Resuscitation and rapid response systems.

Just over 50 years ago, Peter Safar and colleagues began work n preventing mortality from cardiac arrest using a combinaion of rescue breathing and chest compressions, now known s cardiorespiratory resuscitation (CPR).1 Since then, a range of mprovements and additional interventions, e.g., different comression:ventilation ratios, automated defibrillators, intravenous rugs and therapeutic hypothermia, have been introduced. Most f the focus on improving outcome following in-hospital cardiac rrest (IHCA) has had one common denominator – they are recmmended after the arrest has occurred. Furthermore, although he case-mix of those suffering cardiac arrest has undoubtedly hanged, survival from IHCA has remained approximately the ame.2 For several decades, evidence has existed that potentially eversible abnormalities of vital signs were common, sometimes or many hours, before IHCA,3 suggesting that cardiac arrest was otentially preventable. Logically, in the 1990s, this led to the use f abnormal vital signs and other observations as triggers for an xpert-led, rapid response to patients thatmight otherwise have an HCA or die.4 This concept – the Medical Emergency Team (MET) – as patient-centred and implemented across an organisation, simlar to the way cardiac arrest teams had been operating in most ospitals for many years. The key difference was that the MET was ctivated before an arrest. Members of staff working on general wards identified at-risk atients using MET criteria – key predefined vital sign and obserational abnormalities – and triggered the MET response if one or ore of these were identified.4 Unlike the traditional hierarchical pproach to most emergencies (which may cause critical unintenional, but systematic, delays), theMET brings the correct expertise nd skills for the patient’s level of illness immediately. While the concept of identification of at-risk patients followed y a rapid response has remained the core of what has become nown as a Rapid Response System (RRS), there have been many odifications. For example, nuances to the original model have ncluded the inclusionof “staff concern” to theMETcalling criteria5; ttempts to improve the MET calling criteria6; the use of early arning scores7; using a teamwithout a physician8,9; pre-emptive atient visits by aRapidResponse Team (RRT)9,10; the development f RRTs in paediatrics11; and the use of adverse events as markers or potentially preventable gaps in care.12 It soon became clear that s well as early identification and response, a system approachwas lso necessary including auditing and administrative support.13 Early attempts at evaluating RRSs using before-and-after studes demonstrated impressive improvements in cardiac arrest ates.11,14,15 The largest cluster randomised trial, the MERIT study,