Ventilator alarms are essential during mechanical ventilation because they alert medical professionals of changes in a patient’s condition that may require intervention. There are many different types of alarms that may sound, and each one represents a different potential problem.

In this article, we’ll discuss the different types of ventilator alarms, what they mean, and the troubleshooting interventions that should be taken to resolve the issue.

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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 problem related to the patient-ventilator interaction. The alarms can be visual, audible, or both, depending on the mode, settings, patient’s condition, and type of ventilator.

Respiratory therapists or other medical professionals who care for mechanically-ventilated patients must develop a clear understanding of each ventilator alarm in order to provide the best possible care.

Types of Ventilator Alarms

There are several different types of ventilator alarms, including the following:

  1. High Pressure
  2. Low Pressure
  3. Low Volume
  4. High Frequency
  5. Apnea
  6. High PEEP
  7. Low PEEP

Each alarm represents a different potential problem that may require intervention. Let’s take a closer look at each type.

Types of ventilator alarms illustrations in a chart

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

The high pressure alarm is common in patients with respiratory conditions that cause decreased lung compliance or increased airway resistance. Some other causes of this alarm include:

  • Coughing
  • Secretion accumulation
  • Biting the endotracheal tube
  • Kinking in the circuit or artificial airway
  • Impingement of the endotracheal tube on the carina
  • Herniation of the endotracheal tube cuff

Troubleshooting

The following can be used correct problems associated with a high pressure alarm:

  • Perform endotracheal suctioning if indicated
  • Insert a bite block or pharyngeal airway to prevent tube biting
  • Check for a kink in the circuit or artificial airway
  • Administer a bronchodilator to alleviate bronchospasm
  • Relocate the endotracheal tube if it’s not in the correct position
  • Check for water in the circuit
  • Check for patient-ventilator asynchrony
  • Check for a malfunction of the inspiratory or expiratory valves

Low Pressure Alarm

A low pressure alarm in mechanical ventilation is triggered whenever the peak inspiratory pressure (PIP) decreases 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.

Troubleshooting

The following can be used correct problems associated with a low pressure alarm:

  • Check for a leak or disconnection in the circuit
  • Check for a leak in the exhalation valve
  • Check for any loose connections
  • Check for a leak in the pilot balloon
  • Ensure that the endotracheal tube is properly located
  • Ensure that the endotracheal tube cuff is adequately inflated
  • Adjust the ventilator settings as needed

If this alarm is triggered, the respiratory therapist must promptly 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 decreases below a preset low volume threshold. This alarm is useful in ensuring that a patient is receiving and exhaling a minimum tidal volume.

Troubleshooting

Correcting problems associated with a low volume alarm is similar to those for a low pressure alarm. This includes:

  • Check for a leak or disconnection in the circuit
  • Check for a leak in the exhalation valve
  • Check for any loose connections
  • Check for a leak in the pilot balloon
  • Ensure that the endotracheal tube is properly located
  • Ensure that the endotracheal tube cuff is adequately inflated
  • Adjust the ventilator settings as needed

If a leak or disconnection occurs, the respiratory therapist must ensure that the patient is being ventilated and provide manual breaths if necessary until the source is identified and corrected.

High Frequency Alarm

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

The sounding of this alarm can occur when auto-triggering is present due to an incorrect sensitivity setting. It may also be a sign that the patient is in respiratory distress, which means that the cause must be identified and corrected as soon as possible.

Troubleshooting

The following can be used correct problems associated with a high frequency alarm:

  • Adjust the sensitivity setting
  • Perform endotracheal suctioning if indicated
  • Increase the level of pressure support
  • Increase the inspiratory flow setting
  • Increase the FiO2 setting
  • Administer pain or anxiety medication if indicated

Apnea Alarm

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

In addition, most ventilators come with a preset apnea period that is typically around 20 seconds. However, some types of ventilators allow the operator to adjust this time limit.

Troubleshooting

The following can be used correct problems associated with an apnea alarm:

  • Check for a leak or disconnection in the circuit
  • Check for a leak or disconnection in the artificial airway
  • Increase the amount of ventilator support
  • Adjust the sensitivity setting

The sounding of the apnea alarm most commonly occurs whenever there is a disconnection of the circuit from the endotracheal tube.

If 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 and corrected.

High PEEP Alarm

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

Troubleshooting

The high PEEP alarm most commonly sounds whenever auto-PEEP or air trapping is present. Auto-PEEP is a complication during mechanical ventilation when positive pressure remains in the alveoli at the end-exhalation phase of the breathing cycle.

This increases the patient’s work of breathing and can lead to respiratory distress.

Therefore, problems associated with the high PEEP alarm can generally be corrected by prolonging the patient’s expiratory time. In addition, this alarm is often caused by many of the same problems that activate the high pressure alarm.

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

Troubleshooting

The low PEEP alarm most commonly sounds whenever there is a leak in the circuit tubing or endotracheal tube cuff. Therefore, this alarm is often caused by many of the same problems that activate the low pressure/volume alarms.

Another potential cause of the low PEEP alarm is active inspiration by the patient, causing the positive-end expiratory pressure level to drop below the preset alarm setting. This can occur when the inspiratory flow is set too low in relation to the patient’s inspiratory effort.

Ventilator Alarms Troubleshooting and Interventions

As previously mentioned, each type of ventilator alarm is designed to notify the respiratory therapist of a problem that needs to be corrected. The specific cause of the problem can vary, depending on the type of alarm that is sounding.

Ventilator alarm troubleshooting is the process of identifying and correcting the source of the problem that is causing the alarm to sound.

Therefore, it’s important for respiratory therapists to be familiar with the different types of ventilator alarms and their associated troubleshooting techniques.

Final Thoughts

Mechanical ventilation is a lifesaving intervention in patients who are unable to breathe on their own. Respiratory therapists are the primary healthcare professional involved in the management of these patients.

Ventilator alarms are an important part of mechanical ventilation as they help to ensure that the patient is receiving the proper level of ventilator support.

Therefore, respiratory therapists (and students) must be familiar with the different types of ventilator alarms and what they indicate. Hopefully, this article has helped to clear up any confusion surrounding this topic. Thanks for reading!

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.

References

  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
  • Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 7th ed., Mosby, 2019.
  • “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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Medical Disclaimer: The information provided by Respiratory Therapy Zone is for educational and informational purposes only. It should not be used as a substitute for professional medical advice, diagnosis, or treatment. Please consult with a physician with any questions that you may have regarding a medical condition.