In multivariable analysis, history of ACR, younger donor age, and black race retained significance. [OR=6.3, 95% CI: 1.6-25.4, P=.01], [OR=0.9, 95% CI: 0.8-1, P=.04], and [OR=7.3, 95% CI: 1.1-49.9, P=.04], respectively. SCA occurred in 3 patients with a functioning ICD or pacemaker, which failed to restore a perfusing rhythm. SCA occurs relatively early after pediatric HT and is usually fatal. Half of events happen at home. Those who received younger donors, have a history of ACR, or are of black race are at increased risk. ICDs/pacemakers may offer limited protection.

Abstract 13358: Pediatric Defibrillation; Safety and Efficacy of Shocks in Both Ventricular Fibrillation and Sinus Rhythm in a Porcine Model

Introduction: Pediatric sudden cardiac arrest may require the delivery of a defibrillating shock to promote return of spontaneous circulation (ROSC). Fear of harm is a barrier for the use of automated external defibrillators by lay personnel, particularly when the patient is a child. The aim of this study was to observe the effects of delivering pediatric defibrillation shocks to pediatric weight swine who are in a perfusing rhythm or ventricular fibrillation (VF). Methods: Eight swine (10.3-26.8 kg) were studied under anesthesia. Up to 30 shocks were applied using modified samaritan AEDs (HeartSine, UK) to animals either in sinus rhythm or after 30 seconds of VF. Shocks delivered in sinus rhythm were unsynchronized. Four different shock types were applied, utilizing two different waveforms (Waveform-A at 50 J, Waveform-A at 75 J, Waveform-A at 90J and Waveform-B at 50 J). Left ventricular (LV) pressures were recorded invasively (Millar, USA). If the shock was successful, the animal entered a rest period of approximately 5 minutes, after which the next shock was applied. Results: Data presented in Table 1. Out of a total of 77 shocks delivered in sinus rhythm, 2 (2.6%) resulted in conversion to a cardiac arrest rhythm. Analysis of LV pressures demonstrated no significant differences in the change of LV dP/dt from baseline at 1, 10 and 60 seconds post-shock. There was no significant difference in shock success or ROSC between the shock types for defibrillation of VF. Analysis of LV pressures demonstrated no significant differences in the change of LV dP/dt from baseline at at 1, 10 and 60 seconds post-shock between the groups. Conclusions: The results of this study indicate defibrillation shocks applied to swine in sinus rhythm rarely result in conversion to an arrhythmia. Additionally, the variety of shock types demonstrated similar levels of safety and efficacy in this porcine model.

Rewarming With Closed Thoracic Lavage Following 3-h CPR at 27°C Failed to Reestablish a Perfusing Rhythm.

Introduction: Previously, we showed that the cardiopulmonary resuscitation (CPR) for hypothermic cardiac arrest (HCA) maintained cardiac output (CO) and mean arterial pressure (MAP) to the same reduced level during normothermia (38°C) vs. hypothermia (27°C). In addition, at 27°C, the CPR for 3-h provided global O2 delivery (DO2) to support aerobic metabolism. The present study investigated if rewarming with closed thoracic lavage induces a perfusing rhythm after 3-h continuous CPR at 27°C.Materials and Methods: Eight male pigs were anesthetized, and immersion-cooled. At 27°C, HCA was electrically induced, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed by combining closed thoracic lavage and continued CPR. Organ blood flow was measured using microspheres.Results: After cooling with spontaneous circulation to 27°C, MAP and CO were initially reduced by 37 and 58% from baseline, respectively. By 15 min after the onset of CPR, MAP, and CO were further reduced by 58 and 77% from baseline, respectively, which remained unchanged throughout the rest of the 3-h period of CPR. During CPR at 27°C, DO2 and O2 extraction rate (VO2) fell to critically low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. During rewarming with closed thoracic lavage, all animals displayed ventricular fibrillation, but only one animal could be electro-converted to restore a short-lived perfusing rhythm. Rewarming ended in circulatory collapse in all the animals at 38°C.Conclusion: The CPR for 3-h at 27°C managed to sustain lower levels of CO and MAP sufficient to support global DO2. Rewarming accidental hypothermia patients following prolonged CPR for HCA with closed thoracic lavage is not an alternative to rewarming by extra-corporeal life support as these patients are often in need of massive cardio-pulmonary support during as well as after rewarming.

