Anesthesia, Apnea, Respiration; Arrest
Conditions
Brief summary
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.
Detailed 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.
Interventions
PROCEDUREApnoeic oxygenation
After 2mins 45 seconds of pre-oxygenation with high-flow nasal oxygen at Fio2 1.0 at 50L/min, anaesthesia is induced with 1-1.5mcg/kg remifentanil plus 2-3mg/kg propofol. Propofol (10mg/kg/hr) and remifentanil (0.15mcg/kg/min) infusions administered until study conclusion. At the onset of apnoea, 1mg/kg rocuronium administered. Jaw thrust performed. High-flow nasal oxygen adjusted to the randomised flow rate. Videolaryngoscopy after 1 minute of apnoea. Airway patency maintained. Tracheal intubation after 4 minutes of apnoea. Positive pressure ventilation commenced at Spo2 92%. Failure to obtain view of glottis with videolaryngoscope 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 each minute of apnoea until six minutes of apnoea, and every two minutes of apnoea thereafter, until Spo2 92%.
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 in preceding 14 days.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Rise in arterial partial pressure of carbon dioxide | Between 1 and 4 minutes of apnoea | The rate of rise of the partial pressure of carbon dioxide between 60 seconds and 240 seconds of apnoea as measured by arterial blood gas analysis. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Partial pressure of oxygen during apnoea | Following high-flow nasal oxygen administration | As measured by blood gas analysis |
| 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. |
| Change in carbon dioxide elevation before and after HFNO administration | Between 3 and 5 minutes of apnoea | As measured by blood gas analysis |
| Carbon dioxide elevation during the first minute of apnoea | Between 0 and 1 minute of apnoea | As measured by blood gas analysis |
| Change in acid-base status during apnoea | At 1 minute intervals during apnoea | As measured by blood gas analysis |
Countries
Ireland
Outcome results
None listed