Soon after admission to Pediatric intensive care unit, Department of Pediatrics, AIIMS, Raipur, the patient will undergo screening for enrolment based on inclusion and exclusion criteria. If the patient does not meet the inclusion criteria, he/she will be excluded. As hypoxia can be life threatening and delay can be detrimental oxygen therapy will be started as soon as possible as per unit protocol and clinician judgement. After stabilisation, and inclusion into the study informed consent will be obtained from the patient’s legal guardian. Once consent is obtained patient will be randomised using computer generated block randomisation with concealed allocation. The primary details and the disease status of the patient will be recorded in both the groups. Participants will be randomly allocated (1:1) to either the conservative (88%–92%) or conventional (94%-99%) oxygen target group by a computer-generated dynamic procedure (minimisation) with a random component. Patient in the intervention group will be monitored and titrated to maintain oxygen saturation 88- 92 % with titration of FIO2 and pressure support. This will be continued until all respiratory support (delivered invasively or non-invasively) has been discontinued during this PICU admission.

Prior to randomisation, all care will be determined by the clinical team primarily responsible for the child’s treatment and care. Once randomised, all care other than that intended to achieve trial target SpO2 will be determined by the clinical team. Patient will be monitored hourly SpO2 for duration of need of oxygen support. PaO2 will be monitored at baseline and as per patient clinical need and on clinician judgement. At the baseline and at the end of 7 days or end of oxygen therapy whichever is earlier, we will send serum quantitative MDA levels to see oxidative stress in patients. Clinical parameters, need of ventilation support, duration of ventilation, organ dysfunction, mortality will be recorded till day 30 of inclusion and/ or till PEM/ PICU/ HDU stay. Primary and secondary outcome will be recorded in prescribed format for 30 day after enrolment.