 Growing evidence suggests that a significant proportion of in-hospital patient deaths occur after serious adverse events SAEs. Concerns have been raised that too often patients acute deteriorations, particularly on surgical and medical wards outside critical care settings, are identified too late and corrective actions taken too slowly. Many initiatives have been taken to prevent unexpected death by timely recognition, intervention and resuscitation efforts such as Rapid Response Systems RRSs. RRSs have been introduced with the intention to prevent SAEs and to improve patient outcome by facilitating early detection of warning signs for clinical deterioration. These systems have four components 1 an afferent limb for detection and response triggering, 2 an efferent limb with medical or nursing response to prevent deterioration 3 a process improvement limb and 4 a governance and administrative structure. It remains uncertain which elements of RRSs contribute most to patient outcomes such as unplanned re- admission to the intensive care unit, shock, cardiac arrest and unexpected death. In addition, previous studies found that nurse observation, assessment and communication afferent limb are crucial to achieve better patient outcomes, but how to achieve afferent limb sustainability in hospitals is not clear. 