Without intervention, cardiac arrest may lead to permanent neurological injury after just three minutes. The interventions that contribute to a successful outcome after a cardiac arrest can be conceptualized as a chain – the Chain of Survival (Fig. 47.1).
This chapter includes some background to the epidemiology and the prevention of cardiac arrest. It details the principles of initiating CPR in-hospital, defibrillation, advanced life support (ALS), post-resuscitation care and potential modifications to ALS when cardiac arrest occurs intraoperatively.
The 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations summarizes all the current science underpinning CPR. The European Resuscitation Council (ERC) and Resuscitation Council (UK) Guidelines for Resuscitation 2010 are derived from the 2010 consensus document and have been used as source material.
Ischaemic heart disease is the leading cause of death in the world. In Europe, sudden cardiac arrest is responsible for more than 60% of adult deaths from coronary heart disease. In Europe, the annual incidence of emergency medical services (EMS)-treated out-of-hospital cardiopulmonary arrest (OHCA) for all rhythms is 35 per 100 000 population. The annual incidence of EMS-treated ventricular fibrillation (VF) arrest is 17 per 100 000 and survival to hospital discharge is 10.7% for all-rhythm and 21.2% for VF cardiac arrest. There is some evidence that long-term survival rates after cardiac arrest are increasing. On initial heart rhythm analysis, about 25–35% of OHCA victims have VF, a percentage that has declined over the last 20 years. Immediate CPR can double or triple survival from VF OHCA. After VF OHCA, each minute of delay before defibrillation reduces the probability of survival to discharge by about 10%.
The incidence of in-hospital cardiac arrest is difficult to assess because it is influenced heavily by factors such as the criteria for hospital admission and implementation of a do-not-attempt-resuscitation (DNAR) policy. The reported incidence of in-hospital cardiac arrest is in the range of 1–5 per 1000 admissions. Data from the American Heart Association’s National Registry of CPR indicate that survival to hospital discharge after in-hospital cardiac arrest is 17.6% (all rhythms). The initial rhythm is VF or pulseless VT in 25% of cases and, of these, 37% survive to leave hospital; after pulseless electrical activity (PEA) or asystole, 11.5% survive to hospital discharge. Preliminary data from the United Kingdom National Cardiac Arrest Audit (NCAA), which includes all individuals receiving chest compressions and/or defibrillation and attended by the hospital-based resuscitation team (or equivalent) in response to a 2222 call, indicates that the survival to hospital discharge after all-rhythm cardiac arrest is 19.5%.
Cardiac arrest in hospital patients in unmonitored ward areas is not usually a sudden unpredictable event; it is also not usually caused by primary cardiac disease. These patients often have slow and progressive physiological deterioration, involving hypoxaemia and hypotension that has been unnoticed by staff, or recognised but treated poorly. Many such patients have unmonitored arrests, and the underlying cardiac arrest rhythm is usually non-shockable; the preliminary NCAA data show that survival to hospital discharge for this group is just 7%.
2. Monitor such patients regularly using simple vital sign observations (e.g. pulse, blood pressure, respiratory rate, conscious level, temperature and SpO2). Match the frequency and type of observations to the severity of illness of the patient.
6. Introduce into each hospital a clearly identified response to critical illness. This will vary between sites, but may include an outreach service or resuscitation team (e.g. medical emergency team (MET)) capable of responding to acute clinical crises. This team should be alerted, using an early warning system, and the service must be available 24 hours a day.
8. Empower staff to call for help when they identify a patient at risk of deterioration or cardiac arrest. Use a structured communication tool to ensure effective handover of information between staff (e.g. SBAR – Situation-Background-Assessment-Recommendation).
9. Agree a hospital do-not-attempt-resuscitation (DNAR) policy, based on current national guidance. Identify patients who do not wish to receive CPR and those for whom cardiopulmonary arrest is an anticipated terminal event for whom CPR would be inappropriate.
10. Audit all cardiac arrests, ‘false arrests’, unexpected deaths, and unanticipated intensive care unit admissions, using a common dataset. Audit the antecedents and clinical responses to these events. All hospitals should consider joining NCAA (http://www.resus.org.uk/pages/NCAA.htm).
The division between basic life support and advanced life support is arbitrary – the resuscitation process is a continuum. The keys steps are that cardiorespiratory arrest is recognized immediately, help is summoned, and CPR (chest compressions and ventilations) is started immediately and, if indicated, defibrillation attempted as soon as possible (ideally, within 3 min of collapse).
Skills of the responders – in some public places staff may be trained in CPR and defibrillation. All healthcare professionals should be able to recognize cardiac arrest, call for help, and start resuscitation.
Equipment available – AEDs are available in some public places. In hospital, ideally, the equipment used for CPR (including defibrillators) and the layout of equipment and drugs should be standardized throughout the hospital. AEDs should be considered for clinical and non-clinical areas where staff do not have rhythm recognition skills or rarely need to use a defibrillator.
Response system to cardiac arrest and medical emergencies – outside hospital the EMS should be summoned. In hospital, the resuscitation team can be a traditional cardiac arrest team (called when cardiac arrest is recognized) or a MET.
Many trained healthcare staff may not be able to assess a patient’s breathing and pulse sufficiently reliably to confirm cardiac arrest. Agonal breathing is common in the early stages of cardiac arrest and is a sign of cardiac arrest; it should not be confused as being a sign of life/circulation. Agonal breathing can also occur during chest compressions as cerebral perfusion improves, but is not indicative of a return of spontaneous circulation (ROSC). Delivering chest compressions to a patient with a beating heart is unlikely to cause harm.
