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Apnoeic OxygenationPHARAONCT03478774

Physiology Regarding Apnoeic Oxygenation During Nasal Cannula Therapy at Different Flow Rates

A study testing Oxygen 70l/min, Oxygen 10 l/min and Oxygen 2l/min in people with Apnoeic Oxygenation, run by Insel Gruppe AG, University Hospital Bern at 1 site in Switzerland.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This study compares under controlled conditions if different flow rates affect apnoea time after induction of anaesthesia and how CO2 clearance is influenced. Furthermore, this study enables to quantify the effects of increased pCO2 on vital parameters (e.g. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Apnoeic Oxygenation
What is being tested?
Oxygen 70l/min, Oxygen 10 l/min and Oxygen 2l/min
Type of treatment
Surgery or procedure
Could I receive a placebo?
No, everyone receives an active treatment
How many people
125 participants
Where
1 siteSwitzerland
Study dates
25 Mar 2018to 31 Dec 2019
Phase
Interventional
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • > 18 years
  • Written informed consent
  • Undergoing elective surgery
  • Requiring general anesthesia

Who cannot join

  • Any Indication for fibre optic intubation
  • Expected impossible mask ventilation
  • Known coronary heart disease
  • Known heart failure, NYHA classification ≥ 2
  • Therapy including β-receptor antagonists
  • Arrhythmias in need of anti-arrhythmic therapy (e.g. implanted cardio defibrillator)
Show all 24Show fewer
  • Peripheral occlusive arterial disease, Fontaine ≥ 2b
  • Known stenosis of the (common or internal) carotid or vertebral arteries
  • BMI > 35kg/m2 and BMI < 16kg/m2
  • Hyperkalaemia (K > 5.5 mmol/l)
  • Known COPD Gold classification ≥ 2
  • Known pulmonary arterial hypertension, systolic > 35mmHg
  • Known obstructive sleep apnoea syndrome in need of therapy
  • High risk of aspiration (requiring rapid sequence induction intubation)
  • Increased intracranial pressure
  • Intracranial surgery
  • Limited knowledge of German language
  • Absent power of judgement
  • Anaemia, Hb < 100 g/l
  • Pregnancy (pregnancy test in all female patients)
  • Neuromuscular disorder
  • Known or suspected cervical spine instability
  • Nasal obstruction, impossibility of nasal ventilation (both sides patent)
  • Allergies or contra-indications to one or more of the used anaesthesia agents

Trial locations and contacts

1 site in 1 country.

Switzerland1 site

  • University Hospital Inselspital

    Bern, 3008

Other trials in Switzerland

About this study

This study compares under controlled conditions if different flow rates affect apnoea time after induction of anaesthesia and how CO2 clearance is influenced. Furthermore, this study enables to quantify the effects of increased pCO2 on vital parameters (e.g. blood pressure, cardiac output, cerebral perfusion, etc.) The investigators will enroll patients undergoing elective surgery at the University Hospital of Bern, Switzerland.

Once anesthesia has been induced, apnoea will set it. During this period, the investigators will compare different methods of apnoeic oxygenation for a maximum of 15 or 30 minutes.

Before discharge, an interview will be conducted, assessing complications and patient satisfaction.

Read the detailed description

Eligible, consenting adults will be prepared for general anaesthesia in the usual way consisting of ECG, pulse-oximetry, NarcotrendTM, a venous cannula and an arterial line for continuous blood pressure monitoring. They will receive additional monitoring such as transcutaneous measurement of pCO2 and O2, NIRS, and thoracic electrical impedance tomography (EIT, PulmoVista® 500, Draeger, Luebeck, Germany).

Normal pre-oxygenation (until etO2 is > 90% or time > 3 minutes) will occur. Anaesthesia will be started (= "induction") using Propofol and Fentanyl, using NarcotrendTM to measure depth of anaesthesia. All patients will receive a standard dose of neuromuscular blockage to facilitate airway management and total intravenous anaesthesia will be installed. Using the train of four measurement (TOF) full neuromuscular blockage with Rocuronium will be confirmed every 30 seconds. If necessary, additional dosage of neuromuscular blockage will be administered.

After administration of Rocuronium, possibility of mask ventilation will be confirmed and the sealed envelope with the randomization will then be opened. As a study intervention, the assigned method (HFNCT 70 l/min with either jaw thrust or laryngoscopy, or 10 l/min or 2l/min with the standard nasal canula, or 0.25l/min delivery of oxgen via a tracheal tube) will be installed and mask ventilation discontinued starting the apnoea period. Nasopharyngoscopy (EF-N slim, Acutronic, Hirzel, Switzerland) will confirm upper airway patency. Blood gas analysis will be conducted: baseline awake, start of apnoea, first minute after apnoea start, and every 2 minutes thereafter with a maximum of 75ml 150 ml in total. Other measurements (ECG, pulse-oximetry, blood pressure, NIRS, thoracic EIT, NarcotrendTM, PtcO2, PtcCO2) will be measured continuously over the study period The study intervention will end when one of the following criteria (study end-points) is met: SpO2 <92%, PtcCO2 > 100 mmHg or time > 30 minutes.

