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

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.

Study Overview

• Status: Recruiting
• Conditions: Mechanical Ventilation; Artificial Respiration
• Intervention / Treatment: Device: Flow-controlled ventilation (FCV); Device: Conventional volume-controlled ventilation (VCV)

• Study Type: Interventional
• Enrollment (Estimated): 13
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Carine Smitz; Phone Number: +32 3 821 49 30; Email: carine.smitz@uza.be
• Study Contact Backup: Name: Joke De Wachter; Phone Number: +32 3 821 30 42; Email: joke.dewachter@uza.be

Study Locations

• Belgium
  • Antwerp
    • Edegem, Antwerp, Belgium, 2650
      • Recruiting
      • Antwerp University Hospital (UZA)
      • Sub-Investigator: Tom Schepens, M.D., Ph.D.
      • Sub-Investigator: Gregory R De Meyer, M.D.
      • Contact: Carine Smitz; Phone Number: +323 821 49 30; Email: carine.smitz@uza.be
      • Sub-Investigator: Philippe G Jorens, M.D., Ph.D.
      • Sub-Investigator: Vincent Vandebergh, M.D.
      • Sub-Investigator: Stuart G Morrison, M.D.
      • Principal Investigator: Vera Saldien, M.D., Ph.D.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: FCV-VCV; 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.	Device: Flow-controlled ventilation (FCV); 20 minutes of FCV, delivered with the CE-marked Evone ventilator (Ventinova medical, the Netherlands); Device: Conventional 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.
Experimental: VCV-FCV; 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.	Device: Flow-controlled ventilation (FCV); 20 minutes of FCV, delivered with the CE-marked Evone ventilator (Ventinova medical, the Netherlands); Device: Conventional 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Bohr dead space ventilation (VDBr/VT)	Quantified by the Bohr approach with volumetric capnography	During FCV and VCV measurements (20 minutes)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Enghoff dead space ventilation (VDEng/VT)	Quantified by the Enghoff approach with volumetric capnography	During FCV and VCV measurements (20 minutes)
Change in physiological dead space volume (Vdfys)	Measured with volumetric capnography and Enghoff's approach	During FCV and VCV measurements (20 minutes)
Change in airway dead space volume (Vdaw)	Measured with volumetric capnography and Fletcher's approach	During FCV and VCV measurements (20 minutes)
Change in alveolar dead space volume (Vdalv)	As measured with volumetric capnography and Fletcher's approach	During FCV and VCV measurements (20 minutes)
Ventilatory efficiency (VE/VCO2)	Ratio of minute ventilation to carbon dioxide output	During FCV and VCV measurements (20 minutes)
Change in airway driving pressure (∆Paw)	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.	During FCV and VCV measurements (20 minutes)
Change in transpulmonary shunt fraction (Qs/Qt)	calculated with the modified Berggren equation	During FCV and VCV measurements (20 minutes)
Change in global lung hyperdistention (hyperdistentionEIT)	Calculated from electric impedance tomography	During FCV and VCV measurements (20 minutes)
Change in anterio-posterior distribution of ventilation on EIT (AP)	% anterior / % posterior	During FCV and VCV measurements (20 minutes)
Change in right-left distribution of ventilation on EIT (RL)	% right / % left	During FCV and VCV measurements (20 minutes)
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)	Calculated from the arterial waveform (pulse contour analysis) by the HemoSphere monitor	During FCV and VCV measurements (20 minutes)
Change in mean arterial pressure (MAP)	Measured on a radial artery line	During FCV and VCV measurements (20 minutes)
Change in partial pressure of arterial CO2 (PaCO2)	Measured on an arterial blood gas	During FCV and VCV measurements (20 minutes)
Change in peak expiratory flow (PEF)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in peak inspiratory flow (PIF)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in mean airway pressure (MPaw)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in tidal volume (TV)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in respiratory rate (RR)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in minute ventilation (MV)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in inspiratory time (Ti)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in expiratory time (Te)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in ratio of inspiratory time to total breath time (Ti / Tt)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in positive end-expiratory pressure (PEEP)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in peak inspiratory pressure (PIP)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in plateau pressure (Pplat)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in static airway compliance (Caw)	Calculated as tidal volume / airway driving pressure	During FCV and VCV measurements (20 minutes)
Change in end-tidal CO2 (ETCO2)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in global airway resistance (Raw)	As measured by the citrex respiratory monitor	During FCV and VCV measurements (20 minutes)
Change in global airway time constant (TAUaw)	Calculated as global airway resistance x global airway compliance	During FCV and VCV measurements (20 minutes)
Change in total energy	As calculated from monitoring data	During FCV and VCV measurements (20 minutes)
Change in dissipated energy	As calculated from monitoring data	During FCV and VCV measurements (20 minutes)
Change in P/F ratio	Calculated as partial pressure of arterial oxygen divided by inspiratory fraction of oxygen	During FCV and VCV measurements (20 minutes)

Collaborators and Investigators

• Sponsor: University Hospital, Antwerp
• Collaborators: Universiteit Antwerpen
• Investigators: Principal Investigator: Vera Saldien, M.D., Ph.D., Antwerp University Hospital / University of Antwerp

Study record dates

Study Major Dates

• Study Start (Actual): July 22, 2024
• Primary Completion (Estimated): December 30, 2025
• Study Completion (Estimated): April 30, 2026

Study Registration Dates

• First Submitted: April 3, 2023
• First Submitted That Met QC Criteria: September 5, 2023
• First Posted (Actual): September 6, 2023

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: January 20, 2025
• Last Verified: January 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: 003029

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No