The Effect of High-flow Nasal Oxygen Flow Rate on Gas Exchange During Apnoea (Apox-HFNO)

University College Hospital Galway

Status: Completed

Conditions: Apnea; Respiration; Arrest; Anesthesia

Treatments: Procedure: Apnoeic oxygenation

Study type: Interventional

Funder types: Other

Identifiers

NCT05124093

CA2361

Details and patient eligibility

About

Apnoeic oxygenation refers to oxygenation that occurs through the insufflation of oxygen into the lungs in the absence spontaneous respiration or positive pressure ventilation. It is used to extend the time to desaturation at induction of anaesthesia and as a primary oxygenation technique during airway surgery. The impact of high-flow nasal oxygen flow rate selection on gas exchange is poorly understood. Participants in this study will be randomised to receive a certain nasal oxygen flow rate during apnoea and its effect on gas exchange will be measured by blood gas analysis.

Full description

Apnoeic oxygenation with high-flow nasal oxygen has been proposed to result in carbon dioxide clearance. However, this has been poorly quantified.

This study will compare use of nasal oxygen at different flow rates during apnoea with that of a control that does not receive nasal oxygen. Participants are anaesthetised after standardised pre-oxygenation with high-flow nasal oxygen, after which they will receive one of three nasal oxygen flow rates (0, 70, 120 L/min).

The rate of carbon dioxide elevation will be measured by arterial blood gas analysis after the onset of apnoea and compared between the three groups to discern the relative rates of carbon dioxide clearance after the first minute of apnoea. The effect of nasal oxygen flow rate on oxygenation will also be measured.

Enrollment: 114 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

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 in preceding 14 days.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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114 participants in 3 patient groups, including a placebo group

Apnoea without apnoeic oxygenation

Placebo Comparator group

Description:

High-flow nasal oxygen administration ceases at the onset of apnoea.

Treatment:

Procedure: Apnoeic oxygenation

Apnoeic oxygenation with high-flow nasal oxygen at 70 L/min (HFNO)

Active Comparator group

Description:

100% oxygen is administered via high-flow nasal cannulae at 70L/min from the onset of apnoea until four minutes of apnoea has completed.

Treatment:

Procedure: Apnoeic oxygenation

Apnoeic oxygenation with high-flow nasal oxygen at 120 L/min (uHFNO)

Active Comparator group

Description:

100% oxygen is administered via high-flow nasal cannulae at 120L/min from the onset of apnoea until four minutes of apnoea has completed.

Treatment:

Procedure: Apnoeic oxygenation