In this paper we examine how one of the most pervasive technological implementations in the health care domain – the alarm system – is used in anaesthesiology as part of patient monitoring. The utility and appropriateness of alarms in health care domains has been widely addressed in the literature. However, despite this research and the continued proliferation of alarm systems in health care, we argue that we still know little about its practical use in actual health care practice. Studies rarely examine in detail the actual everyday monitoring practices during normal operations in the absence of, or before, problems become critical and alarming. They have mainly considered how medical professionals manage the interpretation and response to alarms. Rather than examining how the anaesthesiologist identify and respond to alarms and critical problems, in this paper we focus on how the anaesthesiologist is actively and prospectively engaged in implementing a situated and emergent organisation of patient monitoring, using a wide range of different technological and material resources.