Objective To identify areas requiring the most urgent improvement in the intensive care unit (ICU); and to accurately determine the positive predictive value of routine critical care patient monitoring alarms, as well as the common causes for false-positive alarms.Design Prospective, observational s

Poor prognosis for existing monitors in the intensive care unit.

The alarms of medical devices are a matter of concern in critical and perioperative care. The frequent false alarms not only are a nuisance for patients and caregivers but can also compromise patient safety and effectiveness of care. The development of alarm systems has lagged behind the technological advances of medical devices over the last 20 years. From a clinical perspective, major improvements of alarm algorithms are urgently needed. We give an overview of the current clinical situation and the underlying problems and discuss different methods from statistics and computational science and their potential for clinical application.

Alarm algorithms in critical care monitoring.

INTRODUCTION:In an intensive care unit, alarms are used to call attention to a patient, to alert a change in the patient's physiology, or to warn of a failure in a medical device; however, up to 94% of the alarms are false. Our purpose in this study was to identify a means of reducing the number of

Improving alarm performance in the medical intensive care unit using delays and clinical context.

Alarms are used in many clinical applications, but they are often less than optimal because the design and implementation of alarms has not always taken the cognitive capacity and processing mechanisms of the user into account. As a result alarms are frequently too loud, irritating, confusing, badly designed, and too numerous, resulting in them often being turned off and hindering, rather than enhancing, task performance. This paper reviews some of the main areas where it is essential to take account of the cognitive system of the user and behavioural processes more generally. Five central areas of concern are discussed: the number of alarms and ways that this might be reduced; false alarm rates and their impact on human responses; the design of alarms and the application of research into auditory cognition on design; intelligent alarm systems; and the proposals for alarm design set out in a recent worldwide medical alarms standard. In each area some background is given and the implications for alarm design and implementation outlined. The conclusion is that there are some indications that alarm design and implementation takes account of relevant research data, but that there is still some way to go before these findings are fully integrated and the situation is improved upon further.

Alarms and human behaviour: implications for medical alarms

The audibility and the identification of 23 auditory alarms in the intensive care unit (ICU) and 26 auditory alarms in the operating rooms (ORs) of a 214-bed Canadian teaching hospital were investigated. Digital tape recordings of the alarms were made and analysed using masked-threshold software developed at the Universite de Montreal. The digital recordings were also presented to the hospital personnel responsible for monitoring these alarms on an individual basis in order to determine how many of the alarms they would be able to identify when they heard them. Several of the alarms in both areas of the hospital could mask other alarms in the same area, and many of the alarms in the operating rooms could be masked by the sound of a surgical saw or a surgical drill. The staff in the OR (anaesthetists, anaesthesia residents, and OR technologists) were able to identify a mean of between 10 and 15 of the 26 alarms found in their operating theatres. The ICU nurses were able to identify a mean of between 9 and 14 of the 23 alarms found in their ICU. Alarm importance was positively correlated with the frequency of alarm identification in the case of the OR, rho = 0.411, but was not significantly correlated in the case of the ICU, rho = 0.155. This study demonstrates the poor design of auditory warning signals in hospitals and the need for standardization of alarms on medical equipment.

Audibility and identification of auditory alarms in the operating room and intensive care unit

Summary

The origin and frequency of alarm soundings in a general purpose intensive therapy unit were recorded by the nursing staff for 3 weeks. Only eight out of a total of 1455 soundings indicated potentially life threatening problems. There were many false alarms from the monitoring system and the infusion rate pump. The overall frequency of soundings varied little by day or night. There is a need for a graded system of alarms to reflect the priority of the disturbance detected.

Survey of alarms in an intensive therapy unit.

The experience with morphine infusions for sedation and pain relief after cardiac surgery in this hospital has been similar to that described by Dr Bray (Anaesthesia 1983; 38: 10768). However, we have used 0.5 mg/kg morphine sulphate (with preservative) diluted to 50 ml with 5% dextrose starting at 2 ml/hour. We have not been aware of vein irritation although frequently the infusion is run through a central vein. A dilute solution might be more preferable to the use of preservative-free morphine, despite the increased fluid load. Significant deterioration occurs when preservative-free morphine (0.2 mg/ml) is left in a plastic syringe for as little as twenty minutes with the probable formation of apomorphine.’ In similar unpublished studies with preservative-containing morphine solution (IOrng/ml diluted to I mg/ml with 5% dextrose), a trace of apomorphine could be detected after twenty-four hours storage in a plastic syringe, so it would seem advisable to change such infusions every 24 hours.

T.M. O'Carroll

Papers

Survey of alarms in an intensive therapy unit.

Oculocardiac reflex from the empty orbit