A prospective physiologic study, in participants with COVID-19 related or non-COVID-19 related acute respiratory distress syndrome (ARDS) requiring mechanical ventilation less than 48 hours. The investigators assessed the effect of different tidal volume guided by different levels of driving pressure on ventilation inhomogeneity and ventilation/perfusion mismatch by electrical impedance tomography (EIT) in supine and/or prone position.
Once enrolled, an EIT dedicated belt containing 16 electrodes was placed around the participant's chest at the fifth or sixth intercostal space and connected it to an EIT monitor (PulmoVista 500; Dräger Medical GmbH, Lübeck, Germany). Data were collected in the enrolled day (Day 1),Day 3 and Day 7 including demographic and anthropometric data, a baseline arterial blood gas measurement, and ventilation parameters including type of supplemental oxygen, respiratory rate, fractional concentration of oxygen in inspired air (FiO2). Volume control mode without spontaneous breathing, PEEP will be set according to best respiratory compliance method, and tidal volume (VT) will be set to reach three levels of driving pressure (High 14-15cmH2O, moderate 10-11 cmH2O, and low 7-8 cmH2O). Each level of VT was maintained 10 minutes in supine and/or prone position. In the last minutes of each phase,the participants received instructions of end expiratory occlusion lasting at least 10 seconds and, 1 seconds after the start, a bolus of 10 mL of 10% NaCl solution was injected via the central venous catheter. Clinical data and outcome will be collected.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
57
Volume control mode without spontaneous breathing, PEEP will be set according to best respiratory compliance method, and tidal volume (VT) will be set to reach three levels of driving pressure (High 14-15cmH2O, moderate 10-11 cmH2O, and low 7-8 cmH2O). Each level of VT was maintained 10 minutes in supine and/or prone position.
Ling Liu
Nanjing, Jiangsu, China
regional compliance using EIT
regional compliance using EIT
Time frame: Day 1
regional ventilation
regional ventilation using EIT
Time frame: Day 1
regional perfusion
regional perfusion using EIT
Time frame: Day 1
Region-ventilation-delay
Region-ventilation-delay using EIT
Time frame: Day 1
driving pressure
measurement as one index of respiratory compliance
Time frame: Day 3
the number of regional lung ventilation
regional ventilation measuring by EIT
Time frame: Day 3
the number of regional lung perfusion
regional perfusion measuring by EIT
Time frame: Day 3
the number of region-ventilation-delay (RVD)
the RVD measuring by EIT
Time frame: Day 3
Value of ventilation-perfusion (V/Q) mismatch
V/Q mismatch was quantified as the percentage of pixels that were classified as ventilated but not perfused (dead space fraction) plus the percentage of those perfused but not ventilated (shunt fraction).
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Time frame: Day 1
Value of ventilation-perfusion (V/Q) mismatch
V/Q mismatch was quantified as the percentage of pixels that were classified as ventilated
Time frame: Day 3
Value of ventilation-perfusion (V/Q) mismatch
V/Q mismatch was quantified as the percentage of pixels that were classified as ventilated
Time frame: Day 7
The Global Inhomogeneity (GI) index
higher values indicating less homogenous ventilation
Time frame: Day 1
The Global Inhomogeneity (GI) index
higher values indicating less homogenous ventilation
Time frame: Day 3
The Global Inhomogeneity (GI) index
higher values indicating less homogenous ventilation
Time frame: Day 7
Blood gas
PaO2
Time frame: Day 1
Ventilation free day
ventilation free day in day 28
Time frame: Day 28
28 day mortality
death in day 28
Time frame: Day 28