Dry ice likely behind why Plano driver passed out

A Plano woman passed out recently while driving her SUV.

The next thing she knew, she was in the emergency room, and doctors believe it's because of the dry ice she had in her car.

The woman does some catering on the side. She had boxes and coolers of ice cream packed with dry ice in the back of her SUV.

She drove a short distance toward the George Bush Turnpike on Coit before passing out behind the wheel.

Rescuers found her in the middle of an intersection with her foot still on the gas pedal and the SUV still in drive.

"I remember the turn at Coit and Park, and then I don't remember anything until I heard somebody say, 'she's back,'" said Janelle Twyford-Silvis.

The dry ice in the SUV started turning to carbon dioxide gas.

"It was packed all the way up to the seats," she said.

And that was robbing her of oxygen.

Her next memory is of waking up in the E.R.

Doctors, unaware of the dry ice, were running tests, ruling out low blood sugar, heart attack, and stroke.

"They finally got ahold of my husband and he was the one who said, 'Did you check for the dry ice?' and it was like oh, that makes some sense," said Twyford-Silvis.

"So, we usually think of carbon monoxide poisoning," said Dr. Mark Gamber with the Medical Center of Plano. "This is a little different. This is carbon dioxide poisoning, and it's a byproduct of dry ice. It took everybody a little bit by surprise. "

The dry ice used to keep the ice cream cold is also popular around Halloween to create a fog or smoke effect.

It wouldn't be harmful in well ventilated areas, but in an SUV with the windows rolled up, it could have been deadly.

"If there's one take home point from this, it's that dry ice has got to be ventilated," said Gamber. "You don't want to be in a closed space with it."

After oxygen treatments and three days in the hospital, Twyford-Silvis is on the mend.

"Getting back in my car was frightening after all of that," said Twyford-Silvis. "It was kind of, 'Do I get back in my car or don't? And you have to get back in your car."

Twyford-Silvis says she hasn't made any deliveries since this happened but is scheduled for her first on Thursday.

She says she's always told at pick-up to roll down her windows, and she usually does.

She's not sure why she didn't the day of the incident.

She's not sure if she got distracted or forgot, but she knows she was only on the road a short time before she passed out.

FOX 4 is on YouTube -- http://bit.ly/fox4subscribe