Patient Safety Tip of the Week

March 5, 2007            Disabled Alarms


Ignoring alarms or intentionally disabling alarms is a topic we’ll revisit over and over (this is one of the “Big 3” root causes that can be found in many root cause analyses of cases with adverse outcomes).


However, we encountered an interesting case in which good intentions almost caused a disastrous outcome. The case was a “near-miss” in which a patient’s oxygen line had become disconnected from the wall source of oxygen. Mechanical ventilators often have an oxygen blender alarm. This is an alarm that is triggered by oxygen concentration falling below the prescribed level. In this particular case, the alarm failed to alert nursing staff that the oxygen content had dropped. At least one other monitoring system also failed to detect a drop in the patient’s O2 saturation. But fortunately the patient’s clinical condition was evaluated by staff and the problem remediated before any harm came to the patient.


In the course of the investigation, a piece of tape was found covering the blender alarm. The alarm, in fact, was functional. It was just not audible because of the tape. It was ultimately determined that during maintenance of the ventilators between use by patients, staff would test the ventilators with compressed air rather than oxygen (as a cost-saving measure). They would tape the blender alarm because it would go off when the compressed air was used instead of oxygen. The protocol used to assess alarms at set-up time for patient use did not include a specific assessment of the blender alarm. No other ventilators in use at this hospital were found to have tape over the blender alarm. However, when the potential issue was mentioned in an alert to other hospitals in this multi-hospital system, six other ventilators in use were found to have tape over the blender alarm!


The lesson learned in this case is that one should have a checklist-type routine for checking alarms immediately before a ventilator is used on a patient. And the checklist should be specific for the ventilator being used. It is not at all uncommon for a hospital to have multiple different models of ventilators and some may have alarms that others do not. Therefore, your protocol should include not only checking those alarms that are on all ventilators but also those that may be specific to the unit being used.


Frankly, this ultimately comes back to a design issue as a root cause. Good design principles would have led to an automated alarm testing protocol that would have to be carried out before a unit could be used in patient care.


The second lesson is also obvious – when you find a disabled alarm, don’t jump and take punitive action on the individual who disabled the alarm. Continue your root cause analysis and you’ll always find some other root cause that led them to disable the alarm and that other staff are likely also disabling such alarms.


Patient Safety Tips of the Week pertaining to alarm-related issues:

March 5, 2007 “Disabled Alarms

March 26, 2007 “Alarms Should Point to the Problem

April 2, 2007 “More Alarm Issues

June 19, 2007 “Unintended Consequences of Technological Solutons

April 1, 2008 “Pennsylvania PSA’s FMEA on Telemetry Alarm Interventions

February 23, 2010 “Alarm Issues in the News Again

March 2, 2010 “Alarm Sensitivity: Early Detection vs. Alarm Fatigue

November 2010 What’s New in the Patient Safety World “Alarms in the Operating Room






Patient Safety Tip of the Week Archive


What’s New in the Patient Safety World Archive