'I was at the park when I heard a mother's cry for help. As a nurse, I sprung into action.'

Heidi Young was enjoying a day in the park with her sons when she heard it.

A woman was crying out for help a few metres away, holding her choking baby face down and attempting to administer back blows.

When nothing changed, the paediatric nurse of two decades sprung into action.

"I walked over, grabbed the baby and started doing choking first aid" Heidi told Mamamia.

"The mum was screaming: 'I didn't know what to do! I didn't know what to do!'."

After five back blows, the baby was still "limp and grey".

"She had her eyes open, but she wasn't breathing," Heidi described. "She had a complete obstruction."

Watch how to help a choking baby. Post continues after video.

"I got to the fifth back blow, and I thought, 'Shit, I'm gonna have to turn her over and start doing chest thrusts'."

"They're very invasive," the nurse explained. "You sort of have to press down the sternum. And you don't really want to have to do that, because it's not very nice."

As Heidi turned the baby over, ready to begin the chest thrusts, she couldn't ignore the "butterflies in (her) stomach".

"I was thinking, 'Oh my God, I've never had to do chest thrusts. Because as a paediatric nurse you are never there when the kids are choking, you get them at the hospital after the event," she said.

"It's not something that we deal with a lot. I just started thinking, 'I really don't want to have to do this'."

Then, the infant vomited.

"She started screaming and arching her back, which was great," Heidi told us, recalling the big "adrenaline release" that followed.

"It's the same as in the hospital in an emergency, you're switched on and cool as a cucumber while it's actually happening. You just do what you need to do, because there's really no other option," said Heidi.

"The second it was resolved, I started shaking," she told Mamamia. "I had to sit on my hands because I couldn't stop. I was just so relieved that it was over and I knew that she was going to be okay."

In that moment, Heidi turned to the "very grateful" mum, who later gifted the nurse a bottle of wine, and said: "Look, I'm a nurse, that's how I knew what to do."

As a paediatric nurse for 23 years, Heidi has worked in many hospitals in Australia and the UK. Image: Supplied.

"I didn't want her to feel bad about not knowing what to do, because lots of people don't," she said.

That day in the park wasn't the only time Heidi had to intervene with a choking child. She recalled a similar moment in a chicken shop when she noticed an 18-month-old struggling to breathe.

"I did exactly the same thing. I didn't quite get to five back blows, but she was gagging and drooling," Heidi said of the child.

It was moments like these that encouraged Heidi to start The Nest, Kids CPR, & Allergy from her parents' house in the UK, where she offers baby first aid courses, including advice on allergies.

"I thought, 'People obviously need this. This mum was screaming: 'I didn't know what to do, I didn't know what to do.' And I'm like, 'Well, I know what to do, let's teach this'."

Describing CPR as "such a simple skill to learn," Heidi encourages everyone to undergo a course.

"Why they don't teach this in antenatal classes, or why it's not government funded, I don't know," she said.

"Birth lasts from two hours to two days, if you're unlucky, and then it's done. But these skills, they're lifelong skills. It takes you an hour to learn how to do it, and you need to refresh yourself every now and again."

Heidi, who is now a clinical nurse specialist in childhood allergy, teaches the classes along with a team of nurses. 

"It's something that you don't need until you absolutely need," she said of CPR. "You never know when your child is going to choke or someone else's child is going to choke. If no one was (in the park) that knew what to do, that might have been a really different story."

Feature Image: Supplied