Local anesthetics are typically used to reduce pain when minor
wounds need to be cleaned or stitched up, but the injections
themselves are often considered the most painful part of the
procedure, according to the National Institutes of Health.
As the study authors describe in the Emergency Medicine Journal
online October 12, there are multiple ways to reduce the associated
pain. They include mixing the local anesthetic with sodium
biocarbonate, applying eutectic mixture of local anesthetics (EMLA)
cream, and warming lidocaine to near body temperature.
But, the authors point out, each method has known drawbacks. The
shelf life for lidocaine is shortened when it is buffered with
sodium bicarbonate or warmed close to body temperature; additional
equipment is needed for storage; tiny precipitates form after mixing
with sodium bicarbonate; and EMLA cream is not approved for use on
The Greek philosopher and physician Hippocrates, often considered
the father of medicine, first described the technique of applying
cold to reduce pain, the researchers noted. Since then, at least in
terms of procedural analgesia, several studies have demonstrated
that a cooling spray or ice cubes effectively reduced pain when
veins and arteries need to be punctured.
The current study, conducted by Dr. SangChun Choi and colleagues at
Ajou University Hospital in the Republic of Korea, involved 50
patients, ages 18 to 65, who were having simple lacerations repaired
in the emergency department.
Half the patients were assigned to receive cryotherapy, in which an
ice cube placed inside a sterile glove was applied to the wound for
two minutes before a lidocaine injection. The other patients
received standard care, with no special treatment before the
Patients were asked to rank their pain after the injection, on a
scale of 1 to 10, with 10 being the worst.
In the ice cube group, half the patients ranked their pain level as
no higher than 2, whereas in the control group, half the patients
had a pain score of 5 or higher.
Overall, the authors report, the results showed that ice cube
cryotherapy could significantly reduce perceived pain from local
anesthetic injections, without increasing wound complications.
“Cryotherapy appears to be safe, pragmatic and effective,” study
authors concluded, noting that in contrast to other known methods to
reduce pain associated with local anesthetic injections, this
approach does not involve the modification of anesthetic
administration, any special equipment, or additional expenses.
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Dr. Ian Gibbons, a senior house officer at Royal Surrey County
Hospital in Guildford who was not involved in the study, commended
the potential of ice cube therapy. He noted in an email to Reuters
Health that it’s relatively cheap and readily available.
Dr. Ryan Stanton, a spokesman for the American College of Emergency
Physicians, told Reuters Health by email, “I don’t think you can
declare it “completely safe” with those small numbers, but ice is
commonly used for analgesia. There is more to determine, but I’m
sure it has a role and it’s cheap with few likely issues.”
Stanton, who was not involved in the study, said the challenge with
ice therapy could be that if administered for too long, it could
lead to tissue damage, and that physicians may be tempted to grab
ice cubes out of dispensers, instead of waiting for a sterile ice
Whether this approach is adopted will likely depend on the
healthcare provider’s personal preference and patient population, he
said, “but I don't expect to see official protocols” calling for ice
The researchers acknowledged several weaknesses of their study. For
example, there weren’t enough patients to show whether pain
reductions might be different in various parts of the body. In
addition, although researchers who collected data on pain scores
were separate from those who gave the injection, it would be easy to
discern which group the patient was part of upon detecting colder
skin. Furthermore, variables including the depth of the needle tip,
the speed of the injection, the amount injected, and choice of local
anesthetic could impact pain scores.
Gibbons also underscored the likelihood of an amplified placebo
effect, noting that “surely people would be able to tell if there
was an ice cube on them?”
Pain scores can also be extremely subjective, he added, “I've seen
people with broken hips describing 1/10 pain and people with nothing
wrong with them playing on their phones describing 10/10 pain.”
Emerg Med J 2017.
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