Laughing gas safety concerns

Jane Bunce
     

The safety of nitrous oxide, the common anaesthetic known as laughing gas, is under a cloud after a new study linked it to higher rates of pneumonia, wound infections and possibly heart attacks.

The Australian-led research team found patients kept unconscious during surgery with anaesthetics other than nitrous oxide suffered fewer life-threatening complications.

Yet nitrous oxide remained "near routine" in surgeries, despite accumulating evidence of its dangerous side-effects, the researchers warn.

The study looked at 2000 patients undergoing major surgery in 13 hospitals in Australia and six others in the UK, Asia and the Middle East.

Patients receiving nitrous oxide as part of their anaesthetic were about one third more likely to suffer wound infection than patients who did not receive the gas, the researchers found. They were twice as likely to suffer pneumonia, nausea and vomiting and about 25 per cent more likely to have a fever.

Overall, 210 patients, or 21 per cent of those given nitrous oxide, suffered a major complication compared with 155. or 16 per cent, of those who were not given the gas.

"The evidence is sufficiently compelling to convince me to change my practice," Australian and New Zealand College of Anaesthetists quality and safety committee chair Alan Merry told New Scientist magazine. The study also found patients who received nitrous oxide had double the rate of heart attacks and three times the death rate.

However, anaesthetists believe the gas remains safe where exposure is minimal, such as for very minor surgery and women in labour.

Research leader Paul Myles of Melbourne's The Alfred Hospital said the side-effects probably occur because the gas interferes with vitamin B12, folic acid and DNA synthesis, which are important for the immune system and wound healing.

It could also occur because administering the weak gas at its standard 70 per cent concentration limits the amount of beneficial oxygen that could be given to the patient.

The results were published in the latest issue of the journal Anesthesiology.
 

Hobart Mercury
Thursday 9/8/2007
Page: 4
Section: General News
Region: Hobart Circulation: 47,947
Type: Capital City Daily