Clinical trial NCT02838524: Acceptable Range of Inspiratory Effort During Mechanical Ventilation
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Elective Cardiac Surgery
Keywords: Spontaneous Breathing Trial
Inspiratory Effort
Mechanical Ventilation
Respiratory muscle load-capacity balance
Lead sponsor: Unity Health Toronto
Sponsor class: OTHER
First posted: 2016-07-20
Enrollment: 43
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Adult patients (age \>17) receiving invasive mechanical ventilation following elective cardiac surgery who will undergo a trial of spontaneous breathing

Brief summary: Partially assisted mechanical ventilation is ideally titrated to maintain adequate inspiratory muscle activity (i.e. preventing disuse atrophy) while avoiding excessive (i.e. fatiguing) inspiratory loads. The advent of ventilator modes enabling flow and pressure assistance in proportion to patient inspiratory effort (i.e. Proportional Assist Ventilation (PAV), Neurally-Adjusted Ventilator Assist (NAVA)) permit careful titration of ventilatory support to achieve desired levels of patient inspiratory effort. However, data on the acceptable range of values for inspiratory effort and respiratory muscle load-capacity balance during mechanical ventilation are currently very limited. Such data are critical to inform a physiologically sound evidence-based approach to titrating partially-assisted ventilatory support. This study is designed to ascertain a physiologically acceptable range of inspiratory effort in mechanically ventilated patients. The study protocol includes measurements of the respiratory system during spontaneous breathing as well as evaluating the diaphragm in real-time with the use of ultrasonography. The experimental design outlined in the present study is predicated on the assumption that the range of values for inspiratory effort and load-capacity balance observed in patients who are successfully weaned from mechanical ventilation represent the safe and appropriate range of target values.


Eligibility criteria: Inclusion Criteria:

- Adult patients (\>17) receiving invasive mechanical ventilation following elective cardiac surgery who will undergo a trial of spontaneous breathing

Exclusion Criteria:

* Pregnant women
* Decompensated cardiac insufficiency or acute coronary syndrome
* Severe COPD
* Contraindications to esophageal catheter placement, namely known esophageal varices

Primary outcomes:
measure: Maximal inspiratory effort generated by a patient
timeFrame: During 10-15 minutes of the spontaneous breathing trial
Secondary outcomes:
measure: Diaphragmatic thickening fraction
timeFrame: 15 minutes
measure: Diaphragmatic excursion
timeFrame: 15 minutes
measure: Success or failure of the spontaneous breathing trial
timeFrame: 15 minutes
measure: Muscular load-capacity balance measured by the tension-time index of the respiratory muscles
timeFrame: 15 minutes
measure: Airway occlusion pressure (P0.1) performed manually and as measured by the ventilator
timeFrame: 15 minutes
Other outcomes:
Locations:
city: Toronto
country: Canada
facility: St. Michael's Hospital
state: Ontario
Study officials:
References:
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