The details of Comprehensive education are as follows:

1. introduce the purpose, method and function of breathing training and the whole process of gastroscopy;
2. instruct patients to take deep breath training, inhaling with his/her nose and exhaling with his/her mouth,
3. provide patients with a disposable dental biting device and repeat exercising deep breathing again until he/she is fully mastered,
4. inform patients to cooperate with the instructions issued by endoscopist and endoscopy nurse during the whole process of gastroscopy,
5. inform patients to inhale with nose and exhale with mouth when the gastroscope passes through the throat, then he/she should perform inhaling and exhaling with his/her nose until the end of the gastroscopy when the endoscopist ask to adjust the breathing method,
6. inform patients that there would be some normal physiological reaction when gastroscopy, such as throat discomfort and nausea/vomiting.

The details of standard education are as follows:

1. inform patients to cooperate with the instructions issued by endoscopist and endoscopy nurse during the whole process of gastroscopy,
2. inform patients that there would be some normal physiological reaction when gastroscopy, such as the throat discomfort and nausea/vomiting.

The details of Comprehensive education are as follows:

1. introduce the purpose, method and function of breathing training and the whole process of gastroscopy;
2. instruct patients to take deep breath training, inhaling with his/her nose and exhaling with his/her mouth,
3. provide patients with a disposable dental biting device and repeat exercising deep breathing again until he/she is fully mastered,
4. inform patients to cooperate with the instructions issued by endoscopist and endoscopy nurse during the whole process of gastroscopy,
5. inform patients to inhale with nose and exhale with mouth when the gastroscope passes through the throat, then he/she should perform inhaling and exhaling with his/her nose until the end of the gastroscopy when the endoscopist ask to adjust the breathing method,
6. inform patients that there would be some normal physiological reaction when gastroscopy, such as throat discomfort and nausea/vomiting.

research assistant records nausea/vomiting/retching times in the whole process of gastroscopy

At the end of the procedure, the patients were asked about the tolerance in the process of gastroscopy by using a 100-mm visual analogue scale. Tolerance includes the extent of pain and nausea. The endpoints were assigned "no nausea or no pain " to the left and "worst possible nausea or worst pain imaginable " to the right.

At the end of the procedure, Endoscopists scored the level of difficulty in introduction of the gastroscope on a 100-mm visual analogue scale. The endpoints were assigned " easiest" to the left and " worst difficult " to the right.

Endoscopists' satisfaction was assessed with 100-mm VAS for the performances of the endoscopes. The endpoints were assigned " worst dissatisfied" to the left and " Most satisfied " to the right.