The Performance of Two Oxygen Delivery Devices Used After General Anesthesia.

The Performance Comparison of Two Oxygen Delivery Devices [Nasal Cannula and Mask] Used After General Anesthesia.

After general anesthesia, there are the risks for airway obstruction, hypoventilation, atelectasis, ventilation-perfusion mismatch, hypercarbia and hypoxemia,so oxygen supplement in PACU seems necessary.

This study aim is to compare the two methods of oxygen supplement which are 1.nasal cannula at O2 flow 4 L/min. 2.oxygen mask with O2 flow 5 L/min. The hypothesis in this study is the 2 methods can equally provide effective oxygen supplement to prevent anesthesia-related hypoxemia. Choosing nasal cannula would be reasonable because it is cheaper and more comfortable to patient.

The incidence and causes of hypoxemia in PACU will be identified, if necessary, a higher flow or changing oxygen delivery system can be used to prevent and treat hypoxemia. If any patients fail from oxygen weaning protocol in PACU and need longer oxygen therapy at ward, the duration of oxygen therapy will be recorded and also the compliance with oxygen delivery devices.

Inclusion Criteria:

• General anesthesia
• Age 18-70 years
• American Society of Anesthesiology (ASA)physical status 1-3
• Elective case

Exclusion Criteria:

• ASA physical status class 4 or more
• Unstable pulmonary diseases
• BMI > 35 kg/m2
• oxygen saturation < 94% when breathing in room air
• Respiratory muscle weakness eg.myasthenia gravis
• Central nervous system abnormalities eg.drowsiness, hypoventilation
• Patients who have been intubated or needed ventilatory support before operation
• Plan to remain intubated after the operation
• Intracranial, intrathoracic and upper abdomen surgery
• Patients who nasogastric tube is inserted
• Airway problems eg. sinusitis
• Nasal cavity related surgery or nasal packing eg. endoscopic sinus surgery
• Patient refusal