Is Spinal Dexmedetomidine Aggravating Hypotension after Tourniquet Deflation?

The addition of dexmedetomidine to spinal anesthesia decreases the incidence of tourniquet pain but may aggravate hypotension after tourniquet deflation.

Fifty patients were included in this prospective, double-blinded, randomized study, randomly divided into two equal groups of 25 patients each. Spinal anesthesia was performed using 2.5 mL of 0.5% hyperbaric bupivacaine plus 0.5 mL of normal saline in control group (Group C) or 2.5 mL of 0.5% hyperbaric bupivacaine plus 0.5 mL (5 μg) of dexmedetomidine in (Group D). Tourniquet pain was treated by 50 mg of meperidine and repeated in a dose of 20 mg, and the total meperidine consumption was calculated. After tourniquet deflation, heart rate and mean blood pressure were measured for 15 min in the operating room and at these times: before induction of anesthesia (baseline), after inflating tourniquet (inflation), 1 min before deflating tourniquet (predeflation), after tourniquet deflation (10 min postdeflation), and maximum blood pressure and heart rate changes. Duration of time that started before the minimum blood pressure and maximum heart rate was changed until recovery was recorded.

Pain after torniquet inflation was significantly higher in the Group C compared to the Group D. The maximal change of blood pressure was lower in the dexmedetomidine than in the control group. The mean time between the maximal change in blood pressure reached and started to recover was 135 ± 14 s in the dexmedetomidine group and 80 ± 31 s in the control group (P < 0.01) and maximal heart rate change was lower in dexmedetomidine group than the control group. The time between the maximal heart rate changes until recovery was 113.2 ± 19 s in the dexmedetomidine group and 53.2 ± 11 s in the control group P < 0.01.

Adding dexmedetomidine to spinal anesthesia decreases the incidence of tourniquet pain but aggravates the hemodynamic effect of tourniquet deflation.