Recently, high flow oxygen therapy (HFOT) is becoming more popular in the treatment of any kind of respiratory failure. Pediatric mechanical ventilation consensus conference (PEMVECC) guidelines suggest measuring oxygen saturation by pulse oximetry (SpO2) in all ventilated children and furthermore to measure partial arterial oxygen pressure (PaO2) in moderate-to-severe disease in order to prevent excessive use of oxygen while preventing hypoxemia and hyperoxemia. This study aims to compare the safety and efficacy of a closed-loop FiO2 controller (CLOC) with conventional control of FiO2 during HFOT of pediatric patients in a pediatric intensive care unit (PICU). The hypothesis of this study is: Close-loop FiO2 controller increases the time spent within clinically targeted SpO2 ranges and decreases the time spent outside clinical target SpO2 ranges as compared to manual oxygen control in PICU patients treated with HFOT.

Inclusion Criteria:

• Pediatric patients older than 1 month and younger than18 years of age; hospitalized at the PICU with the intention of treatment with HFOT at least for the upcoming 5 hours
• Requiring FiO2 ≥ 25% to keep SpO2 in the target ranges defined by the clinician
• Written informed consent signed and dated by the patient or one relative in case that the patient is unable to consent, after full explanation of the study by the investigator and prior to study participation

Exclusion Criteria:

• Patient with indication for immediate noninvasive ventilation (NIMV), or invasive mechanical ventilation (IMV)
• Hemodynamic instability defined as a need of continuous infusion of epinephrine or norepinephrine > 1 mg/h
• Low quality on the SpO2 measurement using finger and ear sensor (quality index below 60% on the SpO2 sensor, which is displayed by a red or orange colour bar)
• Severe acidosis (pH ≤ 7.25)
• Pregnant woman
• Patients deemed at high risk for the need of mechanical ventilation within the next 5 hours
• Patients deemed at high risk for the need of transportation from PICU to another ward, diagnostic unit or any other hospital
• Diseases or conditions which may affect transcutaneous SpO2 measurement such as chronic or acute dyshemoglobinemia: methemoglobinemia, carbon monoxide (CO) poisoning, sickle cell disease
• Formalized ethical decision to withhold or withdraw life support
• Patient included in another interventional research study under consent
• Patient already enrolled in the present study in a previous episode of acute respiratory failure