Standard Pressure Laparoscopic Cholecystectomy，as the standard for cholecystectomy, can lead to about 15% of pulmonary atelectasis. According to literature, low pressure laparoscopic cholecystectomy is thought to probably decrease cardio-pulmonary related complications and postoperative pain. However, the previous studies have presented controversial results. Our study aim to evaluate the potential pulmonary benefit of low pressure laparoscopic cholecystectomy in elderly or patients accompanied with cardio-pulmonary disorders.

Standard Pressure Laparoscopic Cholecystectomy, SPLC；12-16mmHg，as the standard for cholecystectomy, can lead to about 15% of pulmonary atelectasis.

According to literature, Low Pressure Laparoscopic Cholecystectomy, LPLC；8-10mmHg is thought to probably decrease cardio-pulmonary related complications and postoperative pain. However, most of the existing study have combined population with all age scale, bringing bias to the result. Our study aim to evaluate the potential pulmonary benefit of low pressure laparoscopic cholecystectomy in elderly or patients accompanied with cardio-pulmonary disorders.

Inclusion Criteria:

1. Aged 18-85;
2. Patients receiving laparoscopic cholecystectomy due to benign gallbladder diseases;
3. Older patient or accompanied by cardiopulmonary diseases (age>60 years, hypertension, Diabetes Mellitus, coronary heart disease, arrhythmia, chronic bronchitis, emphysema, history of heart surgery, history of lung surgery, history of mediastinal surgery, asthma, et al);
4. Aged older than 60, with or without the above diseases;
5. American society of Aneshesiologists (ASA) II or higher;
6. Informed consent acquired.

Exclusion Criteria:

1. Having contraindication of laparoscopic operations;
2. History at epigastric surgery. -

It will be single blinded. Operator, first assistant and data collector could not be blinded. Whereas patients, nurses, data analyzer, and those who have the access to the primary predictor will be blinded.