Dead Space in Mechanical Ventilation With Constant Expiratory Flow (DeXFLoW)

Antwerp University Hospital (UZA)

Status: Enrolling

Conditions: Artificial Respiration; Mechanical Ventilation

Treatments: Device: Conventional volume-controlled ventilation (VCV); Device: Flow-controlled ventilation (FCV)

Study type: Interventional

Funder types: Other

Identifiers

NCT06024993

003029

Details and patient eligibility

About

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.

Enrollment: 13 estimated patients

Sex: All

Ages: 18 to 70 years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

---

13 participants in 2 patient groups

FCV-VCV

Experimental group

Description:

After titration of ventilation in baseline VCV (all arms), participants will first receive 20 min of baseline-matched FCV and subsequently 20 min of baseline-matched VCV.

Treatment:

Device: Flow-controlled ventilation (FCV)

Device: Conventional volume-controlled ventilation (VCV)

VCV-FCV

Experimental group

Description:

After titration of ventilation in baseline VCV (all arms), participants will first receive 20 min of baseline-matched VCV and subsequently 20 min of baseline-matched FCV.

Treatment:

Device: Flow-controlled ventilation (FCV)

Device: Conventional volume-controlled ventilation (VCV)