1. Department of Anesthesiology, Hebei Medical University, Shijiazhuang, Hebei, China
2. Department of Anesthesiology, Shijiazhuang Traditional Chinese Medicine Hospital, Shijiazhuang, Hebei, China
3. Department of Anesthesiology, Shijiazhuang Peoples’ Hospital, Shijiazhuang, Hebei, China
4. Department of Gynaecology, Shijiazhuang Sixth Hospital, Shijiazhuang, Hebei, China
5. Department of Neurosurgery, Shijiazhuang Peoples’ Hospital, Shijiazhuang, Hebei, China