Low-dose Dexmedetomidine May Reduce Post-op Dementia in Elderly

By Anne Harding

NEW YORK (Reuters Health) - Dexmedetomidine could help prevent dementia in older patients admitted to the intensive care unit (ICU) after non-cardiac surgery, a large new study suggests.

Nine percent of patients given the drug developed postoperative delirium, versus 23% of those who received placebo. "To our knowledge, ours is the first sufficiently powered randomized study that shows the benefit of low-dose dexmedetomidine infusion in this surgical patient population," Dr. Daqing Ma of Imperial College London in the UK and colleagues state in their report, published online August 16 in The Lancet.

Up to half of patients may develop delirium after surgery, and this risk increases with age, the researchers note, while up to 40% of these cases are believed to be due to modifiable causes. Delirium is associated with worse outcomes, including long-term decline in cognitive function.

Dexmedetomidine, a highly selective alpha-2 adrenoreceptor agonist, is increasingly being used for sedation in mechanically ventilated ICU patients, the researchers add, and there is evidence it may be less likely to cause dementia than other sedatives. One study found the drug improved sleep quality in ICU patients. However, the drug may also induce hemodynamic changes.

To investigate whether dexmedetomidine might reduce post-surgery dementia, the researchers randomized 700 patients age 65 and older to receive either a sub-sedative dose (0.1 ug/kg/hr), starting with ICU admission on the day of surgery and stopping in the morning of the first postoperative day, or placebo.

The odds ratio for dementia with dexmedetomidine was 0.35. Hypertension occurred in 18% of patients on placebo, versus 10% of the dexmedetomidine group (OR 0.50). Patients on placebo were also more likely to develop tachycardia (14% vs. 7%, OR 0.44). The incidence of hypotension and bradycardia were similar for both groups.

Patients given the study drug also had less pain and better sleep quality than patients in the placebo group.

"Whether the favorable effects afforded by this novel application of dexmedetomidine result in improved long-term outcomes remains unknown," Dr. Ma and his team conclude.

"This is potentially an exciting result because to date we don't really have any reliable prophylactic interventions to prevent patients from experiencing delirium, so it's really important for us to replicate this study and to find out whether or not this really is a true finding," Dr. Michael Avidan of Washington University School of Medicine in St. Louis told Reuters Health in a telephone interview. Dr. Avidan co-authored an editorial accompanying the new study.

"All too often in medicine, we've had one big study with an impressive finding and then we have immediately changed practice," he added, "only to discover subsequently that the finding isn't robust and other studies aren't able to replicate it."

SOURCE: https://bit.ly/2bMXJ8a and https://bit.ly/2boCL1j

Lancet 2016.

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