Ventilator Alarms

Every ventilator has alarms that are set for the safety of the patient. We have talked a lot about the danger of applying pressure to the fragile alveoli. Using alarms on the ventilator will make sure that the pressures and volumes stay in safe ranges. After setting up your patient and initiating ventilation with your settings, go into your alarm screen and ensure your alarms are appropriate to your settings and patient.

A red siren light that is not currently in use.
Ventilator alarms are a useful tool for keeping you aware of your patient’s status when not present at the bedside.

The standard alarms that are set for all ventilation modes are as follows:

  • High Respiratory Rate
  • High Pressure Limit
  • High Volume
  • Low Volume
  • High Minute Volume
  • Low Minute Volume
If you would like additional information about the ventilator alarms listed above, check out Ventilator Alarms in Mechanical Ventilation.

It is important that you ensure your alarms are adequately set for all patients. Do not set your alarms too close to what your normal numbers are. These alarms are your safety net that your patient will not be exposed to volutrauma or barotrauma, but if your alarm ranges are set too tightly, it could cause any patient movement or change to trigger an alarm. Frequent alarms are disturbing for patients as well as the clinician. We also know that if things are alarming too often, it can cause alarm fatigue in healthcare workers and sometimes important alarms can be overlooked. Suggested ranges for alarm settings are below, but always defer to your health centre’s guidance when it differs from these recommendations:

Alarm Suggested setting Rationale
High RR 30-35 bpm Patient can wake up or rouse from sedation and increase their RR. This alarm is mostly used for spontaneous modes
High Pressure 35 cmH20 (max)
or
+10 cmH20 above your Peak Pressure		 If this limit is hit, it will cut off the breath that is being delivered. This can be very uncomfortable for the patient and cause coughing and asynchrony. Monitor your pressures carefully and try to stay below 30 cmH20 if possible. This is just the maximum limit.
Low Pressure Set 2 cmH20 below PEEP Not set on every ventilator. It is good for sensing a leak or disconnect in the circuit.
High Volume +200 ml from your target volume Monitor your volumes breath to breath. This alarm is set wide to avoid alarm fatigue. We as clinicians want to monitor our tidal volumes tighter than this when we are present, but this alarm will come into play when clinicians are not present.
Low Volume -200 ml from target tidal volume Not important in control modes. Usually used for spontaneous modes
High Minute Volume 20 lpm Set widely on purpose. Usually used in spontaneous modes
Low Minute Volume 3-4 lpm
or
-1 lpm below the MV reading on the ventilator.		 Set widely on purpose. Usually used in spontaneous modes
Apnea time 20 seconds Standard used in adult patients.

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