Critical Care Transport of the Temporary Portable Ventricular Support Device

ObjectiveCardiogenic shock is a critical emergency for which ventricular support devices (VSDs), such as the Impella (AbioMed Inc, Danvers, MA), are placed. Many referring facilities cannot provide cardiac intensive care. This requires a regional approach to the care of patients with VSD. Critical care transport to the regional center is needed and requires specialty trained personnel. As the need for specialty trained personnel increases, appropriate utilization of the personnel needs to be considered. This study illustrates the effective transport and successful management of Impella patients in the transport environment by a downsized specialty trained critical care team. MethodsA retrospective chart review explored critical care transports of patients with Impella devices over a 73-month period. Our goal was to show that with training, protocols, and guidelines a downsized critical care team can effectively transport these high-risk, low-frequency patients. ResultsForty-seven VSD transports occurred within 13,823 transports during the study period. Twenty-seven included an Impella device only. Thirteen were completed by a downsized team. One hundred percent of the transport resulted in the patient having perfusing rhythms and blood pressures at the receiving facility. ConclusionVSDs can be successfully transported between hospitals with small specialty trained critical care transport teams using air or ground assets.

Resuscitating Resuscitation: Advanced Therapies for Resistant Ventricular Dysrhythmias.

More than 640,000 combined in-hospital and out-of-hospital cardiac arrests occur annually in the United States. However, survival rates and meaningful neurologic recovery remain poor. Although "shockable" rhythms (i.e., ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT)) have the best outcomes, many of these ventricular dysrhythmias fail to return to a perfusing rhythm (resistant VF/VT), or recur shortly after they are resolved (recurrent VF/VT). This review discusses 4 emerging therapies in the emergency department for treating these resistant or recurrent ventricular dysrhythmias: beta-blocker therapy, dual simultaneous external defibrillation, stellate ganglion blockade, and extracorporeal cardiopulmonary resuscitation. We discuss the underlying physiology of each therapy, review relevant literature, describe when these approaches should be considered, and provide evidence-based recommendations for these techniques. Esmolol may mitigate some of epinephrine's negative effects when used during resuscitation, improving both postresuscitation cardiac function and long-term survival. Dual simultaneous external defibrillation targets the region of the heart where ventricular fibrillation typically resumes and may apply a more efficient defibrillation across the heart, leading to higher rates of successful defibrillation. Stellate ganglion blocks, recently described in the emergency medicine literature, have been used to treat patients with recurrent VF/VT, resulting in significant dysrhythmia suppression. Finally, extracorporeal cardiopulmonary resuscitation is used to provide cardiopulmonary support while clinicians correct reversible causes of arrest, potentially resulting in improved survival and good neurologic functional outcomes. These emerging therapies do not represent standard practice; however, they may be considered in the appropriate clinical scenario when standard therapies are exhausted without success.

Chest compressions may induce VF from a potentially perfusing rhythm

Chest compressions may induce VF from a potentially perfusing rhythm

Hands-off time for rhythm analysis: which rhythm has large time effects on pause length

Purpose & introduction: The Guidelines 2015 reiterate the importance of limiting hands-off periods to a maximum of 5–10 sec. 1 Soar J. et al. Resuscitation. 2015; 95: 100-147 Abstract Full Text Full Text PDF PubMed Scopus (982) Google Scholar Periodic underlying rhythm checks remain important, as so called see thru™CPR has not been implemented everywhere. 2 Ruiz de Gauna S. et al. Biomed Res Int. 2014; 2014: 386010 Crossref PubMed Scopus (45) Google Scholar Based on the paucity of literature, 3 Kessler D.O. et al. Pediatric Critical Care Medicine. 2017; 18: e311-e317 Crossref PubMed Scopus (16) Google Scholar , 4 Cheskes S. et al. Circulation. 2011; 124: 58-66 Crossref PubMed Scopus (285) Google Scholar we investigated the effect of the underlying rhythm on the duration of the rhythm analysis pause. Our hypothesis was that potentially perfusing rhythms cause longer delays than other rhythms, potentially due to palpation time.

