AIMS AND OBJECTIVES Evaluate continuous vital sign surveillance as a tool to improve patient safety in the medical/surgical unit. BACKGROUND Failure-to-rescue is an important measure of hospital quality. Patient deterioration is often preceded by changes in vital signs. However, continuous multi-parameter vital sign monitoring may decrease patient safety with an abundance of unnecessary alarms. DESIGN Prospective observational study at two geographically disperse hospitals in a single hospital system. METHODS A multi-parameter vital sign monitoring system was installed in a medical/surgical unit in Utah and one in Alabama providing continuous display of SpO2, heart rate, blood pressure and respiration rate on a central station. Alarm thresholds and time to alert annunciations were set based on prior analysis of the distribution of each vital sign. At the end of 4 weeks, nurses completed a survey on their experience. An average alert per patient, per day was determined retrospectively from the saved vital signs data and knowledge of the alarm settings. RESULTS Ninety-two per cent of the nurses agreed that the number of alarms and alerts were appropriate; 54% strongly agreed. On average, both units experienced 10·8 alarms per patient, per day. One hundred per cent agreed the monitor provided valuable patient data that increased patient safety; 79% strongly agreed. CONCLUSIONS Continuous, multi-parameter patient monitoring could be performed on medical/surgical units with a small and appropriate level of alarms. Continuous vital sign assessment may have initiated nursing interventions that prevented failure-to-rescue events. Nurses surveyed unanimously agreed that continuous vital sign surveillance will help enhance patient safety. RELEVANCE TO CLINICAL PRACTICE Nursing response to abnormal vital signs is one of the most important levers in patient safety, by providing timely recognition of early clinical deterioration. This occurs through diligent nursing surveillance, involving assessment, interpretation of data, recognition of a problem and meaningful response.