A man who performed CPR on a teen before she was pronounced dead after huffing butane says if teens gave any thought about what this did to their parents, "they just wouldn't do it".

Christchurch man Rene Heyde was the first on the scene when 17-year-old Poihaere Eru was found lying on the side of a Christchurch road. She had been huffing butane along with two friends, aged 14 and 16.

Heyde, described the scene as "surreal".

"I was just driving home from work about 4.30pm and I saw a girl lying down and there was another girl leaning over her. I thought it may have been a fight or scuffle first off, and I asked the other girl what happened and she wouldn't tell me.

"Another lady stopped and helped. We just got her into the recovery position while I called the ambulance, but then I was performing CPR while we waited for them. I was performing CPR for about 20 minutes while the ambulance got there and sorted themselves.

He said by that stage, the girl's mother had arrived.

"It was just heartbreaking. She was just there talking to her baby - willing her to live."

"I was sort of detached at the time and it was surreal. It wasn't until afterwards that I started to realise what had happened.

"I think it had really just shut down her brain."

Heyde said he thought there were a bunch of girls, but they had initially run away, although one had returned.

"I took pictures of the gas canisters which were hidden in the bushes to show police in case they tried to get rid of them or anything.

"If teenagers thought about what that mother had to go through, they just wouldn't do it," he said.

"It was just horrible. I can't figure out why the hell they do it, because if they just gave it five minutes thought, they would think 'how could I do that to my parents".

Heyde said he was almost certain the group had stolen the canisters - "there was that much of it, it would have cost a fortune" -  and he called for tighter restriction on how it's stored in shops.

"It needs to be locked away and out of immediate reach."

Heyde's plea comes after New Zealand's chief coroner today said the huffing problem was worse in New Zealand than first thought.

Judge Neil MacLean earlier called for the urgent review on the practice when two Dunedin teenagers suffered serious burns when two LPG bottles they were allegedly sniffing exploded in July.

One of the teenagers, Jamie Jury, 18, who suffered burns to 60 per cent of his body, last week woke up from an induced coma at Middlemore Hospital.

Jamie's father, Steven Jury, said he had never heard of "huffing" before tragedy struck his family, but after learning about Eru's death, he now believes it was more common.

"It's something that I never thought would happen, and it's still happening. I don't know how you can stop it," he said.

"I think parents need to just open their eyes a bit. I think I turned a blind eye to some things in some ways, trying to imagine that it wouldn't be happening."

Jury earlier said he knew his son had a go at petrol in the past, but he didn't want to believe it - "now I believe everything," he said.

His son has a long journey to recovery, with doctors initially saying he could be in hospital for up to six months.

Jury said the past week had been "pretty emotional" as the teenager remembers nothing about the fire or how it started.

"He's still not really talking because he is clogged up in the throat with the tube being down there for so long. He's very hard to understand, sort of blurring words," he said.

"He doesn't have a clue what happened, why he is up here. I explained to him that he was in a house fire and it was our house. I showed him photos of our house, but I haven't explained to him how the fire started. I'll wait before I hit him with that one."

A Middlemore Hospital spokeswoman said the second teenager, Brendon McLeod, 17, who also suffered burns in the fire, was transferred to Christchurch Hospital.

RESEARCH

MacLean said research into gas inhalation had produced alarming results, showing it was mostly practised by male teenagers.

The youngest death was of 12-year-old Darius Logan Claxton in New Brighton in May, and the oldest was a man in his late-20s.

MacLean initially believed there had been around 30 huffing-related deaths in the last 11 years, but today said there were more than that.

He would not speculate on the number of deaths, saying there was international evidence that some go unnoticed.

"I don't want to overstate it or understate it until we are reasonably confident that the figure is about right. We are conscious that while in theory the coronial system should have the accurate information, we are not so sure when you go back further in time before 2007.

"International evidence suggests that often it's under-reported overseas because the death is signed off as a stroke or a heart attack," he said.

"It's the tip of the iceberg too because everyone who dies, heaven knows how many others are permanently impaired either mentally or physically."

He said youths were inhaling whatever they could get their hands on, though propane and butane appeared to be more common in New Zealand.

Addiction Centre director Doug Sellman said butane was "not far away from heroin in terms of the risk of overdose".

Butane and other solvents caused users to lose inhibitions. It poisoned the respiratory system, affecting breathing and could increase heart rate.

A surge of adrenaline could cause that beating to become irregular and stop the heart.

MacLean said accessibility may be one reason why youths are turning to inhaling gasses.

"They get their information on what they can get a high on from their ill-informed friends. They just don't realise how dangerous it is."

He said there was no one solution to huffing, with some recommendations suggest it is unwise to be too specific when setting restrictions.

"My first impression is there needs to be some kind of a wider degree of knowledge of the symptoms to be looking out for."

He said huffing was not unique to New Zealand, with the native community in Canada and aboriginal community in Australia also having a problem.

"It's very much a third world problem, in the poorer parts of the world. In New Zealand it's interesting, we are not a third world country but this is a phenomenon. You wonder how does it fit in the present demographics of New Zealand."

McLeod is also working with the Mortality Review Committee and the New Zealand Drug Foundation to get further information on huffing.

He is expecting to release his findings mid-September.

SIGNS HARD TO READ

New Zealand Drug Foundation chief executive Ross Bell said it wasn't easy to pick up symptoms because huffing wasn't only practised by at-risk youth.

"They could be high performing kids doing well at school who on a one off occasion experiment on this stuff. In that kind of case, there are no signs to look out for.

"But if there are kids that might be using these substances on a regular basis there are things that parents can look out for."

Bell said if parents find empty glue containers, lighter refill canisters, or other aerosol cans in the child's possession, it could be a sign.

Chemical smells on their breath or their clothing, paint or chemical stains on their hands, face or clothing, or drunken behaviour were also red flags.

"While it's important to watch out for those signs, parents need to make sure they have an open relationship with their kids," he said.

- © Fairfax NZ News