Stellate ganglion block (SGB) results in a sympathetic block of the head, neck, and upper extremities. In a previous study, the modified injection technique (MIT) was found to exert a better sympathetic block effect on the upper extremities than the classic injection technique (CIT). Therefore, this study was conducted to evaluate the spreading effect of injection volume when the MIT was used in the paratracheal SGB at the 6th cervical level.

One hundred patients were equally divided into 4 groups. Patients in Groups I, II, and III were subjected to paratracheal SGB at the 6th cervical level with 6 ml, 8 ml, 10 ml of 0.5% mepivacaine administered using the CIT, respectively, whereas patients in Group IV were subjected to block with 6 ml of 0.5% mepivacaine by the MIT using a method such as strong pressure at the cephalad portion of the needle entry point. The skin temperature of the second finger was measured before and after SGB, and the occurrence of warm sensation on the face and upper extremities, and the occurrence of hoarseness were evaluated.

The increase in the skin temperature of patients in Groups I, II, III, and IV were 0.28 ± 0.29, 0.52 ± 0.58, 0.82 ± 0.77, and 0.80 ± 0.72, respectively, with the increases in skin temperature observed in the Groups III and IV being statistically significant when compared to Group I (P < 0.05). There were no significant differences observed in the occurrence of warm sensations on the face and upper extremities, or in the occurrence of hoarseness among the groups.

The results of this study could not differentiate the spreading effect of injection volume that occurred when the MIT was used from the effect that occurred as a result of injection of 8 or 10 ml using the CIT. However, the MIT showed better sympathetic block on the upper extremities than the CIT when the same volume was used. Taken together, these results suggest that the spread effect of 6 ml administered by MIT is similar to that of 10 ml administered by CIT.