Recognising that a patient’s condition is deteriorating, and then knowing how to respond, is a fundamental skill in nursing. The NEWS2 and ABCDE tools are designed to help, by supporting nurses’ and other healthcare professionals’ decision-making when under time pressure and in high-stress situations. They provide frameworks for assessing critical physiological changes and prioritising the clinical response. This article briefly explains how each tool works, when they should be used, their potential drawbacks in certain circumstances and why they complement rather than replace clinical expertise.