Physiological Effects of Different Preoxygenation Strategies

Condition(s) studied

Investigational drug(s) / intervention(s)

Nasal cannula (NC): Preoxygenation performed using a nasal cannula delivering supplemental oxygen at a flow rate of 15 L/min, without the use of an additional mask or ventilation device, during spontaneous breathing.

Non-rebreather mask (NRM): Preoxygenation performed using a non-rebreather mask with reservoir, delivering oxygen at a flow rate of 15 L/min. The mask is fitted to ensure an optimal seal, and participants breathe spontaneously without assisted ventilation.

Non-rebreather mask (NRM) plus Nasal cannula (NC): Preoxygenation performed using a non-rebreather mask with reservoir, delivering oxygen at a flow rate of 15 L/min, combined with a nasal cannula delivering supplemental oxygen at 15 L/min. The mask is fitted to ensure an optimal seal, and participants breathe spontaneously without assisted ventilation.

Bag-valve mask (BVM) without PEEP: Preoxygenation performed using a bag-valve mask without a PEEP valve, delivering oxygen at a flow rate of 15 L/min. The mask is held with a two-handed technique to ensure an airtight seal, without providing assisted ventilation, allowing spontaneous breathing.

Bag-valve mask (BVM) without PEEP + nasal cannula (NC): Preoxygenation performed using a bag-valve mask without a PEEP valve, delivering oxygen at a flow rate of 15 L/min, combined with a nasal cannula delivering supplemental oxygen at 15 L/min. The mask is held with a two-handed technique to ensure an airtight seal, without providing assisted ventilation, allowing spontaneous breathing.

Bag-valve mask (BVM) with PEEP: Preoxygenation performed using a bag-valve mask equipped with a PEEP valve set at 10 cmH₂O, delivering oxygen at a flow rate of 15 L/min. The mask is held with a two-handed technique to ensure an airtight seal, without assisted ventilation, during spontaneous breathing.

Bag-valve mask (BVM) with PEEP + nasal cannula (NC): Preoxygenation performed using a bag-valve mask equipped with a PEEP valve set at 10 cmH₂O, delivering oxygen at a flow rate of 15 L/min, combined with a nasal cannula delivering supplemental oxygen at 15 L/min. The mask is held with a two-handed technique to ensure an airtight seal, without assisted ventilation, during spontaneous breathing.

Study summary

The goal of this clinical trial is to evaluate the performance and physiological effects of different preoxygenation devices in healthy adult and pediatric volunteers (children aged 5-12 years). The study aims to determine how these devices influence oxygen delivery, airway pressure, and cardiopulmonary physiology during preoxygenation.

The main questions it aims to answer are:

* What fraction of inspired oxygen (FiO₂) is delivered by non-rebreather masks (NRM) compared to bag-valve masks (BVM) with and without positive end-expiratory pressure (PEEP)?
* How do these devices differ in terms of generated PEEP, inspiratory effort, and their effects on lung ventilation and cardiac function?

Researchers will compare NRM, BVM without PEEP, and BVM with PEEP (each with or without supplemental oxygen via nasal cannula) to evaluate differences in oxygenation and physiological effects.

Participants will:

* Complete multiple 3-minute preoxygenation sessions using each device in randomized order
* Breathe spontaneously through each device, with or without additional oxygen via nasal cannula
* Undergo non-invasive monitoring of oxygen concentration (FiO₂), respiratory parameters, airway pressures, and ultrasound assessment of the lungs, diaphragm, and heart
* Perform a brief breath-holding maneuver to assess airway pressure generation

Eligibility

Primary outcome measure(s)

• Difference in fraction of inspired oxygen (FiO₂) between preoxygenation devices — During each 3-minute preoxygenation session
  Fraction of inspired oxygen (FiO₂) delivered during preoxygenation will be continuously measured at the airway opening using a gas analyzer. FiO₂ values will be recorded breath-by-breath during each 3-minute preoxygenation session under all study conditions. The primary outcome is the difference in mean FiO₂ achieved between the different preoxygenation devices (non-rebreather mask, bag-valve mask without PEEP, and bag-valve mask with PEEP), with and without supplemental oxygen via nasal cannula.

Trial sites (1)

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