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Infusing mild sedative may 'prevent post-op delirium'

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A mild sedative could greatly reduce the risk of patients experiencing delirium after an operation, according to a study involving UK researchers.

Sedating patients after they undergo an operation may reduce the risk of post-operative delirium by up to 65%, suggests the study by Imperial College London and the Peking University First Hospital.

“Post-operative delirium is a huge challenge for the medical community”

Daqing Ma

The researchers said they thought the sedative may help the brain “recover and reset”. For their study, they assessed 700 patients age 65 or older who were about to undergo major surgery.

Half received a low dose of the sedative dexmedetomidine after their operation – as an infusion directly into a vein in their arm – while half received a placebo salt-water infusion. The patients received the infusion of sedative or placebo around an hour after surgery, and for the next 16 hours.

Both groups received the same general anaesthetic before undergoing their operation. They were then assessed for symptoms of delirium every day for a week after their procedure.

The results revealed that 23% of patients in the placebo group developed delirium, compared with only 9% among those who received the sedative, said the study authors in The Lancet.

The commonly-used sedative, which is considered safe and does not affect breathing, leaves a patient relaxed and drowsy, yet conscious.

“This sedative may be a potential method of preventing post-operative delirium”

Daqing Ma

The authors noted that previous research had indicated the drug might help prevent delirium, but theirs was the largest study to show such beneficial effects. The study also confirmed there were no side effects, they said.

The researchers acknowledged that they were currently unsure how dexmedetomidine worked in relation to delirium, but suggested that it may allow the brain to rest and recover immediately after surgery.

Co-lead author Professor Daqing Ma, from Imperial College, said: “Previous studies have shown that patients who struggle to sleep after their operation – perhaps because they are in pain or on a busy, noisy ward – are at increased risk of delirium.”

He added that dexmedetomidine seemed to not only trigger sleep, but to mimic the natural state the brain entered during sleep.

“Although other sedatives induce sleep, they do not trigger the natural ‘sleep state’ the brain requires to rest, reset, and recover,” he said.

Further results showed the patients given the sedative had fewer post-operative complications than the placebo group, and were discharged from hospital earlier, said the researchers.

Imperial College London

Taking mild sedative may prevent post-op delirium

Daqing Ma

They now plan to assess if the sedative has long-term benefits beyond the seven-day period in the current study.

Professor Ma added: “There is still much more work to do around post-operative delirium, as we still don’t fully understand what is happening in the brain, and why some patients are more at risk.

“However, these findings suggest this sedative may be a potential method of preventing post-operative delirium in some patients,” he said.

Post-operative delirium usually strikes within the first two days of waking from general anaesthetic and may affect up to one in three people after a major operation, with the over-65s most at risk.

Symptoms range from relatively mild, such as patients not knowing their name or where they are, to more severe, such as aggression, believing people are trying to harm them or hallucinations.

The causes are unknown, but one theory is that major surgery can trigger inflammation throughout the body, which in some cases can spread to the brain. The risk of the condition increases with age, and it seems to strike more often when patients undergo major, lengthy operations.

It can last from a few hours to a couple of days, and some research suggests it may be linked to an increased risk of older patients later developing dementia.

Professor Ma said: “Post-operative delirium is a huge challenge for the medical community – and incredibly distressing for patients and their families.

“In many cases patients become almost child-like, and do not understand where they are, what is happening, and become very upset. Hospital staff have also been injured by delirious patients becoming aggressive,” he added.

The latest research was funded by the Braun Anaesthesia Scientific Research Fund and Wu Jieping Medical Foundation.

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Readers' comments (2)

  • Pussy

    What an outmoded word delirium is! In all my years of nursing I have never used it and it has to be said it is not used in common medical parlance! It sounds very quaint!

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  • After experiencing this first hand as a patient and a nurse, I recommend that more research is undertaken swiftly. It was the worst 2 weeks of my life on an HDU as a patient believing the nurses were doing more harm than good. I didn't dare tell my family until I left the unit I was so frightened and I'm 42 yrs old.

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