The effect of adjuvant epinephrine concentration on the vasoactivity of the local anesthetics bupivacaine and levobupivacaine in human skin.
OBJECTIVE
The recommended optimal concentration of adjuvant epinephrine for use with local infiltration anesthesia is usually 5 microg/mL. However, a lower dose might be as effective at prolonging the anesthetic effects, while limiting the risk of hazards associated with unintentional intravascular injection. The aim of our study was to determine the lowest effective vasoconstrictor concentration of epinephrine in human skin for a range of doses of bupivacaine and its less-vasodilatory S(-) isomer, levobupivacaine.


METHODS
We injected combinations of 0.125%, 0.25%, and 0.75% bupivacaine and levobupivacaine with 1.25, 2.5, and 5 microg/mL epinephrine into the forearm skin of 10 healthy volunteers and measured the resulting blood flow changes over 1 hour using laser Doppler imaging.


RESULTS
All 3 concentrations of epinephrine produced marked vasoconstriction, both alone and in combination with all 3 doses of the anesthetics ( P <.001 in all cases). There was almost no difference in effect between the 3 epinephrine concentrations.


CONCLUSIONS
We conclude that 1.25 microg/mL epinephrine produces a comparable vasoconstrictor effect in human skin to that of higher concentrations when coinjected with clinical doses of bupivacaine and levobupivacaine and may be equally effective for infiltration anesthesia.
Vascular Diseases Research Unit, The Institute of Cardiovascular Research, Dundee, United Kingdom. d.j.newton@dundee.ac.uk
David J
DJ
Newton
Graeme A
GA
McLeod
Faisel
F
Khan
Jill J F
JJ
Belch
D000759:Adjuvants, Anesthesia / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D019162:Anesthetics, Combined / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology; D002045:Bupivacaine / Q000031:analogs & derivatives / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D005542:Forearm; D006801:Humans; D017078:Laser-Doppler Flowmetry; D000077554:Levobupivacaine; D008297:Male; D012016:Reference Values; D012867:Skin / Q000098:blood supply* / Q000187:drug effects*; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000759:Adjuvants, Anesthesia; D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D014662:Vasoconstrictor Agents; D000077554:Levobupivacaine; D002045:Bupivacaine; D004837:Epinephrine