Time Course of Neuro-ventilatory Efficiency During a Spontaneous Breathing Training

Summary

The TONES trial aims to evaluate the neuroventilatory efficiency (NVE = tidal volume / peak voltage of diaphragm contraction) measured during a zero-assist manoeuvre (ZAM, i.e. with PEEP but without pressure support). This novel parameter, NVE-ZAM, will be studied in a blocked, crossover, repeated measures design.

Possible confounders, such as activity of respiratory muscles other than the diaphragm, are included.

The investigators hypothesized that

* the NVE during a zero-assist maneuver has a low variability and high repeatability at the same level of PEEP (within subjects, within blocks)
* NVE-ZAM trends differ between participants (between subjects, within blocks) and between PEEP levels (within subjects, between blocks)

The primary aim is to study the variability and repeatability of the NVE-ZAM within subjects and within blocks.

Additionally, the effect of PEEP, muscle fatigue and recruitment of the accessory and expiratory muscles of respiration on the NVE-ZAM will be studied in an exploratory analysis (in multiple combinations of within and between subjects and/or blocks).

Conditions

• Ventilator Weaning
• Respiration, Artificial
• Respiratory Muscles
• Respiratory Failure
• Critical Care

Interventions

DIAGNOSTIC_TEST

Inspiratory hold

A short period (\< 30 seconds) during which both inspiratory and expiratory valves of the ventilator circuit are closed at the end of inspiration. It is used to asses expiratory force generation (maximal expiratory pressure, MEP) and frequently used in clinical practice.

DIAGNOSTIC_TEST

Expiratory hold

A short period (\< 30 seconds) during which both inspiratory and expiratory valves of the ventilator circuit are closed at the end of expiration. It is used to asses static PEEP and inspiratory force generation (maximal inspiratory pressure, MIP \& occlusion pressure, ∆Pocc) and is frequently used in clinical practice.

DIAGNOSTIC_TEST

Ultrasound of respiratory muscles

Ultrasound of the diaphragm, parasternal intercostal muscle and internal oblique muscle will be performed during each block. Thickening fractions, calculated as thickness at end-inspiration minus thickness at end-expiration divided by thickness at end-expiration, are used to assess the contribution of the muscle to the tidal volume. A median over 5 breaths will be calculated.

OTHER

PEEP 10

Positive End-Expiratory Pressure of 10cmH2O for 30 minutes

OTHER

PEEP 5

Positive End-Expiratory Pressure of 5cmH2O for 30 minutes

OTHER

PEEP 0

Positive End-Expiratory Pressure of 0cmH2O for 30 minutes

Sponsors & Collaborators

• Research Foundation Flanders

  collaborator OTHER

• University Hospital, Antwerp

  lead OTHER

Principal Investigators

• Philippe G Jorens, MD, PhD · Head of the department of critical care medicine, Antwerp University Hospital

Study Design

Allocation

RANDOMIZED

Purpose

DIAGNOSTIC

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

80 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2022-06-15

Primary Completion

2023-12-31

Completion

2023-12-31

Countries

• Belgium

Study Locations