Comparison of effects of lidocaine hydrochloride, buffered lidocaine, diphenhydramine, and normal saline after intradermal injection.
OBJECTIVE
To evaluate pain and the spread of analgesia when local anesthetics are given as an intradermal injection into the dorsal aspect of the hand.


METHODS
Randomized, double-blinded, placebo-controlled study.


METHODS
University medical center.


METHODS
40 consenting adult volunteers.


METHODS
Volunteers were randomly assigned to receive a 0.25-mL injection of either lidocaine hydrochloride (1%), buffered lidocaine, diphenhydramine (1%), or placebo (0.9% sodium chloride solution) into the dorsal aspect of both hands.


METHODS
The volunteers used a visual analog scale to compare the pain of needle insertion and solution injection. Then at 1, 2, 5, 10, 20, and 30 minutes after intradermal injection, the extent of the analgesic area was marked on a strip of tape placed horizontally across the hand. Then at 32 minutes after intradermal injection, the extent of the analgesic area was marked on a strip of tape placed vertically across the hand. The volunteers were called each day and asked the duration of their numbness or hyperesthesia until their hands were no longer numb or sore.


RESULTS
Buffered lidocaine during intradermal infiltration was found to be significantly (p < 0.05) less painful than either lidocaine hydrochloride or diphenhydramine and equivalent to placebo. Diphenhydramine and lidocaine hydrochloride during intradermal infiltration induced significantly (p < 0.05) more pain than buffered lidocaine or placebo. Lidocaine hydrochloride displayed a significantly (p < 0.05) larger diameter of analgesia than placebo by 1 minute after the injection, buffered lidocaine by 2 minutes after injection, and diphenhydramine by 5 minutes after injection. By 20 minutes after injection, diphenhydramine diameter of analgesia was significantly (p < 0.05) larger than placebo but significantly less than buffered lidocaine. By 30 minutes after injection, diphenhydramine diameter of analgesia was equivalent to placebo whereas buffered lidocaine and lidocaine diameters were still significantly (p < 0.05) larger than placebo. Diphenhydramine injection resulted in numbness that lasted significantly (p < 0.05) longer than other study solutions whereas buffered lidocaine and lidocaine injections resulted in numbness that lasted significantly longer than placebo. Diphenhydramine injection resulted in hyperesthesia that lasted for 2 or more days in 12 of the volunteers.


CONCLUSIONS
There is a reduction of infiltration pain using buffered lidocaine as opposed to lidocaine and diphenhydramine. Although lidocaine injection resulted in a slightly faster spread of analgesic diameter, buffered lidocaine was equivalent to lidocaine from minute 2 until minute 30. Therefore, to obtain optimal anesthetic conditions, we recommend that buffered lidocaine be given 2 minutes before performing catheterization, whereas diphenhydramine should be given 5 minutes before catheterization, but only when buffered lidocaine cannot be used.
Department of Anesthesiology, Division of Critical Care Medicine, The Ohio State University Medical Center, 410 West 10th Avenue, Columbus, OH 43210, USA.
Yun
Y
Xia
Edward
E
Chen
David L
DL
Tibbits
Thomas E
TE
Reilley
Thomas D
TD
McSweeney
D000328:Adult; D000704:Analysis of Variance; D000779:Anesthetics, Local / Q000008:administration & dosage*; D004155:Diphenhydramine / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006225:Hand / Q000503:physiopathology; D006801:Humans; D006987:Hypesthesia / Q000209:etiology; D007271:Injections, Intradermal; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D010146:Pain / Q000139:chemically induced* / Q000188:drug therapy* / Q000503:physiopathology; D010147:Pain Measurement; D012965:Sodium Chloride / Q000008:administration & dosage*; D013997:Time Factors
D000779:Anesthetics, Local; D012965:Sodium Chloride; D004155:Diphenhydramine; D008012:Lidocaine