How to standardize 3 finger positions of examiner for palpating radial pulses at wrist in traditional Chinese medicine

This study was to provide a standardized definition of the positioning method of finger placement on the radial artery for pulse diagnosis in traditional Chinese medicine (TCM); that is, to define the locations of Cun, Guan and Chi in TCM. A total of 200 subjects (100 males and 100 females, 18-40 years of age) were recruited from the general population. According to ancient TCM records, the "6% of the elbow length" (ELx6%) is used as the standard method of establishing the length of Cun. We hypothesized that the highest point of "prominent bone" (PB) is the lower limit of Cun, so "the distance between the distal wrist crease and the highest point of the PB" (DWP) is considered the length of Cun. If this hypothesis holds, then we can define the locations of Cun, Guan and Chi by using the ratio 6:6:7 from the ancient TCM records. The distribution of relative bias and paired t-test were used to verify the findings. The mean value of relative bias of DWP compared with ELx6% was close to 0% (males=2.1%, SD=12.2%; females=0.2%, SD=12.6%). The paired t-test confirmed that there was no significant difference (p>0.05) between the mean values of the DWP and ELx6%. Therefore, it is reasonable to assume that the length of the Cun is equal to the length of the DWP. Our findings confirm that the location of Cun is from the distal wrist crease to the highest point of PB.