The Joint Commission's National Patient Safety Goals, directs health care providers to improve the identification of clinical deterioration in hospitalized patients and select “a suitable method that enables health care staff members to directly request additional assistance from a specially trained individual(s) when the patient's condition appears to be worsening.”1
Rapid response systems are designed to address this goal and RRTs or METs have become increasingly prevalent in the US hospital systems as the means to intervene in the care of hospitalized patients with acute clinical deterioration.2,3 RRTs are called to evaluate and treat not only the patients who had a cardiorespiratory arrest (for which traditional code teams exist), but also to assess patients who are having symptoms indicative of an impending cardiorespiratory or neurologic deterioration, thus supplementing traditional code teams in scope and frequency of response.2,3,4,5 RRTs may be called for signs of clinical deterioration, such as vital sign abnormalities, arrhythmias, dyspnea, and altered consciousness. A demand on the limited number of intensive care unit (ICU) beds requires more acute and complex patient care to be delivered on the general wards, outside of the ICU.6
Rapid Response Activation
The RRT team is activated in instances of perceived patient deterioration and recognition of clinical deterioration. RRT calls are most commonly prompted by cardiorespiratory and neurologic symptoms identified by hospital staff (clinical and nonclinical) or even family members.
The identification of prearrest physiology such as abnormal vital signs, or a sudden change in vital signs, can help identify clinical deterioration minutes to hours before a serious adverse event, often providing sufficient time to deliver an intervention.7,8,9 Indeed, diurnal variation of RRT activation rates generally correlate with the timing of caregiver visits.10 Delays in provider notification and failure to seek help in a timely manner by ward personnel can also contribute to suboptimal outcomes and increased mortality even when RRT systems are in place.11,12 Providing objective criteria as a guide for the activation of RRT improves utilization of the RRT systems.
Studies have searched for the minimal criteria for RRT activation. Universally, vital signs monitoring and evaluation of mental status is reproducible and effective.13 Trigger systems that rely on these parameters alone are known as single and multiple parameter systems based on the number of physiologic criteria included (Figure 6–1). Continuous vital sign monitoring is not feasible for non-ICU patients; so the optimal frequency of vital sign monitoring is patient dependent and difficult to generalize to all patient populations.14
Example of a rapid response activation care based on single-parameter system. Cards can be distributed, or posted, to instruct clinical staff about activating the rapid response team.
In a review of current early warning systems for recognizing and responding to clinically deteriorating patients, relevant policies were examined to determine the vital sign parameters and trigger thresholds that activate RRT. Most hospitals scored respiratory rate, heart rate, systolic blood pressure, and consciousness level as triggers, and some additionally scored urine output, oxygen saturation, and need for oxygen administration. The thresholds for classifying the values as abnormal varied between the hospitals and were chosen seemingly arbitrarily based on local preferences and expertise.15 A study of 400 rapid response calls at a large Australian teaching hospital found the most common reasons for RRT activation to be hypoxia (41%), hypotension (28%), altered consciousness (23%), tachycardia (19%), increased respiratory rate (14%), and oliguria (8%). Infection, pulmonary edema, and arrhythmias featured prominently as underlying morbidities and were thought to be responsible for 53% of all triggers for RRT calls.16
Traditional ICU scoring systems, such as the sequential organ failure assessment (SOFA) score or the multiple organ dysfunction score (MODS) which are used to predict ICU mortality have been adopted by some institutions as markers for clinical deterioration of non-ICU patients.
The National Early Warning Score Design and Implementation Group (NEWSDIG) in the United Kingdom developed the VitalPac Early Warning Score (ViEWS), a validated scoring system for the early detection of clinical deterioration and prediction for cardiac arrest or need for ICU transfer. The aggregate weighted system scores physiologic parameters to determine the need for more frequent monitoring or ICU-level care. The parameters include respiratory rate, oxygen saturation, supplemental oxygen use, temperature, systolic blood pressure, heart rate, and level of consciousness. Higher scores indicate the need for more frequent reassessment and higher level of care (Figure 6–2A, B, C). Similar scoring systems such as the cardiac arrest risk triage (CART) have been developed using logistic regression. The CART score has been validated for in-hospital cardiac arrest (AUC 0.84) and the need for ICU transfer (AUC 0.71).17 Over 100 track and trigger systems have been developed in recent years, making it extremely difficult to accurately compare and validate them with each other.
