title: Hypoperfusion in response to epinephrine in local anaesthetics: Investigation of dependence on epinephrine concentration, spread of hypoperfusion and time to maximal cutaneous vasoconstriction.
abstract: OBJECTIVE
  The present study aimed to examine hypoperfusion in response to epinephrine following the administration of a local anaesthetic. The concentration of epinephrine that causes maximal hypoperfusion, the spread of hypoperfusion in the tissue and the time to the stabilization of hypoperfusion were investigated.
  
  
  METHODS
  Blood perfusion was monitored using laser Doppler velocimetry and laser speckle contrast imaging of random-pattern advancement flaps (1 × 4 cm) or intact skin on the pig flank. Epinephrine was either injected cumulatively (0.1, 1.0, 10 or 100 μg/ml) after injecting 20 mg/ml lidocaine, to determine the concentration response, or given as a single dose (12.5 μg/ml epinephrine+20 mg/ml lidocaine). Control experiments were performed with saline or lidocaine (without epinephrine).
  
  
  RESULTS
  Increasing concentrations of epinephrine resulted in a gradual decrease in skin perfusion, approaching a minimum after injecting 10 μg/ml. The area of hypoperfusion was 12 mm in radius, and the time from the injection to the stabilization of hypoperfusion was approximately 120 s. After the administration of 10 μg/ml epinephrine in flaps with small pedicle, 25% blood perfusion still remained.
  
  
  CONCLUSIONS
  Local anaesthetic with an epinephrine concentration of approximately 10 μg/ml appears to be adequate for vasoconstriction before surgery. Incisions were required to be delayed only for 2 min following local anaesthetic with epinephrine in pigs. The remaining 25% blood perfusion observed after the administration of epinephrine supports the use of epinephrine in flaps with a small pedicle. Obviously, these experimental findings must be clinically assessed before being considered for infiltration anaesthesia during plastic surgery procedures.
authors.affiliation: Lund University, Skane University Hospital, Department of Clinical Sciences Lund, Ophthalmology, Lund, Sweden.
authors.forename: Rafi
authors.initials: R
authors.lastname: Sheikh
authors.affiliation: Lund University, Skane University Hospital, Department of Clinical Sciences Lund, Ophthalmology, Lund, Sweden.
authors.forename: Khashayar
authors.initials: K
authors.lastname: Memarzadeh
authors.affiliation: Lund University, Skane University Hospital, Department of Clinical Sciences Lund, Urology, Lund, Sweden.
authors.forename: Christian
authors.initials: C
authors.lastname: Torbrand
authors.affiliation: Lund University, Skane University Hospital, Department of Clinical Sciences Lund, Ophthalmology, Lund, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Blohmé
authors.affiliation: Lund University, Skane University Hospital, Department of Clinical Sciences Lund, Ophthalmology, Lund, Sweden. Electronic address: malin.malmsjo@med.lu.se.
authors.forename: Malin
authors.initials: M
authors.lastname: Malmsjö
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004837:Epinephrine / Q000494:pharmacology*; D017078:Laser-Doppler Flowmetry; D008012:Lidocaine / Q000493:pharmacokinetics* / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D012867:Skin / Q000098:blood supply; D013524:Surgical Flaps / Q000098:blood supply; D034421:Sus scrofa; D013552:Swine; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D000779:Anesthetics, Local; D004338:Drug Combinations; D014662:Vasoconstrictor Agents; D008012:Lidocaine; D004837:Epinephrine
keywords: Epinephrine; Laser Doppler velocimetry; Laser speckle contrast imaging; Lidocaine; Local anesthetic; Perfusion