LO07: Double sequential external defibrillation improves termination of ventricular fibrillation and return of spontaneous circulation in shock-refractory out-of- hospital cardiac arrest

Introduction: Despite significant advances in resuscitation efforts, there are some patients who remain in ventricular fibrillation (VF) after multiple shocks during out-of-hospital cardiac arrest (OHCA). Double sequential external defibrillation (DSED) has been proposed as a treatment option for patients in shock refractory VF. We sought to compare DSED to standard therapy with regards to VF termination and return of spontaneous circulation (ROSC) for patients presenting in shock refractory VF. Methods: We performed a retrospective review of all treated adult OHCA who presented in VF and received a minimum of three successive shocks over a two year period beginning on Jan 1, 2015 in four Canadian EMS agencies. Using ambulance call reports and defibrillator files, we compared VF termination (defined as the absence of VF at the rhythm check following defibrillation and 2 minutes of CPR) and VF termination into a perfusing rhythm with ROSC between patients who received standard therapy (CPR, defibrillation, epinephrine and antiarrhythmics) and those who received DSED (after on-line medical consultation) for shock refractory VF. Cases of traumatic cardiac arrest and those who presented in VF but terminated VF prior to 3 successive shocks were excluded. Results: Among 197 patients who met the study criteria for shock refractory VF, 161 (81.7%) patients received standard therapy and 36 (18.3%) received DSED. For the primary outcome, VF termination was significantly higher for DSED compared to standard therapy (63.9% vs 18.0%; Δ45.9%; 95% CI: 28.3 to 60.5). For the secondary outcome of VF termination into ROSC, DSED was associated with significantly higher ROSC compared to standard care (33.3% vs 13%; Δ20.3%; 95% CI:13.0 to 33.3). The median (IQR) number of failed standard shocks prior to DSED was 8 (6, 10). When DSED terminated VF, it did so with a single DSED shock in 69.6% of cases. Conclusion: Our observational findings suggest improved VF termination and ROSC are associated with DSED compared to standard therapy for shock refractory VF. An appropriately powered randomized controlled trial is required to assess the impact of DSED on patient-important outcomes.

Detection of spontaneous pulse using the acceleration signals acquired from CPR feedback sensor in a porcine model of cardiac arrest.

BackgroundReliable detection of return of spontaneous circulation with minimal interruptions of chest compressions is part of high-quality cardiopulmonary resuscitation (CPR) and routinely done by checking pulsation of carotid arteries. However, manual palpation was time-consuming and unreliable even if performed by expert clinicians. Therefore, automated accurate pulse detection with minimal interruptions of chest compression is highly desirable during cardiac arrest especially in out-of-hospital settings.ObjectiveTo investigate whether the acceleration (ACC) signals acquired from accelerometer-based CPR feedback sensor can be used to distinguish perfusing rhythm (PR) from pulseless electrical activity (PEA) in a porcine model of cardiac arrest.MethodsCardiac arrest was induced in 49 male adult pigs. ECG, arterial blood pressure (ABP) and ACC waveforms were simultaneously recorded during CPR. 3-second segments containing compression-free signals during chest compression pauses were extracted and only those segments with organized rhythm were used for analysis. PR was defined as systolic arterial pressure >60 mmHg and pulse pressure >10 mmHg, while PEA was defined as an organized rhythm that does not meet the above criteria for PR. Peak correlation coefficient (CCp) of the cross-correlation function between pre-processed ECG and ACC, was used to discriminate PR and PEA.Results63 PR and 153 PEA were identified from the total of 1025 extracted segments. CCp was significantly higher for PR as compared to PEA (0.440±0.176 vs. 0.067±0.042, p<0.01) and highly correlated with ABP (r = 0.848, p<0.001). The area under the receiver operating characteristic curve, sensitivity, specificity and accuracy were 0.965, 93.6%, 97.5% and 96.7% for the ACC-based automatic spontaneous pulse detection.ConclusionsIn this animal model, the ACC signals acquired from an accelerometer-based CPR feedback sensor can be used to detect the presence of spontaneous pulse with high accuracy.

