Adverse Outcomes of Interrupted Precordial Compression During Automated Defibrillation

Abstract

Background-Current versions of automated external defibrillators (AEDs) require frequent stopping of chest compression for rhythm analyses and capacity charging. The present study was undertaken to evaluate the effects of these interruptions during the operation of AEDs. Methods and Results-Ventricular fibrillation was electrically induced in 20 male domestic swine weighing between 37. 5 and 43 kg that were untreated for 7 minutes before CPR was started. Defibrillation was attempted with up to 3 sequential 150-J biphasic shocks, but each was preceded by 3-, 10-, 15-, or 20-second interruptions of chest compression. The interruptions corresponded to those that were mandated by commercially marketed AEDs for rhythm analyses and capacitor charge. The sequence of up to 3 electrical shocks and delays were repeated at 1-minute intervals until the animals were successfully resuscitated or for a total of 15 minutes. Spontaneous circulation was restored in each of 5 animals in which precordial compression was delayed for 3 seconds before the delivery of the first and subsequent shocks but in none of the animals in which the delay was Ͼ15 seconds before the delivery of the first and subsequent shocks. Longer intervals of CPR interventions were required, and there was correspondingly greater failure of resuscitation in close relationship to increasing delays. The durations of interruptions were inversely related to the durations of subthreshold levels of coronary perfusion pressure. Postresuscitation arterial pressure and left ventricular ejection fraction were more severely impaired with increasing delays. Key Words: cardiopulmonary resuscitation Ⅲ fibrillation Ⅲ defibrillation Ⅲ compression Ⅲ myocardium A utomated external defibrillators (AEDs) provide the single best option for improving the currently poor outcomes of out-of-hospital cardiopulmonary resuscitation (CPR) performed by bystanders. Fundamental to the operation of AEDs is the capability of automated ECG rhythm analyses, during which CPR is interrupted. Previous experimental studies had demonstrated both decreased resuscitability and greater impairment of postresuscitation myocardial function and survival when precordial compression was interrupted for 20 seconds in small animals. 1-3 Because current versions of AEDs prompt "hands-off" intervals of Ͼ10 seconds for rhythm analyses before advising the rescuer to deliver an electrical shock, as documented below, we hypothesized that such interruptions would adversely affect the outcomes of CPR. Conclusions-InterruptionsThreshold levels of coronary perfusion pressure (CPP) are identified as major determinants of successful cardiac resuscitation. 4 -7 Interruptions in precordial compression predictably result in declines in CPP and therefore delays in restoring threshold values of CPP. 5,6 We therefore anticipated that increasing the length of intervals of interrupted chest compression results in corresponding decreases in the success of CPR and greater severity of postresuscitation myocardial dysfunction.These co...

Ruptura gástrica por reanimação cardiopulmonar: relato de caso

“…Estudos recentes demonstram que mesmo profissionais especializados falham na aplicação da técnica ideal 10 . Comumente observa-se ventilação excessiva, interrupção freqüente ou baixa freqüência das compressões torácicas, resultando em diminuição do débito cardíaco e da pressão de perfusão coronária 11,12 . Além disso, sua difusão em escala cada vez maior trás como conseqüência o aumento na prevalência de complicações relacionadas à manobra, com nítida predominância de traumas toráci-cos, dentre os quais destacam-se fraturas de costelas e esterno, pneumomediastino e pneumotórax 3,4,6,7 .…”

“…A clássica disposição de três choques seguidos, sem interposição de manobras de RCP, foi abandonada por conta do alto grau de sucesso do primeiro choque com os modernos desfibriladores bifásicos 16,17 . Não se justifica, portanto, o longo intervalo que se verificava entre os três choques e a retomada da RCP -em média de 29 a 37 segundos 12,18 . Ainda que em vários serviços de urgência sejam utilizados desfibriladores monofásicos, não se recomenda lançar mão de três choques sucessivos, devendose proceder a seqüência choque  RCP  verificações de ritmo e pulso, já com uma energia inicial de 360J se desfibrilador com corrente monofásica ou o equivalente a essa energia se desfibrilador for bifásico (tipicamente 120-200J, dependendo do equipamento utilizado) 10 na manutenção da perfusão coronariana e encefálica, essenciais para o bom prognóstico desses pacientes.…”

“…Essa alteração visa dar maior ênfase à manutenção da circulação, ao mesmo tempo em que poderá proporcionar menor risco de complicações relacionadas à ventilação artificial, seja devido à má técnica ou pelo potencial efeito maléfico de ventilação excessiva freqüentemente oferecida nesses casos ocasionando aumento da pressão intratorácica e intra-abdominal 6, 14,15,19 . No primeiro caso a conseqüência é a diminuição do retorno venoso às câmaras cardíacas reduzindo assim perfusão encefá-lica e coronariana 11,12,19 . No segundo a ventilação mecâ-nica é dificultada, podendo levar a hipoxemia, também contribuindo para uma diminuição do retorno venoso e do débito cardíaco, aumentando a lesão neurológica já existente e possibilitando a ocorrência de isquemia de ór-gãos intra-abdominais com risco de acidose metabólica e translocação bacteriana 19 .…”

Inter Association Task Force Recommendations on Emergency Preparedness andManagement of Sudden Cardiac Arrest in High School andCollege Athletic Programs: A Consensus Statement

“…68,69 Rhythm analysis for a 3-shock sequence in older AEDs results in delays up to 37 seconds between delivery of the first shock and delivery of the first postshock chest compression. 70 The new AHA guidelines necessitate reprogramming of all previously purchased AEDs, as they are programmed with older ''stacked shocks'' protocols. Institutions that have AEDs with older protocols should contact their vendors to reprogram the AED.…”

Cardiopulmonary Resuscitation

“…However, literally minutes are currently wasted after application of automated defibrillators (AEDs) because they are used for repetitive rhythm analysis and capacitor charging. 5 These adverse effects of AEDs prompted at least 2 modifications. The first idea, which is a concept for guiding the further development of the technology, is to define 2 discrete types of cardiac arrest.…”