Ketamine not effective in surgery study | National Institutes of Health (NIH) by Tianna Hicklin, Ph.D. – June 20, 2017
At a Glance:
Researchers found that low doses of ketamine did not reduce delirium, postoperative pain, or other complications related to major surgeries.
The results suggest that the common practice of giving ketamine to patients during surgery may need to be re-evaluated.
Patients who are ill or undergoing surgery sometimes experience delirium, a confused mental state that includes changes in awareness, thinking, judgment, sleeping patterns, and behavior.
Patients who become delirious after surgery can have longer hospital stays and be at a higher risk of dying.
Opioid pain relievers are thought to be a risk factor for delirium and are addictive.
Ketamine is commonly used in the operating room as an alternative to opioids to prevent pain from surgery and reduce the need for opioids.
The team randomly assigned the patients to three treatment groups. Patients received either a placebo, a 0.5 mg/kg dose of ketamine, or a 1.0 mg/kg dose ketamine following general anesthesia but prior to any surgical incision. Patients were evaluated for delirium from 1 to 3 days following the surgery.
There were no significant differences between the groups in patients experiencing delirium (19.82%, placebo; 17.65%, 0.5 mg/kg; 21.3%, 1.0 mg/kg).
Nor were there any significant differences across groups in pain experienced in the days following the surgery.
“We were particularly surprised by the lack of an effect on postoperative pain,” says the study’s senior author, Dr. George Mashour of the University of Michigan. “Giving single doses of ketamine during surgery to prevent postoperative pain is increasingly common, but our data challenge that practice and suggest that even after decades of use, more research is required if we hope to understand ketamine.”
We found that the current practice of giving low doses of ketamine to patients during surgery is not having the desired effect,” Avidan says.
“So we need to determine whether higher doses might be more effective, or we need to find other alternatives to opioids.”
However, less than one year before the above study, the opposite was found to be true in a different study:
Role of ketamine for analgesia in adults and children – Free full-text PMC5009833/ – 2016 Jul-Sep
In summary, ketamine is a strong analgesic employable in subanesthetic without major neuropsychiatric adverse effects
Ketamine decreases pain intensity in the postoperative period, and it has been shown clinically to
- decrease opioid consumption,
- decrease the side effects of opioids and
- increase the time for rescue analgesics
all these are attractive properties that suggest a role for ketamine as a useful adjuvant in the treatment of postoperative pain.
In addition to further exploring the role of ketamine as an adjuvant for perioperative pain control, continued research is needed to determine if perioperative ketamine is useful for the treatment of pain after surgery known to result in severe pain and in the prevention and treatment of chronic pain.
This certainly leaves me wondering which is true, since these studies cannot possibly both be valid, can they?
Am I missing something here?