Abstract

Copyright © 2010 Elsevier Ireland Ltd

Clinical paper

ViEWS — Towards a national early warning score for detecting adult inpatient deterioration

David R. Prytherch, Gary B. Smith, Paul E. Schmidt and Peter I. Featherstone

Portsmouth Hospitals NHS Trust, United Kingdom
University of Bournemouth, United Kingdom
University of Portsmouth, United Kingdom

Received 25 January 2010; received in revised form 12 April 2010; accepted 15 April 2010; available online 15 July 2010.

Summary

Aim of study
To develop a validated, paper-based, aggregate weighted track and trigger system (AWTTS) that could serve as a template for a national early warning score (EWS) for the detection of patient deterioration.

Materials and methods
Using existing knowledge of the relationship between physiological data and adverse clinical outcomes, a thorough review of the literature surrounding EWS and physiology, and a previous detailed analysis of published EWSs, we developed a new paper-based EWS – VitalPAC™ EWS (ViEWS). We applied ViEWS to a large vital signs database (n=198,755 observation sets) collected from 35,585 consecutive, completed acute medical admissions, and also evaluated the comparative performance of 33 other AWTTSs, for a range of outcomes using the area under the receiver-operating characteristics (AUROC) curve.

Results
The AUROC (95% CI) for ViEWS using in-hospital mortality with 24h of the observation set was 0.888 (0.880–0.895). The AUROCs (95% CI) for the 33 other AWTTSs tested using the same outcome ranged from 0.803 (0.792–0.815) to 0.850 (0.841–0.859). ViEWS performed better than the 33 other AWTTSs for all outcomes tested.

Conclusions
We have developed a simple AWTTS – ViEWS – designed for paper-based application and demonstrated that its performance for predicting mortality (within a range of timescales) is superior to all other published AWTTSs that we tested. We have also developed a tool to provide a relative measure of the number of “triggers” that would be generated at different values of EWS and permits the comparison of the workload generated by different AWTTSs.

Abstract

Copyright © 2009 British Journal of Nursing

Clinical paper

Improving accuracy and efficiency of early warning scores in acute care

MA Mohammed, R Hayton, G Clements, G Smith, D Prytherch

Summary

Background
Early warning scores (EWS) are an integral part of the care of acutely ill patients. Unfortunately, in the few studies where the accuracy of EWS has been tested it has been found to be lacking, with serious implications for quality of care. Aim: to determine if the provision of computer-aided scoring could increase the accuracy and efficiency of EWS calculations, when compared with the traditional pen-and-paper method, and to determine if it was acceptable to users.

Design
26 nurses from two surgical assessment wards in two hospitals were studied. The study was conducted in three phases. Phase 1 - a classroom-based exercise where nurses were given ten patient vignettes and asked to derive EWS using traditional pen-and-paper methods; Phase 2 - the same as phase 1, but using a hand-held computer to derive EWS; Phase 3 - the same as phase 2, but was a follow-up exercise undertaken in the ward environment, 4 weeks after computer-aided scoring was implemented in the two wards. Each phase closed with a user perception/attitudes questionnaire.

Results
Accuracy and efficiency - phase 1 was associated with a significantly lower overall accuracy (152/260, 58%) compared with phase 2 (96%; difference in proportions 38%, 95% confidence interval 31-44%, P<0.0001). There was a small but significant reduction in accuracy from phase 2 (96%) to phase 3 (88%) (8% difference, P=0.006). The mean time to derive an EWS reduced from 37.9 seconds in phase 1 to 35.1 seconds in phase 2 (P=0.016), down to 24.0 seconds in phase 3 (P<0.0001). User acceptability: in phase 1, nurses favoured the pen-and-paper method in all respects except accuracy. In phase 2, nurses’ views shifted significantly in favour of the hand-held computer, with little deterioration in the follow-up phase 3.

Conclusions
A hand-held computer helps to improve the accuracy and efficiency of EWS in acute hospital care and is acceptable to nurses.

Abstract

Copyright © 2006 Elsevier Ireland Ltd

Clinical paper

A review, and performance evaluation, of single-parameter 'track and trigger' systems

Gary B. Smith, David R. Prytherch, Paul E. Schmidt, Peter I. Featherstone and Bernie Higgins

Portsmouth Hospitals NHS Trust & University of Bournemouth, United Kingdom Portsmouth Hospitals NHS Trust & University of Portsmouth, United Kingdom Medical Statistician, ARDSU, University of Portsmouth, United Kingdom

Received 18 April 2008; accepted 3 May 2008. Available online 11 July 2008.

