J Korean Soc Emerg Med.  1998 Dec;9(4):601-606.

Comparison of Pain induced by injection of Local Anesthetic Solution warmed to Body Temperature versus at Room Temperature

• Wang SJ
• Park JH
• Chung JM

Abstract

BACKGROUND: Infiltration of the skin and subcutaneous tissue with local anesthetic solutions may cause transient pain and discomfort. Heating local anesthetic solutions to body temperature has been suggested as a way of reducing the pain associated with injection. We designed a double blind crossover volunteer study to investigate the effect of warming lidocaine on the pain associated with subcutaneous injection.
METHODS
Participants were 40 healthy adult volunteers,22 years of age and older, and they were the medical, nursing stay and medical students. They underwent 1ml subcutaneous injections of the study agent through 25-gauge needles. Following a standard crossover protocol, 'room temperature' lidocaine(20degrees C ) was injected into one midvolar forearm and body temperature' lidocaine(37degrees C ) into the opposite arm. Pain assessed by visual analogue pain scores and 'volunteer's comparison of pain on injection.
RESULTS
Twenty-six volunteers thought that lidocaine at 20degrees C was more painful and four thought that lidocaine at 37degrees C was more painful, ten volunteers did not express a difference. Median pain score for injection at 20 degrees C was 37 and at 37 degrees C was 35.5. Difference of two median scores was 6.5.
CONCLUSION
The simple procedure of warming to body temperature reduced the pain associated with subcutaneous injection of lidocaine. It is an inexpensive and practical method That should be considered for routine use in the ED.

MeSH Terms

Adult
Arm
Body Temperature*
Forearm
Heating
Hot Temperature
Humans
Injections, Subcutaneous
Lidocaine
Needles
Nursing
Skin
Students, Medical
Subcutaneous Tissue
Volunteers
Lidocaine