Five-year-old Autumn Ferguson went into a Regina dental clinic with a few cavities and left in an ambulance on life support.

The girl's lungs collapsed while receiving oxygen in the wrong way under general anesthesia, according to the surgical centre's own admission.

Autumn's parents are still in shock that routine dental surgery could take such a bad turn, and that it would be so difficult for them to get answers.

"I find out later that it was touch-and-go and that my daughter almost didn't make it," the child's father Spencer Ferguson said. "It's been absolute hell."

In August, Autumn was getting excited to start kindergarten. But first, the little girl needed to have some teeth pulled and get a couple tooth caps. Her usual dentist attempted to freeze Autumn's gums with a needle but "it freaked her out," her father said.

So she was referred to Children's Dental World on Victoria Avenue, which operates a dental clinic and a surgical centre, CDW Surgical Solutions.

Autumn's parents were told the Aug. 19 surgery would take two hours at most.

From our standpoint, there was a mistake made. - Dr. Ken Ringaert, anesthesiologist at CDW Surgical Solutions

Three hours later, Autumn's mother Brittany Ambrose, who was in the waiting room, was told that something had gone wrong. Shortly after, an ambulance arrived, and Ambrose was told Autumn wasn't breathing on her own.

"She was kept very much in the dark," Ferguson said. "There was nobody there to comfort her. There was nobody there to support her."

Autumn hugs a teddy bear she got from medical staff as she's being airlifted to Saskatoon a second time for followup care. (Submitted by Spencer Ferguson)

Ferguson said a social worker and medical staff at Regina General Hospital informed him that Autumn had suffered bilateral pneumothorax — collapsed lungs.

Autumn was airlifted to Saskatoon and has spent most of the last seven weeks in hospital and seeing specialists. Ferguson said a brain scan did not detect damage. Doctors have warned him that he'll have to restrict Autumn's movements while her injured lungs heal.

Medical documents show the little girl has scarring between her vocal cords and trachea. She is still having trouble breathing. She's awaiting throat surgery in Edmonton to repair the damage.

'A pretty scary situation'

Ferguson said he called the dental clinic repeatedly to try to get answers.

On Aug. 30, Dr. Ken Ringaert, an anesthesiologist with CDW Surgical Solutions, called Ferguson to apologize for mistakes that were made in the recovery room. He said he was not in charge of the anesthesia, and was only called into the room when things took a bad turn.

He led the clinic's investigation afterwards.

Ferguson recorded the 20-minute conversation, and CBC News reviewed the recording.

Ringaert said he had ruled out equipment problems, and confirmed it was human error. The doctor said the procedure was "uneventful" except that Autumn's lips appeared swollen so the team decided to leave a breathing tube in while the girl was taken into the recovery room.

At that point, Ringaert said, Autumn was hooked up to high pressure oxygen without a relief valve.

"Basically, the oxygen went in, and it had nowhere to get out, and that's how she got the pneumothorax," Ringaert said.

Pneumothorax is the presence of air or gas between the lungs and the chest wall, causing lung collapse.

"From our standpoint, there was a mistake made," Ringaert told Ferguson.

The five-year-old didn't get to start kindergarten in September. She received too much oxygen in the wrong way under general anesthesia during dental surgery, alleges her father. (Submitted by Spencer Ferguson)

"It was pretty obvious that she had that kind of an injury, but it wasn't really obvious as to how it happened at the time," Ringaert told Ferguson in their phone conversation.

"I don't want to leave you with the impression that this was, you know, like chickens running around with their heads cut off. It was a pretty scary situation for about two minutes in the recovery room when this first happened. Once we took her back into the operating room and she was stabilized very, very, very quickly."

Ringaert said everyone at the clinic felt "horrible," including the anesthesiologist who was in charge, Dr. Martin Weirich, and the recovery room nurse who Ringaert alleges hooked up the oxygen in the wrong way.

Ringaert told Ferguson that the clinic has handled 1,500 surgical cases in the last two years and has never had a patient admitted to hospital.

"It's devastating to everyone in the clinic that this happened. And you know, I mean it really, really, makes you, you know, take a step back and look at everything, everything about our system, everything about our people," Ringaert said.

When contacted by CBC News, CDW Surgical Solutions said it could not comment on specific cases because of patient confidentiality.

Traumatizing experience

Ferguson said he was "caught off guard" that the clinic admitted a mistake was made. He said he's too focused on his daughter's healing to pursue legal action at this point, but won't rule it out.

Autumn was allowed home on Saturday, but she is restricted to her house while the family waits for her to undergo throat surgery in Edmonton. They're nervous about putting the little girl through another operation.

"You can tell she's traumatized," Ferguson said. "Before, she was running around, dancing, singing, playing. Now, she'll come sit on the couch and cuddle with me and not move or just want to sleep. She doesn't want to do anything anymore, just tired."

His aunt, Joanne Ferguson, has set up a GoFundMe to help the young couple cope financially.

"Just to supplement the incomes that they've lost. I know if I miss a couple of days' work, I worry about bills. I worry about rent. That stuff doesn't stop coming because somebody gets sick, or because you have to stay home," she said.

Spencer Ferguson, a plumber, has had to miss a lot of work and said he's grateful that he has an understanding boss at Comfort Mechanical. His wife works for SaskTel and didn't submit her application for family leave before the current labour disruption.