Melbourne paediatric anaesthetist Balvindar Kaur said the rising prevalence of obese children having surgery meant anaesthetists were having to use special equipment, such as large blood-pressure cuffs and ultrasound machines to find veins, because the layers of fat around their arms were so thick.

Sometimes it could be difficult and time consuming to find a vein for an intravenous line before surgery, she said, with the needle having to go into their neck because there were no other options.

Dr Kaur said a growing number of children were having their tonsils removed to treat sleep apnoea – a condition in which the walls of the throat come together or collapse during sleep to block the airway.

The anaesthetist, who works at the Royal Children's Hospital and Dental Hospital in Melbourne, said up to 60 per cent of obese children suffer from sleep apnoea compared  with 1 per cent of children at a healthy weight.

"They [obese children] get enlargement of the tissue around the tonsils and that soft tissue obstructs their breathing. That's why they don't breathe well, that's why they don't sleep well and that's why they don't necessarily metabolise well because they're tired all the time … so by relieving that obstruction they breathe better and move a bit better," she said at the Australian and New Zealand College of Anaesthetists annual scientific meeting in Adelaide.

Dr Kaur, who works privately for the Melbourne Paediatric Anaesthetic Group, said she was also seeing obese children presenting for dental surgery partly because their high-sugar diets had damaged their teeth. Some of these children were drinking large amounts of sugary soft drinks such as Coca-Cola. She and her colleagues recently treated a 10-year-old who weighed 70kg and a six-year-old who weighed 60kg. Both were about double the recommended weight for their age.

Obese children presented unique challenges for anaesthetists, Dr Kaur said, because compared with other children, they had double the risk of high blood pressure, asthma and gastric reflux. They also have 27 times the risk of type  2 diabetes.

For this reason, Dr Kaur said she tried to assess obese children well before surgery to ensure she had enough time to calculate suitable drug doses, potentially prepare a second anaesthetist, and source appropriate equipment such as larger beds and airway tools to fit them.

"Most children have a clean, pristine medical history … but with obese children I have to ask about their lungs and other systems … and some of them have heart troubles in their adolescent years that have required stress testing."

Because obese children have additional pressure on their heart and lungs, Dr Kaur said they were more likely to have low oxygen levels during surgery and need care in a high-dependency unit after surgery to ensure their breathing returned to normal.

"That puts a strain on the system because they can't just come in for day surgery and go home. They need to stay overnight," she said.

"They're also sensitive to painkillers like morphine. They have a far less requirement because of their abnormal breathing patterns, even after corrective surgery. We don't give them as much because they won't resume normal breathing for themselves at the end of (surgery)."

With one in five children now overweight or obese in Australia, Dr Kaur said the government should do more to address the problem which is predicted to get worse. She said Australia was lagging behind the US, UK and Europe in dedicating specific resources, research and strategies to prevent the rising obesity rate in children.

"Obesity has overtaken smoking as the leading cause of premature death, and is the single biggest public health threat. This is compromising children's health and development and putting a great strain on medical resources."

Given anaesthetists often met obese children and their parents when they were having surgery, Dr Kaur said the specialists were in a unique position to talk to them about the health impacts of their size and the improvements that could be seen if they lost some weight.

While it was a difficult issue to broach because obese children have low self-esteem and their parents may feel their parenting is under fire, she said it was a serious health issue that should be discussed in a productive way.

"We need a bit more education and means for tackling it," she said. "We need upskilling and resources from all angles to allow us to better educate parents and children about this problem."

Julia Medew travelled to the Australian and New Zealand College of Anaesthetists' annual scientific meeting courtesy of the college.