Early Warning and Rapid Response Systems

Introduction

Rapid response teams arose out of the realization that inpatients are at risk for serious adverse events that were usually preceded by physiologic signs of instability that were not always recognized by ward staff. ^, These teams have evolved over time since the concept appeared in the medical literature in the 1990s. These teams of responders vary in composition, but most have critical care experience and training and were developed in an effort to reduce hospital mortality by responding to, or preventing, serious adverse events.

Failure to rescue was originally defined as the death of a patient after developing a treatable condition, but has been refined to include these adverse events that could have been prevented or limited in severity by timely intervention or escalation of care. This has become an important safety indicator that attempts to measure a hospital’s ability to recognize and manage complications. In 2008 the Joint Commission established Patient Safety Goal #16 to improve recognition and response to changes in a patient’s condition. This has provided momentum to the international movement to develop and refine rapid response systems. Since their genesis, these teams have experienced a gradual transition from a primarily reactive response to a more proactive, early recognition model that utilizes early warning scoring systems, incorporating physiologic variables and trends to identify patients earlier in the process of deterioration.

The Rapid Response System

The term “rapid response system” describes the hospital-wide approach to recognition and treatment of a patient who is deteriorating. The major components are the afferent limb, the efferent limb, administrative (which oversees day-to-day function of the RRT), and audit and quality improvement.

The afferent limb describes the triggering mechanism for the activation of the rapid response team. A wide range of criteria for activation currently exists worldwide, ranging from complex early warning scoring systems to vital sign trends, specific cutoff points for individual vital signs (single parameter systems), and the instincts of the bedside nurse that “something is not right” (staff worried criterion). Experts feel that some objective criteria should be utilized, allowing standardization and education of staff, but that subjective reasons for escalating should not be deemphasized as this provides opportunities to intervene in patients for whom the objective criteria are unmet or not applicable. There is no set of calling criteria considered all-inclusive, as patient populations vary in their baseline physiology. In addition, there may be a need to customize calling criteria because of the variability in the expertise of the responders and availability of intensive care unit (ICU) beds, as well as other systems and processes for clinical deterioration. Experts have proposed a set of clinical indicators that suggest the need for ICU admission, which can easily be adapted into a hospital’s ICU admission criteria (see Table 38.1 ).

Table 38.1

Ten Clinical Indicators Suggesting the Need for ICU Admission

Clinical Indicator	Feature
Potentially threatened airway	Stridor, noisy breathing, airway swelling
Sustained tachypnea	Respiration rate >26 or increased work of breathing
Cyanosis/hypoxemia despite Fio ₂>0.4	Spo ₂<90%
Sustained tachycardia	Heart rate >120
Systolic blood pressure (SBP) <100 mmHg	Sustained SBP <100 or trend below baseline
Altered skin color	Cyanosis, mottling, cool periphery
Altered level of consciousness	Decreased Glasgow coma scale, new delirium, focal deficit
Frequent/prolonged seizures	Seizures recurrent or >5 min
Increasing creatinine	Rising creatinine level
Increasing lactate level	Serum lactate >3 mmol/L and rising

Not all patients who demonstrate one or more of these indicators will require ICU admission, but at the very least, timely evaluation and intervention should be considered, and the patient should be closely monitored for further deterioration. For the afferent limb to be effective, this triggering mechanism should not only be utilized by the bedside nurse but also be available to other caregivers and even to family members who recognize deterioration.

The efferent limb refers to the responding team, including the members and the equipment they carry. As will be described, the composition of the team varies between institutions and situation but typically follows one of the following models ( Table 38.2 ). The response should be available and timely all hours of the day, and there should be no negative consequences for activations considered unnecessary by the responding team. These team members are typically experienced high-acuity providers with critical care experience. They should project calm reassurance and the ability to diagnose and initiate treatment, and possess the authority to transfer to a higher level of care as needed.

