title: The effect of propofol infusion with topical epinephrine on cochlear blood flow and hearing: An experimental study.
abstract: OBJECTIVE
  Propofol is the most commonly used intravenous (IV) anesthetic agent and is associated with hypotension upon induction of anesthesia. Intravenous propofol infusion has several properties that may be beneficial to patients undergoing middle ear surgery. Topical application of concentrated epinephrine is a valuable tool for achieving hemostasis in the middle ear and during mastoid surgery. The purpose of the present study was to determine the effects of propofol infusion with topical epinephrine on cochlear blood flow (CBF) and hearing in rats.
  
  
  METHODS
  Twenty one male Sprague-Dawley rats were divided into three groups. The rate of intravenous infusion of propofol was 4-6 ml/kg/hour. The first group (control group, n = 7) was given IV infusion of phosphate buffered saline (PBS) with topical application of PBS in the round window. In study group A (n = 7), the effect of topical phosphate buffered saline with IV infusion of propofol on CBF and hearing was evaluated. In study group B (n = 7), additional effects of topical epinephrine with IV infusion of propofol on CBF and hearing were evaluated. The laser Doppler blood flowmeter, CBF, and the mean arterial blood pressure (MAP) were measured and analyzed. Additionally, hearing test using auditory brainstem response (ABR) was performed in both groups.
  
  
  RESULTS
  In both groups, infusion of propofol induced a time-dependent decrease in MAP. Approximately 30 min after the start of the propofol infusion, the CBF started to decrease slowly. The decrease in CBF was significantly greater in the study group compared to the control group. The threshold was elevated in the study group relative to the control group.
  
  
  CONCLUSIONS
  During middle ear surgery, use of IV infusion of propofol with topical epinephrine cotton ball or cottonoid application is not recommended.
authors.affiliation: Department of Otolaryngology, Chonnam National University Medical School, Gwangju, South Korea. Electronic address: chulsavio@hanmail.net.
authors.forename: Chul Ho
authors.initials: CH
authors.lastname: Jang
authors.affiliation: Department of Otolaryngology, Chonnam National University Medical School, Gwangju, South Korea.
authors.forename: Yong Beom
authors.initials: YB
authors.lastname: Cho
authors.affiliation: Department of Biology, College of Natural Sciences, Chosun University, Gwangju, South Korea.
authors.forename: Jun Sik
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Biomechatronics, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, South Korea.
authors.forename: Geun Hyung
authors.initials: GH
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, Center for Marine-Integrated Biomedical Technology (BK 21 Plus), Pukyong National University, South Korea.
authors.forename: Won-Kyo
authors.initials: WK
authors.lastname: Jung
authors.affiliation: School of Biomedical Sciences, Charles Sturt University, Bathurst, Australia.
authors.forename: Sok Cheon
authors.initials: SC
authors.lastname: Pak
mesh_terms: D000287:Administration, Topical; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects*; D003051:Cochlea / Q000098:blood supply*; D004837:Epinephrine / Q000008:administration & dosage*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006309:Hearing / Q000502:physiology*; D007262:Infusions, Intravenous; D017078:Laser-Doppler Flowmetry; D008297:Male; D015742:Propofol / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*
chemical_list: D018686:Anesthetics, Intravenous; D014662:Vasoconstrictor Agents; D015742:Propofol; D004837:Epinephrine
keywords: Cochlear blood flow; Mean arterial blood pressure; Middle ear surgery; Propofol; Topical epinephrine