Dexmedetomidine in neurosurgical anesthesia

Dexmedetomidine is a new selective alpha2-adrenoreceptor agonist that can be described as a useful, safe adjunct in neuroanesthesia and neurocritical care practice. This alpha2-adrenoreceptor agonist offers a unique "cooperative sedation" +/- anxiolysis and analgesia without respiratory depression. Cerebral effects are generally consistent with a desirable neurophysiological profile, including neuroprotective characteristics. In addition, sympatholytic and antinociceptive properties allow for hemodynamic stability at critical moments of neurosurgical stimulation. This paper reviews the pharmacokinetic profiles and current clinical uses of dexmedetomidine in the area of neurosurgery patient care.

The Influences of Clonidine Premedication on the A-lineTM ARX Index and Hemodynamics during Anesthesia Induction with Propofol / 대한마취과학회지

BACKGROUND:Clonidine, an alpha2-adrenergic receptor agonist, has been shown to have a sedative effect and to suppress hemodynamics when used as a premedicant. We evaluated the change of AEP index and hemodynamics after clonidine premedication and induction with propofol. METHODS:The study design was a prospective, randomized, double-blind study. 90 patients who were scheduled for elective surgery were randomly assigned in 3 groups (Group 1, 2 and 3). In groups 2 and 3, the patients were administered 2 microgram/kg or 4 microgram/kg of i.v. clonidine 30 minutes before the induction of propofol anesthesia, respectively. We measured A-lineTM ARX index (AAI), systolic blood pressure, mean arterial pressure, diastolic blood pressure and heart rate at the ward; before the administration of clonidine premedication, before induction, just before intubation and 1 minute after endotracheal intubation, and compared these parameters among the 3 groups. RESULTS:Each dose of clonidine had a suppressive effect before the induction of anesthesia and suppressed hemodynamics successfully during intubation. In groups 2 and 3, the AAI was lower than in group 1 (P < 0.05), but 7 patients had bradycardia and 3 patients had been hypotensive in group 3. CONCLUSIONS: Intravenous injection of 2 microgram/kg clonidine as a premedicant reduced AAI significantly (P < 0.05) compared to the control group, with good hemodynamic stability. Therefore, we believe that AAI can be used to predict hypnotic state during propofol anesthesia.

The Influences of Clonidine Premedication on the Bispectral Index and Hemodynamics during the Induction of Anesthesia and Endotracheal Intubation with Propofol / 대한마취과학회지

BACKGROUND: The bispectral index (BIS) has been used as an indicator of a sedative state. In this study, we investigated the influence of intravenous clonidine 2 or 3 microgram/kg on the bispectral index and cardiovascular response to anesthetic induction. METHODS: The study design is prospective, randomized and double-blind. Ninety patients scheduled to undergo elective surgery under general anesthesia were divided into 3 groups. Each group received no premedication (group 1, n = 30), clonidine 2 microgram/kg (group 2, n = 30) and clonidine 3 microgram/kg (group 3, n = 30). The sedation and responsiveness scores of the Modified Observer's Assessment of Alertness/Sedation Scale (MOAAS/S) were measured before induction and the BIS, blood pressure, and heart rate were measured at before induction, after propofol injection, and after intubation. RESULTS: The BIS was significantly lower in groups 2 and 3 than in group 1 before anesthetic induction and intubation. Mean blood pressure was significantly lower in groups 2 and 3 than in group 1 before anesthetic induction, after propofol infusion and after intubation. Heart rate was also significantly lower in groups 2 and 3 than in group 1 after intubation. The sedation score and MOAAS/S were significantly lower in groups 2 and 3 than in group 1. CONCLUSIONS: Clonidine-premedicated patients appear to maintain stable hemodynamics during anesthetic induction and intubation. The bispectral index can be objectively used in clonidine-premedicated patients when evaluating the degree of sedation.