All of this information is inaccurate. Letby didn't lie and claim not to know about air embolism in babies. That's not your fault, because it has been presented that way by journalists, specifically Judith Moritz's and Jonathan Coffey in their book, Unmasking Lucy Letby. That gets a lot of attention because Moritz is the BBC's main voice on Letby.
What Letby said is that when air embolisms were discussed on her unit, it was usually with regard to adults (that would be women delivering by Caesarean section especially). She never said she didn't know about them in babies: in fact she was clear that they'd had training in avoiding them, but not much else.
That means too that the text exchange - such was about another baby, not Baby O, but that is another thing Moritz gets wrong, was a perfectly reasonable discussion of a real risk.
So, according to Moritz and Coffey:
>When she was questioned by police, Letby said all nursing staff would be aware of the dangers of an air embolus [the air bubble itself], but she claimed she didn’t know much beyond this. She said ‘I don’t know exactly what [an air embolism] is. When we were taught about lines, we were taught about clearing lines because that’s what it would lead to.’ She also told police she was only aware of air embolisms in adults.
But - we have the transcript of the police interview, and they've quoted partially and misrepresented it. It's quite shocking how they have twisted it - either dreadfully careless or just not truthful.
Someone on Reddit has transcribed the interview, with link to video sources
https://www.reddit.com/r/LucyLetbyTrials/s/nIccei5cMA
Here is the relevant part.
Q: And what about air embolisms, Lucy? Did you receive any training in relation to those?
LL: No.
Q: Okay. Were you aware of them or?
LL: Not really, no.
Q: Have you heard of them before?
LL: Yes.
Q: When was that?
LL: I've heard of them more from an adult perspective.
Q: And tell me what that was in relation to.
LL: I don't know specifics. Like sometimes we've had mums on the unit who've been unwell and it's been found they've had AAP, pulmonary embolism. So that's just how I've heard of it via that.
Q: Specifically whilst working on the neonatal unit, have you ever come across it before?
LL: No.
Q: Has the air embolism training ever popped up in respect of dangers with other training that you might have had?
LL: Not that I can think of specifically.
Q: No, or any sort of general nursing training before you qualified?
LL: It's been mentioned in terms of line care. You'd have to be mindful that you don't leave a line open and things like that. But it's not something that's discussed frequently in any detail.
Q: When you say line care, you needed that competency assessment in May 2015 that we talked about, the safe administration of medication by the different lines. Is that the type of training that you're referring to?
LL: Yes. I'm not sure if that's on the list or not.
I hope Moritz and Coffey are planning to fix this in the revised edition. It's one thing having opinions on the case, but this claim of theirs is just objectively false.