Intraoperative Ketamine on Chronic Pain After Mastectomy
Status:
Unknown status
Trial end date:
2020-06-01
Target enrollment:
Participant gender:
Summary
Preventive analgesia is when an administered analgesic drug provides reduction in pain beyond
its duration of action. This can be used to reduce acute postoperative pain and prevent
occurrence of chronic post-surgical pain.
According to the International Association for the Study of Pain (IASP), chronic pain can be
defined as pain that persisted beyond the time of normal tissue healing (usually 3 months)
and that was not related to other causes. Mastectomy is associated with a high incidence of
chronic post-surgical pain. Breast cancer is the most common malignancy affecting females
around the world. Many undergo mastectomy as part of curative treatment. However, a
significant proportion of patients experience chronic post-surgical pain. This results in
significant negative impact on physical, psychological and social wellbeing.
Ketamine is an intravenous anaesthetic drug with analgesic effects. It can be used to treat
both acute and chronic pain. A recent meta-analysis of different surgeries showed that
patients receiving ketamine had a modest but statistically significant reduction in incidence
of chronic post-surgical pain. In a small sample single dose pilot study, patients given low
dose intravenous ketamine intraoperatively had a statistically non-significant reduction in
incidence of pain around the surgical scar at three months after radical mastectomy.
Randomized control trials with larger sample sizes are needed to determine the effectiveness
and optimal dosing regime of ketamine for reduction of chronic post-mastectomy pain. It is
therefore hypothesized that intravenous ketamine given intraoperatively will reduce the
incidence and severity of chronic pain after modified radical mastectomy. A double blind
randomized controlled trial comparing placebo group with two different doses of ketamine is
proposed.
The mechanism of action of ketamine in reducing pain is complex and multiple. How ketamine
can prevent and reduce chronic pain is unknown. Ketamine has been shown to reduce immediate
gene expression at site of mechanical injury. Transient Receptor Potential Vanilloid 1
(TRPV1) and Transient Receptor Ankyrin 1 (TRPA1) are receptors shown to mediate acute and
chronic pain. Ketamine, shown to affect gene expression, may alter the expression of TRPV1
and TRPA1 via epigenetic mechanisms.