Acupuncture for Relief of Gag Reflex

The aim of the study is to test whether stimulation of acupuncture points CV24 and P6 is better than placebo acupuncture in treatment of gagging in patients undergoing elective transesophageal echocardiography (TEE)

Inclusion Criteria: 1. Patients with an American Society of Anesthesiologists physical status of I to III scheduled for elective ambulatory transesophageal echocardiography (TEE) without sedation 2. TEE time does not exceed 30 minutes 3. Patients without previous opioid and psychotropic medication 4. Patients aged between 30 and 65 years, able to use visual analogue scale 100 mm 5. Patients who have given written informed consent Exclusion Criteria: 1. Current psychiatric disease 2. Local skin infection at the sites of acupuncture 3. Aged \< 30 or \> 65 years 4. TEE time more than 30 min 5. Patients who consumed opioid medication at least 6 months before surgery 6. Patients with the history of: i) psychiatric disease; ii) insulin-dependent diabetes mellitus; iii) radio- or chemotherapy; iv) peripheral polyneuropathy. 7. Patients who are unable to understand the consent form or to use visual analogue scale 100 mm