Table 1 Staff and parent perspectives from interviews, focus groups and questionnaires by theme

Trial acceptability

Parent support influenced by the nature of the intervention

“‘I think it’s a brilliant idea, so I am all, I am all for it” (Parent 80, interview mother, permissive).

“It’s just how are they gonna give the Paracetamol, when they are gonna give it. I mean if it was more severe, um, more of an invasive study, um, I might have been a bit, I might have had to query it a little bit more but I was happy with, with everything” (Parent 53, interview, father, restrictive).

Main reasons for consent—trust in doctors/wanting to help others

“If we can find the information to help other children in the future; that would be good” (Parent 35, interview, mother, restrictive).

“She’s in a hospital. I mean them people know better than me, so I understand that they would never put a child in harm’s way” (Parent 81, interview, father, restrictive).

Reasons for declining consent

Concerns about their child being in pain or discomfort (3 parents)

“We just felt because he could not tell us how he was feeling, like whether he was okay, or whether he was in pain, it was very difficult” (Parent 84, interview, mother, permissive)

Concern about increased workload (1 parent)

“I think allowing her paracetamol to help her temp and heart rate benefits her not tiring” (Parent 68, questionnaire, mother).

Concerns about negative impact due to child’s pre-existing medical conditions (3 parents)

“I think it was, if he had no other underlying medical condition then, and maybe if we had not have been in hospital for 16 weeks previous to that, then possibly, yeah” (Parent 84, interview, mother, permissive).

Risk of seizures due to family history (1 parent)

“My nephew has seizures [..] So we just decided that we just did not want that to even be a possibility” (Parent 84, interview, mother, permissive).

Incapacity and research evidence needed (1 parent)

“At the time he had too much other stuff going on for us to even think about being involved in the study[…] it’s seeing whether there is any research and proof that giving paracetamol straight away is the right thing to do or whether it would go away by itself” (Parent 83, interview, mother, permissive).

Deintensification as a reason for withdrawing consent

“The only time we eventually pulled him from the trial and gave him paracetamol was when he was awake and he was a lot more distressed, and that was harder for me to watch, especially, especially the way he was, and I said, look, if it’s gonna help, I’d rather you gave him it, but when he was sedated and he was ventilated and everything, he did get a temperature and, like I say, he brought it back down himself” (Parent 49, interview, mother, permissive).

“He was withdrawn because, um, he did not actually have a temperature at all and he was in a little bit of pain once he’d been extubated. So they wanted to give him some Paracetamol but he did not have any temperature any way” (Parent 76, interview, mother, permissive).

Staff concerns and protocol adherence

“I thought it [permissive threshold] was too high because at that stage the patient I was looking after was, was very distressed and very uncomfortable from what I remember I gave paracetamol because I did not fi-, I did not think it was fair on the child to leave them that hot and that distressed” (Staff 01, focus group 3).

“we are much happy to, happier to be compliant, erm, if the child was intubated and ventilated and knocked out” (Staff 05, focus group 2).

Research without prior consent

Acceptable in the proposed trial

“I do not think there’s any other way better to go about it” (P79, interview, mother, restrictive).

“So many of the trials that we have done over the last few years have worked in the same way, without getting consent and things, it’s actually more normal than, hold on a minute, I cannot do that, we need to get consent first” (Staff 01, focus group 5).