Experience With Wearable Cardioverter-Defibrillators at 2AcademicMedical Centers.

This study sought to characterize the experience in a cohort of patients prescribed a wearable cardioverter-defibrillator (WCD) over a 2-year interval at 2 academic medical centers. The WCD is available for patients felt to be at high risk of sudden cardiac death. However, there is a lackof randomized data to guide its use and prescribing patterns vary. We retrospectively reviewed indications and therapies of all WCD prescriptions over a 2-year period from 2largeacademic medical centers. Data on compliance and treatment events of patients wearing the WCD were reviewed. Among the 147 patients prescribed a WCD, 80% were male with an age of 59 ± 14 years. The WCD was prescribed for the following reasons: primary prevention in the setting of a left ventricular ejection fraction≤35% (53%), secondary prevention when an implantable cardioverter-defibrillator was not implanted (16%), implantable cardioverter-defibrillator explantation (23%), and other high-risk scenarios for arrhythmic sudden death (9%). The median wear duration was 50 days (interquartile range [IQR]: 25 to 85 days) with a median of 21.0 h of wear per day (IQR: 15.0 to22.8h). High-voltage treatment was delivered in 3 separate patients, 2 of whom died. The third patient received 3WCD shocks without restoration of a perfusing rhythm and ultimately was resuscitated by emergency responders. No patients received inappropriate therapies. Events requiring therapy were rare and no lives were directly saved by the WCD. Future efforts are needed to improve identification of patients most likely to benefit from a WCD.

Reliable detection of perfusing rhythms in automated external defibrillators

Reliable detection of perfusing rhythms in automated external defibrillators

Does the choice of definition for defibrillation and CPR success impact the predictability of ventricular fibrillation waveform analysis?

BackgroundQuantitative analysis of ventricular fibrillation (VF), such as amplitude spectral area (AMSA), predicts shock outcomes. However, there is no uniform definition of shock/cardiopulmonary resuscitation (CPR) success in out-of-hospital cardiac arrest (OHCA). The objective of this study is to investigate post-shock rhythm variations and the impact of shock/CPR success definition on the predictability of AMSA. MethodsA total of 554 shocks from 257 OHCA patients with VF as initial rhythm were analyzed. Post-shock rhythms were analyzed every 5s up to 120s and annotated as VF, asystole (AS) and organized rhythm (OR) at serial time intervals. Three shock/CPR success definitions were used to evaluate the predictability of AMSA: (1) termination of VF (ToVF); (2) return of organized electrical activity (ROEA); (3) return of potentially perfusing rhythm (RPPR). ResultsRhythm changes occurred after 54.5% (N=302) of shocks and 85.8% (N=259) of them occurred within 60s after shock delivery. The observed post-shock rhythm changes were (1) from AS to VF (24.9%), (2) from OR to VF (16.1%), and (3) from AS to OR (12.1%). The area under the receiver operating characteristic curve (AUC) for AMSA as a predictor of shock/CPR success reached its maximum 60s post-shock. The AUC was 0.646 for ToVF, 0.782 for ROEA, and 0.835 for RPPR (p<0.001) respectively. ConclusionsPost-shock rhythm is unstable in the first minute after the shock. The predictability of AMSA varies depending on the definition of shock/CPR success and performs best with the return of potentially perfusing rhythm endpoint for OHCA.

