Rapid response systems and the emergency department

Introduction and definitions

Predicting and managing the risk of deterioration is fundamental to emergency care. This process commences at the point of initial triage and continues for the duration of the emergency care episode. Over the last three decades, emergency departments (EDs) have developed systematic approaches to the assessment, risk management and clinical care of specific patient groups including trauma, stroke, sepsis and acute coronary syndrome that have improved patient outcomes. Rapid response systems (RRSs) are well established for patients who deteriorate on hospital wards. Such systems provide a framework to assist staff in the identification of a deteriorating patient, as well as guidelines for the expected response when deterioration occurs. In Australia, national standards mandate that all acute care facilities have an RRS for the recognition and response to deteriorating ward patients. However, a similar systematic approach for the recognition and response to deteriorating ED patients following their initial triage have only emerged in recent years.

The term RRS describes an entire system. The major components of RRS are the afferent limb to detect clinical deterioration, an efferent limb (the responding team), and audit and governance limbs. The ‘afferent’ limb provides clinicians with an objective definition of deterioration, largely based on vital sign derangement or clinician concern ( Table 29.8.1 ). Most RRSs also enable activation for clinician concern, thus allowing RRS activation for deteriorating patients in whom the vital signs are not deranged. The ‘efferent’ limb describes the structured and expected response to RRS activation. Rapid response teams (RRTs) are composed of staff who manage deteriorating hospital patients with the preventing SAE. When the team leader is a doctor, the RRT is called a medical emergency team (MET). A MET should have a number of competencies, including abilities in the following areas :

• prescription of therapies

• advanced airway management skills

• insertion of invasive vascular lines

• commencement of intensive care level of care at the bedside.

The most common type of response in Australia is the MET; however, other types of review team include the nurse led RRT and critical-care outreach team, which differ in their staff composition, skill set and mechanism of activation. Additional components of the RRS include quality improvement and clinical governance arms, which permit the audit and evaluation of SAEs and the implementation of hospital-wide strategies to prevent recurrence. Quality systems that enable collection and analysis of RRS data are important to establish ‘dose’ or frequency of activation, the causes of deterioration and to track patient outcomes.

Principles underlying rapid response system

Historic studies demonstrated that in-hospital cardiac arrest or unplanned intensive care unit admission were often preceded by abnormal physiological signs in the hours before these events. Further, there is a well-documented relationship between abnormal vital signs and mortality. The intent of RRSs is to prevent SAEs, and thereby improve patient outcomes by the early recognition of, and response to, deteriorating patients. Most Australian health services have a two-tiered RRS comprising the cardiac arrest team (CAT) and the MET. There are now three systematic reviews demonstrating that the introduction of an RRS is associated with a reduction in in-hospital cardiac arrests, and one revealed a reduction in all-cause hospital mortality. Benefit has been observed for both adult and paediatric patients. The in-hospital mortality of patients who have an RRS review is as high as 34%, suggesting that recognition and response to clinical deterioration should occur earlier than RRS review. As a result, a number of Australian health services have added a third ‘pre-MET’ tier to their RRS, whereby the thresholds for escalation of care are lower and care is escalated to the parent unit.

Clinical deterioration in emergency department patients

The epidemiology of clinical deterioration in ED patients is an area of developing knowledge. Approximately 20% to 25% of ED patients exhibit one of more abnormal vital signs during ED care. Between 1.5% and 23% of ED patients experience clinical deterioration that fulfils ED-specific or hospital-wide RRS activation criteria at some stage during their ED care. By way of contrast, one or more abnormal observations are reported at any point in time in 3% to 14% of ward patients. It may be expected that a considerable number of ED patients will have vital sign abnormalities by virtue of the fact their illness or injury has resulted in ED attendance. There are 7.8 million attendances to Australian EDs annually : if 1.5% to 23% of ED patients have abnormal vital signs, as many as 1.8 million ED attendances may have physiological abnormalities making physiological instability an issue of significant concern.

Interpreting the results of studies of ED patient deterioration has been challenging in part due to the variable patient populations included: all ED patients in treatment spaces (so excluding waiting room patients) ; patients with specific presenting complaints (abdominal pain, chest pain, shortness of breath and febrile illness) ; and patients in general treatment areas of the ED (so excluding patients in resuscitation and fast track areas). Recent Australian studies show that the most common vital sign derangements fulfilling hospital MET criteria during ED care are tachypnoea, tachycardia and hypotension.