Rapid response system

The afferent component, also known as the track-and-trigger system, uses standardized tools to track early signs of reversible clinical deterioration and trigger a call to the efferent component.[1] Examples of afferent tools include single-parameter calling criteria and multi-parameter early warning scores.[1] These tools can predict clinical deterioration based upon the patient’s trait (e.g. has epilepsy) and detect deterioration through the patient’s state (e.g. high respiratory rate).[2] Single-parameter calling criteria require that only one criterion be met before activating the efferent component. Criteria may be based on vital signs, diagnoses, events, subjective observations, or concerns of the patient.[2] Multi-parameter tools are more complex in that they combine several parameters into a single early warning score (EWS).[2]

The efferent component is a multidisciplinary team trained in early resuscitation interventions and advanced life support that rushes to the deteriorating patient’s bedside to prevent respiratory and cardiac arrest in order to improve the patient’s outcomes. Often called the medical emergency team (MET), rapid response team (RRT), critical care outreach team (CCOT), or rover team, the team responds to calls placed by clinicians or families at the bedside who have detected deterioration. It may also provide proactive outreach to patients at high risk for deterioration. Composition of the teams may vary but often include one critical care attending physician or fellow, at least one nurse, and a respiratory therapist.[3]

The process improvement component uses evidence-based evaluation of the RRS to determine its effectiveness and to improve the system through targeted interventions. It works closely with the administrative component, clinicians (especially those on RRTs), and quality improvement experts to evaluate three measures: outcomes measures, process measures, and balancing measures.[3]

Rates of hospital-wide mortality and respiratory and cardiac arrest, which are exceedingly rare and may or may not be preventable, are common outcome measures.[4] The overall effectiveness of the RRS in improving patient safety is controversial due to the variability across studies in whether they reduce these rates.[4][5] More recent work uses proximal outcome measures, such as the Children’s Resuscitation Intensity Scale (measures level of care within 12 hours pre-transfer),[6] the Clinical Deterioration Metric (measures level of care within 12 hours post-transfer),[7] and UNSAFE transfers (measures level of care within 1 hour post-transfer).[8]

Process measures determine if the RRS is used as intended. Measures include the MET call rate, percentage of MET calls that result in transfer to the ICU, the time between initial physiologic abnormality and admission to ICU, timing of calls, reasons for MET calls, and evaluation of EWSs using sensitivity and specificity.[9][10][11]

Balancing measures evaluate any unintended consequences of the RRS. Identified barriers to activating the MET include the primary team’s overconfidence in their ability to stabilize the patient, poor communication, hierarchal problems, and hospital culture.[12][13][14] Interventions to overcome barriers include improved intradisciplinary staff education, protocol requiring activation when calling criteria are met, and use of “champions” to foster cultural change.[15][16]

The administrative component oversees the planning, implementation, and maintenance phases for the RRS. A formal committee of frontline clinicians and ward and ICU leaders operate the administrative component.[3] Cost effectiveness of RRS implementation has not been rigorously studied.[17]