Pre-oxygenation With Facemask Oxygen vs High-flow Nasal Oxygen vs High-flow Nasal Oxygen Plus Mouthpiece Oxygen

Overview

Pre-oxygenation increases oxygen reserves in the body to reduce the likelihood of oxygen desaturation on induction of general anaesthesia. Pre-oxygenation with facemask is the commonest method method of pre-oxygenation. High-flow nasal oxygen is a newer alternative. This study randomises participants to receive pre-oxygenation by one of three methods: facemask, high-flow nasal oxygen, high-flow nasal oxygen plus mouthpiece.

Full Title of Study: “Pre-oxygenation With Facemask Oxygen vs High-flow Nasal Oxygen vs High-flow Nasal Oxygen Plus Mouthpiece Oxygen – a Randomised Controlled Trial”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: January 13, 2021

Detailed Description

The administration of supplemental oxygen prior to induction of anaesthesia is known as pre-oxygenation. Pre-oxygenation increases oxygen reserves in the body with the purpose of delaying the time until oxygen desaturation after breathing stops (apnoea) following the administration of an anaesthetic. In the last decade, clinicians have begun utilising high-flow nasal oxygen for pre-oxygenation. However, the rationale for this is based largely on its ability to achieve ongoing oxygenation after the onset of apnoea (apnoeic oxygenation). This study isolates oxygen administration with high-flow nasal oxygen to the period when the person is breathing, without ongoing oxygen administration during the apnoea period, to quantify its effects during the pre-oxygenation period only. A third group of participants breathes oxygen through a mouthpiece in addition to receiving oxygen via high-flow nasal cannulae. The effect of these pre-oxygenation methods will be measured by the time taken until oxygen saturation levels decline to the lower end of the normal range (92%), along with other parameters such as blood oxygen levels.

Interventions

  • Other: Pre-oxygenation
    • Induction of anaesthesia after 2mins 45 seconds of pre-oxygenation with 1-1.5mcg/kg remifentanil plus 2-3mg/kg propofol. Propofol (10mg/kg/hr) and remifentanil (0.15mcg/kg/min) infusions commenced until study conclusion. Positive pressure ventilation commenced at Sp02 92%. Failure to intubate the patient during the first minute of apnoea results in withdrawal from the study. Blood samples obtained from an arterial catheter immediately prior to commencing pre-oxygenation, after 90 and 180 seconds of pre-oxygenation, after one minute of apnoea, and every two minutes during the apnoeic period.

Arms, Groups and Cohorts

  • Experimental: Facemask oxygen (FM)
    • 100% oxygen administered via facemask through circle system with adjustable pressure-limiting valve at 0 cmH20. Participant instructed to ‘breathe normally’
  • Active Comparator: High-flow nasal oxygen (HFNO)
    • 100% oxygen administered via high-flow nasal cannulae at 50 L/min. Participant instructed to ‘keep the mouth closed and breathe normally’
  • Active Comparator: High-flow nasal oxygen plus mouthpiece oxygen (HFNO+MP)
    • 100% oxygen administered via high-flow nasal cannulae at 50 L/min. Additionally, 100% oxygen administered via mouthpice through circle system with adjustable pressure-limiting valve at 0 cmH20. Participant instructed to ‘keep the mouth closed and breathe normally’.

Clinical Trial Outcome Measures

Primary Measures

  • Time to oxygen desaturation
    • Time Frame: Immediately after the intervention
    • The time period from the onset of apnoea (determined by visual inspection) until an oxygen saturation of 92% is measured by pulse oximetry.

Secondary Measures

  • Arterial partial pressure of oxygen after pre-oxygenation.
    • Time Frame: At 3 minutes of pre-oxygenation
    • As measured by blood gas analysis
  • Arterial partial pressure of carbon dioxide change during pre-oxygenation
    • Time Frame: At 0 and 3 minutes
    • As measured by blood gas analysis
  • Change in arterial partial pressure of carbon dioxide during apnoea
    • Time Frame: At 0, 1, 2 minutes and each 2 minutes thereafter
    • As measured by blood gas analysis
  • Change in acid-base status during apnoea
    • Time Frame: At 0, 1, 2 minutes and each 2 minutes thereafter
    • As measured by blood gas analysis
  • Correlation between end-tidal carbon dioxide measurement and arterial partial pressure of carbon dioxide
    • Time Frame: Etco2 obtained at the time of resumption of ventilation. Paco2 obtained from the preceding blood gas measurement.
    • The EtCO2 value used for comparison is the highest value recorded during the first five respiratory cycles by manual ventilation with the adjustable pressure-limiting valve set at 20cmH20.

Participating in This Clinical Trial

Inclusion Criteria

  • 18 years of age or older – ASA 1 or 2 – Receiving a general anaesthetic for non-emergent surgery Exclusion Criteria:

  • ASA score ≥3 – BMI ≥ 30 kg/m2 – Nasal obstruction – Baseline SpO2 ≤95% on room air – Anticipated difficult airway management – Requirement for awake intubation – Pregnancy – Positive PCR test for coronavirus.

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University College Hospital Galway
  • Provider of Information About this Clinical Study
    • Principal Investigator: John Laffey, +Michael Callaghan – principal investigator – University College Hospital Galway
  • Overall Official(s)
    • Michael Callaghan, MB BCh BAO, Principal Investigator, Consultant Anaesthesiologist

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