Clinical paperHospital-wide physiological surveillance–A new approach to the early identification and management of the sick patient☆
Introduction
Preventable critical illness and death is receiving serious attention in developed healthcare systems1, 2, 3, 4, especially in acute hospital admissions5, 6, 7. It is estimated that approximately 23,000 in-hospital cardiac arrests in the UK8, and at least 20,000 unanticipated intensive care unit (ICU) admissionsb in England, Wales and Northern Ireland, may be avoidable with better care9, 10, 11. Patients suffering these events often exhibit premonitory physiological deterioration9, 12, 13, 14. Abnormalities of pulse rate, blood pressure, temperature, etc., occur before 79% of in-hospital cardiac arrests and in 54% of in-hospital deaths and emergency ICU admissions14. In some cases the deterioration is well documented, but with little discernable evidence of intervention8, 14, 15, 16. In others, the monitoring and recording of vital signs appears to be infrequent or incomplete8, 9, 14, 16, 17, 18, 19, 20.
In response to these findings, healthcare providers have introduced “track and trigger” systems21, 22, 23, 24, 25, 26, to allow early identification of patients with physiological abnormalities, and rapid response teams (RRT), e.g., medical emergency or critical care outreach teams9, 27, 28, 29, 30, 31, 32, to facilitate rapid and appropriate management. Two main types of “track and trigger” systems exist – the “early warning score” (EWS) and “calling criteria”. EWS systems allocate points in a weighted manner based on the derangement of patient's physiology from an arbitrarily agreed “normal” range. The points assigned to one or more vital sign or, more often, their summed value, are used to direct care or alert an RRT21, 22, 23, 24, 33. Systems that incorporate “calling criteria” activate an RRT response when one or more routinely measured physiological variables reach an extremely abnormal value25, 26. However, even when “track and trigger” systems are used, the recording of vital signs, patient chart completion and RRT activation remain sub-optimal17. Further, a circadian pattern of RRT activation has been reported, suggesting that processes for identifying patient deterioration may vary through the day34.
The ability of “track and trigger” systems to influence the incidence of adverse outcomes is governed by the nature and frequency of vital signs observations. If vital signs are not measured, documented or acted upon, appropriate clinical action is unlikely. The crucial preliminary step in the detection of clinical deterioration, and in understanding the mechanisms that lead to clinical crises, is the identification of a clear, documented vital signs plan for each patient. This should include unambiguous instructions regarding the variables to be measured, the frequency of measurement and the need for each vital signs dataset to be complete. Ideally, the frequency of vital signs measurement should be related to the patient's severity of illness and should adapt to changing clinical situations. The vital signs dataset should include all potentially relevant variables, in order that those variables that are early markers of deterioration can be identified and accurate “track and trigger” models can be established. Currently, most “track and trigger” systems exclude measurements of peripheral percentage saturation of haemoglobin with oxygen (SpO2), because its clinical significance depends upon the percentage oxygen concentration being delivered, which is often not recorded.
In addition to being measured regularly, vital signs data must be recorded regularly, accurately and legibly on charts that are user-friendly. If an EWS system is used, calculations and recording must also be accurate and legible. Where an EWS system is used, the weightings and total scores must be validated against appropriate clinical outcomes, and there should also be a clear EWS algorithm for triggering a suitable clinical response to a sick or deteriorating patient.
Having collected and charted the raw and derived physiological data, it should be made available to staff with the appropriate skills to intervene effectively and the clinical response should be of appropriate speed and content. Making data available to members of the patient's primary clinical team, the RRT and other healthcare staff, in real-time, wherever they are in the hospital, should facilitate earlier intervention with improved clinical outcomes.
One possible method for improving vital signs monitoring and recording on general hospital wards might include the use of electronic, multi-variable patient monitoring, such as occurs in most intensive care units, perhaps augmented with an automated observation system incorporating telemetry. Current obstacles to this approach are that there is no commercially available device that monitors the full range of necessary variables, patient mobility might be restricted, nurse–patient contact would be reduced and the cost of implementation could be expected to be high. An alternative, pragmatic approach might simply be to improve upon the existing paper-based EWS systems by using simple, existing, hand-held technology to record vital signs observations and wireless networking to disseminate the information to clinicians. This approach avoids complex expensive redesign of the clinical process, and focuses on doing what we currently do more frequently, accurately, efficiently and effectively. We describe our progress in developing such a surveillance system.
Section snippets
Hospital-wide physiological surveillance
The essential component of our hospital-wide patient surveillance system is the bedside collection of routine vital signs data (i.e., pulse rate, blood pressure, respiratory rate, temperature, neurological status, urine output and SpO2) and their entry into commercially available, personal digital assistants (PDA) running specifically designed software (VitalPAC™; The Learning Clinic). The PDAs act as “thin clients” linked by a wireless local area network (W-LAN) to the hospital's intranet
Discussion
Improvements in the safety of critically ill patients require changes to the way in which acute hospital services are organized and delivered5, 6, 7. Recent innovations in acute care have included new methods for recognizing21, 22, 23, 24, 25, 26 and responding to9, 27, 28, 29, 30, 31, 32 patient deterioration. Both rely upon regular, accurate measurement and documentation of vital signs, yet there has been little critical appraisal of these processes, which appear to be ritualised and rarely
Conclusions
We have described the use of existing, hand-held computer technology to record vital signs observations at the bedside and to integrate these with other patient data residing on the hospital intranet. These data are immediately available to any member of the hospital healthcare team with access to the hospital intranet. The ability to increase the frequency, completeness and accuracy of vital signs data collection is one of the essential steps in improving the early identification of patient
Conflicts of interest statement
VitalPAC™ is a collaborative development of The Learning Clinic and Portsmouth Hospitals NHS Trust.
Acknowledgments
The authors would like to acknowledge the patience, co-operation and critical appraisal of the nursing and medical staff from Portsmouth Hospitals NHS Trust and Shrewsbury and Telford NHS Trust who have helped to develop and refine the VitalPAC™ software and to introduce the system to clinical practice.
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A Spanish translated version of the summary of this article appears as Appendix in the online version at doi:10.1016/j.resuscitation.2006.03.008.