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.
Contents
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.[citation needed] | ||
| 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.
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
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- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ http://www.rcplondon.ac.uk/resources/national-early-warning-score-news
- ↑ http://www.wellingtonicu.com/Data/NZEWS%20Proposal.pdf
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ Brown, H. (2010). Graded Response Observation Chart (Leeds Teaching Hospitals Trust - Revision date: November 2012)
- ↑ http://www.wellingtonicu.com/AboutUs/Services/EWS/
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ National Institute for Health and Clinical Excellence. Clinical guideline 50: Acutely ill patients in hospital. London, 2007.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 16.0 16.1 Modified Early Warning Score MEWS, document by The Management Team for the County Hospital of Sundsvall-Härnösand. 2011-02-07
