Summer 2010 - The British Pain Society

PAIN SHORTCUTS (CONTINUED)
for more than 28 days before entry
into the study and remained on
the same medications and doses
throughout the study. Subjects had
not had ketamine before.
Appropriate exclusion criteria
were applied and the subjects
randomised to either the ketamine
or the placebo group.
The subjects received a full
neurological examination and
pain evaluation at the start of the
study. The subjects were asked
to complete a short form McGill
questionnaire, quality of life
questionnaire and a seven question
pain questionnaire weekly until the
start of the infusions.
The subjects all wore an activity
watch for at least 2 weeks prior to
treatment and 2 weeks following
treatment. The subjects underwent
sensory and motor tests 2 weeks
prior to treatment and at 1 and 3
months post treatment.
On all 10 infusion days the subjects
were monitored for cardiac
rhythm, blood pressure, pulse
and oxygen saturation. Subjects
were given Clonidine 0.1mg orally
and midazolam 2mg IV prior to
the infusion and 2mg IV following
the 4 hour infusion. All subjects
were infused with 100ml normal
saline with or without ketamine
for 4 hours daily for 10 days ( 5
days on, 2 days off, 5 days on)The
maximum ketamine infusion rate
was 0.35mg/kg/h, not to exceed
25mg/hr. On the first day the IV
ketamine infusion was set to 50%
of the max rate, 75% max rate on
the second day and maximum rate
on the third day and maintained
at maximum rate for the duration
on the study. Following the
last infusion the subjects were
reviewed at 2 weeks and then
monthly for 3 months. They were
asked to wear the activity watch
from the last infusion until the 2
week post infusion visit and were
asked to complete the short form
McGill, quality of life and pain
questionnaires weekly until the end
of the study 3 months after the last
infusion.
The study was stopped at the
halfway point because an interim
analysis was conducted which
showed there was little placebo
effect .This meant that statistical
significance could be reached in
many of the study parameters with
a smaller number of study subjects
than was originally anticipated. Also
further experience with outpatient
ketamine infusions showed that
50mg/hr provided much greater
pain relief for a greater period of
time.
10 subjects were in the placebo
group and 9 subjects in the
ketamine group. The study
showed a significant reduction
in pain (p