Scoring

Calculate a safety score for an alarm system

Use the following table to calculate the safety score of an alarm system, as follows:

  1. The first column describes the risks that you may need to consider
  2. The second column is for defining the significance of the risks described in the first column. Enter here the value that is most adequate to your installation.
  3. The third column describes the protection means that you should consider in the evaluation of a particular alarm system
  4. The fourth column is for defining the score of the particular alarm system regarding the implementation of the recommended protection

The risks

Risk level
1-10

Recommended protection

Score
1-10

Excessive sound alarms

  1. The sound disrupts the user's current attention
  2. Users get used to the sound alarm, gradually disregard the alarms
  3. Users are liable to shut the sound temporarily off, and then forget to enable it
 3

Avoiding unnecessary sound alarms

  1. Apply sound alarms only in emergency
  2. Avoid sound for information signals and for non-urgent alarm conditions, such as technical failures of sensors
 5

Unnoticed alarm conditions

The users might fail to notice the existence of alarm conditions. Alarm conditions may be unnoticed because:

  1. The alarm system is turn off
  2. The alarm limits are set to extreme values
  3. The sound is muted, either temporarily or by mistake
  4. Speaker malfunctioning
  5. Visual backup does not exist, or is unnoticeable
  6. The user is not familiar with the system
 8

Assuring that the alarm condition is noticeable

  1. The system should provide visual indication that it is on
  2. Users should not be required to anticipate the rate of false alarms or missed alarms based on knowledge of the alarm limits. The alarm limits should expressed in terms of safety levels
  3. The system should provide a single two-way means for sound control
  4. The system should provide visual indication that the alarm is muted
  5. Test sound should be heard on enabling the sound
  6. The system should continuously test the sound level and provide visual indication when it might not be heard.
  7. Visual alarm should be used as backup of the sound alarms
  8. The visual backup and indications should be salient and visible from all around the patient
  9. The users may practice the alarms in a training mode.
 7

Recognition errors

The user might not get the proper sense of emergency:

  1. Sound melodies by 60601-1-8 are misleading
  2. Visual alarms of emergency are not well distinguished from visual indications used for normal monitoring.
  3. The user is not familiar with the system alarms in different alarm conditions
 3

Assuring proper recognition of the alarm conditions

  1. Sound alarms should be used only for emergency situations
  2. Visual alarms in emergency should be attentive, using flashing and bold colors
  3. The alarm characteristics (pitch, speed, sharpness, colors) should correspond to the emergency level.
  4. The users may practice the alarms various alarm conditions in a training mode.
 8

Troubleshooting errors

The user might fail to identify the source for the alarm.

Example: the injection that run out of fluid

 2

Facilitate mapping from monitor to responsible sensor

The sensors should include status indicators

 2
Sum of Risk Levels 16 Sum of (Scores X Risk Level) 99

Usability Score

The Usability Score of the alarm system is calculated as the ratio 99 / 16 = 6.2