The Modified Early Warning Score (MEWS) is a standardized system used by healthcare providers to quickly identify adult patients showing signs of clinical deterioration. This tool aggregates routine bedside measurements into a single, objective score. The MEWS serves as an early warning of a potential serious adverse event, such as cardiac arrest or the need for intensive care. Using a uniform method to track a patient’s status, the system prompts a timely and appropriate response from the medical team and ensures subtle changes are not overlooked.
The Physiological Measurements Used
The MEWS relies on five fundamental physiological parameters that reflect the body’s immediate functions. These measurements are collected frequently and compared against established normal ranges.
The first parameter is the respiratory rate, which tracks the number of breaths per minute and is often the earliest indicator of a patient’s worsening condition. Another element is the heart rate, which measures the number of times the heart beats per minute, reflecting circulatory status.
Systolic blood pressure is measured because significant deviations can point to issues with fluid balance or organ perfusion. Body temperature is included to detect signs of infection or severe metabolic changes. Finally, the patient’s level of consciousness is assessed using the AVPU scale (Alert, Voice, Pain, Unresponsive) to gauge neurological status.
How the Points Are Assigned
Each of the five physiological measurements receives an individual score, and the total MEWS is calculated by summing these scores. The scoring system assigns points based on how far a measurement deviates from the expected normal range. A measurement within the optimal range receives zero points, indicating a stable status.
As a parameter moves outside the normal range, it is assigned an increasing number of points, typically one, two, or three. For example, a respiratory rate of 15 breaths per minute receives a score of zero. However, a rate that drops to less than nine breaths per minute is a severe deviation and is assigned a score of three, reflecting immediate concern that the patient is not breathing adequately.
Similarly, an extremely low systolic blood pressure, such as below 70 mmHg, is assigned three points, while a reading between 101 and 199 mmHg receives zero points. The level of consciousness also follows this tiered system: a patient who is Alert scores zero, but a patient who is Unresponsive is assigned a score of three. The total MEWS provides a rapid, quantified assessment of the patient’s overall physiological distress.
What Different Scores Indicate
The final MEWS total score triggers specific clinical actions, guiding staff on how urgently and how often the patient needs to be assessed.
Low Risk (Score 0–2)
A score of zero to two is considered low risk. This means the patient is stable, their vital signs are within acceptable limits, and they can continue with routine monitoring. No immediate intervention is required.
Medium Risk (Score 3–4)
A medium-risk score, typically three or four, is a warning signal that the patient’s condition is beginning to change. This score requires increased surveillance, such as checking vital signs every one to two hours, and mandates a review by a registered nurse or the primary medical team. This escalation aims to catch deterioration early and determine the underlying cause.
High Risk (Score 5 or Greater)
A total MEWS of five or greater is considered a high-risk score and necessitates an urgent response from senior medical staff. This score often automatically triggers the activation of a Rapid Response Team (RRT). The RRT consists of providers skilled in critical care who quickly assess the patient to stabilize them and determine if transfer to a higher level of care, such as the Intensive Care Unit, is necessary.