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

Apnoeic Oxygenation Clinical Trial

— PHARAO  

Official title:

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

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT03478774
• Other study ID #: 2018-00293
• Status: Completed
• Phase: N/A
• Start date: March 25, 2018
• Est. completion date: December 31, 2019

Study information

• Verified date: February 2021
• Source: University Hospital Inselspital, Berne
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical 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. 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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 125
• Est. completion date: December 31, 2019
• Est. primary completion date: December 31, 2019
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• > 18 years

• Written informed consent

• Undergoing elective surgery

• Requiring general anesthesia

Exclusion Criteria:

• Any Indication for fibre optic intubation

• Expected impossible mask ventilation

• Known coronary heart disease

• Known heart failure, NYHA classification = 2

• Therapy including ß-receptor antagonists

• Arrhythmias in need of anti-arrhythmic therapy (e.g. implanted cardio defibrillator)

• 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

Related Conditions & MeSH terms

• Apnea
• Apnoeic Oxygenation

Intervention

Drug:
• Oxygen 70l/min
HFNCT will be provided using OptiFlow by Fisher&Paykel.
• Oxygen 10 l/min
Medium flow will be applied with a humidifier (Hudson RCI) and a standard nasal cannula.
• Oxygen 2l/min
Low flow will be applied with a humidifier (Hudson RCI) and a standard nasal cannula.

Procedure:
• Jaw thrust
Continuous
• Videolaryngoscopy
Continuous

Drug:
• oxygen 0.25l/min
0.25l/min of oxygen via an endotracheal tube

Locations

Country	Name	City	State
Switzerland	University Hospital Inselspital	Bern

Sponsors (1)

Lead Sponsor	Collaborator
University Hospital Inselspital, Berne

Country where clinical trial is conducted

Switzerland, 

References & Publications (2)

Gustafsson IM, Lodenius Å, 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. — View Citation

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. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	pCO2 increase in kPa/min	pCO2 will be measured transcutaneously throughout the apnea period	15 or 30 minutes (maximum apnea time)
Secondary	Lowest Saturation	Lowest SpO2 in %	During apnea period (until end-point is met or max. 15 or 30 minutes)
Secondary	Change in PaO2 in kPa	Blood gas analyses as well as transcutaneous measurement	During apnea period (until end-point is met or max. 15 or 30 minutes)
Secondary	Change in cardiac output in L/min	Cardiac output will be measured using pulse pressure measurement	During apnea period (until end-point is met or max. 15 or 30 minutes)
Secondary	Change in cerebral perfusion in %	Near infrared spectroscopy will be measured continuously	During apnea period (until end-point is met or max. 15 or 30 minutes)
Secondary	Changes in end-expiratory lung impedance	To quantify atelectasis during apnoeic oxygenation	During apnoea time (until end-point is met or max. 15 or 30 minutes)
Secondary	Change in invasive blood pressure	Measurement of change due to hypercarbia	During apnoea time (until end-point is met or max. 15 or 30 minutes)
Secondary	Standard monitoring	3 pole ECG	During apnoea time (until end-point is met or max. 15 or 30 minutes)
Secondary	Depth of anaesthesia	Using Narcotrend-EEG	During apnoea time (until end-point is met or max. 15 or 30 minutes)
Secondary	Bilateral brain oxygenation	Using NIRS	During apnoea time (until end-point is met or max. 15 or 30 minutes)
Secondary	Arterial blood gas analyses	pH	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.
Secondary	Arterial blood gas analyses	pCO2 in mmhg	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.
Secondary	Arterial blood gas analyses	pO2 in mmhg	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.
Secondary	Arterial blood gas analyses	SaO2 in %	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.
Secondary	Arterial blood gas analyses	Potassium in mmol	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.
Secondary	Arterial blood gas analyses	Bicarbonate in mmol	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.
Secondary	Postoperative questionnaire	Visual analogue scale (VAS) : pain, nausea, vomiting, feeling worried or anxious, feeling sad or depressed, injuries, discomfort, any complications	Morning of first postoperative day
Secondary	Standard monitoring	Pulse oximetry SpO2 in %	During apnoea time (until end-point is met or max. 15 or 30 minutes)