Literature Review

CARDIOCEREBRAL RESUSCITATION

     Ewy GA, Kern KB. Recent advances in cardiopulmonary resuscitation: Cardiocerebral resuscitation. J Am Coll Cardiol 53(2):149–57, Jan 13, 2009.

     Cardiocerebral resuscitation (CCR) is a new approach for resuscitation of patients with cardiac arrest. It is composed of three components: 1) continuous chest compressions for bystander resuscitation; 2) a new emergency medical services algorithm; and 3) aggressive post-resuscitation care. The CCR method has been shown to dramatically improve survival in the subset of patients most likely to survive cardiac arrest: those with witnessed arrests and shockable rhythms on arrival of EMS.

     The CCR method advocates continuous chest compressions without mouth-to-mouth ventilations for witnessed cardiac arrest. It advocates either prompt or delayed defibrillation, based on the three-phase time-sensitive model of ventricular fibrillation (VF) articulated by Drs. Myron Weisfeldt and Lance Becker. For bystanders with access to AEDs and EMS personnel who arrive during the electrical phase (i.e., the first 4–5 mins. of VF arrest), the delivery of a prompt defibrillator shock is recommended. However, EMS personnel most often arrive after the electrical phase—in the circulatory phase of VF arrest. During the circulatory phase of VF arrest, the fibrillating myocardium has used up much of its energy stores, and chest compressions that perfuse the heart are mandatory prior to and immediately after a defibrillator shock. Endotracheal intubation is delayed, excessive ventilations are avoided, and early-administration epinephrine is advocated.

COMMENT

     CCR has been one of the exciting advances in the treatment of cardiac arrest. It was only a few years ago, before the AHA 2005 guidelines, when the emphasis was on establishing an advanced airway, continuous ventilation, giving medications (often down the ET tube) and multiple "stacked" shocks with careful rhythm interpretations between—all with long pauses in already-poorly performed chest compressions. All of that has changed, and outcomes have improved as a result.

     CCR is a better approach—and a better name. It reminds us that our goal is to restart the heart while preserving the brain. With that in mind, the treatments make sense. In the first 4–5 minutes, prompt defibrillation will restart the heart and restore normal circulation to the brain. If more than five minutes have passed (or will pass before a defibrillator is available), continuous chest compressions are started as early as possible, preferably by bystanders. There is plenty of oxygen in the blood, and high-quality chest compressions will circulate that oxygenated blood to the heart and brain. Defibrillation follows, with little or even no pause in chest compressions. Once circulation is restored, the patient is transported for aggressive in-hospital post-resuscitation care, such as with hypothermia and coronary angiography.

     The results have been impressive. Where CCR has been used, cardiac arrest survival has increased substantially. Kellum, et al (Ann Emerg Med 52:244, 2008), reported an increase in neurologically intact survival from 15% to 39% in patients with witnessed cardiac arrests from shockable rhythms. Bobrow, et al (JAMA 299:1,158, 2008), saw survival increase from 5% to 18%.

     Many questions still need to be answered, though. First, although CCR seems to result in better outcomes than the 2000 guidelines, we don't know if it's better than the 2005 guidelines, which incorporated many of the changes found in CCR. Second, epinephrine is advised in CCR but not proven to be beneficial. And third, we do not know how well CCR works for non-shockable rhythms, or for cardiac arrest from non-cardiac causes.

DEFIB THREAT TO BYSTANDERS

     Hoke RS, Heinroth K, Trappe HJ, Werdan K. Is external defibrillation an electric threat for bystanders? Resuscitation 2009

     Safety precautions during defibrillation and cardioversion are taken very seriously. The actual hazard for bystanders and rescuers, however, has rarely been investigated. Recently, continuing chest compressions during defibrillation has been suggested to improve outcome from cardiac arrest. This article is to review reports on electric shocks to persons other than patients and to discuss the pertinent biomedical principles.

     Methods—Systematic search in medical literature databases and consecutive hand-search of reference lists.

     Results—A total of 29 adverse events are reported in the medical literature: seven due to accidental or intentional defibrillator misuse, three due to device malfunction, four during training/maintenance procedures, and 15 during regular resuscitation efforts. Tingling sensations and minor burns are frequently reported consequences of inadvertent shocks. There are no accounts of immediate life-threatening conditions or long-term disability in rescuers/bystanders inflicted by defibrillation/cardioversion of a patient. Discharging a defibrillator directly to a healthy person's chest can be lethal.

     Conclusions—External electric therapy is likely to be safer than traditionally assumed, especially with self-adhesive thoracic electrodes.

COMMENT

     Interruptions in compressions reduce forward blood flow and diminish the likelihood of successful defibrillation, return of spontaneous circulation, survival and brain function. Pauses of as little as five seconds before or after defibrillation can worsen outcomes. However, studies have shown that interruptions in CPR are common, and compressions are done for only about half the total time of resuscitation. One of the causes of chest compression interruption is the process of defibrillation. This article suggests that, especially with electrode pads replacing paddles, the risks of defibrillation may be less than we thought. As an example, one reviewed study found that volunteer rescuers wearing standard exam gloves who pushed on patients' chests with wires connecting them to the patients could not feel any electrical shocks during cardioversion.

     Angelo Salvucci, Jr., MD, FACEP, is an emergency physician and medical director for the Santa Barbara County and Ventura County (CA) EMS agencies.