The quality of chest compressions is often poor and, in particular, frequent and unnecessary interruptions often occur. Even short interruptions to chest compressions may compromise outcome. The correct hand position for chest compression is the middle of the lower half of the sternum. The recommended depth of compression is at 5–6 cm and the rate is 100–120 compressions min− 1. Allow the chest to recoil completely in between each compression. If available, use a prompt and/or feedback device to help ensure high-quality chest compressions. The person providing chest compressions should change about every 2 min, or earlier if unable to continue high-quality chest compressions. This change should be done with minimal interruption to compressions.
During CPR, perfusion of the brain and myocardium is, at best, 25% of normal; successful ROSC is more likely the higher the coronary perfusion pressure (CPP). Chest compressions increase the amplitude and the frequency of the VF waveform and increase the likelihood that attempted defibrillation will be successful. Pauses in chest compressions of just 10 seconds before shock delivery (pre-shock pause) reduce the chances of successful defibrillation. Frequent interruptions in chest compressions reduce survival from cardiac arrest: each time chest compressions are stopped the CPP decreases rapidly and takes time to be restored to the same level once the compressions are restarted.
Arrhythmias associated with cardiac arrest are divided into two groups: shockable rhythms (VF/VT) and non-shockable rhythms (asystole and PEA). The principle difference in management is the need for attempted defibrillation in patients with VF/VT. Subsequent actions, including chest compression, airway management and ventilation, vascular access, injection of adrenaline, and the identification and correction of reversible factors, are common to both groups. The ALS algorithm (Fig. 47.3) provides a standardized approach to the management of adult patients in cardiac arrest.
The first monitored rhythm is VF/VT in approximately 25% of cardiac arrests, both in or out of hospital. VF/VT will also occur at some stage during resuscitation in about 25% of cardiac arrests with an initial documented rhythm of asystole or PEA. Having confirmed cardiac arrest, help (including a defibrillator) is summoned and CPR initiated, beginning with chest compressions, with a compression:ventilation (CV) ratio of 30:2. When the defibrillator arrives, chest compressions are continued while applying self-adhesive pads. The rhythm is identified and treated according to the ALS algorithm.
Once the defibrillator is charged, pause the chest compressions, quickly ensure that all rescuers are clear of the patient and then give one shock. The person doing compressions, or another rescuer may deliver the shock. This sequence should be planned before stopping compressions.
If intravascular (i.v./intraosseous) access has been obtained, give adrenaline 1 mg and amiodarone 300 mg once compressions have resumed. On completion of CPR for 2 min, pause briefly to check the monitor:
If an organized rhythm is seen during a 2-minute period of CPR, do not interrupt chest compressions to palpate a pulse unless the patient shows signs of life (this may include a sudden increase in end-tidal carbon dioxide [PECO2] if this is being monitored) suggesting ROSC. If there is any doubt about the existence of a pulse in the presence of an organized rhythm, resume CPR. If the patient has ROSC, begin post-resuscitation care.
A single precordial thump has a very low success rate for cardioversion of a shockable rhythm and is only likely to succeed if given within the first few seconds of the onset of a shockable rhythm. There is more success with pulseless VT than with VF. Delivery of a precordial thump must not delay calling for help or accessing a defibrillator. It is reasonable to attempt a precordial thump if VF occurs intraoperatively, but do not delay the call for a defibrillator.
Pads Versus Paddles: Self-adhesive defibrillation pads have practical benefits over hand-held paddles for routine monitoring and defibrillation and are much preferred to standard defibrillation paddles. Use of self-adhesive pads enables the operator to defibrillate the patient from a safe distance and to deliver a shock more rapidly than with paddles.
Safe Use of Oxygen: In an oxygen-enriched atmosphere, sparks from defibrillator paddles applied poorly can cause a fire. The use of self-adhesive defibrillation pads instead of manual paddles reduces the risk of sparks occurring.
Leave the ventilation bag connected to the tracheal tube or other airway adjunct. Alternatively, disconnect the ventilation bag from the tracheal tube and move it at least 1 m from the patient’s chest during defibrillation.
Single Versus Three-Shock Strategy: If defibrillation is attempted immediately after the onset of VF, it is unlikely that chest compressions will improve the already very high chance of ROSC associated with second or third shocks (i.e. myocardial levels of oxygen and adenosine triphosphate are likely to be adequate for the first minute or so). Thus, if VF/VT occurs during cardiac catheterization or in the early post-operative period after cardiac surgery (when chest compressions could disrupt vascular sutures), consider delivering up to three-stacked shocks before starting chest compressions. This three-shock strategy may also be considered for an initial, witnessed VF/VT cardiac arrest if the patient is already connected to a manual defibrillator – this situation will exist perioperatively if defibrillation pads were applied before induction of anaesthesia.
Defibrillation Energy: All modern defibrillators deliver shocks with a biphasic waveform. The initial biphasic shock should be at least 150 J. Because of the lower efficacy of monophasic defibrillators for terminating VF/VT, the recommended initial energy level for the first shock using a monophasic defibrillator is 360 J. If an initial shock has been unsuccessful, deliver the second and subsequent shocks with a higher energy level if the defibrillator is capable of delivering a higher energy. Manufacturers should display the effective waveform energy range on the face of the biphasic device. If you are unaware of the effective energy range of the device, use 200 J for the first shock.
Pulseless electrical activity (PEA) is defined as the absence of any palpable pulse in the presence of cardiac electrical activity that would be expected to produce a cardiac output. There may be some mechanical myocardial contractions that are too weak to produce a detectable pulse or blood pressure – this is sometimes described as ‘pseudo-PEA’. PEA may be caused by reversible conditions that can be treated if they are identified and corrected. A relative overdose of an induction drug is a well-recognized cause of intraoperative cardiac arrest.