Functional Residual Capacity Under Apnoeic Oxygenation with Different Flow Rates in Children (FUTURE)

Functional Residual Capacity Under Apnoeic Oxygenation with Different Flow Rates in Children: a Single-centre Prospective Randomized Controlled Trial

During induction of general anaesthesia physiological breathing stops and needs to be artificially established with facemask ventilation, and finally tracheal intubation or placement of a supraglottic airway. During the airway management, when lungs are not or only poorly ventilated, there is a risk for atelectasis. These atelectasis can contribute to respiratory adverse events (e.g. pulmonary infection or respiratory insufficiency) during or after general anaesthesia. High-flow nasal oxygen (HFNO) is the administration of heated, humidified and blended air/oxygen mixture via a nasal cannula at rates ≥ 2 L/kg/min. HFNO used during airway management (i.e. intubation) can extend the tolerance for apnea, the time from end of physiological breathing until artificial ventilation is established. The main objective of this study is thus to investigate the variations of poorly ventilated lung units (i.e., silent spaces) as a surrogate for functional residual capacity measured by electrical impedance tomography to dynamically assess atelectasis formation and regression under apnoeic oxygenation with different flow rates.

Study Overview

• Status: Completed
• Conditions: Apnea; Anesthesia; Intubation Complication; Children, Only; Atelectasis; Ventilation Therapy; Complications; Apnea Infant
• Intervention / Treatment: Other: 0.2 L/kg/min, FiO2 1.0 + continuous jaw thrust; Other: 2 L/kg/min, FiO2 1.0 + continuous jaw thrust; Other: 4 L/kg/min, FiO2 1.0 + continuous jaw thrust; Other: 2 L/kg/min using OptiFlow-Switch system, FiO2 1.0 + continuous jaw thrust

Detailed Description

High-flow nasal oxygen (HFNO) is the administration of heated, humidified and blended air/oxygen via nasal cannula at rates ≥ 2 L/kg/min. HFNO is an open system that can be used with nasal prongs of different sizes and was developed in neonatal intensive care unit for preterm babies with apnoea as alternative to continuous positive airway pressure (CPAP). Due to its ease of use and safety to apply to a wide range of indication HFNO is increasingly gaining interest for providing respiratory support in paediatric patients and in adults in ICU with respiratory failure. In adult populations, the use of HFNO permits to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia. An application for HFNO in adults and children, is the extension of safe apnoea in patients who were undergoing general anaesthesia for hypopharyngeal or laryngo-tracheal surgery. This method, the so-called safe apnoeic oxygenation, also prevents hypoxemia in children during intubation. By using this technique, Patel et al. demonstrated a significate prolongation of apnoea time and proposed a ventilatory effect, as these studies revealed a slower increase in pCO2 than physiologically was expected. In these studies, researchers compared their data to studies from the 1950-ies, where CO2 increase during apnoea was investigated. In contrast, the investigators' previous research projects with HFNO did not confirm the claimed ventilatory effect in children and adults.

Furthermore studies performed in spontaneously breathing neonates and adults have shown the ability of HFNO to generate some increase in pharyngeal pressure, which could explain the improvement of oxygenation despite prolongation of apnea time. The investigators' previous study on adult patients showed that a relevant increase of pressure was nearly absent while patient's mouth was open. Currently, there is no data on the physiological pressure that is generated in the subglottic airway in apneic children treated with HFNO. The traditional measurement of intratracheal pressure with a catheter in the trachea is considered to pose a risk in small children.

The main objective of this study is thus to investigate the variations of poorly ventilated lung units (i.e., silent spaces) as a surrogate for functional residual capacity measured by electrical impedance tomography to dynamically assess atelectasis formation and regression under apnoeic oxygenation with different flow rates.

Eligible children will receive premedication with Midazolam rectal/oral 0.5 mg/kg or Dexmedetomidine nasal 2 mcg/kg 30 minutes before the beginning of the procedure (local SOPs of the paediatric anaesthesia departments). Mandatory monitoring will consist of non-invasive peripheral oxygen saturation (SpO2), heartrate (HR), and non-invasive blood pressure (NIBP). An intravenous line for drugs injection will be placed.

