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Emergency! In the eighth part of our series, Neil Goldsack, Richard Marshall, Hugh Montgomery, and David Howell instruct you how to deal with patients who have had a cardiac arrest Introduction Picture the scene. You have just spent five or six years in medical school, and now you are about to begin your first day as a doctor. You stand there proud, in your new white coat, BNF tucked handily in the pocket, stethoscope hung nonchalantly around your neck, and bleep at the ready. Suddenly and without warning, that first fateful bleep goes off: "Cardiac arrest-- ward 16 !" What do you do? A number of thoughts cross your mind. "I mustn't run, or I'll get there before the registrar, and they will expect me to know what to do"; "Walk slowly, then the anaesthetist will pass me in the corridor"; or "I'll walk in the other direction." Unfortunately, medical school often fails to prepare you for this event. You have read what to do, but now you have to put it into practice. This article will give you some practical hints on how to help when you are faced with a patient who has a cardiac arrest and will take some of the fear away for you. A cardiac arrest is the most acute emergency that you will get called to. Seconds really do matter. If you arrive too late, then the resuscitation is unlikely to be successful. First we will deal with basic life support and then go on to advanced life support and the algorithms. We urge you to memorise them, so you can at least begin to manage the cardiac arrest if your registrar arrives after you. We would also urge you to attend one of the many advanced life support courses that are currently available throughout the country. Basic life support1 If you come across a patient, either in the hospital or out in the community, who has collapsed on the floor it is important to ascertain if he or she is in cardiac arrest and then to start giving basic life support (see box 1). This technique is often tested at your final MBBS examinations. Learn it and practise it often with your local resuscitation officer. The approach
Advanced life support The most common situation when your skills will be called for is when a cardiac arrest is in progress and you arrive while basic life support is being given. Knowledge of the advanced cardiac arrest algorithms is essential at this stage (see figure). However, usually your role will be to assist your registrar as he or she manages the cardiac arrest (see box 2). Usually this entails either the establishment of a venous line, the drawing of blood and ensuring that it gets to the laboratory, performing an arterial blood gas analysis, or doing chest compressions or defibrillation or both. It is also possible that the anaesthetist may need your help to bag the patient while getting the anaesthesia equipment ready for intubation. As a house officer it is not really your duty to manage a cardiac arrest, a senior member of the medical staff should do this. It is important, however, to know how safely and effectively to perform defibrillation. Make sure that you familiarise yourself with the defibrillators in your hospital as soon as you arrive. When the paddles are charged and you are asked to defibrillate the patient then make sure that gel pads are applied to the patient, check, then tell everyone to stand clear of the patient and check that the anaesthetist has removed the oxygen from the patient. Only then is it safe to defibrillate. After the administration of the shock, the paddles should be left in position, recharged, and you should wait for the decision from your registrar as to if another shock is indicated. He or she will decide this on the basis of any change in the cardiac rhythm. Furthermore, hospitals are increasingly using automated defibrillators. These detect the cardiac rhythm and can themselves decide the need for shocks to be delivered. These machines charge themselves to the correct voltage and tell you what needs to be done at each stage. These machines may ultimately obviate the need for a registrar to be present at cardiac arrests. The Resuscitation Council (UK) has recently simplified the advanced life support algorithms (figure).2 Unfortunately, basic life support is unlikely to result in the recommencement of spontaneous cardiac rhythm, and so these algorithms need to be memorised. A cardiac monitor needs to be placed as soon as possible after arrival. The possible rhythms encountered during a cardiac arrest are now split into ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) and non-VF/VT. These latter rhythms include both asystole and electromechanical dissociation (complexes visible on an electrocardiography monitor with no discernible cardiac output). Often it can be difficult to decide if a rhythm is asystole or VF; if this is the case then the rhythm should be treated as VF and defibrillation given.
VF/pulseless VT In the case of VF or pulseless VT the initial defibrillation should be 200 Joules, followed by a further 200J, and then a third shock of 360J should be administered. A pulse check between these shocks should only be done if there is a change in rhythm on the monitor to a rhythm that is compatible with a cardiac output. Otherwise these shocks should be given as quickly as possible. If VF persists then one minute of cardiopulmonary resuscitation should be given, venous access obtained, 1 mg adrenaline given, and the patient intubated. After this minute of cardiopulmonary resuscitation, if there is still VF, then three further shocks of 360J should be given, again with a pulse check only if there is a rhythm change. Adrenaline should be administered after three minutes. If after 12 shocks the patient remains in VF then consideration should be given to the administration of antiarrhythmic drugs including lignocaine or bretylium.
Non-VF/VT In the case of asystole, basic life support should be given for three minutes Electromechanical dissociation (EMD) usually has a very poor prognosis. However, this can be improved if an underlying cause can be found and treated. You should look hard for a cause, since finding one is often the patient's only chance of survival (see box 3). If no cause can be found then cardiopulmonary
Summary It is essential that you know how to manage a cardiac arrest as a house officer. Although the situation instils fear into most people, a calm approach will go a long way to alleviate this. Be sure that as a medical student you take every opportunity to learn both basic and advanced life support. Many thanks to Dr M C Colquhoun, Honorary Secretary of the Resuscitation Council, for permission to publish these guidelines.
Hugh Montgomery cardiology specialist registrar David Howell Medical Research Council fellow Richard Marshall Wellcome fellow University College and Middlesex Hospital, London Neil Goldsack respiratory specialist registrar Chest Clinic, North Middlesex Hospital, London Resuscitation for the Citizen
Next month--the management of patients presenting with chest pain.
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