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).[1] Scores were developed in the late 1990s when studies showed that in-hospital deterioration and cardiac arrest were often preceded by a period of increasing abnormalities in the vital signs.

Early warning score
Purposedetermine degree of illness

Principles

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):

Score 3 2 1 0 1 2 3
Respiratory rate (breaths/min) >35 31–35 21–30 9–20 <7
SpO2 (%) <85 85–89 90–92 >92
Temperature (C) >38.9 38–38.9 36–37.9 35–35.9 34–34.9 <34
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
AVPU Alert Verbal Pain Unresponsive

A score of five or more is statistically linked to increased likelihood of death or admission to an intensive care unit.[2]

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.[3]

Optimal use

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.[4] 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.[5] There is however some evidence that certain parameters are better at predicting which patients will die within 24 hours than others.[6] 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.[1]

Variations

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).

These include:

Name Acronym Description Citation
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 [7]
Modified Early Obstetric Warning Score MEOWS Designed to support the use of Track and Trigger for all women receiving care from maternity services [8]
Modified Early Warning Score MEWS Modified to meet the requirements of many people in various clinical situations. [2]
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) [9][1]

National Early Warning Score, UK
NEWS2 chart

In the UK, the Royal College of Physicians developed the National Early Warning Score (NEWS) in 2012 to replace local or regional scores.[9][10][11] The NEWS score is the largest national EWS effort to date and has been adopted outside the UK.[1]

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.[1] Additional implementation guidance was issued in March 2020.[12] While many hospitals still use other scores, it has been proposed that all healthcare organisations should use the same score, plus clinical judgement, for diagnosis in the interest of patient safety.[13]

History

The first recorded EWS was developed by a team in James Paget University Hospital, Norfolk, United Kingdom, and presented at the May 1997 conference of the Intensive Care Society.[4][14]

See also

References
  1. 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.
  2. Subbe C.P.; Kruger M.; Gemmel L. (2001). "Validation of a modified Early Warning Score in medical admissions". Quarterly Journal of Medicine. 94 (10): 521–6. doi:10.1093/qjmed/94.10.521. PMID 11588210.
  3. Douw, G; Schoonhoven, L; Holwerda, T; Huisman-de Waal, G; van Zanten, AR; van Achterberg, T; van der Hoeven, JG (20 May 2015). "Nurses' worry or concern and early recognition of deteriorating patients on general wards in acute care hospitals: a systematic review". Critical Care (London, England). 19: 230. doi:10.1186/s13054-015-0950-5. PMC 4461986. PMID 25990249.
  4. Wright MM, Morgan RJ, Williams F (1997). "An early warning scoring system for detecting developing critical illness". Clin Intensive Care. 8: 100. doi:10.3109/tcic.8.2.93.110 (inactive 31 July 2022).{{cite journal}}: CS1 maint: DOI inactive as of July 2022 (link)
  5. Psirides A, Hill J, Hurford S (2013). "A review of rapid response team activation parameters in New Zealand hospitals". Resuscitation. 84 (8): 1040–1044. doi:10.1016/j.resuscitation.2013.01.022. PMID 23376581.
  6. Prytherch DR, Smith GB, Schmidt PE, Featherstone PI (2010). "ViEWS—Towards a national early warning score for detecting adult inpatient deterioration". Resuscitation. 81 (8): 932–937. doi:10.1016/j.resuscitation.2010.04.014. PMID 20637974.
  7. Cadman, Jeni. "PEWS – NHS Institute for Innovation and Improvement". www.institute.nhs.uk. Retrieved 2016-05-10.
  8. "MEOWS – Norfolk and Norwich University Hospital MEOWS Guidelines". www.nnuh.nhs.uk. Retrieved 2016-05-10.
  9. 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.
  10. National Institute for Health and Clinical Excellence. Clinical guideline 50: Acutely ill patients in hospital. London, 2007.
  11. "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.
  12. "National Early Warning Score (NEWS) 2. Standardising the assessment of acute illness severity in the NHS. Additional Implementation Guidance March 2020". Retrieved 2 June 2020.
  13. Inada-Kim, Matt; Nsutebu, Emmanuel (20 March 2018). "NEWS 2: an opportunity to standardise the management of deterioration and sepsis". BMJ. 360: k1260. doi:10.1136/bmj.k1260. PMID 29559439. S2CID 4210138.
  14. 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. S2CID 785355.
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