Volume Support/Assist Control Mode Ventilation and Diaphragmatic Atrophy

  • End date
    Jan 11, 2024
  • participants needed
  • sponsor
    University of Chicago
Updated on 4 October 2022


The objective of the study is to determine how controlled mode ventilation and support mode ventilation impact ventilator-free days and diaphragmatic atrophy.


Ventilator-induced diaphragmatic dysfunction (VIDD) is characterized by diaphragmatic atrophy and weakness leading to an inability to liberate from the ventilator. Patients with VIDD have increased intensive care unit and hospital length of stay, higher reintubation rates, and need for tracheostomy. There are two commonly used modes of ventilation in the ICU - controlled and support mode ventilation. Conventional practice is to initiate mechanical ventilation with controlled mode followed by a support mode to facilitate weaning and eventual extubation. However, this approach may induce irreversible diaphragmatic atrophy. Observational studies suggest that controlled ventilation is associated with higher rates of diaphragmatic atrophy than support modes of ventilation. Diaphragmatic atrophy occurs within the first 24 hours of mechanical ventilation. To date, it remains unknown whether early initiation of support mode ventilation prevents VIDD and its associated complications in comparison to controlled mode ventilation.

The investigators hypothesize that by initiating subjects on support mode ventilation, an associated increase in ventilator-free days will be seen in comparison to subjects on controlled mode ventilation. Subjects on support mode ventilation will have less diaphragmatic atrophy and weakness than subjects on controlled mode ventilation. To investigate this hypothesis,investigators are conducting a phase III randomized trial examining the effects of volume support mode versus assist control mode ventilation on ventilator-free days and rate of diaphragm atrophy.

enrolled subjects requiring mechanical ventilation will be randomized to either volume support mode or assist control mode within 24 hours of mechanical ventilation initiation. Diaphragm thickness will be measured by ultrasound daily and subsequently diaphragm atrophy rate will be calculated in each arm. The operator acquiring ultrasound images will be blinded to the ventilator mode that the subject was randomized to. Subjects in the study will follow standard ICU sedation awakening trials and spontaneous breathing trials. The medical team in charge of the subject will determine when the subject will be liberated from the ventilator.

There will be up to a 24 hour period from initiation of standard, non-study mechanical ventilation during which the subject can be consented and enrolled. This will allow the research team time to contact the subject and/or family in order to obtain informed consent. Once randomized, all subjects will be initiated on study mode of ventilation. The medical team will direct other aspects of care.

The phase III trial will be powered to determine if there is a statistically significant difference in rate of diaphragm atrophy and ventilator-free days between volume support mode and assist control mode.

Condition Mechanical Ventilation Complication
Treatment Volume Support Mode Mechanical Ventilation, Assist Control Mode Mechanical Ventilation
Clinical Study IdentifierNCT03901924
SponsorUniversity of Chicago
Last Modified on4 October 2022


Yes No Not Sure

Inclusion Criteria

subjects > 18 years of age that have been intubated and mechanically ventilated for < 36
hours at the time of screening will be eligible for enrollment

Exclusion Criteria

cardiopulmonary arrest
history of diaphragmatic paralysis or neuromuscular disease
chronic obstructive pulmonary disease (COPD) or asthma exacerbation with evidence of
auto-PEEPing requiring intubation
neuromuscular blockade
expectation to be liberated from ventilator in < 24 hours
history of mechanical ventilation in the last 6 months
presence of tracheostomy
high cervical spine injury
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