Despite the overall improvement in cardiovascular disease outcomes in the past decade, the survival of people following an Out of Hospital Cardiac Arrest (OHCA) has remained relatively low, at about 5 to 10% (Sasson et al, 2010). This lack of improvement in OHCA survival is disappointing, however, there are currently several promising interventions emerging that demonstrate the potential to improve these outcomes in the future. The well-established methodological chain of survival that follows as rapidly as possible after an OHCA event, and the two procedures involved therein, can only be said to be as strong or reliable as the weakest link, with the central links depicting the integration of cardiopulmonary resuscitation (CPR) and defibrillation as the fundamental components of early resuscitation in an attempt to restore life (Nolan et al, 2006). This is where recent protocols have been focusing in order to improve patient outcomes by ensuring that the core element of ongoing chest compressions is emphasized. Getting bystanders involved at an early stage is also important, as lay people are the most likely to arrive first at the scene of a cardiac arrest and many of them lack the confidence and training to offer help they are quite capable of providing. Successful strategies that can be employed to increase the level of bystander CPR performance include increasing coverage of CPR training, improving dispatcher assisted CPR, and increased participation of CPR by reassuring people that their efforts can be successful. Furthermore, untrained bystanders who may be dissuaded from performing CPR, as they are unwilling to provide ventilation, should be encouraged to perform compressions only. There is unequivocal evidence demonstrating an inverse relationship between the time taken to perform the first defibrillation on the patient, and survival from Ventricular Fibriliation (VF). A key factor in combating OHCA, therefore, would be an increased number of public access defibrillation units, combined with good quality chest compressions (Nolan et al, 2006). On the other hand however, a 2-tier response system in which Emergency Medical Services (EMS) oversee the activity of lay volunteers and non-medical EMS equipped with automatic external defibrillators (AEDs), have also shown considerable promise.
The quality of CPR delivered is crucial to survival. In practice health care professionals, as well as willing- and trained bystanders, should continue to combine compression and ventilation with a ratio of 30:2. Minimizing interruptions in chest compressions is essential, as well as making sure that chest compressions are deep (≥5-6 cm) and fast (≥100-120/ min), and that full release of pressure is ensured betwen compressions (Koster et al, 2010).
The evidence of using novel devices, such as those which prompt or give feedback, and devices that provide mechanical chest compressions, though limited, are encouraging, and therefore any potential strategies showing promise should be studied in more detail. When additional tasks such as defibrillation, airway management, vascular access and drug administration are carried out, the overriding consideration should still be to avoid interruptions in chest compression. In addition alternative defibrillation strategies should be adopted such as charging the defibrillator during chest compressions rather than charging it during a pause, as is the case in the traditional sequence. This is due to the fact that the former requires only a brief pause of chest compression to deliver the shock while traditionally the pre-shock pause is much longer.
Following successful resuscitation from OHCA, interventions in the postresuscitation care phase can also substantially impact patient outcome. There are some encouraging findings regarding early primary percutaneous coronary intervention and thrombolysis, although greater clarity should be provided for precisely when these interventions are to be performed. Furthermore, for comatose survivors of OHCA, therapeutic hypothermia can improve outcome (Walters et al, 2011), as can a system of regionalized speciality care for OHCA incorporating advances in post-resuscitation interventions.
Unfortunately, there is only limited data on factors associated with survival after OHCA in the UK. Such data collected across the nation still lacks consistency, which makes it harder to improve care quality and warranted the House of Commons Committee of Public Accounts 2010–2012 to call for NHS ambulance services to produce more reliable data and to reduce variation in statistics (House of Commons Committee of Public Accounts, 2011). All ambulance services are now collecting and reporting data on their survival figures for OHCA as part of the National Quality Indicators initiative, which will allow more accurate regional outcome comparisons for OHCA.
The good news is that there are already interventions shown to positively affect OHCA survival (Perkins et al, 2011), though to be able to show actual improvements of survival outside the hospital or in the field, a more structured approach to the problem will have to be adopted. Health-care workers will therefore have to collect data on the most important factors affecting cardiac arrest in a more consistent manner and for each individual case. The analysis of such quality data should allow us to identify potential strengths and weaknesses of current practice more accurately, and ultimately drive improvements for patient outcome.