Abstract
Background and Purpose: There are many benefits of administering dexmedetomidine perioperatively. The pharmacokinetics (PK) and pharmacodynamics (PD) of intravenous, intranasal and oral dexmedetomidine that was administered before anesthesia were compared in this study, and the effects of dexmedetomidine on the surgical field visibility in tympanoplasty was evaluated. Methods: A single-blind, randomized controlled trial was conducted in a university-affiliated hospital where 45 patients who underwent tympanoplasty under general anesthesia were randomly allocated into three groups. Dexmedetomidine was administered by intravenous infusion at 0.8 μg.kg−1 for 10 min, intranasal instillation at a drop rate of 1 μg.kg−1 and oral intake at 4 μg.kg−1 ten minutes before the induction of anesthesia. The PK and PD of dexmedetomidine after a single low dose administration and its effect on the surgical field in tympanoplasty were analysed. Results: A plasma concentration of dexmedetomidine of 220 pg/ml was achieved immediately after intravenous infusion and at 13.2 and 70.3 min for intranasal and oral administration, respectively. Dexmedetomidine decreased the heart rate (HR) and mean arterial pressure (MAP) in all three groups, although these values remained higher in the oral dexmedetomidine group at all eight time points. Intravenous dexmedetomidine provided the best visualization of the surgical field for opening of the tympanic sinus, 30 min after the start of the infusion (p < 0.05). Intranasal dexmedetomidine provided a significantly better visual field than oral dexmedetomidine for the repair of a tympanic membrane perforation using the fascia temporal muscle (p < 0.05). Conclusion: A single low dose of dexmedetomidine administered intravenously or intranasally could decrease HR and MAP, improve surgical field visibility and be appropriate for deliberate hypotension for surgical procedures of 1–2 h in length. Trial registration: Clinicaltrials.gov identifier: NCT03800641.
Highlights
Dexmedetomidine is an α2-adrenoceptor agonist with sedative, anxiolytic, analgesic and sympatholytic effects (Weerink et al, 2017; Pan et al, 2019), with its perioperative infusion improving the survival of patients undergoing cardiac surgery by five years (Peng et al, 2021)
Dexmedetomidine decreased the heart rate (HR) and mean arterial pressure (MAP) in all three groups, these values remained higher in the oral dexmedetomidine group at all eight time points
Intravenous dexmedetomidine provided the best visualization of the surgical field for opening of the tympanic sinus, 30 min after the start of the infusion (p < 0.05)
Summary
Dexmedetomidine is an α2-adrenoceptor agonist with sedative, anxiolytic, analgesic and sympatholytic effects (Weerink et al, 2017; Pan et al, 2019), with its perioperative infusion improving the survival of patients undergoing cardiac surgery by five years (Peng et al, 2021). The effective range of plasma concentration of dexmedetomidine was reported to be 0.22–2.50 ng/ml for patients in the intensive care unit (Fujita et al, 2013). The maximal concentration (Cm) of dexmedetomidine in the plasma is less than 0.1 ng/ml after 2 μg/kg was administered orally (Anttila et al, 2003). At low plasma concentrations, dexmedetomidine may reduce MAP and HR by activating presynaptic α2adrenoceptors in the central nervous system and vascular endothelial cells, causing vasodilation (Colin et al, 2017) which may have a potential role in deliberate hypotension. The pharmacokinetics (PK) and pharmacodynamics (PD) of intravenous, intranasal and oral dexmedetomidine that was administered before anesthesia were compared in this study, and the effects of dexmedetomidine on the surgical field visibility in tympanoplasty was evaluated
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