Abstract 12827: Detection of Spontaneous Pulse Using Acceleration Signals Acquired From CPR Feedback Sensor in Porcine Model of Cardiac Arrest

Background: Reliable detection of return of spontaneous circulation (ROSC) without long interruptions of chest compressions is part of high-quality cardiopulmonary resuscitation (CPR) and routinely done by checking pulsation of carotid or femoral arteries. The purpose of the current study was to investigate whether acceleration signals acquired from a CPR feedback sensor can be used to distinguish perfusing rhythm from pulseless electrical activity (PEA) in a porcine model of cardiac arrest. Methods: The experimental data were collected from 50 male adult pigs with prolonged cardiac arrest and CPR. ECG, arterial blood pressure and acceleration signals were synchronously recorded at a sample rate of 300 Hz. The acceleration signal (ACC) was acquired from an accelerometer-based CPR sensor that was placed on the surface of the animal’s chest over the heart. During chest compression pauses 3-second segments of signals were extracted. ROSC was defined as systolic arterial pressure (SAP) &gt;60 mmHg and pulse pressure (PP) &gt;10 mmHg in the presence of an organized rhythm. ACC was pre-processed using a narrow band-pass filter with the center frequency from 0.5 to 7.5Hz. Cross-correlation function was calculated between ECG and filtered ACC to obtain the peak correlation coefficient (CCp). Area under the receiver operating characteristic curve (AUC) was used to evaluate the ability of CCp to detect ROSC. Results: A total of 216 segments were obtained with 63 in perfusing rhythm and 153 in PEA. The filtered ACC tracings (ACC’) in perfusing rhythm showed periodic oscillations synchronized with R waves, but no periodic oscillations were observed for PEA. Compared with PEA, heart rate (159.0±50.7 vs. 86.0±44.9 bpm, p &lt;0.01), SAP (143.3±38.3 vs. 18.9±13.3 mmHg, p &lt;0.01), pulse pressure (42.3±14.5 vs. 5.6±8.3 mmHg, p &lt;0.01) and CCp (0.443±0.171 vs. 0.096±0.085, p &lt;0.01) were significantly higher for perfusing rhythm. The AUC was 0.95 when CCp was used to differentiate ROSC from PEA. Using a cut-off threshold of 0.244, the sensitivity and specificity were 90.5% respectively. Conclusions: In this animal model, the acceleration signals acquired from a CPR feedback sensor can be used to distinguish perfusing rhythm from PEA.

Diagnostic Dilemma in the Treatment of a Fatal Case of Bloody Diarrhea.

Although diarrhea is the most commonly reported pediatric illness in the United States, mortality is usually a rare and unexpected event. We report the case of a healthy 13-month-old male that succumbed to a diarrheal illness of unclear etiology. Presenting signs included frequent nonbloody stools that progressed to frankly bloody stools over 72 hours. Associated symptoms included fever, tenesmus, relief with stool passage, and significant fatigue. On examination, the patient appeared tired and lay with legs curled toward his chest. The abdominal exam was remarkable for hypoactive bowel sounds, diffuse tenderness to palpation without guarding or rebound pain, and intermittent prolapse of rectal tissue. Abdominal plain films demonstrated a paucity of bowel gas, especially in the rectum; and ultrasound revealed thickening of bowel loops in the left lower quadrant. Abdominal computed tomography scan showed decreased enhancement of the mucosa of the rectosigmoid colon. The patient deteriorated rapidly with cardiorespiratory arrest occurring 48 hours after admission. Despite a protracted effort at cardiopulmonary resuscitation, perfusing heart rate or rhythm could not be reestablished. Autopsy revealed infarction and necrosis of the rectosigmoid colon with invasive gram-negative bacilli. Here we present his perplexing case, diagnostic evaluations, and suggest a unifying diagnosis.

