The continuum of critical illness for an individual can span the period before and beyond hospital admission. Resuscitation is often required outside the critical care environment. The 'cardiac arrest' team has evolved to use a more proactive, early intervention approach, utilising a range of rapid response systems and instruments to detect deterioration in patients' clinical status (see Chapter 3). It is well recognised that improved outcomes from cardiac arrest are dependent on early recognition and initiation of the 'chain of survival' .This chapter introduces the resuscitation systems and processes in both the pre-hospital and the in-hospital settings.