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 six cardinal vital signs (Respiratory rate, SaO2, Temperature, Blood pressure, Heart rate, AVPU response) and one other observation.

The basis of an EWS

The resulting observations are compared to a normal range to generate a single composite score, for instance based on the following diagram:

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 Voice Pain Unconscious

A score of five or more is statistically linked to increased likelihood of death or admission to an intensive care unit.[1]

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).

The ideal EWS

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.[2] 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.[3] There is however some evidence that certain parameters are better at predicting which patients will die within 24 hours than others.[4] This has led to a call in several countries[5][6] for the development of a national early warning score that would allow a standardised approach to assessing and responding to deteriorating patients.

Early Warning Score 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. [1]
National Early Warning Score NEWS Developed by UK Royal Colleges to provide a national standard in the UK for Early Warning Scores [9]

Regional variation

Leeds Teaching Hospitals Trust (LTHT), England 2011

(accurate as of February 2011)[10]

Score 3 2 1 0 1 2 3
Systolic BP <45% <30% 15% down Normal for patient 15% up 30% up >45%
Heart rate (BPM) <30 <40 41-50 51-100 101-110 111-130 >130
Respiratory rate (RPM) <8 — 8-11 12-20 21-25 26-30 >30
Oxygen Saturations (%) <85 >85 >90 >95 — — —
Respiratory Support CPAP BiPAP >60% O2 Nil — — —
AVPU — — New Confusion Alert Voice Pain Unconscious
Urine Output (mls) <80 80-119 120-200 >200 >800 — —
Pain Score Severe Moderate Mild None — — —

Wellington Hospital, New Zealand 2012

(accurate as of January 2012)[11]

This matrix links the MEWS with a coloured band that corresponds to that on the observation chart. This not only provides visual cues to deterioration but also makes it easier to assign a score once the colours are learned.

The Early Warning Score matrix for Wellington Hospital, Wellington, New Zealand.
A coloured Early Warning Score matrix.

This system also demonstrates 'single parameter' triggering whereby an extreme deterioration results in a mandatory MET call which ensures immediate attendance by a Medical Emergency Team to the bedside of the sickest patients.

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.[12][13][14] The NEWS score is the largest national EWS effort to date, but still remains problematic in the UK due to its lack of universal implementation ability (it has exclusion criteria) and it has yet to have its retrospective validation study published.[15]

Sundsvall Regional Hospital, Sweden

The following parameters are used to estimate MEWS at Sundsvall Regional Hospital, Sweden:[16]

Score 3 2 1 0 1 2 3
Respiratory rate < 9 9-14 15-20 21-29 ≥ 30
Pulse ≤ 40 41-50 51-100 101-110 111-129 ≥ 130
Systolic blood pressure ≤ 70 71-80 81-100 101-199 ≥ 200
Temperature (°C) ≤ 35 35.1-36 36.1-38 38.1-38.5 ≥ 38.6
AVPU New-onset confusion Alert Reacts to voice Reacts to pain Unresponsive

Following are guidelines for re-estimating MEWS:[16]

MEWS New control
0 Within 24 hours
1 Within 8–12 hours
2 Within 4–8 hours
3 Within 1–2 hours
≥4 Contact with mobile intensive care team

See also

References

  1. 1 2 Subbe C.P.; Kruger M.; Gemmel L. (2001). "Validation of a modified Early Warning Score in medical admissions". Quarterly Journal of Medicine. 94: 521–6. doi:10.1093/qjmed/94.10.521.
  2. ↑ Morgan RJ, Williams F, Wright MM (1997). "An early warning scoring system for detecting developing critical illness". Clin Intensive Care. 8: 100.
  3. ↑ Psirides A, Hill J, Hurford S. "A review of rapid response team activation parameters in New Zealand hospitals". Resuscitation. 84: 1040–1044. PMID 23376581. doi:10.1016/j.resuscitation.2013.01.022.
  4. ↑ Prytherch DR, Smith GB, Schmidt PE, Featherstone PI. "ViEWS—Towards a national early warning score for detecting adult inpatient deterioration". Resuscitation. 81: 932–937. PMID 20637974. doi:10.1016/j.resuscitation.2010.04.014.
  5. ↑ http://www.rcplondon.ac.uk/resources/national-early-warning-score-news
  6. ↑ http://www.wellingtonicu.com/Data/NZEWS%20Proposal.pdf
  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. ↑ "The Royal College of Physicians (RCP) has led the development of a new National Early Warning Score (NEWS) report". www.rcplondon.ac.uk. Retrieved 2016-05-10.
  10. ↑ Brown, H. (2010). Graded Response Observation Chart (Leeds Teaching Hospitals Trust - Revision date: November 2012)
  11. ↑ http://www.wellingtonicu.com/AboutUs/Services/EWS/
  12. ↑ 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.
  13. ↑ National Institute for Health and Clinical Excellence. Clinical guideline 50: Acutely ill patients in hospital. London, 2007.
  14. ↑ "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.
  15. ↑ Smith GB, Prytherch DR, Meredith P, Schmidt PE, Featherstone PI (Apr 2013). "The ability of the National Early Warning Score (NEWS) to discriminate patients at risk of early cardiac arrest, unanticipated intensive care unit admission, and death". Resuscitation. 84 (4): 465–70. PMID 23295778. doi:10.1016/j.resuscitation.2012.12.016.
  16. 1 2 Modified Early Warning Score MEWS, document by The Management Team for the County Hospital of Sundsvall-Härnösand. 2011-02-07
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