Dexmedetomidine premedication before intravenous regional anesthesia in minor outpatient hand surgery.
OBJECTIVE
To assess the efficacy and safety of intravenous (i.v.) dexmedetomidine, an alpha-2 agonist, as a premedication before i.v. regional anesthesia.


METHODS
Randomized, double-blind, placebo-controlled study with two parallel groups.


METHODS
Day-case surgery unit, Department of Surgery, Turku University Hospital, Turku, Finland.


METHODS
30 healthy ASA physical status I outpatients scheduled for minor hand surgery with i.v. regional anesthesia.


METHODS
Patients were assigned to one of two groups to receive either dexmedetomidine 1 microgram/kg i.v. (n = 15) or saline placebo i.v. (n = 15) 10 minutes before exsanguination and inflation of a tourniquet. Regional blockade was induced with 0.5% lidocaine 3 mg/kg (maximum 200 mg). Additional fentanyl 1 microgram/kg intraoperatively and oxycodone 0.05 mg/kg postoperatively were administered for analgesia if needed.


RESULTS
Dexmedetomidine preoperatively induced 16% to 20% decreases in systolic blood pressure (p < 0.001), diastolic blood pressure (p < 0.001), and heart rate (p < 0.001), which were mainly abolished within the 4-hour postoperative follow-up period. A clinically significant decrease in arterial oxygen saturation was not observed. The subjective intensity of pain during tourniquet inflation was similar in both groups, but fewer intraoperative (p = 0.009) opioid analgesics were needed in the dexmedetomidine group. Dexmedetomidine decreased sympathoadrenal responses: plasma norepinephrine concentration decreased to one-fourth of the baseline level (p < 0.001), and one of its main metabolites, 3,4-dihydroxyphenylglycol, decreased by 27% (p < 0.001). Dexmedetomidine also prevented an increase in plasma epinephrine concentration following tourniquet inflation (p = 0.003). Dexmedetomidine induced subjective sedation (p = 0.002), but the Maddox Wing test did not show any statistically significant differences between the groups. General effectiveness was graded superior in the dexmedetomidine group (p < 0.001).


CONCLUSIONS
Dexmedetomidine is an effective premedication before i.v. regional anesthesia because it reduces patient anxiety, sympathoadrenal responses, and opioid analgesic requirements.
Jaakola
M L
ML
Department of Anesthesiology, Turku University Hospital, Finland.
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage*; D000328:Adult; D000556:Ambulatory Surgical Procedures; D000765:Anesthesia, Conduction; D000771:Anesthesia, Intravenous; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D004837:Epinephrine / Q000097:blood; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D006225:Hand / Q000601:surgery*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D007093:Imidazoles / Q000008:administration & dosage*; D008297:Male; D020926:Medetomidine; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000097:blood; D013511:Minor Surgical Procedures; D016343:Monitoring, Intraoperative; D009638:Norepinephrine / Q000097:blood; D010146:Pain / Q000517:prevention & control; D010919:Placebos; D011229:Preanesthetic Medication; D014111:Tourniquets
D000316:Adrenergic alpha-Agonists; D006993:Hypnotics and Sedatives; D007093:Imidazoles; D010919:Placebos; D008734:Methoxyhydroxyphenylglycol; D020926:Medetomidine; C010117:3,4-dihydroxyphenylglycol; D005283:Fentanyl; D009638:Norepinephrine; D004837:Epinephrine