EIT Study With Healthy Patients
Condition: Healthy Participants
Study type: Interventional
Phase: Phase 1

Summary: 
      Patients with severe respiratory diseases such as chronic obstructive pulmonary disease
      (COPD) or obesity-hypoventilation syndrome (OHS) can benefit from having non-invasive
      ventilation (NIV). Non-invasive ventilation consists of a machine (ventilator) that is
      blowing air through a mask. NIV provides patients with a bigger expansion of their lung when
      they are breathing. This better expansion helps patients to have more oxygen and less waste
      gas (or carbon dioxide) in their body.

      These improvements enhance survival and quality of life. In order to provide appropriate
      ventilation for each patient, the ventilator can generate different types of blowing:

        -  Continuous positive airway pressure (CPAP) which delivers a constant pressure to the
           mask

        -  Pressure support ventilation (PSV) which delivers a constant pressure to the mask and,
           on top of that, delivers more pressure when the patient begins to breathe in.

        -  Pressure control ventilation (PCV), which is similar to PSV, but use a fixed time to
           generate the flow when the patient begins to breathe in.

      These different types of blowing have consequences on patient comfort as well as on the
      improvement of their ventilation.

      To assess the improvement of the ventilation, the investigators currently use blood tests,
      however, these reflect overall output and may miss more subtle changes in breathing that
      could affect how patients feel.

      Electrical impedance tomography (EIT) is a new technology that involves wearing a belt of
      sensors around the chest that provides information on how well the lungs are being filled
      with air by the ventilator. It allows a non-invasive assessment of the effect of NIV onto
      lung ventilation in real-time.

      The investigators hope to use the EIT technology to assess in real-time patients lung
      ventilation when they are using the NIV. The investigators hope that EIT will provide them
      with information on which type of blowing is more effective and more comfortable than the
      others.
    

Detailed description: 
      Chronic lung disease can sometimes progress to the extent that patients can no longer clear
      the waste gas from their blood. Treatment can be offered with a mask and machine (ventilator)
      that helps people breathe and aims to improve their lung condition. It is common for people's
      lungs to be affected variably, i.e. left more than right or top of lung more than bases of
      lungs. The way in which the ventilator is set may affect how well the machine deals with
      these differences. If the lung is better ventilator patients may find the machine more
      comfortable and it may be more effective.

      Electrical impedance tomography (EIT) is a new technology that involves wearing a belt of
      sensors around the chest that provides information on how well the lungs are being filled
      with air by the ventilator. It allows the assessment of these differences, which previously
      required the use of invasive equipment to obtain.

      Optimising ventilator settings in the administration of non-invasive ventilation (NIV) can be
      improved with the addition of individual physiological data. This approach is limited due to
      the invasive techniques required to obtain this information, often leading to less ideal NIV
      settings promoting patient-ventilator asynchrony. It has been recently demonstrated by our
      group that all patients established on domiciliary NIV have a degree of patient-ventilator
      asynchrony and that the commonest type of asynchrony are triggering issues. Triggering
      asynchrony is promoted by mismatch between a patient's intrinsic positive end-expiratory
      pressure (iPEEP) and applied expiratory positive airway pressure (EPAP) with these
      ineffective efforts contributing to an increased work of breathing and patient discomfort.
      Previous strategies used to optimise patient triggering have involved the placement of
      oesophageal catheters in order to measure neural respiratory drive (NRD) to the diaphragm by
      electromyography (EMG) but again this process is invasive and often poorly tolerated.
      Electrical Impedance Tomography (EIT) is a non-invasive, bedside monitoring technique that
      provides semi-continuous, real-time information about the regional distribution of the
      changes in electrical resistivity of the lung tissue due to variations in ventilation in
      relation to a reference state.

      Information is gained by repeatedly injecting small alternating electric currents (usually 5
      mA) at high frequency of 50 - 80 kHz through a system of skin electrodes (usually 16) applied
      circumferentially around the thorax in a single plane between the 4th and 6th intercostal
      space. While an adjacent pair of electrodes 'injects' the current ('adjacent drive
      configuration'), all the remaining adjacent passive electrode pairs measure the differences
      in electric potential. A resistivity (impedance) image is reconstructed from this data by a
      mathematical algorithm using a two dimensional model and a simplified shape to represent the
      thoracic cross-section.

      The resulting image possesses a high temporal and functional resolution making it possible to
      monitor dynamic physiological phenomena (e.g. delay in regional inflation or recruitment) on
      a breath by breath basis. It is important to realize that the EIT images are based on image
      reconstruction techniques that require at least one measurement on a well-defined reference
      state. All quantitative data are related to this reference and can only indirectly quantify
      (relative) changes in local lung impedance (but not absolute).

      EIT can be used in mechanically ventilated patients to assess recruitment and to optimise
      ventilator settings to reduce risk of iatrogenic ventilator associated lung injury.

      To date, EIT has only been validated in patient invasively ventilated or during
      self-ventilation.

      The investigators hope to use the EIT technology to assess patients breathing using different
      ventilator modes in order to see if one is more effective and or more comfortable than the
      others. The investigators can use this information to help them set ventilators for future
      patients.
    

Intervention name(s): NIV Group
Intervention type(s): Device
Intervention description(s): Each patient will be using Non Invasive Ventilation (NIV) and will use it on each possible ventilation mode in a random order with a 10 minutes washout period between modes.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: EIT; NIV