Summary

Objectives
There is no up-to-date literature review of physiologically-based, single-parameter weighted 'track and trigger' systems (SPTTS) and little data on their sensitivity and specificity to predict adverse outcomes. The aim of this study was to describe the SPTTS in clinical use and measure their sensitivity and specificity when using admission vital signs data for predicting in-hospital mortality.

Materials and methods
We performed a systematic review of the literature to describe the SPTTS, their components and their differences. We measured their sensitivity and specificity for predicting in-hospital mortality when using a database of 9987 admission vital signs datasets.

Results
We identified 39 unique classes of SPTTS, of which 30 were evaluated. There was considerable variation in the physiological variables used, together with significant variation in the physiological values used to trigger a medical emergency or critical care outreach team. There was marked variation in sensitivity (7.3–52.8%), specificity (69.1–98.1%), positive predictive values (13.5–26.1%), negative predictive values (92.1–94.2%) and the potential number of calls triggered (234–3271).

Conclusions
There is a wide range of unique, but very similar, SPTTS in clinical use. Although specificities were high, sensitivities were too low to provide institutions with confidence that these SPTTS could identify patients at risk of in-hospital death using admission vital signs. Institutions may wish to consider these data when selecting which, if any, single-parameter track and trigger systems to introduce.

Abstract

Copyright © 2008 Elsevier Ireland Ltd

Clinical paper

Should age be included as a component of 'track and trigger' systems used to identify sick adult patients?

Portsmouth Hospitals NHS Trust & University of Bournemouth, United Kingdom Portsmouth Hospitals NHS Trust & University of Portsmouth, United Kingdom Nenagh Hospital, Ireland ARDSU, University of Portsmouth, United Kingdom

Received 21 December 2007; revised 1 February 2008; accepted 2 March 2008. Available online 27 May 2008.

Summary

Aim of study
Few published "track and trigger systems" used to identify sick adult patients incorporate patient age as a variable. We investigated the relationship between vital signs, patient age and in-hospital mortality and investigated the impact of patient age on the function as predictors of in-hospital mortality of the two most commonly used track and trigger systems.

Materials and methods
Using a database of 9987 vital signs datasets, we studied the relationship between admission vital signs and in-hospital mortality for a range of selected vital signs, grouped by patient age. We also used the vital signs data set to study the impact of patient age on the relationship between patient triggers using the "MET criteria" and "MEWS", and in-hospital mortality.

Results
At hospital discharge, there were 9152 (91.6%) survivors and 835 (8.4%) non-survivors. As admission vital signs worsened, mortality increased for each age range. Where groups of patients had triggered a certain MET criterion, mortality was higher as patient age increased. Mortality varied significantly with age (p < 0.05; Fishers exact test) for breathing rate >36 breaths min-1, systolic BP < 90 mmHg and decreased conscious level. For each age group, mortality also increased as total MEWS score increased. As the number of simultaneously occurring MEWS abnormalities, or simultaneously occurring MET criteria, increased, mortality increased for each age range.

Conclusions
Age has a significant impact on in-hospital mortality. Our data suggest that the inclusion of age as a component of these systems could be advantageous in improving their function.

Abstract

Copyright © 2006 Elsevier Ireland Ltd

Review paper

Review and performance evaluation of aggregate weighted 'track and trigger' systems

Gary B. Smith, David R. Prytherch, Paul E. Schmidt and Peter I. Featherstone

Portsmouth Hospitals NHS Trust and University of Bournemouth, UK Portsmouth Hospitals NHS Trust and University of Portsmouth, UK

Received 30 October 2007; revised 26 November 2007; accepted 13 December 2007. Available online 4 February 2008.

Summary

Objectives
There is no up-to-date literature review of physiologically based, aggregate weighted 'track and trigger'; systems (AWTTS) and few data on their predictive ability for serious adverse outcomes. The aim of this study was to describe the AWTTS in clinical use and assess their ability to discriminate between survivors and non-survivors of hospital admission, based on an initial set of vital signs.

Materials and methods
A systematic review of the literature was performed, to describe the AWTTS, their components and their differences. Their ability to discriminate between survivors and non-survivors was evaluated using the area under the receiver-operating characteristics (AUROC) curve, and a database of 9987 vital signs datasets.

