What is a Clinical Early Warning Score?
An Early Warning Score (EWS) is a standardized system in healthcare that helps medical staff assess a patient's condition and determine their risk of clinical deterioration. By assigning a numerical value to key physiological parameters, the EWS offers an objective measure of how unwell a patient is. This moves beyond relying solely on a clinician's subjective judgment and provides a consistent approach to patient monitoring.
The Core Principles of an EWS
The fundamental idea is that changes in vital signs often happen before major adverse events. A score of zero usually means the patient's condition is stable, while higher scores indicate a greater risk of deterioration.
The 'Afferent' and 'Efferent' Limbs:
- Afferent Limb (The 'Track and Trigger'): This involves healthcare staff tracking and calculating the patient's score based on their observations.
- Efferent Limb (The Response): This is the defined action taken when the score reaches a certain level. The action is based on the score and can range from increased monitoring to involving a rapid response team.
How is an EWS calculated? The National Early Warning Score 2 (NEWS2)
Different EWS systems exist, but the National Early Warning Score 2 (NEWS2) is a well-known example used in the UK. It is based on six vital signs and two clinical parameters, with points given for measurements outside the normal range. These points are added up for a total score.
NEWS2 Physiological Parameters and Scoring
NEWS2 considers the following parameters for scoring:
- Respiratory Rate: Higher scores for rates outside the normal range.
- Oxygen Saturation: Lower saturation means a higher score. NEWS2 has a specific scale for patients with type 2 respiratory failure.
- Supplemental Oxygen: A point is added if the patient is receiving extra oxygen.
- Systolic Blood Pressure: Scores increase if blood pressure is outside the normal range.
- Pulse Rate: Both very low and very high pulse rates result in higher scores.
- Consciousness: A score is given for new confusion or decreased consciousness.
- Temperature: Scores are allocated for readings outside the normal range.
The Function and Impact of an EWS
Standardizing and Improving Patient Care
Using a standardized EWS like NEWS2 ensures that all staff assess patients using the same criteria. This consistency improves patient safety, especially when staff work in different areas. The EWS provides a framework for regular monitoring, helping to ensure that changes in a patient's condition are noticed promptly.
Driving Clinical Response and Communication
A key function of an EWS is to trigger a timely response. A high score acts as an alert that a patient needs more urgent attention, leading to a defined escalation process. This may involve contacting a more senior team, such as a Rapid Response Team (RRT). The EWS score provides a quick, objective summary for communication during handovers.
Enhancing Patient Safety and Outcomes
By helping detect deterioration early and prompting a faster response, EWS is linked to better patient outcomes. Timely intervention can prevent serious events like unplanned ICU admissions or death. This systematic approach has been shown to reduce cardiac arrests and hospital mortality.
Comparing Different Early Warning Scores (NEWS2 vs. MEWS)
Although the goal is similar, different EWS systems can vary. Here's a comparison of two systems:
| Feature | National Early Warning Score 2 (NEWS2) | Modified Early Warning Score (MEWS) |
|---|---|---|
| Parameters | Respiratory Rate, Oxygen Saturation, Supplemental Oxygen, Systolic Blood Pressure, Pulse Rate, Consciousness, Temperature | Respiratory Rate, Pulse Rate, Systolic Blood Pressure, Temperature, Consciousness |
| Key Differentiation | Includes oxygen saturation and scoring for supplemental oxygen use. Has a specific chart for patients with chronic respiratory conditions. | A simpler system often without oxygen saturation. Some versions may include other factors. |
| Standardization | Officially endorsed and widely used in the NHS for system-wide standardization. | Varies between institutions, leading to inconsistencies. |
| Application | Standard tool for assessing acute illness in adults across different settings in the UK. | Often used in specific settings or for certain patient groups, less standardized. |
Conclusion
An Early Warning Score is a crucial tool in healthcare for improving patient outcomes by ensuring timely recognition and response to deterioration. By converting physiological observations into a simple, objective score, the EWS gives clinicians a structured way to assess a patient's condition. Its main function is to trigger a rapid escalation of care, helping to prevent serious adverse events and improve patient safety. Implementing a standardized system like NEWS2 has shown a positive impact on patient care and mortality. The NHS offers comprehensive resources on using NEWS2, emphasizing its importance in patient safety.
