A Formal Approach to Detecting and Correcting Simultaneous Masking in the IEC 60601-1-8 International Medical Alarm Standard

State University Of New York At Buffalo, Buffalo NY

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Abstract

Project Summary / Abstract The failure of humans to respond to auditory medical alarms has resulted in numerous patient injuries and deaths and is thus a major safety concern. The widely used IEC 60601-1-8 international medical alarm standard was created to improve alarm discernibility and identi?cation. It gives designers a collection of reserved sounds for use in common alarm conditions as well as instructions for designing new alarm sounds. Unfortunately, the melodic tonal patterns of IEC 60601-1-8's alarms are particularly susceptible to simultaneous masking, a condition where concurrent sounds interact in ways that make one or more of them imperceptible due to physical limitations of human perception. This is very dangerous because humans can only respond to medical alarms they can perceive. Detecting masking experimentally can be very dif?cult because it may only occur for very speci?c combinations of multiple alarms and temporal overlaps between them. To address this, we developed a novel computational method that uses formal modeling, psychophysical modeling, and veri?cation analyses to mathematically prove whether a con?guration of medical alarms can produce masking. In this work, we will update this method to enable its use in the evaluation of the masking potential of IEC 60601-1-8 medical alarms. We will then use the method to analyze the standard and identify changes to it that will prevent masking from occurring. In doing this, we will accomplish three speci?c aims. First, we will extend the method to include features not currently supported by it. This will include accounting for sub-frequencies in IEC 60601-1-8 alarm tones and the ability to search through the standard's open parameters. Second, we will use the extended method to evaluate the reserved alarms of IEC 60601-1-8 and identify open parameters within the standard that will avoid masking. Third, we will develop a procedure that engineers can use with the method to analyze and design IEC 60601-1-8-compliant alarms that will avoid masking. This project has the potential to profoundly impact patient safety. By exposing a signi?cant problem with IEC 60601-1-8, we will have identi?ed dangerous conditions that will need to be addressed. By giving engineers the information they need to design standard-compliant devices that help ensure the perceivability of alarms, newly created or updated medical devices will be safer than those from previous generations. Ultimately, by increasing the chance that medical alarms are perceivable, the responsible human will be more likely to respond appropriately and thus protect patients from preventable death and injury.