Figure 5. Systolic arterial pressure (SAP) and diastolic arterial pressure (DAP). Compared with readings before the block, SAP decreased significantly in the saline group (P < 0.05) and in the groups receiving 90 and 300 micro gram clonidine (P < 0.05 and P < 0.001). DAP decreased significantly in the groups receiving 90 and 300 micro gram clonidine (P < 0.01 in both groups). For the 300-micro gram clonidine group, SAP was significantly lower 40 and 60 min after the block than in the group not receiving clonidine (P < 0.01 at each time-point).