A method is disclosed for treating benign conditions, such as enlarged tonsils and / or adenoids located in a patient's throat or nasopharynx, or soft tissue lesions located in a patient's oropharynx or larynx. According to the method, a space containing the patient's nasopharynx, oropharynx or pharynx and larynx is isolated from the patient's trachea and lungs using an inflatable cuff tracheostomy tube or nasotracheal tube inserted in the patient's trachea. The cuff is inflated to occlude the trachea. The patient is placed in a supine position, whereupon at least a portion of the space containing the nasopharynx and / or oropharynx and larynx is filled with saline. An endoscope is then inserted into the space to view the operative site in which the tonsils or tissue lesion are to be treated. An electrosurgical instrument having an active tissue treatment electrode and a return electrode connected to an electrosurgical generator is then inserted into the space, either along side the endoscope or through the endoscope's working channel. The generator is then operated to apply a radio frequency voltage between the active and return electrodes of the electrosurgical instrument, whereby a conduction path is formed between the active and return electrodes, at least partially through the saline, whereupon the active electrode is manipulated to debulk or otherwise treat the soft tissue lesion or enlarged tonsils and / or adenoids.