When any of the end points is reached, patient-centred standard anaesthesia care will be continued, as planned for the case.

A post-operative interview will be conducted before discharge to evaluate injuries during airway management (bleeding, sore throat, hoarseness), pain, postoperative nausea and vomiting.

Being tested
Oxygen 70l/min, Oxygen 10 l/min, Oxygen 2l/min, Jaw thrust, Videolaryngoscopy

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Oxygen 70l/minDrug

    Also called high flow

    HFNCT will be provided using OptiFlow by Fisher\&Paykel.

  • Oxygen 10 l/minDrug

    Also called medium flow

    Medium flow will be applied with a humidifier (Hudson RCI) and a standard nasal cannula.

  • Oxygen 2l/minDrug

    Also called low flow

    Low flow will be applied with a humidifier (Hudson RCI) and a standard nasal cannula.

  • Jaw thrustProcedure or surgery

    Continuous

  • VideolaryngoscopyProcedure or surgery

    Continuous

  • oxygen 0.25l/minDrug

    Also called minimal flow

    0.25l/min of oxygen via an endotracheal tube

Study groups in NCT03478774
Study groupRoleWhat they receive
ControlActive comparatorThese patients will receive HFNCT with oxygen 70l/min after induction of general anesthesia. Throughout the entire measurement period of 15 or 30 minutes, continuous videolaryngoscopy will be performed.
Receives: Drug: Oxygen 70l/min; Procedure: Videolaryngoscopy
High flowExperimentalThese patients will receive HFNCT with oxygen 70l/min after induction of general anesthesia. Throughout the entire measurement period of 15 or 30 minutes, jaw thrust will be performed.
Receives: Drug: Oxygen 70l/min; Procedure: Jaw thrust
medium flowExperimentalThese patients will receive oxygen 10l/min after induction of general anesthesia. Throughout the entire measurement period of 15 or 30 minutes, jaw thrust will be performed.
Receives: Drug: Oxygen 10 l/min; Procedure: Jaw thrust
low flowExperimentalThese patients will receive oxygen 2l/min after induction of general anesthesia. Throughout the entire measurement period of 15 or 30 minutes, jaw thrust will be performed.
Receives: Drug: Oxygen 2l/min; Procedure: Jaw thrust
minimal flowExperimentalThese patients will receive a standard tracheal tubes after induction of general anesthesia, with 100% Oxygen and Minimum-flow 0.25l/min. The measurement period is 15 or 30 minutes.
Receives: Drug: oxygen 0.25l/min

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. pCO2 increase in kPa/min

    pCO2 will be measured transcutaneously throughout the apnea period

    Measured: 15 or 30 minutes (maximum apnea time)

Secondary outcomes (17)

  1. Lowest Saturation

    Lowest SpO2 in %

    Measured: During apnea period (until end-point is met or max. 15 or 30 minutes)

  2. Change in PaO2 in kPa

    Blood gas analyses as well as transcutaneous measurement

    Measured: During apnea period (until end-point is met or max. 15 or 30 minutes)

  3. Change in cardiac output in L/min

    Cardiac output will be measured using pulse pressure measurement

    Measured: During apnea period (until end-point is met or max. 15 or 30 minutes)

  4. Change in cerebral perfusion in %

    Near infrared spectroscopy will be measured continuously

    Measured: During apnea period (until end-point is met or max. 15 or 30 minutes)

  5. Changes in end-expiratory lung impedance

    To quantify atelectasis during apnoeic oxygenation

    Measured: During apnoea time (until end-point is met or max. 15 or 30 minutes)

  6. Change in invasive blood pressure

    Measurement of change due to hypercarbia

    Measured: During apnoea time (until end-point is met or max. 15 or 30 minutes)

  7. Standard monitoring

    3 pole ECG

    Measured: During apnoea time (until end-point is met or max. 15 or 30 minutes)

  8. Depth of anaesthesia

    Using Narcotrend-EEG

    Measured: During apnoea time (until end-point is met or max. 15 or 30 minutes)

  9. Bilateral brain oxygenation

    Using NIRS

    Measured: During apnoea time (until end-point is met or max. 15 or 30 minutes)

  10. Arterial blood gas analyses

    pH

    Measured: At 0, 1, 3, 5, 7, 9, 11, 13 and 15 minutes of apnoea or 0,1,3,5,7,9,13,15,17,19,21,23,25,27,29 and 30 min of apnoea.