Abstract 16917: Hemodynamic Effects of Synchronized Chest Compression in a Porcine Post Countershock PEA Model

Purpose: Post countershock Pulseless Electrical Activity (PCC-PEA) is encountered frequently during resuscitation from cardiac arrest. External chest compression (CC) remains the principal treatment for PCC-PEA, but unsynchronized CC may interfere with myocardial recovery. We investigated the efficacy of CC synchronized to PEA’s R waves as compared to standard CC in an animal model. Methods: Seven domestic pigs weighing 35-42 kg were anesthetized, endotracheally intubated and mechanically ventilated. Aortic and right atrial pressures were invasively monitored and coronary perfusion pressure (CPP) calculated. Carotid blood flow (CBF) was continuously monitored by a flow probe. VF was electrically induced and left untreated for 3 minutes before delivering the 1st shock. If the post countershock rhythm remained in VF a 2nd shock was delivered after an additional period of VF from 1 to 2 minutes. Countershocks were continued until PEA was obtained. If shock resulted in a perfusing rhythm, VF was re-induced. After PEA was induced, 15 seconds of chest compression or medium energy pacing were delivered to the animal per another concurrent protocol. The rate of standard CC was 100. Animals were then randomized to receive synchronized or standard CC for 15 seconds, with continuous alternation of therapy for the maximum 120 seconds before the 1 st administration of epinephrine. A standard CPR rescue protocol continued for maximum of 20 minutes. If ROSC was achieved, the animal received at least 4 minutes for recovery before the study sequence was repeated. Results: A total of 32 matched synchronization pairs were obtained from 7 animals. The PEA pulse pressure was 2.47 + 2.34 mmHg and the PEA rate was 74 + 16.5. CC with R wave synchronization maintained CBF (53.6 vs. 46.7, p=0.11) and CPP (15.6 vs. 16.6 mmHg, p=0.34), and increased CBF stroke volume (=CBF/PEA rate) (0.76 vs. 0.47 ml, p=0.0004) as compared to standard CC. Conclusions: During near complete electromechanical dissociation (true PEA), synchronization of external chest compression with R waves maintained CBF and CPP despite lower compression rates as compared to standard chest compression without synchronization. This may represent a first observation that synchronization may be beneficial even in true PEA.

Abstract 10134: Potassium Cardioplegia During CPR for Porcine VF Arrest: A Blinded Randomized Controlled Trial

Introduction: Potassium cardioplegia-induced transient asystole may conserve myocardial energy and improve outcome in ventricular fibrillation (VF) cardiac arrest. Hypothesis: We hypothesized potassium infusion during VF arrest would lead to an increase in intra-arrest amplitude spectrum area (AMSA) prior to defibrillation, and improved hemodynamic parameters in those animals that attained return of spontaneous circulation (ROSC). Methods: Twelve swine were randomized to KCl or placebo in a randomized controlled trial, and 10 were included in an amended protocol. After initiation of monitoring, induction of anesthesia, and instrumentation of the aorta and right atrium, VF was electrically induced. After 4 minutes, 1.5 meq/kg KCl or placebo was infused in blinded fashion in a peripheral ear vein and mechanical chest compressions and ventilations were begun. Initial defibrillation was performed 10 minutes post VF induction, as appropriate. Animals without ROSC received continued resuscitation per Advanced Cardiac Life Support(ACLS) guidelines for 10 more minutes. Animals that achieved ROSC were monitored for 30 more minutes. The primary outcome, change in AMSA from just before study drug infusion to 5 minutes post infusion, was compared using nonparametric statistics. Results: Six animals were randomized to KCl and 4 to Placebo. KCl infusion induced approximately 1 minute of transient asystole at the dosage used. The mean change in normalized AMSA was -0.24 in the KCl and 0.21 in the Placebo group, with a median difference of -0.50 (95%CI -0.79 to -0.09), p=0.038, favoring Placebo. Five of 6 (83%) animals in the KCl group and 2 of 4 (50%) in the Placebo group developed an organized, though not necessarily, perfusing rhythm with the difference in proportion 33% (95% CI -33 to 86). One of 6 (17%) animals in the KCl and 2 of 4 (50%) in the Placebo group achieved ROSC with the difference in proportion -33% (95%CI -93 to 33). Hemodynamics were not quantitatively compared post ROSC due to limited survivors. One animal in each group required norepinephrine infusion. Conclusions: Potassium as a single agent did not benefit AMSA or ROSC in this porcine model of VF arrest.