Clinical paperDocumenting Rapid Response System afferent limb failure and associated patient outcomes☆
Introduction
Rapid Response Systems (RRS) are becoming widely adopted. They evolved upon the basis that adverse events, such as deaths, cardiac arrests (CA) and unanticipated Intensive Care Unit (ICU) admissions, are often preceded by documented abnormalities in vital signs and a failure to respond to these signs being associated with increased mortality.1, 2, 3 RRS, the first of which was the medical emergency team (MET), are designed to provide a timely and structured response to physiological derangements with the aim of preventing these adverse events. Since the advent of RRS, cardiac arrests and associated mortality rates have fallen by 20–50% in various institutions.4, 5, 6, 7
Performance measurement of systems responding to patients is an important aspect of system maintenance to ensure maximal efficiency and efficacy. The sustainability of any system whose aims are the prevention of adverse events is in part reliant upon a process of audit and feedback of performance indicators.8 Other healthcare systems, such as those responding to trauma patients, have feedback mechanisms in place, which improve overall effectiveness by identifying areas of concern and then stimulating appropriate change.9, 10 Since RRS are a relatively recent phenomenon preferred performance measurements are still evolving and untested. For example, the rates of CA per hospital admissions and unanticipated admissions to the ICU from general wards are two such indicators of RRS efficacy that have been suggested.11
The detection of, and early Rapid Response Team (RRT) activation for, at risk patients constitutes the afferent limb of a Rapid Response System.12 It is known that critically unwell patients who receive early goal-directed therapy have reduced short and long-term mortality rates.13 Similarly, delay in transfer of patients requiring intensive care is associated with higher mortality rates.13, 14, 15, 16 Based on the importance of timely responses, hospital events, such as CA, unanticipated ICU admissions and RRT calls with documented calling criteria for which there was no activation of a RRT constitute afferent limb failure (ALF) and are thus a potential performance measure.
The aim of this study is to measure and describe MET afferent limb failure as a reflection of RRS performance and its impact on patient outcomes.
Section snippets
Setting
The Royal Adelaide Hospital, is a 650-bed tertiary referral, university affiliated (University of Adelaide) hospital. The MET system was introduced in 2003. It is overseen by a multidisciplinary hospital committee and a dedicated nursing MET coordinator who manages a MET database, follows up MET calls, MET related Australian Incident Monitoring (AIMS) reports and undertakes education. There are two types of calls – Code Blue or MET call. A Code Blue is called in response to a CA, respiratory
Events
There was a total 443 patients, with 575 events, of which 35 (6.1%) were CA, 395 (68.7%) MET calls, and 145 (25.2%) unanticipated ICU admissions. A total of 98 (22.1%) patients had more than one event (most often a MET call), with one patient having 6 events during the study period.
Patient demographics and severity of illness measures are shown in Table 1. Age and gender were evenly distributed between MET calls and ICU admissions. Patients who had CA, tended to be of female gender, older, and
Discussion
Afferent limb failure is common, particularly prior to an unanticipated ICU admission, and least likely to precede a cardiac arrest. ALF is most likely in the 4-h period prior to an event, and involves extreme abnormalities in vital signs. Despite substantial delays, ALF was not associated with overall higher hospital mortality, longer ICU LOS, increased severity of illness upon admission to ICU, or an increase in the documentation of NFR orders during an event. However patients with ALF and
Conclusions
In conclusion, it appears that the measurement and reporting of ALF is a useful performance measure of RRS as it is likely to positively influence unanticipated ICU admissions. It is also likely to point towards deficiencies in MET education, documentation of vital signs and otherwise undetected factors that contribute to a reluctance to call a MET. In a mature RRS there are fewer events with prior abnormal vital signs. The potential benefit to be gained by recording, reporting and using ALF as
Conflict of interest
None.
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.03.019.