  11. Arterial blood gas analyses

    pCO2 in mmhg

    Measured: At 0, 1, 3, 5, 7, 9, 11, 13 and 15 minutes of apnoea or 0,1,3,5,7,9,13,15,17,19,21,23,25,27,29 and 30 min of apnoea.

  12. Arterial blood gas analyses

    pO2 in mmhg

    Measured: At 0, 1, 3, 5, 7, 9, 11, 13 and 15 minutes of apnoea or 0,1,3,5,7,9,13,15,17,19,21,23,25,27,29 and 30 min of apnoea.

  13. Arterial blood gas analyses

    SaO2 in %

    Measured: At 0, 1, 3, 5, 7, 9, 11, 13 and 15 minutes of apnoea or 0,1,3,5,7,9,13,15,17,19,21,23,25,27,29 and 30 min of apnoea.

  14. Arterial blood gas analyses

    Potassium in mmol

    Measured: At 0, 1, 3, 5, 7, 9, 11, 13 and 15 minutes of apnoea or 0,1,3,5,7,9,13,15,17,19,21,23,25,27,29 and 30 min of apnoea.

  15. Arterial blood gas analyses

    Bicarbonate in mmol

    Measured: At 0, 1, 3, 5, 7, 9, 11, 13 and 15 minutes of apnoea or 0,1,3,5,7,9,13,15,17,19,21,23,25,27,29 and 30 min of apnoea.

  16. Postoperative questionnaire

    Visual analogue scale (VAS) : pain, nausea, vomiting, feeling worried or anxious, feeling sad or depressed, injuries, discomfort, any complications

    Measured: Morning of first postoperative day

  17. Standard monitoring

    Pulse oximetry SpO2 in %

    Measured: During apnoea time (until end-point is met or max. 15 or 30 minutes)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted27 Mar 2018
  2. Study start25 Mar 2018
  3. Primary completion31 Dec 2019
  4. Study completion31 Dec 2019

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Single group
Model description
single centre, prospective, randomized-controlled trial
Masking
Single blind
Who is masked
Participant
Enrolment
125 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT03478774
Sponsor's protocol ID
2018-00293
Other IDs
2018
Acronym
PHARAO
Status last verified
Feb 2021
First submitted
8 Mar 2018
Last updated
3 Feb 2021
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Undecided

Publications

  • Patel A, Nouraei SA. Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways. Anaesthesia. 2015 Mar;70(3):323-9. doi: 10.1111/anae.12923. Epub 2014 Nov 10.

    PubMed 25388828

  • Gustafsson IM, Lodenius A, Tunelli J, Ullman J, Jonsson Fagerlund M. Apnoeic oxygenation in adults under general anaesthesia using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) - a physiological study. Br J Anaesth. 2017 Apr 1;118(4):610-617. doi: 10.1093/bja/aex036.

    PubMed 28403407

  • Schweizer T, Hartwich V, Riva T, Kaiser H, Theiler L, Greif R, Nabecker S. Limitations of transcutaneous carbon dioxide monitoring in apneic oxygenation. PLoS One. 2023 Jun 1;18(6):e0286038. doi: 10.1371/journal.pone.0286038. eCollection 2023.

    PubMed 37262066

  • Riedel T, Burgi F, Greif R, Kaiser H, Riva T, Theiler L, Nabecker S. Changes in lung volume estimated by electrical impedance tomography during apnea and high-flow nasal oxygenation: A single-center randomized controlled trial. PLoS One. 2022 Sep 28;17(9):e0273120. doi: 10.1371/journal.pone.0273120. eCollection 2022.

    PubMed 36170281

  • Theiler L, Schneeberg F, Riedel T, Kaiser H, Riva T, Greif R. Apnoeic oxygenation with nasal cannula oxygen at different flow rates in anaesthetised patients: a study protocol for a non-inferiority randomised controlled trial. BMJ Open. 2019 Jul 11;9(7):e025442. doi: 10.1136/bmjopen-2018-025442.

    PubMed 31300494

Questions about this trial

What is this clinical trial studying?

A study testing Oxygen 70l/min, Oxygen 10 l/min and Oxygen 2l/min in people with Apnoeic Oxygenation, run by Insel Gruppe AG, University Hospital Bern at 1 site in Switzerland.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 24 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 3 Feb 2021. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

pCO2 increase in kPa/min (time frame: 15 or 30 minutes (maximum apnea time)). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT03478774, which also lists 5 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Feb 2021.

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