By Paurakh Rajbhandary, senior biomedical engineer, VitalConnect.
The need for hospitals and physicians to recognize and react to patients showing early signs and symptoms of clinical deterioration has resulted in the creation of a rapid response system (RRS). Patient deterioration prior to adverse events including cardiac arrest and ICU admission has been reported with hemodynamic antecedents in 60 percent of critical events. For example, patients who develop cardiopulmonary arrests exhibit clinical deterioration such as respiratory distress as early as eight hours in advance of arrest in 84 percent of the patients.
The RRS system, aimed at detecting precursors to and reducing such avoidable adverse events, comprises of track-and-trigger or afferent (detection) component for event detection, and efferent (response) component comprising of rapid response team (RRT) or medical emergency team for intervention and prevention of patient deterioration. Rapid response systems also comprises of administrative components and continual process improvement.
MET criteria is commonly used as an afferent triggering metric currently in many healthcare systems, but MET criteria is based on threshold of single vital or physiological measurement. The need of a good afferent component to RRS has been previously pointed out. Early warning score (EWS) combines multiple vital measurements to create a more comprehensive yet simple unified score that has been clinically validated to indicate increased risk of patient deterioration.
Among several different versions of early warning scores currently used in different healthcare settings, National Early Warning Score (NEWS) is standardized and endorsed by National Health Services (NHS) and Royal College of Physicians (RCP) in an effort to eliminate lack of consistency in the clinical workflow.
NEWS is an aggregate score calculated based on six physiological parameters: respiratory rate, oxygen saturations, temperature, systolic blood pressure, pulse rate, level of consciousness, and whether the patient is using supplemental oxygen. A sub-score within from zero to three is allocated to each of these parameters, giving an aggregated NEWS score between zero and 20 reflecting how patient status varies from the norm. The sub-score contribution criteria for each of the parameters has been determined and validated clinically by the NHS and Royal College of Physicians. The NEWS score dictates clinical urgency, the magnitude of response as well as frequency of clinical monitoring of the patient.
NEWS has demonstrated superior performance in determining patients at risk of cardiac arrest, unanticipated intensive care unit (ICU) admission or death within 24 hours of a NEWS value compared to 33 other early warning scores. Sensitivity and specificity performance of early warning scores dictates the trade off between alarm fatigue and ability to flag all deteriorating patients. Studies have shown that NEWS provides the best compromise between sensitivity and specificity allowing hospitals and healthcare providers to predict and reduce the aforementioned deterioration and improve patient outcome.
National Health Service (NHS) has been pushing to implement NEWS in all of its hospitals since its initial launch in 2012, having achieved implementation at 70 percent of acute trusts in England and with other forms of early warning scores in the remaining trusts. Variation in early warning scores systems can lead to confusion and potentially compromise performance of the detection of patient deterioration, patient safety and positive outcome. With this in mind, NHS are launching a campaign to increase NEWS use to 100 percent at acute and ambulance settings by March 2019.