The Paediatric Refill Study (PRefill)

Following recruitment, patients will have two devices placed on their skin, one on a limb (e.g. forearm), and one on their chest. They will be fixed to the skin using medical adhesive tape. The devices will be left on for around 1 hour on the "well patients" who are on a general paediatric ward. At the end of this time a member of the research team will remove the devices.

For patients going to the paediatric intensive care unit (PICU) the devices will be used to gather the CRT data before admission (where possible), during and following discharge from the PICU. The PICU participants will have the device left on during their stay, with the agreement of the clinical team caring for the patient, with the device being resited every 4-6 hours as is normal practice for medical devices attached to the skin. Data will be collected in this way during the PICU stay (which is typically 2-3 days) or until the patient is transferred to the general ward. Before they go home, these participants will be monitored again for up to an hour with the CRT devices to obtain data when they are well.

Collecting data in this way should allow us to show that our CRT device can detect a 30% difference in perfusion between the well and the unwell patient. By comparing well patient to unwell patient, and by comparing unwell patient, with themselves when well. For each participant we will collect routine demographic details, medical history details, Fitzpatrick skin colour assessment (that is their skin tone according to a recognised scale), height, weight and vital signs. Where taken, we will collect clinically relevant data in relation to the treatment received and results of clinical investigations for correlation with our device data. Patients on the PICU will have noninvasive measures of perfusion performed by the clinical team. The research team will also perform these at agreed times suitable to the care of the patient. This will include capillary refill and ultrasound assessment of blood flow (cardiac output).

We will also conduct a semistructured interview with the patient and/or their parents/carer at the time of the study to gain feedback on the device. This should take about 15 minutes and will take the form of a semistructured interview. We will also seek user (i.e. healthcare professionals) feedback on the device and the accompanying GUI using a semistructured interview (approximately 15 minutes).

Inclusion criteria

• Children & Young Adults
• Patients aged 1 month to 15 years with parental or legal guardian written informed consent.
• Patients groups:
• Patients who require PICU or high dependency care
• Matched controls who are well (PEWS<3)
• Must have a realistic prospect of survival
• Parents/carers (for the interview element of the study):
• Parents/carers of children recruited into the PRefill study
• Healthcare professionals (for the interview element of the study):
• Healthcare professionals who have cared for a child with the device on

Exclusion criteria

• Children & Young Adults
• Known pregnancy
• Underlying cardiac anomaly likely to affect perfusion,
• PEWS ≥3 (in matched well controls)
• Severe eczema/burns/other skin condition on site where CRT device needs to be positioned
• Known allergy to medical adhesive
• Parents/carers (for the interview element of the study):
• Unable to communicate despite translation services
• Healthcare professionals (for the interview element of the study)
• None