Evaluation of Different Methods for Preoxygenation
Condition: Anesthesia
Study type: Interventional

Summary: 
      The goal of this randomised cross-over study is to compare pre-oxygenation using a standard
      nasal cannula to pre-oxygenation using humidified high-flow nasal oxygen and a tight-fitting
      facemask in adult volunteers with a BMI below 30 not suffering from pulmonary or cardiac
      comorbidity.

      The main question it aims to answer is:

      - Are there any differences in the effectiveness of pre-oxygenation using a standard nasal
      cannula compared to using a traditional facemask and pre-oxygenation using humidified
      high-flow nasal oxygen?

      Participants will be pre-oxygenated with 100% oxygen during four minutes intervals. All
      participants will be pre-oxygenated with various flow rates using a standard nasal cannula, a
      facemask and humidified high-flow nasal oxygen. End-tidal oxygen concentrations will be
      measured continuously in order to evaluate the effectiveness of pre-oxygenation.

      Each volunteer will be pre-oxygenated repeatedly, with different flow rates, with all three
      methods of pre-oxygenation and act as its own control.

      During facemask pre-oxygenation volunteers will be pre-oxygenated using both tidal volume
      breathing for four minutes and with eight vital capacity breaths. During pre-oxygenation
      using the standard nasal cannula flow rates will vary between 15 and 50 l/min.
      Pre-oxygenation using humidified high-flow nasal oxygen will be performed with flow rates
      varying between 30 and 50 l/min. Series will be conducted with volunteers breathing with both
      opened and closed mouth as well as with four minutes of tidal volume breathing and eight
      vital capacity breaths.

      All volunteers will start with facemask pre-oxygenation. They will thereafter be randomised
      to pre-oxygenation with either a standard nasal cannula or humidified high-flow nasal oxygen.
      Lastly, they will be pre-oxygenated with the remaining method according to the randomisation.
    

Detailed description: 
      Pre-oxygenation before anaesthesia induction is mostly performed using a tight-fitting
      facemask. Recently, studies have shown that pre-oxygenation using humidified high-flow nasal
      oxygen is equally effective as pre-oxygenation using a standard tight-fitting facemask.
      Pre-oxygenation using humidified high-flow nasal oxygen has several potential advantages
      including improved patient comfort and the possibility of a seamless transition from
      pre-oxygenation to apnoeic oxygenation. Unfortunately, this technique requires an additional
      machine which can be expensive and also difficult to use in settings outside a hospital.

      In this study, pre-oxygenation using a standard nasal cannula delivering a high flow of
      oxygen will be compared with standard facemask pre-oxygenation and pre-oxygenation using
      humidified high-flow nasal oxygen in adult volunteers with a BMI below 30 not suffering from
      pulmonary or cardiac comorbidity.

      The main question it aims to answer is:

      - Are there any differences in the effectiveness of pre-oxygenation using a standard nasal
      cannula compared to using a traditional facemask and pre-oxygenation using humidified
      high-flow nasal oxygen?

      Participants will be pre-oxygenated with 100% oxygen during four minutes intervals. All
      participants will be pre-oxygenated with various flow rates using a standard nasal cannula, a
      facemask and humidified high-flow nasal oxygen. End-tidal oxygen concentrations will be
      measured continuously in order to evaluate the effectiveness of pre-oxygenation.

      Each volunteer will be pre-oxygenated repeatedly, with different flow rates, with all three
      methods of pre-oxygenation and act as its own control.

      During facemask pre-oxygenation volunteers will be pre-oxygenated using both tidal volume
      breathing for four minutes and with eight vital capacity breaths. During pre-oxygenation
      using the standard nasal cannula flow rates will vary between 15 and 50 l/min.
      Pre-oxygenation using humidified high-flow nasal oxygen will be performed with flow rates
      varying between 30 and 50 l/min. Series will be conducted with volunteers breathing with both
      opened and closed mouth as well as with four minutes of tidal volume breathing and eight
      vital capacity breaths.

      All volunteers will start with facemask pre-oxygenation. They will thereafter be randomised
      to pre-oxygenation with either a standard nasal cannula or humidified high-flow nasal oxygen.
      Lastly, they will be pre-oxygenated with the remaining method according to the randomisation.
    

Intervention name(s): Humidified high-flow nasal oxygen; Standard nasal cannula; Facemask
Intervention type(s): Device; Device; Device
Intervention description(s): Humidified high-flow oxygen delivered via the Optiflow device; Oxygen delivered with high flows via a standard nasal cannula; Oxygen delivered with facemask
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: All volunteers will start with pre-oxygenation using a traditional facemask (vital breathing for four minutes vital and eight vital capacity breaths). They will thereafter be randomised to continue with either pre-oxygenation using a standard nasal cannula or humidified high-flow nasal oxygen.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Preoxygenation; Oxygenation; High-flow nasal oxygen; Low-flow nasal oxygen