HYPOTHESIS:

During anesthetic pre-oxygenation with high FiO2, pulmonary atelectasis occur, especially in patients < 6 years old, where FRC and pulmonary closing volume may overlap. New borns and children <1 year old are especially vulnerable.

OBJECTIVES:

1. Validate "air test" as a individualized and non-invasive diagnostic method of clinically significant atelectasis in pediatrics.
2. Determine what other factors contribute to atelectasis development in pediatrics

METHODS:

30 pediatric patients will be studied with ages ranged between 45 postconceptional weeks and16 years old.

Baseline SpO2 and lung ultrasound will be performed for each patient upon arrival at the operating theatre before preoxygenation with FiO2 of 1.0 SpO2 will be measured 15 min after intubation during a 5 min long "air test" trial (FiO2 0.25). lung collapse will be verified by lung ultrasound at the end of the 15 min trial. Lung collapse will be eventually granted upon lung US verification by a blind researcher.

Inclusion Criteria:

• General anesthesia
• Perioperative risk classification (ASA) I, II, III
• Newborns (postconceptional age> 45 weeks) to 16 years
• Need for oral / nasotracheal intubation

Exclusion Criteria:

• ASA > III
• Basal SpO2 < 97% on air in supine position
• Preoperative need for oxygen therapy and / or high-flow nasal cannulas
• Expected Difficult airway
• Presence of craniofacial disorders that may compromise ventilation
• Hemodynamic instability and / or need for inotropics
• History of untreated heart disease
• Presence or history of pneumothorax
• Presence of untreated congenital pulmonary disorders
• Refusal to participate in the study

IPD will be published in a peer reviewed journal

Upon publishment in journal

Lung Collapse will be diagnosed by a blind researcher that does not know the air test results