Figure 2. Mean (+/− SD) RR interval (A) and systolic blood pressure (SBP; B) at the same time intervals as in Figure 1(Treatment x Study period interaction for mean RR interval P = 0.03; SBP P < 0.001). (C and D) The SD of RR interval and SBP for each of the periods. SD of RR interval is increased and SD of SBP decreased postoperatively by clonidine (Treatment x Study period interaction P = 0.01 for SD of RR; P > 0.05 for SD of SBP with P = 0.03 between groups). *Significant difference between groups;[dagger] significant difference from respective baseline value by post hoc Tukey's tests.