Results
A total of 33 unique AWTTS were identified with AUROC (±95% CI) ranging from 0.657 (0.636–0.678) to 0.782 (0.767–0.797). 12 AWTTS (36%) discriminated reasonably well between survivors and non-survivors, the top four performing AWTTS incorporated age as a component (AUROCs ranging from 0.722 to 0.782). The top two systems also incorporated temperature.

Conclusions
There is a wide range of unique, but very similar, AWTTS in clinical use. There is no consistency regarding their physiological components, but the majority differ only in minor variations in the weightings for physiological derangement and/or the cut-off points between physiological weighting bands. The performance of most systems tested was poor when used to discriminate between survivors and non-survivors, although 36% discriminated reasonably well. Our results suggest that physiology can be used to predict outcome, but that further work is required to improve the AWTTS models.

Abstract

Copyright © 2006 Elsevier Ireland Ltd

Clinical paper

Hospital-wide physiological surveillance – A new approach to the early identification and management of the sick patient

Gary B. Smith, David R. Prytherch, Paul Schmidt, Peter I. Featherstone, Debbie Knight, Gill Clements and Mohammed A. Mohammed

Portsmouth Hospitals NHS Trust & University of Bournemouth, United Kingdom Portsmouth Hospitals NHS Trust & University of Portsmouth, United Kingdom Portsmouth Hospitals NHS Trust, United Kingdom Shrewsbury and Telford NHS Trust, United Kingdom University of Birmingham, United Kingdom

Received 8 February 2006; accepted 10 March 2006. Available online 30 August 2006.

Summary

Hospitalised patients, who suffer cardiac arrest and require unanticipated intensive care unit (ICU) admission or die, often exhibit premonitory abnormalities in vital signs. Sometimes, the deterioration is well documented, though there is little discernable evidence of intervention. In other cases, monitoring and recording of vital signs is infrequent or incomplete. Healthcare providers have introduced 'track and trigger' systems to allow early identification of patients with physiological abnormalities, and rapid response teams to facilitate rapid and appropriate management. However, even when 'track and trigger' systems are used, the recording of vital signs, patient chart completion and team activation remain sub-optimal.

We have developed a system for collecting routine vital signs data at the bedside using standard personal digital assistants (PDA). The PDAs act as "thin clients"; linked by a wireless local area network (W-LAN) to the hospital's intranet system, where raw and derived data are integrated with other patient information, e.g., name, hospital number, laboratory results. It is possible for raw physiology data, early warning scores (EWS), vital signs charts and oxygen therapy records to be made instantaneously available to any member of the hospital healthcare team via the W-LAN or hospital intranet. Early and direct contact with members of the patient's primary clinical team or rapid response team can be made through an automated alerting system, triggered by the EWS data. The ability to capture physiological data at the bedside, and to make these available to anyone with appropriate access rights at any time and in any place, should provide previously unattainable, clinical and administrative benefits. Analysis of the raw physiological data and patient outcomes will also make it possible to validate existing and future 'track and trigger' systems.

Abstract

Copyright © 2006 by the BMJ Publishing Group Ltd.

Quality Improvement Report

Using the internet to deliver education on drug safety

B D Franklin, K O'Grady, J Parr, I Walton

Academic Pharmacy Unit, Hammersmith Hospitals NHS Trust; The School of Pharmacy, University of London, London, UK

Academic Pharmacy Unit, Hammersmith Hospitals NHS Trust, London, UK

Directorate of Nursing, Hammersmith Hospitals NHS Trust, London, UK

Medicine for the Elderly, Hammersmith Hospitals NHS Trust, London, UK

Correspondence to:
B D Franklin
Pharmacy Department, Hammersmith Hospitals NHS Trust, London W12 0HS, UK

Background
Medication administration errors (MAEs) occur in 3–8% of all non-intravenous drug doses given in UK hospitals; higher rates have been reported for intravenous drugs. Educational interventions are often advocated as one way of reducing these rates. However, group education sessions are often not practical. We developed internet-based educational modules on drug safety, and evaluated their effect on MAEs.

Methods
11 modules were developed on different aspects of drug safety and delivered via commercially available software. All nursing staff on one ward were encouraged to participate. MAEs were identified using observation; the denominator used to calculate MAE rates was the number of opportunities for error. We aimed to observe 56 drug rounds before and after asking staff to complete the package.

