Retrospective data collection. The aim of this study is to investigate impact of high-flow nasal oxygen on safety(lowest oxygen saturation), efficiency (intubation time, need for multiple attempts) in patients underwent awake fiberoptic bronchoscope guided intubation.

Inclusion Criteria:

1.Patients who underwent awake fiberoptic bronchoscope guided intubation for surgery

Exclusion Criteria:

1. Cases in which other procedures (e.g. arterial line cannulation) were performed prior to endotracheal intubation after entering operation room
2. Patients with Incomplete records of oxygen saturation, attempt number, and time taken for awake intubation

Patients who underwent awake fiberoptic bronchoscope guided intubation for surgery