Ventilator alarms serve a very important purpose because they alert the Respiratory Therapist or medical professional whenever an issue is present.

This guide breaks down all of the ventilator alarms to hopefully make the learning process easier for you. So if you’re ready, let’s get started.

What is a Ventilator Alarm?

A ventilator alarm is a safety mechanism on the mechanical ventilator that uses a set of parameters to provide alerts whenever there is a potential problem related to the patient-ventilator interaction.

The alarms can be visual, audible, or both, depending on the ventilator setting and the patient’s condition. In order to learn each of the different ventilator alarms, you must develop an understanding of the Ventilator Settings and Modes.

Types of Ventilator Alarms:

The following are examples of the common alarms that are typically programmed into most mechanical ventilator machines:

  • High Pressure
  • Low Pressure
  • Low Volume
  • High Frequency
  • Apnea
  • High PEEP
  • Low PEEP

Keep in mind that certain machines may include other types of ventilator alarms within their settings. These are just some of the most common examples. Please check with the manufacturer for a full list of each alarm for the ventilator that you’re interested in.

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High Pressure Alarm

A high pressure alarm in mechanical ventilation is triggered whenever the circuit pressure exceeds a preset pressure limit during the inspiratory phase. This is common in respiratory conditions that decrease lung compliance and/or increase airway resistance.

The preset high pressure limit for this alarm is typically set around 10 cmH2O above the peak inspiratory pressure (PIP).

Some other causes of the triggering of this alarm include coughing, secretion accumulation, patient biting the ET tube, or a kink in the circuit.

Low Pressure Alarm

A low pressure alarm in mechanical ventilation is triggered whenever the peak inspiratory pressure (PIP) falls below a preset designated level. This most commonly occurs whenever there is a leak or disconnection in the system.

The preset low pressure level for this alarm is typically set around 5-10 cmH2O below the PIP.

If this alarm is triggered, the Respiratory Therapist must first ensure that the patient is being ventilated. If the cause of the alarm is unknown, the patient should be manually ventilated until the source of the leak is identified.

Low Volume Alarm

A low volume alarm in mechanical ventilation is triggered whenever the expiratory volume falls below a preset low volume threshold. This is useful in ensuring that the patient is receiving and exhaling a minimum tidal volume.

Similar to the low pressure alarm, this alarm will also sound whenever there is a leak or disconnection in the system.

When this is the case, the Respiratory Therapist must ensure that the patient is being ventilated and provide manual breaths if necessary until the source is identified and corrected.

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High Frequency Alarm

A high frequency alarm in mechanical ventilation is triggered whenever the total frequency exceeds a preset high frequency limit. This is useful in minimizing tachypnea and hyperventilation.

The activation of this alarm can occur when autotriggering is present due to an incorrect sensitivity setting. It can also be a sign of respiratory distress which means that the cause should be identified and corrected as soon as possible.

Some potential ways to do so include adjusting the sensitivity setting, and/or increasing the pressure support, peak flow, or FiO2.

Apnea Alarm

An apnea alarm in mechanical ventilation is triggered whenever the total frequency drops below a preset low frequency limit. This is useful in ensuring that a minimum number of breaths are delivered to the patient.

Also, most ventilators come with a preset apnea period that is typically around 20 seconds although some allow the operator to adjust this time limit.

The activation of an apnea alarm most commonly occurs whenever there is a disconnection of the circuit from the ET tube.

When this occurs, the Respiratory Therapist must ensure that the patient is being ventilated by delivering manual breaths until the source of the disconnection is identified.

This book (in paperback format) has sample TMC Practice Questions on mechanical ventilation.

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High PEEP Alarm

A high PEEP alarm in mechanical ventilation is triggered whenever the level of PEEP exceeds a preset high PEEP limit. This is useful in ensuring that too much PEEP isn’t delivered to the patient.

This alarm most commonly occurs whenever auto-PEEP or air trapping is present.

Auto-PEEP is a complication that occurs when a positive pressure remains in the alveoli at the end-exhalation phase of the breathing cycle. This increases the work of breathing for the patient, however, it can be reduced by prolonging the expiratory time.

Low PEEP Alarm

A low PEEP alarm in mechanical ventilation is triggered whenever the level of PEEP falls below a preset low PEEP limit. This most commonly occurs whenever there is a leak in the circuit tubing or ET tube cuff.

This alarm is useful in ensuring that a desired level of PEEP is being delivered to the patient.

Final Thoughts

As a Respiratory Therapist or someone who works in critical care, it’s extremely important to familiarize yourself with each of the types of Ventilator Alarms.

Because, if you don’t, how will you know what’s going on with your patient?

Hopefully, you will be able to reference this guide to make the learning process much easier. Thank you so much for reading and as always, breathe easy my friend.

References

The following are the sources that were used while doing research for this article:

  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020. [Link]
  • Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013. [Link]
  • Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 7th ed., Mosby, 2019. [Link]
  • “Ventilator Safety.” National Center for Biotechnology Information, U.S. National Library of Medicine, 10 Aug. 2020, www.ncbi.nlm.nih.gov/books/NBK526044.
  • Scott, Brady. “Mechanical Ventilation Alarms and Alarm Fatigue.” PubMed, Oct. 2019, pubmed.ncbi.nlm.nih.gov/31213570.
  • Cvach, Maria. “Ventilator Alarms in Intensive Care Units: Frequency, Duration, Priority, and Relationship to Ventilator Parameters.” PubMed, Jan. 2020, pubmed.ncbi.nlm.nih.gov/30234538.

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