After start of anaesthesia (="induction"), adequate face-mask ventilation will be established. The sealed envelope for randomisation will then be opened. Standard anaesthesia will be continued using of intravenous propofol. Anaesthetic depth will be assessed using NarcotrendTM (NarcotrendTM, Hannover, Germany), maintaining values between 40 and 60. Additional study related non-invasive monitoring: transcutaneous tcCO2 and O2 (ToscaTM, Radiometer, Neuilly-Plaisance, France) measurement, thoracic electrical impedance tomography (EIT, PulmoVista 500, Draeger, Luebeck, Germany) and NIRS (Niro-200NX (Hamamatsu, Tokyo, Japan). ECG, pulse-oximetry, blood pressure, Narcotrend (NarcotrendTM, Hannover, Germany), thoracic EIT will be measured continuously, starting before induction while spontaneous breathing and ending 1 minute after the recruitment-manoeuvre. All patients will receive neuromuscular blockade medication of 2 x ED95 (standard intubation dose) to facilitate airway management. Neuromuscular block will be assessed using train-of-four (TOF) monitoring (TOF-Watch, Organon Ltd, Dublin, Ireland). A TOF value of zero before apnoea start and throughout the whole procedure will be deemed essential.

After that one minute of pressure support mask ventilation (Pmax 20 cm H20) with a backup respiratory rate of 20/min, normalized at a volume of 6-8 ml.kg-1 with 100% oxygen and will be applied. The ventilation will be discontinued, and the child will be left apnoeic for 5 minutes receiving oxygen according to the randomisation.

Children will be randomized to receive three different flow rates of 100% oxygen, warmed and humidified with the OptiFlow device (Fisher&PaykelTM, Auckland, New Zealand):

• group 1): 0.2 l/kg/min + continuous jaw thrust
• group 2): 2 l/kg/min + continuous jaw thrust
• group 3): 4 l/kg/min + continuous jaw thrust (control group)
• Group 4): 2 l/kg/min with OptiFlow FiO2 1.0 using OptiFlow-Switch system by Fisher&Paykel.

The nostrils must not be occluded by the nasal cannula by more than 50%. The time until desaturation from SpO2 100% to SpO2 95% will be measured. A chest ultrasound at end of intervention after definitive airway management will prove that no pneumothorax developed during the procedure.

Break-up criteria during apnoea are: SpO2 below 95%, transcutaneous CO2 above 70 mmHg, or time of apnoea >5 minutes, a decrease of NIRS >30% from baseline.

• Study Type: Interventional
• Enrollment (Actual): 108
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Bern, Switzerland, 3010
    • Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 1 second to 16 years (Child)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Written informed consent by legal guardian
• Paediatric patients undergoing elective surgery requiring general anaesthesia at the Bern University Hospital - Inselspital in Bern
• Child weight between 10-20kg
• American Society of Anesthesiology (ASA) physical status 1 & 2 (healthy child, no severe co-morbidities)

Exclusion Criteria:

• Known or suspected difficult intubation
• Oxygen dependency
• Congenital heart or lung disease
• Obesity BMI (kg/m2) >30
• High aspiration risk (requiring rapid sequence intubation).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group 1: Low-flow apnoeic oxygenation; Group 1) 0.2 L/kg/min using OptiFlow system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0;	Other: 0.2 L/kg/min, FiO2 1.0 + continuous jaw thrust; Apnoeic Oxygenation with flow rate 0.2 L/kg/min using OptiFlow system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0
Experimental: Group 2: High-flow apnoeic oxygenation; Group 2) 2 L/kg/min using OptiFlow system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0;	Other: 2 L/kg/min, FiO2 1.0 + continuous jaw thrust; Apnoeic Oxygenation with flow rate 2 L/kg/min using OptiFlow system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0
Active Comparator: Group 3: Control group apnoeic oxygenation; Group 3) 4 L/kg/min using OptiFlow system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0;	Other: 4 L/kg/min, FiO2 1.0 + continuous jaw thrust; Apnoeic Oxygenation with flow rate 4 L/kg/min using OptiFlow system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0
Experimental: Group 4: High-flow apnoeic oxygenation; Group 4): 2 l/kg/min with OptiFlow FiO2 1.0 using OptiFlow-Switch system by Fisher&Paykel	Other: 2 L/kg/min using OptiFlow-Switch system, FiO2 1.0 + continuous jaw thrust; Apnoeic Oxygenation with flow rate 2 L/kg/min using OptiFlow-Switch system by Fisher&Paykel and an oxygen inspiration concentration FiO2 of 1.0

