The Effect of Intravenous Dexamethasone and Dexmedetomidine on Analgesia Duration of Supraclavicular Brachial Plexus Block: A Randomized, Four-Arm, Triple-Blinded, Placebo-Controlled Trial

Abstract

Intravenous dexamethasone and dexmedetomidine, in conjunction with peripheral nerve blockade, have each been reported to prolong the duration of analgesia. This study tested whether combined use further prolongs analgesia duration after supraclavicular brachial plexus block (BPB) in patients undergoing orthopedic upper extremity surgery. One hundred twenty patients were randomized 1:1:1:1 to Control (saline bolus and midazolam infusion [0.05 mg/kg loading, 20 µg/kg/h thereafter]); DMED (saline bolus and dexmedetomidine infusion [1 μg/kg loading, 0.4 μg/kg/h thereafter]); DEXA (dexamethasone [10 mg] bolus and midazolam infusion); and DMED-DEXA (dexmedetomidine infusion and dexamethasone bolus) groups. The primary outcome was the duration of postoperative analgesia, defined as the time from the end of the BPB to the first dose of analgesia via a patient-controlled device. Median (interquartile range) times to first dose of analgesia in the Control, DMED, DEXA, and DMED-DEXA groups were 8.1 (6.2-11.6), 9.0 (8.1-11.3), 10.7 (8.1-20.5), and 13.2 (11.5-19.1) hours, respectively (p < 0.001). Pairwise comparisons showed significant prolongation of analgesia in the DEXA included groups compared with the non-DEXA included groups (DEXA vs. control, p = 0.045; DEXA vs. DMED, p = 0.045; DMED-DEXA vs. control, p < 0.001; DMED-DEXA vs. DMED, p < 0.001). A mixed effect model showed that dexamethasone was the only significant factor for the prolongation of analgesia (p < 0.001). Intravenous dexamethasone prolonged the analgesia duration of supraclavicular BPB after orthopedic upper extremity surgery. The concurrent use of mild to moderate sedation dose of intravenous dexmedetomidine in addition to intravenous dexamethasone showed no additional benefit to the prolongation of analgesia.

Keywords: brachial plexus block; dexamethasone; dexmedetomidine; intravenous adjuvant; postoperative analgesia; regional anesthesia.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure A1

Survival analysis of the duration of sensory blockade. The crossing points of the dotted and colored solid lines indicate median duration of the corresponding strata (groups). There was no difference in sensory block duration (p = 0.430).

Figure A2

Survival analysis of the duration of motor blockade. The crossing points of the dotted and colored solid lines indicate median duration of the corresponding strata (groups). There was no difference in motor block duration (p = 0.895).

Figure A3

Changes in systolic blood pressure during and after surgery in the four study groups. The systolic blood pressure recorded at 0, 5, 10, and 30 min after the start of sedation and 0, 10, and 30 min after the end of sedative infusion.

Figure A4

Changes in heart rate during and after surgery in the four study groups. The heart rate recorded at 0, 5, 10, and 30 min after the start of sedation and 0, 10, and 30 min after the end of sedative infusion.

Figure 1

Schedule of drug administration to patients in the four study groups. Patients in the Control group received a 2 mL bolus of normal saline, followed by infusion of midazolam (0.05 mg/kg loading dose and a 20 µg/kg/h continuous dose). Patients in the DMED group received a 2 mL bolus of normal saline, followed by infusion of dexmedetomidine (1.0 µg/kg loading dose and a 0.4 µg/kg/h continuous dose). Patients in the DEXA group received a 2 mL bolus of dexamethasone, followed by infusion of midazolam. Patients in the DMED-DEXA group received a 2 mL bolus of dexamethasone, followed by infusion of dexmedetomidine.

Figure 2

CONSORT flow diagram. * Data loss regarding the primary outcome (patient-controlled analgesia data).

Figure 3

Survival analysis of the duration of analgesia. PCA, patient-controlled analgesia. The crossing points of the dotted and colored solid lines indicate median duration of the corresponding strata (groups). Median (IQR) times to first request for analgesia differed significantly among the Control (8.1 [6.2 to 11.6] hours), DMED (9.0 [8.1 to 11.3] hours); DEXA (10.7 [8.1 to 20.5] hours), and DMED-DEXA (13.2 [11.5 to 19.1] hours) groups (p < 0.001).

Figure 4

Changes in depth of sedation during and after surgery in the four study groups. mRSS (modified Ramsay Sedation Scale) 5 and 10 min after the start of sedation and every 10 min thereafter, up to 50 min.