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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Facemask oxygen (FM) | Experimental | 100% oxygen administered via facemask through circle system with adjustable pressure-limiting valve at 0 cmH20. Participant instructed to 'breathe normally' |
|
| High-flow nasal oxygen (HFNO) | Active Comparator | 100% oxygen administered via high-flow nasal cannulae at 50 L/min. Participant instructed to 'keep the mouth closed and breathe normally' |
|
| High-flow nasal oxygen plus mouthpiece oxygen (HFNO+MP) | Active Comparator | 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'. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Pre-oxygenation | Other | 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. |
| Measure | Description | Time Frame |
|---|---|---|
| Time to oxygen desaturation | The time period from the onset of apnoea (determined by visual inspection) until an oxygen saturation of 92% is measured by pulse oximetry. | Immediately after the intervention |
| Measure | Description | Time Frame |
|---|---|---|
| Arterial partial pressure of oxygen after pre-oxygenation. | As measured by blood gas analysis | At 3 minutes of pre-oxygenation |
| Arterial partial pressure of carbon dioxide change during pre-oxygenation |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Michael Callaghan, MB BCh BAO | Consultant Anaesthesiologist | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University Hospital Galway | Galway | Ireland |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 34402044 | Derived | Lyons C, McElwain J, Coughlan MG, O'Gorman DA, Harte BH, Kinirons B, Laffey JG, Callaghan M. Pre-oxygenation with facemask oxygen vs high-flow nasal oxygen vs high-flow nasal oxygen plus mouthpiece: a randomised controlled trial. Anaesthesia. 2022 Jan;77(1):40-45. doi: 10.1111/anae.15556. Epub 2021 Aug 17. |
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The sharing of anonymised patient-specific data that underlie results in any publication.
Post publication of results for up to fifteen years
Investigator will consider requests to share patient-specific anonymised data in electronic format for the purpose of meta-analysis
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| ID | Term |
|---|---|
| D001049 | Apnea |
| ID | Term |
|---|---|
| D012120 | Respiration Disorders |
| D012140 | Respiratory Tract Diseases |
| D012818 | Signs and Symptoms, Respiratory |
| D012816 | Signs and Symptoms |
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|
As measured by blood gas analysis
| At 0 and 3 minutes |
| Change in arterial partial pressure of carbon dioxide during apnoea | As measured by blood gas analysis | At 0, 1, 2 minutes and each 2 minutes thereafter |
| Change in acid-base status during apnoea | As measured by blood gas analysis | At 0, 1, 2 minutes and each 2 minutes thereafter |
| Correlation between end-tidal carbon dioxide measurement and arterial partial pressure of carbon dioxide | 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. | Etco2 obtained at the time of resumption of ventilation. Paco2 obtained from the preceding blood gas measurement. |
| D013568 | Pathological Conditions, Signs and Symptoms |