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total change in lung impedance	The total change in lung impedance measured in silent spaces and end-expiratory lung impedance (EELI) by using electrical impedance tomography (EIT), normalized to the impedance amplitude during mechanical ventilation at 6-8 ml.kg-1 measured after 5 min of apnea compared to baseline measurement. Data given in percent (%) for silent spaces and delta EELI.	5 Minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time until desaturation to SpO2 95%	In case of desaturation within the predefined apnoea time: time (in seconds) until desaturation from peripheral saturation (SpO2) 100% to 95%, measured by peripheral pulse oximetry in percent (%).	5 Minutes
Changes in transcutaneous CO2	Changes in transcutaneous carbon dioxide (tcCO2) in mmHg/min during apnoea time	5 Minutes
Changes in brain oxygenation	Changes in brain oxygenation measured by near infrared spectroscopy (NIRS) during apnoea time given in percent (%)	5 Minutes
Changes in silent spaces and EELI after 1 min PSV	The total change in lung impedance measured in silent spaces and end-expiratory lung impedance (EELI) by using electrical impedance tomography, normalized to the impedance amplitude during mechanical ventilation at 6-8 ml.kg-1 after induction and 1 minute of pressure supported ventilation with backup frequency (PSV) at 6-8 ml/kg. Data given in percent (%) for silent spaces and delta EELI.	5 Minutes
Changes in silent spaces and EELI after airway management	Changes in silent spaces and end-expiratory lung impedance (EELI) by using electrical impedance tomography after airway management (i.e. supraglottic airway or intubation). Data given in percent (%) for silent spaces and delta EELI.	5 Minutes
Changes in silent spaces and EELI after recruitment manoeuvre	Changes in silent spaces and end-expiratory lung impedance (EELI) by using electrical impedance tomography after recruitment manoeuvre and 1 minute of mechanical ventilation at 6-8 ml/kg. Data given in percent (%) for silent spaces and delta EELI.	5 Minutes
Time to 25%, 50% and 75% of total change in lung impedance	Time to 25%, 50% and 75% of total change in lung impedance by using electrical impedance tomography in seconds (s).	5 Minutes

Collaborators and Investigators

• Sponsor: Thomas Riva
• Investigators: Principal Investigator: Alexander Fuchs, M.D., Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital,; Study Director: Thomas Riva, M.D., Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital,

Study record dates

Study Major Dates

• Study Start (Actual): January 9, 2023
• Primary Completion (Actual): April 30, 2024
• Study Completion (Actual): May 2, 2024

Study Registration Dates

• First Submitted: December 21, 2022
• First Submitted That Met QC Criteria: December 21, 2022
• First Posted (Actual): January 5, 2023

Study Record Updates

• Last Update Posted (Actual): September 19, 2024
• Last Update Submitted That Met QC Criteria: September 12, 2024
• Last Verified: May 1, 2024

More Information

Terms related to this study

• Keywords: Atelectasis; Apnoeic oxygenation; Paediatric anaesthesia; Functional residual capacity; High-flow nasal oxygen; Silent spaces
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Lung Diseases; Signs and Symptoms, Respiratory; Pulmonary Atelectasis; Apnea
• Other Study ID Numbers: Fuchs-Riva2022

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No