This is a randomized controlled study. Some parameters were provided by preliminary test, provided theα=0.05,and β=0.20, the sample size can be estimated to be 2000 by the Open Epi Version 2.Patients will be recruited on the basis of predefined criterias. A researcher will take charge of the recruitment. Participants provide written consent and no financial incentives are provided. They are divided into experimental group and control group randomly. We need to collect their basic information including ages, genders, heights, weights, underlying diseases, surgical procedures and levels classified by ASA. Blood pressure, heart rate and other vital signs during the tube drawing process will be recorded. All the contents needed to be recorded had been compiled into a watch list with detailed instructions for filling in. All the personal information and observation records of participants will be kept in secret and only used for research. Developing standard operating procedure and training all the researchers. A third party will assess the accuracy, completeness and representativeness of registry data. Experimental data will be analysed with the help of statisticians.