Table 38.2

Types of Response Team

Type	Leader	Focus	Function
Medical Emergency Team (MET)	Physician	Clinically important deterioration	Active interventions
Rapid Response Team (RRT)	Nurse	Abnormal vital signs, Ward staff concern	Assessment, triage, call in resources
Critical Care Outreach (CCO)	Nurse	Follow up ICU discharges, abnormal vital signs, pre-emptive review following ward nurse referral	Assessment, triage, call in resources
Code Blue Team	Varies	Responds to cardiac arrest	Cardiopulmonary resuscitation/advanced cardiovascular life support (CPR/ACLS) protocol

Leadership and management of the rapid response system are essential to maintain an environment of patient safety. This key element should oversee team member selection and competency verification, sustained education of hospital staff, purchase and maintenance of equipment, collection and analysis of data from team activations, and communication of these data to hospital leadership to ensure patient safety and quality improvement. Rapid response systems will be limited in their effectiveness or may even fail if these critical elements are not addressed in an ongoing way, and success is impossible to achieve without hospital leadership support.

The administrative and quality improvement component is key in the collection and analysis of data, to allow feedback and appropriate allocation of resources. When coupled with hospital administrative support, this allows the team to improve function over time and to adapt to new challenges.

Composition

In contrast to a typical code team, which is called emergently to the bedside in response to an acute life-threatening event such as cardiac or respiratory arrest, rapid response teams are often activated for trending abnormal vital signs, early signs of respiratory distress such as tachypnea or increasing oxygen requirements, or a decrease in level of consciousness. The composition of these teams varies according to the needs and resources of the institution. Physician-led teams are conventionally titled medical emergency teams. Other teams may be led by advanced practice providers (nurse practitioners or physician’s assistants), critical care nurses, or even respiratory therapists. These are often referred to as rapid response teams, though the terminology varies. Critical care outreach services were initially deployed in the UK and led by nurses, with goals of avoiding admissions to the ICU, enabling discharges from the ICU, and educating ward staff. Their roles have expanded since then, and they are being utilized in more countries. More recently, specialized teams have been constructed to provide rapidly deployable expertise for specific subgroups of patients such as sepsis response teams and pulmonary embolism response teams. ^, Many of these teams have also assumed a role in facilitating limitations of care discussions, particularly in the oncology patient population.

Evidence

Due to the cost of implementing and maintaining rapid response systems, numerous trials have been performed to evaluate the effect on cardiopulmonary arrest events and in-hospital mortality in order to justify the cost. Earlier studies showed mixed results, with Chan et al., Shah et al., and Segon et al. failing to demonstrate the benefit of rapid response teams, while Lighthall et al. and Beitler et al. showed improved inpatient cardiac arrests and improved hospital-wide mortality. The earlier studies were limited by some variables, including institutional acceptance of rapid response teams, low utilization of calling criteria, and newly developed teams without protocols to intervene effectively at the bedside of a deteriorating patient. An early systematic review and meta-analysis by Chan et al. concluded that “although RRTs have broad appeal, robust evidence to support their effectiveness in reducing hospital mortality is lacking.” The MERIT investigators enrolled 125,000 patients from 23 Australian hospitals in a randomized trial of medical emergency team implementation and found no difference in unexpected mortality, cardiac arrests, or unplanned ICU admissions. These earlier studies and systematic reviews did not independently show reduction in hospital mortality or inpatient cardiac arrests but were able to show a significant impact when included in later meta-analyses. These later meta-analyses consistently show reduction in inpatient cardiac arrests. In a 2015 article, Maharaj et al. reviewed 29 eligible studies and showed that rapid response systems were associated with a reduction in hospital mortality and cardiopulmonary arrest. A meta-regression did not identify physician presence as a significant factor in this mortality reduction. The review by Winters et al. published in 2013 demonstrated a reduction in cardiorespiratory arrest rates outside of the ICU in pediatric and adult patients with rapid response systems, but total hospital mortality was not reduced in adults. They noted that more recent studies were more likely to show positive results. The currently available data support that rapid response teams reduce inpatient cardiac arrests ( Table 38.3 ) and suggest that rapid response systems help to achieve the goals of identifying patients who would benefit from a higher level of care.

Table 38.3

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