Early warning score
An early warning score (EWS) is a guide used by medical services to quickly determine the degree of illness of a patient. It is based on the vital signs (respiratory rate, oxygen saturation, temperature, blood pressure, pulse/heart rate, AVPU response). Scores were developed in the late 1990s when studies showed that in-hospital deterioration and cardiac arrest was often preceded by a period of increasing abnormalities in the vital signs.
The resulting observations are compared to a normal range to generate a single composite score, for instance based on the following diagram (an early modified EWS):
|Respiratory rate (breaths/min)||>35||31-35||21-30||9-20||<7|
|Systolic BP (mmHg)||>199||100-199||80-99||70-79||<70|
|Heart rate (bpm)||>129||110-129||100-109||50-99||40-49||30-39||<30|
Within hospitals, the EWS is used as part of a "track-and-trigger" system whereby an increasing score produces an escalated response varying from increasing the frequency of patient's observations (for a low score) up to urgent review by a rapid response or Medical Emergency Team (MET call). Concerns by nursing staff may also be used to trigger such call, as concerns may precede changes in vital signs.
Throughout the world the EWS is based on the principle that clinical deterioration can be seen through changes in multiple physiological measurements, as well as large changes within a single variable. However, the scale is calibrated to different populations and sometimes expanded to include additional parameters, specific to different parts of the world. The parameters scored may vary, as well as the weighting of the scores for worsening deterioration. Some systems also assign scores to other parameters including urine output, oxygen saturation, flow rate of oxygen administration and pain scores.
There is a lack of consensus on what constitutes the 'ideal' early warning score system. Comparing different systems in clinical use shows variation in which parameters are scored and how those scores are assigned to differing levels of deterioration. There is however some evidence that certain parameters are better at predicting which patients will die within 24 hours than others. This has led to a call in several countries for the development of a national early warning score that would allow a standardised approach to assessing and responding to deteriorating patients.
A range of Early Warning Scores have been developed in response to the needs of specific patient types (e.g. PEWS for children) or to support local best practice (NEWS in the UK).
|Paediatric Early Warning Score||PEWS||Designed to support the use of Track and Trigger with patients under 16, who have different normal ranges for observations|||
|Modified Early Obstetric Warning Score||MEOWS||Designed to support the use of Track and Trigger for all women receiving care from maternity services|||
|Modified Early Warning Score||MEWS||Modified to meet the requirements of many people in various clinical situations.|||
|National Early Warning Score||NEWS & NEWS2||Developed by the Royal College of Physicians to provide a national standard in the UK for Early Warning Scores (2012 and 2017)|||
National Early Warning Score, UK
In the UK, the Royal College of Physicians has introduced a national early warning score (NEWS) to replace local or regional scores. The NEWS score is the largest national EWS effort to date and has been adopted outside the UK.
A second version of the score was introduced in 2017. The revised version was optimised for the identification of sepsis, alternative oxygen targets in people with underlying lung disease, and the onset of delirium.
- Williams B (ed)., ed. (2017). National Early Warning Score (NEWS) 2 - Standardising the assessment of acute illness severity in the NHS. ISBN 978-1-86016-682-2.
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- Cadman, Jeni. "PEWS - NHS Institute for Innovation and Improvement". www.institute.nhs.uk. Retrieved 2016-05-10.
- "MEOWS - Norfolk and Norwich University Hospital MEOWS Guidelines". www.nnuh.nhs.uk. Retrieved 2016-05-10.
- National Early Warning Score Development and Implementation Group (NEWSDIG) (2012). National Early Warning Score (NEWS): standardising the assessment of acute-illness severity in the NHS. London: Royal College of Physicians. ISBN 978-1-86016-471-2.
- National Institute for Health and Clinical Excellence. Clinical guideline 50: Acutely ill patients in hospital. London, 2007.
- "Acute care toolkit 6: the medical patient at risk: recognition and care of the seriously ill or deteriorating medical patient" (PDF). Royal College of Physicians of London. May 2013.
- Gao, H; McDonnell, A; Harrison, DA; Moore, T; Adam, S; Daly, K; Esmonde, L; Goldhill, DR; Parry, GJ; Rashidian, A; Subbe, CP; Harvey, S (April 2007). "Systematic review and evaluation of physiological track and trigger warning systems for identifying at-risk patients on the ward". Intensive care medicine. 33 (4): 667–79. doi:10.1007/s00134-007-0532-3. PMID 17318499.