Anesthesia, Apnea, Respiration; Arrest
Conditions
Brief summary
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.
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
OTHERPre-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.
Sponsors
University College Hospital Galway
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Time to oxygen desaturation | 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
| Measure | Time frame | Description |
|---|---|---|
| Arterial partial pressure of oxygen after pre-oxygenation. | At 3 minutes of pre-oxygenation | As measured by blood gas analysis |
| Arterial partial pressure of carbon dioxide change during pre-oxygenation | At 0 and 3 minutes | As measured by blood gas analysis |
| Change in arterial partial pressure of carbon dioxide during apnoea | At 0, 1, 2 minutes and each 2 minutes thereafter | As measured by blood gas analysis |
| Change in acid-base status during apnoea | 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 | 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. |
Countries
Ireland
Outcome results
None listed