1) Satiety, intra-abdominal pressure is too high, there are vomiting, regurgitation aspiration highly dangerous, recurrent
vomiting flow history of the patient.
2) The patients of throat infection or other pathological changes.
3) Must maintain the operation of continuous positive airway pressure. Air pressure should be greater than 25 cmh2o
chronic respiratory disease patients.
4) The patients of respiratory tract bleeding.
5) The patients of tonsil abnormal enlargement. Patients with potential airway obstruction, such as compression,
softening, throat tracheal tumor, abscess, hematoma , etc.
6) Other uses in clinicians’ guidance.