1. Department of Proctology, The First Affiliated Hospital of Jiamusi University, Jiamusi, Heilongjiang 154003, P.R. China
2. Department of Central Sterile Supply, The First Affiliated Hospital of Jiamusi University, Jiamusi, Heilongjiang 154003, P.R. China
3. Department of Anesthesiology, The First Affiliated Hospital of Jiamusi University, Jiamusi, Heilongjiang 154003, P.R. China
4. Department of Otolaryngology, The First Affiliated Hospital of Jiamusi University, Jiamusi, Heilongjiang 154003, P.R. China