Artificial Respiration, Mechanical Ventilation
Conditions
Brief summary
Conventional continuous mandatory mechanical ventilation relies on the passive recoil of the chest wall for expiration. This results in an exponentially decreasing expiratory flow. Flow controlled ventilation (FCV), a new ventilation mode with constant, continuous, controlled expiratory flow, has recently become clinically available and is increasingly being adopted for complex mechanical ventilation during surgery. In both clinical and pre-clinical settings, an improvement in ventilation (CO2 clearance) has been observed during FCV compared to conventional ventilation. Recently, Schranc et al. compared flow-controlled ventilation with pressure-regulated volume control in both double lung ventilation and one-lung ventilation in pigs. They report differences in dead space ventilation that may explain the improved CO2 clearance, although their study was not designed to compare dead space ventilation within the group of double lung ventilation. Dead space ventilation, or wasted ventilation, is the ventilation of hypoperfused lung zones, and is clinically relevant, as it is a strong predictor of mortality in patients with the acute respiratory distress syndrome (ARDS) and is correlated with higher airway driving pressures which are thought to be injurious to the lung (lung stress). This trial aims to study the difference in dead space ventilation between conventional mechanical ventilation in volume-controlled mode and flow controlled-ventilation.
Interventions
20 minutes of FCV, delivered with the CE-marked Evone ventilator (Ventinova medical, the Netherlands)
DEVICEConventional volume-controlled ventilation (VCV)
20 minutes of conventional VCV, delivered with the CE-marked Aisys CS3 (GE Healthcare, USA) or Flow-i (Getinge, Sweden) ventilators.
Sponsors
Universiteit Antwerpen
University Hospital, Antwerp
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
During analysis the groups (flow-controlled ventilation and volume-controlled ventilation) will be blinded. Participants know that they will be exposed to both modes of ventilation, but are unaware of the randomized sequence (FCV-VCV or VCV-FCV). It is impossible to mask the investigators delivering the intervention.
Intervention model description
Crossover volume-controlled ventilation and flow-controlled ventilation
Eligibility
Sex/Gender
ALL
Age
18 Years to 70 Years
Healthy volunteers
No
Inclusion criteria
* Adults \[18-70\] yrs * General anaesthesia for elective surgery * Arterial line, central venous line and endotracheal tube as part of standard of care * Expected duration of controlled mechanical ventilation ≥ 60 minutes * Supine position (0±10°)
Exclusion criteria
* One lung ventilation * Known pregnancy * Increased intra-abdominal pressure (pneumoperitoneum or obesity (BMI \> 30kg/m2)) * COPD GOLD IV or home oxygen dependence * Cardiac pacemaker, implantable cardioverter-defibrillator (ICD) or thoracic neurostimulator * Skin lesions (e.g. injury, inflammation) at the level where the Electrical Impedance Tomography (EIT) band is to be applied * Clinical signs of raised intracranial pressure * Potential interference with the surgery due to the setup of the study instruments. * Patient refusal to participate
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Bohr dead space ventilation (VDBr/VT) | During FCV and VCV measurements (20 minutes) | Quantified by the Bohr approach with volumetric capnography |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in physiological dead space volume (Vdfys) | During FCV and VCV measurements (20 minutes) | Measured with volumetric capnography and Enghoff's approach |
| Change in airway dead space volume (Vdaw) | During FCV and VCV measurements (20 minutes) | Measured with volumetric capnography and Fletcher's approach |
| Change in alveolar dead space volume (Vdalv) | During FCV and VCV measurements (20 minutes) | As measured with volumetric capnography and Fletcher's approach |
| Ventilatory efficiency (VE/VCO2) | During FCV and VCV measurements (20 minutes) | Ratio of minute ventilation to carbon dioxide output |
| Change in airway driving pressure (∆Paw) | During FCV and VCV measurements (20 minutes) | Calculated as the difference between the plateau pressure (Pplat) during an inspiratory pause and the dynamic positive end-expiratory pressure (PEEP), as no expiratory hold is possible on the Evone. |
| Change in transpulmonary shunt fraction (Qs/Qt) | During FCV and VCV measurements (20 minutes) | calculated with the modified Berggren equation |
| Change in global lung hyperdistention (hyperdistentionEIT) | During FCV and VCV measurements (20 minutes) | Calculated from electric impedance tomography |
| Change in anterio-posterior distribution of ventilation on EIT (AP) | During FCV and VCV measurements (20 minutes) | % anterior / % posterior |
| Change in right-left distribution of ventilation on EIT (RL) | During FCV and VCV measurements (20 minutes) | % right / % left |
| Change in 4-layered distribution of ventilation on EIT | During FCV and VCV measurements (20 minutes) | — |
| Change in centre of ventilation on EIT | During FCV and VCV measurements (20 minutes) | — |
| Change in cardiac index (CI) | During FCV and VCV measurements (20 minutes) | Calculated from the arterial waveform (pulse contour analysis) by the HemoSphere monitor |
| Change in mean arterial pressure (MAP) | During FCV and VCV measurements (20 minutes) | Measured on a radial artery line |
| Change in partial pressure of arterial CO2 (PaCO2) | During FCV and VCV measurements (20 minutes) | Measured on an arterial blood gas |
| Change in peak expiratory flow (PEF) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in peak inspiratory flow (PIF) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in Enghoff dead space ventilation (VDEng/VT) | During FCV and VCV measurements (20 minutes) | Quantified by the Enghoff approach with volumetric capnography |
| Change in tidal volume (TV) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in respiratory rate (RR) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in minute ventilation (MV) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in inspiratory time (Ti) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in expiratory time (Te) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in ratio of inspiratory time to total breath time (Ti / Tt) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in positive end-expiratory pressure (PEEP) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in peak inspiratory pressure (PIP) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in plateau pressure (Pplat) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in static airway compliance (Caw) | During FCV and VCV measurements (20 minutes) | Calculated as tidal volume / airway driving pressure |
| Change in end-tidal CO2 (ETCO2) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in global airway resistance (Raw) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
| Change in global airway time constant (TAUaw) | During FCV and VCV measurements (20 minutes) | Calculated as global airway resistance x global airway compliance |
| Change in total energy | During FCV and VCV measurements (20 minutes) | As calculated from monitoring data |
| Change in dissipated energy | During FCV and VCV measurements (20 minutes) | As calculated from monitoring data |
| Change in P/F ratio | During FCV and VCV measurements (20 minutes) | Calculated as partial pressure of arterial oxygen divided by inspiratory fraction of oxygen |
| Change in mean airway pressure (MPaw) | During FCV and VCV measurements (20 minutes) | As measured by the citrex respiratory monitor |
Countries
Belgium
Contacts
Primary ContactCarine Smitz
Backup ContactJoke De Wachter
Outcome results
None listed