Skip to main content
OpenTrials
Completed

NCT Number: NCT05124093

The Effect of High-flow Nasal Oxygen Flow Rate on Gas Exchange During Apnoea

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.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Apnea Anesthesia Pathological Conditions, Signs and Symptoms Respiration Disorders Respiration; Arrest Respiratory Tract Diseases Signs and Symptoms Signs and Symptoms, Respiratory

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University Hospital Galway

Galway, Ireland

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Apnoeic oxygenation

Procedure

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%.

Primary outcomes

  1. Rise in arterial partial pressure of carbon dioxide

    Time frame: 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 outcomes

  1. Partial pressure of oxygen during apnoea

    Time frame: Following high-flow nasal oxygen administration

    As measured by blood gas analysis

  2. 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.

  3. Change in carbon dioxide elevation before and after HFNO administration

    Time frame: Between 3 and 5 minutes of apnoea

    As measured by blood gas analysis

  4. Carbon dioxide elevation during the first minute of apnoea

    Time frame: Between 0 and 1 minute of apnoea

    As measured by blood gas analysis

  5. Change in acid-base status during apnoea

    Time frame: At 1 minute intervals during apnoea

    As measured by blood gas analysis

Sponsors and collaborators

Lead sponsor

University College Hospital Galway

Other

Registry information

Official study title

A Randomised Controlled Trial of Apnoeic Oxygenation With No-flow vs High-flow vs Ultra High-flow Nasal Oxygen

Acronym: Apox-HFNO

Important dates

Study start
2021
Primary completion
2022
Study completion
2022
First posted
Nov 17, 2021
Registry last updated
Jul 11, 2022

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.