The National Early Warning Score physiologic parameters scoring chart. A, alert; P, any response to pain; V, any response to voice; U, unresponsive/unconscious. (Reproduced with permission from Royal College of Physicians. National Early Warning Score (NEWS): Standardising the assessment of acuteillness severity in the NHS. Report of a working party. London: RCP, 2012.)
The National Early Warning Score threshold and triggers. (Reproduced with permission from Royal College of Physicians. National Early Warning Score (NEWS): Standardising the assessment of acuteillness severity in the NHS. Report of a working party. London: RCP, 2012.)
The National Early Warning Score outline for recommended frequency of monitoring and clinical response. (Reproduced with permission from Royal College of Physicians. National Early Warning Score (NEWS): Standardising the assessment of acuteillness severity in the NHS. Report of a working party. London: RCP, 2012.)
More recently, prediction models using vital sign, demographic, location, and laboratory data in electronic health records have been developed as early warning systems for adverse outcomes on the wards. The models are able to calculate a risk score based on computerized data to alert caregivers with automated, real-time, information regarding patient deterioration. Compared to manually calculated systems, automated systems are the least error prone to calculation errors and are the least labor intensive. Although potentially quite useful, these automated scoring systems should not be regarded as the sole solution for detecting patient deterioration; the systems are highly sensitive and may overestimate clinical deterioration or need for higher level of care. Rather, their use could be an adjunct to alert staff to the need to further clinically assesses patients.18
A large systematic review demonstrated that implementation of single parameter triggering systems alone are unlikely to improve hospital survival, and that there was only weak evidence in the reduction of cardiac arrest. In contrast, aggregate weighted scoring systems improved hospital survival and reduced both unexpected ICU admission and cardiac arrest rates.19
Typical call rates are 20 to 40 per 1000 admissions and the in-hospital mortality of such patients is 24% to 34%.3,20 Although the MERIT study, a multicenter, cluster-randomized, controlled trial of RRT systems failed to demonstrate that implementation of RRTs led to a decrease in cardiac arrests, ICU admissions, or unexpected deaths;21 post hoc analysis showed a significant improvement in outcomes when the data were analyzed in an as-treated model rather than an intention-to-treat model.22 Further single-center trials also point to improved outcomes in hospitals that implemented RRTs.20 A meta-analysis of 18 studies reviewing the effectiveness of RRT systems in acute care settings demonstrated that the implementation of RRTs is associated with reduced rates of cardiorespiratory arrests outside of the ICU with relative risk reduction of 33%.23 In addition, a retrospective study of nearly 6 million admissions over a 10-year period showed the presence of a hospital RRT system for more than 2 years was associated with 0.14% absolute risk reduction of in-hospital mortality across a major metropolitan health network, which translated to 56 lives saved per year in a hospital with 40,000 admissions per year.24 Mortality benefits after the introduction of RRTs are not always immediate and may take time to become apparent.
In general, triage decisions based on rapid response evaluation regarding transfer of patients to the ICU or general ward care seem to be appropriate. In a large study, 12.7% of patients that had RRT activation required repeat RRT activation and of those around 80% were transferred to the ICU. A total of 0.4% died within 24 hours of the index RRT activation, with half of the mortalities occurring as unexpected cardiac arrests on the wards, while the other half occurred in the setting of ICU care, or palliative care, after the repeat RRT call.25
Inappropriate triage and disposition of unrecognized critical illness at the time of initial admission are contributing factors to unfavorable patient outcomes. Indeed, RRTs occurring early in hospitalizations (hospital days 0 and 1) constitute approximately 27% of all calls and partially reflect suboptimal triage decisions.10
The composition of the RRT can vary significantly based on the hospital system and available resources.26 Teams are often comprised of multidisciplinary staff that may include critical care medicine fellows or attendings, internal medicine housestaff or hospitalists, respiratory therapists, physician assistants, nurse practitioners or an ICU nurse. Studies evaluating ideal team composition are sparse.27 It is difficult to assess the optimal team composition and subsequent outcomes due to the amount of variation that exists. While it has been shown that response teams led by attending intensivists and senior medical residents had similar outcomes, teams led by nurses alone had equivocal outcomes.19