The effect of pre-anesthetic administration of dexmedetomidine on the consumption of opioids in postoperative gynecologic patients

Background: This study was designed to assess whether pre-anesthetic administration of dexmedetomidine reduces the postoperative consumption of opioids, in patients receiving patient-controlled fentanyl after gynecological laparotomy. Methods: This was a prospective, randomized, double-blind, controlled study. Ten minutes before induction of anesthesia, 36 patients scheduled for elective gynecological laparotomy were assigned to receive either normal saline (group N) or dexmedetomidine 1 μg/kg (group D). A patient-controlled analgesia (PCA) device was used to administer fentanyl for the postoperative 24 h period. Cumulative fentanyl consumption and pain score were assessed at postoperative 30 min, 6 h and 24 h. Patient’s satisfaction for pain control and other side effects (nausea, sedation score) were recorded for all corresponding time points. Results: There was no significant difference between the groups in cumulative fentanyl consumption (Group N: 11.1 ± 3.2 μg/kg, Group D 10.3 ± 2.9 μg/kg, P value: 0.706). The incidence of side-effects did not differ between the groups. Both groups showed similar blood pressure after anesthesia induction. However, 10 min after anesthesia induction, the heart rates in group D were significantly lower than group N (P = 0.0002). Conclusions: In patients undergoing gynecological laparotomy, the pre-anesthetic administration of single loading dose dexmedetomidine (1 μg/kg) given 10 min before anesthesia induction did not reduce the PCA consumption of postoperative fentanyl or the pain score. Keywords: Adrenergic alpha-2 receptor agonists; Dexmedetomidine; Fentanyl; Patient-controlled analgesia; Postoperative pain