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Pharmacokinetics of low-dose dexmedetomidine and effect on surgical field visibility for middle ear microsurgery: a randomised controlled trial
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  • Jinhong Wu,
  • Yuan Han,
  • Yu Lu,
  • Yan Zhuang,
  • Wenxian Li,
  • Ji'e Jia
Jinhong Wu
Fudan University Eye Ear Nose and Throat Hospital
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Yuan Han
Fudan University Eye Ear Nose and Throat Hospital
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Yu Lu
Fudan University Eye Ear Nose and Throat Hospital
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Yan Zhuang
Fudan University Eye Ear Nose and Throat Hospital
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Wenxian Li
Fudan University Eye Ear Nose and Throat Hospital
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Ji'e Jia
Fudan University Eye Ear Nose and Throat Hospital

Corresponding Author:[email protected]

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Abstract

Background and Purpose Dexmedetomidine has many benefits in perioperative administration. This study aims to describe the pharmacokinetics (PK) of intravenous, intranasal and oral administration of dexmedetomidine before anaesthesia induction, and evaluate the effects of dexmedetomidine on the visibility of the surgical field in tympanoplasty. Methods This single-blind, randomised controlled trial in a university-affiliated hospital. Forty-five patients underwent tympanoplasty under general anaesthesia were enrolled. Patients were randomly allocated, in blocks of 3, to dexmedetomidine 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. PK of dexmedetomidine after a single low-dose administration and effect on the surgical field in tympanoplasty were analyzed. Results: A dexmedetomidine concentration 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 heart rate (HR) and MAP in all three groups, although these values remained higher in the oral dexmedetomidine group at all the eight time points. Intravenous dexmedetomidine provided the best visualisation 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 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 can decrease HR and MAP and improve surgical field visibility, and appropriate for deliberate hypotension for surgical procedures 1-2 h in length.