Figure 1. Duration of analgesia provided by the different intrathecal solutions: C15 (n = 10): 15 micro gram clonidine; C30 (n = 10): 30 micro gram clonidine; S2.5 (n = 13): 2.5 micro gram sufentanil; S2.5C15 (n = 13): 2.5 micro gram sufentanil + 15 micro gram clonidine; S5 (n = 12): 5 micro gram sufentanil; S5C15 (n = 13): 5 micro gram sufentanil + 15 micro gram clonidine; S2.5C30 (n = 13): 2.5 micro gram sufentanil + 30 micro gram clonidine; S5C30 (n = 13): 5 micro gram sufentanil + 30 micro gram clonidine. Results are expressed as means. The statistical analysis was performed using one-way analysis of variance followed by Student-Newman-Keuls procedures.