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NCT Number: NCT06024993

Dead Space in Mechanical Ventilation With Constant Expiratory Flow

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.

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Key information

Conditions

Mechanical Ventilation Artificial Respiration

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Antwerp University Hospital (UZA)

Edegem, Antwerp, 2650, Belgium

Location status: Recruiting

Location contact

Carine Smitz

CONTACT

[email protected]

+323 821 49 30

Gregory R De Meyer, M.D.

SUB_INVESTIGATOR

Philippe G Jorens, M.D., Ph.D.

SUB_INVESTIGATOR

Stuart G Morrison, M.D.

SUB_INVESTIGATOR

Tom Schepens, M.D., Ph.D.

SUB_INVESTIGATOR

Vera Saldien, M.D., Ph.D.

PRINCIPAL_INVESTIGATOR

Vincent Vandebergh, M.D.

SUB_INVESTIGATOR

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Flow-controlled ventilation (FCV)

Device

20 minutes of FCV, delivered with the CE-marked Evone ventilator (Ventinova medical, the Netherlands)

Conventional volume-controlled ventilation (VCV)

Device

20 minutes of conventional VCV, delivered with the CE-marked Aisys CS3 (GE Healthcare, USA) or Flow-i (Getinge, Sweden) ventilators.

Primary outcomes

  1. Change in Bohr dead space ventilation (VDBr/VT)

    Time frame: During FCV and VCV measurements (20 minutes)

    Quantified by the Bohr approach with volumetric capnography

Secondary outcomes

  1. Change in Enghoff dead space ventilation (VDEng/VT)

    Time frame: During FCV and VCV measurements (20 minutes)

    Quantified by the Enghoff approach with volumetric capnography

  2. Change in physiological dead space volume (Vdfys)

    Time frame: During FCV and VCV measurements (20 minutes)

    Measured with volumetric capnography and Enghoff's approach

  3. Change in airway dead space volume (Vdaw)

    Time frame: During FCV and VCV measurements (20 minutes)

    Measured with volumetric capnography and Fletcher's approach

  4. Change in alveolar dead space volume (Vdalv)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured with volumetric capnography and Fletcher's approach

  5. Ventilatory efficiency (VE/VCO2)

    Time frame: During FCV and VCV measurements (20 minutes)

    Ratio of minute ventilation to carbon dioxide output

  6. Change in airway driving pressure (∆Paw)

    Time frame: 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.

  7. Change in transpulmonary shunt fraction (Qs/Qt)

    Time frame: During FCV and VCV measurements (20 minutes)

    calculated with the modified Berggren equation

  8. Change in global lung hyperdistention (hyperdistentionEIT)

    Time frame: During FCV and VCV measurements (20 minutes)

    Calculated from electric impedance tomography

  9. Change in anterio-posterior distribution of ventilation on EIT (AP)

    Time frame: During FCV and VCV measurements (20 minutes)

    % anterior / % posterior

  10. Change in right-left distribution of ventilation on EIT (RL)

    Time frame: During FCV and VCV measurements (20 minutes)

    % right / % left

  11. Change in 4-layered distribution of ventilation on EIT

    Time frame: During FCV and VCV measurements (20 minutes)

  12. Change in centre of ventilation on EIT

    Time frame: During FCV and VCV measurements (20 minutes)

  13. Change in cardiac index (CI)

    Time frame: During FCV and VCV measurements (20 minutes)

    Calculated from the arterial waveform (pulse contour analysis) by the HemoSphere monitor

  14. Change in mean arterial pressure (MAP)

    Time frame: During FCV and VCV measurements (20 minutes)

    Measured on a radial artery line

  15. Change in partial pressure of arterial CO2 (PaCO2)

    Time frame: During FCV and VCV measurements (20 minutes)

    Measured on an arterial blood gas

  16. Change in peak expiratory flow (PEF)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  17. Change in peak inspiratory flow (PIF)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  18. Change in mean airway pressure (MPaw)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  19. Change in tidal volume (TV)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  20. Change in respiratory rate (RR)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  21. Change in minute ventilation (MV)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  22. Change in inspiratory time (Ti)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  23. Change in expiratory time (Te)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  24. Change in ratio of inspiratory time to total breath time (Ti / Tt)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  25. Change in positive end-expiratory pressure (PEEP)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  26. Change in peak inspiratory pressure (PIP)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  27. Change in plateau pressure (Pplat)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  28. Change in static airway compliance (Caw)

    Time frame: During FCV and VCV measurements (20 minutes)

    Calculated as tidal volume / airway driving pressure

  29. Change in end-tidal CO2 (ETCO2)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  30. Change in global airway resistance (Raw)

    Time frame: During FCV and VCV measurements (20 minutes)

    As measured by the citrex respiratory monitor

  31. Change in global airway time constant (TAUaw)

    Time frame: During FCV and VCV measurements (20 minutes)

    Calculated as global airway resistance x global airway compliance

  32. Change in total energy

    Time frame: During FCV and VCV measurements (20 minutes)

    As calculated from monitoring data

  33. Change in dissipated energy

    Time frame: During FCV and VCV measurements (20 minutes)

    As calculated from monitoring data

  34. Change in P/F ratio

    Time frame: During FCV and VCV measurements (20 minutes)

    Calculated as partial pressure of arterial oxygen divided by inspiratory fraction of oxygen

Study contacts

Contact information is provided by the study sponsor or research team.

Carine Smitz

CONTACT

[email protected]

+32 3 821 49 30

Joke De Wachter

CONTACT

[email protected]

+32 3 821 30 42

Sponsors and collaborators

Lead sponsor

University Hospital, Antwerp

Other

Collaborators

  • Universiteit Antwerpen

Registry information

Acronym: DeXFLoW

Important dates

Study start
2024
Primary completion
2025
Study completion
2026
First posted
Sep 6, 2023
Registry last updated
Jan 22, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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