Results
The 19 nurses who administered drugs on the study ward all agreed to participate. Of these, 12 (63%) nurses completed all 11 modules. Pre-education, 82 (6.9%) errors were identified in 1188 opportunities for error. Afterwards, 66 (5.0%) errors were identified in 1397 opportunities for error (95% confidence interval (CI) for the difference –3.8% to 0%). The MAE rate for non-intravenous drugs was 6.1% pre-education and 4.1% afterwards (95% CI for the difference –3.8% to –0.2%). Most errors with regard to intravenous doses were due to fast administration of bolus injections.

Conclusions
An interactive educational package focusing on patient safety was developed, with a high rate of uptake among nursing staff on the study ward. A reduction in non-intravenous MAEs was observed after the use of the package, but no significant change was seen in the overall error rate.

Abbreviations
MAEs, medication administration errors

Abstract

Copyright © 2006 Elsevier Ireland Ltd

Clinical paper

Calculating early warning scores – A classroom comparison of pen and paper and hand-held computer methods

David R. Prytherch, Gary B. Smith, Paul Schmidt, Peter I. Featherstone, Kate Stewart, Debbie Knight and Bernie Higgins

Portsmouth Hospitals NHS Trust & University of Portsmouth, UK Portsmouth Hospitals NHS Trust & University of Bournemouth, UK Portsmouth Hospitals NHS Trust, UK ARDSU, University of Portsmouth, UK

Received 24 November 2005; accepted 5 December 2005. Available online 27 June 2006.

Summary

To assist in the early detection of critical illness, many hospitals now use a 'track and trigger' system that allocates points to routine vital signs measurements on the basis of their derangement from an arbitrarily agreed "normal" range. These points are summed to provide an early warning score (EWS). Little is known about the accuracy with which EWS are calculated and charted. We compared the speed and accuracy of charting the weighted value attributed to each vital sign, and of calculating the EWS, using the traditional pen and paper method with that using a specially programmed, personal digital assistant (VitalPAC™). Incorrect entries or omissions occurred in 24 (29%) of 84 EWS computed using pen/paper compared to 8 (10%) computed using the VitalPAC™ method. Fewer incorrect clinical actions were indicated using EWS derived via the VitalPAC™ method (4/84, 5%) than from those calculated using pen/paper (12/84, 14%). The mean time (±S.D.) taken for participants to calculate and chart a set of weighted values and EWS using the pen/paper method was 67.6 ± 35.3 s (n = 84). The corresponding time taken to enter a set of physiological data using the VitalPAC™ was 43.0 ± 23.5 s (n = 84). By comparison with the conventional pen/paper method, the use of VitalPAC™ was on average 1.6-times faster. The use of a device such as VitalPAC™ offers significant advantages both in speed and accuracy of recording of EWS.

Abstract

Copyright © 2004 Elsevier Ireland Ltd

Long-term effect of introducing an early warning score on respiratory rate charting on general wards

Jackie McBride, Debbie Knight, Jo Piper and Gary B Smith

Portsmouth Hospitals NHS Trust, Queen Alexandra Hospital, Portsmouth PO6 3LY, UK

Received 29 September 2004; accepted 23 October 2004. Available online 11 January 2005.

Summary

The respiratory rate is an early indicator of disease, yet many clinicians underestimate its importance and hospitals report a poor level of respiratory rate recording. We studied the short- and long-term effects of introducing a new patient vital signs chart and the modified early warning score (MEWS), which incorporates respiratory rate on the prevalence of respiratory rate recording in six general wards of our hospital. Prior to the commencement of the study, the average percentage of occupied beds where at least one respiratory rate recording had been made in a single 24-h period was 29.5 ± 13.5%. After the introduction of the new vital signs chart to all six wards, and the introduction of MEWS to three wards, this rose to 68.9 ± 20.9%. When all six wards had been using both the new chart and the MEWS system for almost 1 year, the figure had reached 91.2 ± 5.6%. During the pre-introduction period, there was no difference in the prevalence of respiratory rate recording between the specialties (orthopaedic, 26.9%; surgery, 32.9%; medicine, 29.8%; p = 0.118). During the second two audit periods, the prevalence of respiratory rate monitoring was consistently higher on medical wards than on surgical and orthopaedic wards (p < 0.001). The study confirms the long-term beneficial effect of introducing the MEWS system on respiratory rate recording into the general wards of our hospital. As respiratory rate abnormalities are early markers of disease, it is hoped that improved monitoring will have an impact on the nature and timeliness of the response to critical illness. This may have an impact on the future incidence of potentially avoidable cardiac arrest, deaths and unanticipated intensive care unit admission.