A cardiac arrest is defined as the sudden abrupt loss of heart function and is the terminal event in sudden cardiac death.¹ According to the recently published cardiovascular strategy from the Department of Health, there are approximately 5,000 sudden cardiac deaths each year in Ireland. That equates to approximately 14 deaths per day. Some 75% of these sudden collapses happen in the pre-hospital environment.² Of these, about 100 are under the age of 35. 

The causes of sudden cardiac death are varied, such as coronary artery disease, cardiomyopathy and arrhythmias. The European Task Force on Sudden Cardiac Death has recommended a time limit of five minutes from a cardiac arrest to defibrillation in a community setting. Currently, those suffering from a cardiac arrest have a 5-10% chance of surviving to a hospital discharge. 

The key to successful resuscitation lies in effective cardiopulmonary resuscitation (CPR) until defibrillation can occur. The chance of survival reduces by 10% by each minute that CPR and defibrillation are delayed. Indeed, early CPR and defibrillation within two minutes of a cardiac arrest can lead to survival rates of over 60%. GPs will experience cardiac arrests on an occasional basis but it is important that they are familiar with the current international guidelines on CPR to optimise this chance of survival.

The International Liaison Committee on Resuscitation (ILCOR) was set up in 1992 to establish a consensus between the major international resuscitation organisations on CPR guidelines based on the latest scientific evidence. The last meeting of ILCOR was in October 2010 at which new CPR guidelines were announced.⁴ The previous guidelines were issued in 2005. These have been endorsed by the European Resuscitation Council for adoption and it is expected that they will be implemented nationally in the coming months. The changes on this occasion are certainly not as drastic as the 2005 guidelines. In this article we will review the main changes in basic life support (BLS) and give a brief summary of the changes and the science behind the changes. 

A huge emphasis is now placed on the importance of bystander CPR and encouraging bystanders to respond even if they have never been trained in CPR. On making a 999/112 call, callers are now encouraged by the control room call-taker to perform compression-only CPR. This is to ensure that all victims receive early compressions. 

It is worth noting that attending a class and practising CPR improves performance during a cardiac arrest and would certainly put these new changes into context. 

Compressions

The 2010 guidelines continue to put emphasis on high quality CPR and uninterrupted chest compressions. This can be achieved by a:

• Compression rate of at least 100/min (which has increased since 2005)
• Compression depth of at least 5cm (two inches) in adults, in children approx 5cm (two inches) and in infants approx 4cm (1.5 inches). These depths are deeper than 2005 depths
• Allow complete chest recoil
• Minimise interruptions in chest compressions; in other words the less time spent with hands off the chest, the better the chance of a favourable outcome for the victim.

Research has shown that the only people who survive cardiac arrest are those who have had early chest compressions. Compressions create blood flow and oxygen delivery to the heart, brain and vital organs by increasing intrathoracic pressure and compressing the heart directly. If compressions are not deep enough this will result in inadequate blood flow and oxygenation. Compressions need to be uninterrupted. If compressions are interrupted for a period of 10 seconds, blood flow is adversely affected and a long period of chest compressions will be then required to return an adequate cardiac output.

Ventilations

The ratio of compressions to ventilations remains at 30:2 in adult, infant and child. There are no changes in the following but it is worth recapping them:

• Avoid excessive ventilations
• Breaths should be given over one second each
• Rescue breaths are given at one breath every five to six seconds
• Do not over-ventilate the victim.

Once again, ventilations are being de-emphasised. One of the big changes is the elimination of ‘look, listen and feel’. The reason for this is that many rescuers find it difficult to recognise adequate breathing. They spend a long period of time checking for breathing and therefore delay chest compressions. Agonal breathing is often mistaken for adequate breathing. We will discuss the new CAB sequence below. Responders now briefly check for breathing as they are checking for a response and pulse while shouting for help. Basically, all of the initial steps have been put together while adding to the speed of commencing compressions.

Change of sequence from ABC to CAB

One of the biggest changes in the 2010 guidelines is the change from ABC to CAB. Therefore, instead of airway, breathing and circulation we will now do compressions, airway, breathing. 

This change was brought about because of the importance of early chest compressions. It was found that compressions are regularly delayed by responders being slow to recognise cardiac arrest, confusing agonal breathing with normal breathing and delaying while assembling face masks and other devices. Agonal breathing is a shallow and slow breathing pattern which is often irregular in nature and provides no effective oxygenation.

On finding a collapsed victim, the new sequence is:

• Check for responsiveness. While checking this, scan the chest for no breathing or no normal breathing (‘head tilt’, ‘chin lift’, and ‘look listen and feel’ are gone). While checking for breathing also check the pulse simultaneously
• Call for an automated external defibrillator (AED)/defibrillator and call emergency services on 999 or 112
• Start chest compressions
• Continue compressions and breaths at a ratio of 30:2
• When AED arrives, attach it with minimal interruptions.

AED use

The AED should be attached to the victim as soon as it arrives on scene. There should be minimal interruptions in chest compressions while attaching the pads. A new recommendation is the use of AEDs on infants. In the 2005 guidelines it was recommended that AEDs could be used on children but this recommendation has now been further extended to include infants. It is preferable to use child AED pads but if these are not available, adult pads can be used. Remember, two minutes of CPR are performed on children and infants prior to attaching the AED except in a sudden collapse, when it should be attached immediately.

Chain of survival

Immediate recognition of cardiac arrest and activation of the emergency response system

• Early CPR with an emphasis on chest compressions
• Rapid defibrillation
• Effective advanced life support
• Integrated post-cardiac arrest care. 

A fifth link has been added to the chain of survival, now emphasising the importance of post-cardiac arrest care:

Early CPR

In summary, the guidelines have been further simplified to ensure that those in cardiac arrest are quickly identified as being in cardiac arrest and that they receive high quality uninterrupted CPR and defibrillation early. To read more on the new guidelines, read Circulation, November 2010 edition. For CPR classes go to www.irishheart.ie/resus and click onto affiliated training sites for course providers. For information, see www.phecc.ie  

Acknowledgement: Brian Carlin, lecturer in emergency medicine, UCD

References 

1. Ireland. Task Force on Sudden Cardiac D, Maurer B. Reducing the risk : a strategic approach. Dublin: Dept. of Health and Children; 2006.
2. Irish Heart Foundation. www.irishheart.ie/iopen24/resuscitation-programme-background-t-9_252.html
3. Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death (ACC/AHA/ESC 2006 Guidelines for Management of Patients With) EHJ 2006;27:2099–2140
4. Circulation. 122(18) (Supplement 3):S639, November 2, 2010