Voice, Distinct Alert Tones Cut Nurse Alarm Response Time to Emergency Events

Response times improved by up to 59% faster, Ohio State study says.

A new alarm system that helps nurses distinguish between emergency and all other alarms can save lives by getting nurses to the bedside of patients in cardiac arrest faster, a new study says.

The new procedure also reduces the number of alarms nurses get, according to researchers at The Ohio State University School of Health and Rehabilitation Sciences and The Ohio State University Wexner Medical Center.

"The reductions ranged from 15% to 59% faster response time during the study and they continued to improve after the study ended," Emily Patterson, principal investigator and professor in the School of Health and Rehabilitation Sciences, said in a press release.

The research team focused on the secondary alarm notification system (SANS), which sends alarms by mobile phone so nurses can receive notifications regardless of where they are on the hospital unit. It’s a common strategy that hospitals use to reduce alarm response time, and it’s used in addition to alerts at the bedside and nursing station.

SANS alerts, which can be triggered by hospital staff, patients, or machines, usually sound the same and may be accompanied by a message on the phone screen.

Ohio State researchers wanted to help nurses using SANS distinguish between emergency and all other alarms while suppressing redundant alarms or those with high false alarm rates.

For emergency alarms that require immediate action, such as code blue, researchers incorporated a distinct beacon tone and digitized speech identifying the alarm. These emergency alarms are triggered by a medical professional who identified a patient at risk of dying and are less likely to be false alarms.

For machine-triggered alarms, such as abnormal heart rhythms, only one sound served as both beacon and triggering event. The initial onset and escalation was delayed by 20 seconds on the SANS so that the nurse could respond if already in the patient’s room before it went off.

For patient-initiated alarms to request medication, water, or assistance, a sound resembling a futuristic telephone was used.

"We documented nurse alarm and response time at three hospitals for 14 months prior to implementing the alarm changes, and then we followed the same nursing units for another 25 months after the changes," Patterson said. "There was a statistically significant reduction in duration time for the code blue alarm at all three hospitals and the alarm burden fell by 20–38%. We believe by reducing the overall number of alarms, we allowed nurses to better identify code blue alarms."

Future grant-funded research led by study co-investigator Mike Rayo, an assistant professor in the College of Engineering, will focus on how auditory alarms can be integrated into visual displays to better inform nurses of patient emergencies.

The findings are published in Human Factors.