Effect of High Flow Humidified Oxygen on Non-ventilated Lung During Thoracic Surgery: a Cross-over Study Compared With Conventional CPAP (Continuous Positive Airway Pressure)

The investigators hypothesize that HFHO may be an alternative tool to supply oxygen to non-ventilated lung during one lung ventilation. CPAP can improve oxygenation at a cost of lung hyperinflation which is an unwanted condition during thoracic surgery especially the video-assisted one.

Recruiting adult patients who undergo lung surgeries that requires one-lung ventilation. Exclusion criteria include the followings:-

1. Emergency case.
2. Patients with severe COPD(Chronic Obstructive Pulmonary Diseases).
3. Patients with moderate baseline hypoxemia (SpO2 < 90% on room air).
4. Patients with severe hemoptysis.
5. Patients with upper or lower airway abnormalities.
6. Patients undergo pulmonary lavage.
7. Patients with known pulmonary hypertension.
8. Patients with known pulmonary/tracheobronchial infections.
9. Patients with suspected difficult airway.
10. Patients with BMI over 35.
11. Pregnant patients.

Following a standard anesthetic practice. All participants will receive an intravenous based anesthetic with or without regional blocks. The appropriate sized double lumen endobronchial tube will be placed and fiberoptic bronchoscope is used to verify a proper position. Patient will also get an arterial line for frequent ABG (Arterial Blood Gases) samplings.

Computer generated randomization will divide patients into 2 groups. Baseline ABG will be drawn. After one lung ventilation commenced for 20 minutes, the 2nd ABG will be drawn, the surgeon who was blinded to the intervention will evaluate the quality of lung collapse using 5-point Likert scale. Then, patients will either receive a CPAP or HFHO (depends on randomization) for 20 minutes. Up on 1st intervention completion, the 3rd ABG and lung collapse evaluation will be performed.