Mild Sedatives May Prevent Delirium After Operations, Says a Lancet Study

London : A mild sedative could greatly reduce the risk of people experiencing delirium after undergoing an operation, a new study has found.

The study suggests sedating patients may reduce the risk of post-operative delirium by up to 65 per cent.

The condition may affect up to one in three people who have a major operation, causing confusion and hallucinations with the over-65s particularly at risk.

The team, including scientists at Peking University First Hospital in China, believes the sedative may help the brain 'recover and reset' after surgery.

Post-operative delirium usually strikes within the first two days of a person waking from general anaesthetic.

The symptoms range from relatively mild, such as a person not knowing their name or where they are, to more severe, such as aggressive behaviour or even hallucinations.

"Post-operative delirium is a huge challenge for the medical community - and incredibly distressing for patients and their families," said Professor Daqing Ma, from the Imperial College London in the UK.

"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," said Professor Ma.

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.

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

In the new study, researchers assessed 700 patients age 65 or older who were about to undergo major surgery.

Half received a low dose of a type of sedative called dexmedetomidine after the 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.

This sedative, which is commonly used for medical procedures and in veterinary medicine, leaves a patient relaxed and drowsy, yet conscious. The drug is considered safe as it does not affect breathing.

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 procedure.

The results showed that nearly one in four patients in the placebo group - 23 per cent - developed delirium. However only just under one in ten patients - 9 per cent - who received the sedative developed the condition.

Scientists are still unsure how the sedative works, but one theory is it allows the brain to rest and recover immediately after surgery, said Professor Ma.

The study was published in The Lancet journal.