How to Address the Asynchrony Issues of Mechanical Ventilation

Patient-ventilator asynchrony is a common problem, as delivery of ventilatory support often does not correspond with patient demand.1 The adverse effects associated with asynchrony include1:

  • Increased or wasted work of breathing
  • Patient discomfort
  • Increased need for sedation
  • Confusion during the weaning process
  • Prolonged mechanical ventilation
  • Longer hospital stay
  • Possible higher mortality rates

In this blog post, we’ll discuss how asynchrony can affect your patients — and how you can address the issues it can cause.

Related: Can a ventilator filter choice help protect clinicians from contagious respiratory pathogens? See the lessons learned from two Canadian hospitals managing viral outbreaks.

Issue #1: Breathing on a ventilator can be difficult 

Difficulty while breathing on a ventilator can lead to patient discomfort and asynchrony, which is relatively common in ventilated patients. In fact, as many as 80 percent of patients with chronic obstructive pulmonary disease (COPD) experience this problem.2 It can take the form of ineffective triggering, double triggering, auto triggering, or instances when the duration of the ventilator’s inspiratory cycle doesn’t match that of the patient. 

How does this affect your patients? Patients with high rates of ineffective triggering tend to have poorer outcomes, increased duration of mechanical ventilation, shorter ventilator-free survival, and longer hospital stays.1

To help reduce instances of asynchrony, you can now use software technology. For example, proportional assist ventilation (PAV+) lets the patient dictate when they breathe and the time between breaths, so they can breathe naturally. Essentially, PAV+ software allows your patients to decide when the breath starts, how fast it is, and when it ends. This can significantly reduce asynchrony and increase the time span of synchrony.3

Related: Want to learn more about how to evaluate asynchrony? Watch this video.

Issue #2: Heavy sedation can cause adverse patient effects 

Patients may experience discomfort or distress while on a mechanical ventilator. To help cope with psychological or physical issues, sedation may be an option. However, recent studies show that sedating critically ill patients — especially continuously and intravenously — is associated with poor outcomes, including longer time on mechanical ventilation.1

Avoid using sedation and neuromuscular blocking agents on a regular basis to improve synchrony. Consider these options only after you have optimized synchrony. Due to depth of sedation, the asynchrony in some patients with ineffective triggering may not be obvious until you identify the problem by carefully examining the patient and ventilator waveforms.1

To avoid over-sedation, you can adjust the mechanical ventilator to meet your patients’ ventilatory requirements and make them more comfortable — without adding sedation.

Related: Learn more about managing ICU sedation for agitated patients and improving outcomes. Visit this website.

Issue #3: Patients may lose muscle mass/strength

Another concern for patients on mechanical ventilation is the potential loss of muscle mass and strength. Depending on their level of recovery, you can overwork patients on a ventilator, which leads to fatigue. You can also underwork them, which leads to atrophy. 

It’s important to identify the proper amount of work patients should be doing on a ventilator to optimize their muscle management and minimize muscle atrophy. For example, if a patient is fully supported by a ventilator, significant muscle degradation of the diaphragm may occur within 18 hours.4

You can address this issue with innovations such as PAV+ software. PAV+ software helps manage ventilation by providing variable support in lower and higher demand states while giving feedback on the work required of the patient.

Find out how you can leverage PAV+™ software in your hospital. Download the clinical evidence guide.


Please pay close attention to warnings and their associated consequences as described in the Puritan Bennett™ 980 ventilator operator’s manual.

The ventilator system is not intended to be a comprehensive monitoring device and does not activate alarms for all types of conditions. Do not operate the ventilator in a magnetic resonance imaging (MRI) environment. Risks associated with using a mechanical ventilator include but are not limited to hypoxemia, hypercarbia, hypocarbia, and infection.

1. Epstein SK. How often does patient ventilator asynchrony occur and what are the consequences? Respir Care. 2011;56(1):25–38.

2. de Wit M, Miller KB, Green DA, Ostman HE, Gennings C, Epstein SK. Ineffective triggering predicts increased duration of mechanical ventilation. Crit Care Med. 2009;37(10):2740–2745.

3. Costa R, Spinazzola G, Cipriani F, et al. A physiologic comparison of proportional assist ventilation with load-adjustable gain factors (PAV+™) versus pressure support ventilation (PSV). Intensive Care Med. 2011;37:1494–1500.

4. Schepens T, Verbrugghe W, Dams Karolien, Corthouts B, Parizel PM, Jorens, PG. The course of diaphragm atrophy in ventilated patients assessed with ultrasound: a longitudinal cohort study. Crit Care v 19; 2015

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About the Author

Gary Milne is the Clinical and Technical Director of Ventilation. He has been with Medtronic for 25 years and has been a clinical lead for much of his career. He holds twelve patents on ventilator design and a bachelor of science in respiratory therapy from Indiana University.