By: 9 December 2015
Paving the way to ever-safer anaesthesia

Paving the way to ever-safer anaesthesia

Researchers at Lancaster University have made a breakthrough with a safer anaesthesia which could help prevent patients suffering stress to the body and from feeling pain or becoming aware during anaesthesia.

The breakthrough could help provide a new guide for anaesthetists and lead to much quicker recovery times for patients following operations, as greater optimisation of dosage could lead to drugs being significantly reduced.

In a study published in Anaesthesia, researchers tested a new, more nuanced form of investigating the subtle clues sent out by the human body during anaesthesia – particularly the cardiovascular signals that can indicate the state of the pain-monitoring autonomous nervous system. The results have proved more reliable than existing methods.

The article, entitled ‘The discriminatory value of cardiorespiratory interactions in distinguishing awake from anaesthetised states: A randomised observational study’, found that by looking at how key indicators – such as ECG, respiration, skin temperature, pulse and skin conductivity – interacted with one another, researchers could much more accurately predict whether a patient was awake or anaesthetised. They also helped distinguish between the effects of two commonly used anaesthetic drugs, propofol and sevoflurane.

The study measured the depth of anaesthesia of 27 patients in good health during surgery in the UK and in Norway. Readings were taken at a high frequency – several hundred samples per heart beat – for 30 minutes while the patients were awake before their surgery and for up to 30 minutes during general anaesthesia. The signals showed, with a high degree of accuracy, how the patients reacted to the anaesthetics.

“The likelihood of waking up during surgery is extremely small but, if it happened, it could be a distressing experience. So we are delighted to pave the way to a new tool for gauging depth of anaesthesia,” said Peter McClintock, of Lancaster University.

The collaborative research involved consultant anaesthetists from University Hospitals of Morecambe Bay NHS Trust in North West England.

Andrew Smith, consultant anaesthetist at Royal Lancaster Infirmary, added: “This publication is highly topical given the recent audit on accidental awareness under general anaesthesia conducted by the Association of Anaesthetists of Great Britain and Ireland and the Royal College of Anaesthetists. While it is early days, the prospect of a monitor of anaesthetic depth that relies on measurements of the circulation and respiration is very attractive. I look forward to further collaboration with Lancaster University in the interests of enhancing the care of patients in the NHS locally and nationally in the future.”

Source: Lancaster University



Kenwright, D.A., Bernjak, A., Draegni, T., et al. (2015) The discriminatory value of cardiorespiratory interactions in distinguishing awake from anaesthetised states: a randomised observational study. Anaesthesia 70, 1356–1368.