Functional Residual Capacity Under Apnoeic Oxygenation With Different Flow Rates in Children

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.

Inclusion Criteria:Written informed consent by legal guardianPaediatric patients undergoing elective surgery requiring general anaesthesia at the Bern University Hospital - Inselspital in BernChild weight between 10-20kgAmerican Society of Anesthesiology (ASA) physical status 1 & 2 (healthy child, no severe co-morbidities)Exclusion Criteria:Known or suspected difficult intubationOxygen dependencyCongenital heart or lung diseaseObesity BMI (kg/m2) >30High aspiration risk (requiring rapid sequence intubation).