Casualty’s Christmas special will highlight “unnoticed” issues around hospital blood shortages, one of its stars has said.

Barney Walsh, who plays nurse Cameron Mickelthwaite, told the PA news agency the festive episode would also show how life could change quickly at any time of year, and “honour” emergency service workers who gave up their time over Christmas.

It comes after a teaser trailer for the special called All I Want For Christmas – which will see Holby City Hospital face a blood shortage – was released, in which a voiceover can be heard saying “the hospital is on amber warning, blood supplies are low”.

The 27-year-old, who is the son of The Chase presenter Bradley Walsh, told PA: “(It’s) highlighting key issues that otherwise would go somewhat unnoticed.

“Something that I learned whilst doing this episode is how quickly blood stores can go in an ED (emergency department) and in a resus (resuscitation area) in particular.

“We see at the beginning of the episode Cam stocking the blood and by the end of the episode we see how dire the situation is, and that’s something that I wasn’t aware of personally, how quickly blood can go in hospital.

“And that is absolutely true, it can just go like that, so just (highlighting) little key issues like that in the episode I think is really important and always an honour.”

The episode will feature talking heads from real-life contributors who have faced problems as a result of blood donation issues in the UK, as well as interviews with key workers in the NHS.

Walsh added: “What I love about Christmas time is being with family, and love, and cosy, and everything Christmas. It’s so easy to take that for granted when none of that would exist without your health and the NHS is responsible, the NHS is there for us, for our health.

“For these people to be there, working on Christmas and sacrificing their time, we’re playing it for a show, but these guys actually do sacrifice their time, not just Christmas, every day of the year for the benefit of the general public, and that’s worth honouring, absolutely.”

Michael Stevenson, who plays paramedic Iain Dean, added: “All of the emergency services for that matter, the knock-on effect for everybody is incredible.

“I think this episode does have a catastrophic sort of incident that sparks the episode off, but there are also moments in there showing an example about how somebody’s life can change in an instant.

“And whether it’s Christmas or the middle of summer, you don’t know what’s around the corner and that can be from a shock diagnosis, you know you’re going into hospital for one thing, and sometimes don’t come out, or don’t come out for a very long time.

“So it highlights that as well, that no matter what time of year, no matter how festive you’re feeling, or how much you want to get into the Christmas spirit, there’s always something around the corner that might mean that you’re going to need this supply of blood and the attention of the emergency services.”

The Casualty Christmas special will be on BBC iPlayer from 6am on Saturday December 21, and will air on BBC One at 9.20pm that night. It will be followed by the next series of Casualty, titled Public Property, from Saturday December 28.