Point-of-care ultrasound (PoCUS) is a rapidly evolving method of clinical assessment within the intensive care unit (ICU) with training predominantly aimed at physicians. Routine whole-body PoCUS (lungs, heart, abdomen and blood vessels) when conducted by physicians benefits patient care and outcomes including reducing the risk of prolonged ICU stay (>7 days) and mechanical ventilation as well as reducing utilisation of other diagnostic tests. However, physician-only use of PoCUS does not allow for use as a routine assessment method in the ICU due to the low physician to patient ratio and poor ultrasound accreditation rate.

Providing other healthcare professionals such as Advanced Critical Care Practitioners (ACCPs), ICU nurses and physiotherapists with PoCUS skills increases the proportion of trained staff to perform routine PoCUS in the ICU. This could aid earlier identification of abnormal pathology, earlier treatment, and prevent patient deterioration. The advancement of handheld PoCUS technology is making ultrasound more portable, cheaper and easier to use.

The increased accessibility of PoCUS combined with growing evidence of its diagnostic accuracy compared to other modes of imaging means PoCUS use is gaining traction globally. However, little to no research exists investigating the feasibility of implementing scheduled interprofessional PoCUS in the ICU and its impact on patient outcomes.

This study aims to evaluate the acceptability and feasibility of a quick and simple whole body ultrasound scan performed by trained ACCPs, ICU nurses, physiotherapists, and doctors at set time points throughout the patients ICU stay. The investigators want to find out the most common barriers and facilitators to intervention implementation and to explore the key clinical outcomes for use in a future definitive RCT.

PoCUS is a non-invasive procedure that does not use harmful radiation. PoCUS therefore minimises patient risk and has superior diagnostic capabilities compared to the stethoscope. Non-medics can learn and utilise PoCUS with comparable accuracy. Routine whole-body PoCUS could enable more informed and timely clinical decision-making regarding lifesaving interventions such as patient positioning (proning), ventilatory support, and fluid balance optimisation. PoCUS could decrease time spent in diagnostic testing outside the ICU, minimising spread of infection through reduced patient contact, and reduce risk associated with patient transfers to scanning. Increased PoCUS use therefore has the potential to positively impact more patients, with less disruption to patient care.

In addition, increased routine PoCUS use by multiple professions will create a shared communication platform with the potential to enhance interdisciplinary collaboration. PoCUS use meets the growing demand for advanced assessment skills in the ICU, increasing autonomy and improving staff retention. PoCUS may reduce service costs by limiting the need for other imaging. In addition, the economic value of fewer diagnostic tests and the potential for improved patient outcomes could be significant. Storage solutions for diagnostic imaging present an ongoing challenge throughout the healthcare service. Imaging is stored on multiple platforms, making reviewing of images often location dependent. Identifying the most accessible storage platform for routine image review could significantly influence utilisation of images during patient assessment.

The investigator's aim is to evaluate the acceptability and feasibility of the INSIGHT Intervention within the ICU environment. This comprises performing a whole body PoCUS (INSIGHT) scan on days 1, 3, and 7 of ICU admission, with review by the clinical team.

The INSIGHT Scan is a whole-body PoCUS scan which comprises imaging the following windows:

1. subcostal
2. inferior vena cava cardiac view
3. left hemidiaphragm
4. bladder
5. right hemidiaphragm
6. six major central veins (left/right internal jugular/ subclavian/ femoral veins)

Design and Setting: A mixed-methods study across 2 adult ICUs (30 beds) within the critical care centre at KCH, London.

The Study will be conducted in two stages:

Stage 1 Aim: The aim of this stage is to identify and address the acceptability and feasibility of the INSIGHT intervention from the perspective of key stakeholders.

The primary objectives will be to:

1. Assess barriers and facilitators to delivering the delivering the INSIGHT intervention
2. Refine the INSIGHT intervention so that it is acceptable to key stakeholders
3. To have a clear understanding of intervention fidelity and ability to recruit participants (33, 34)

The following feasibility outcomes will be evaluated:

1. availability of a trained staff member to perform the INSIGHT scan when an eligible patient is identified
2. barriers to completing the INSIGHT scan
3. barriers to accessing INSIGHT scan images during ward round
4. barriers to incorporating the INSIGHT scan into routine clinical care
5. number of eligible patients (screening data)
6. screening and recruitment methods (number of 'missed' patients and reason for non-enrolment)

ICU Patient Sample: Convenience sampling will be used to recruit 20 adult (18 years or over) ICU patients.

ICU Staff Sample: Prior to stage 1 commencement, a minimum of 10 staff members will have completed the training and will be approached for consent to participate in this study.

Fifteen INSIGHT-trained and non INSIGHT-trained clinical staff will be recruited using purposive sampling (ACCPs, nurses, doctors, physiotherapists) to either attend one of two focus groups.

Data collection methods:

• Go-along interviews with trained staff whilst performing the INSIGHT scan
• Ward round observations
• Questionnaires will be distributed to staff before any patients receive an INSIGHT scan, the after 5, 10, 15, and 20 patients have been scanned
• Focus groups

Stage 2 Aim: To evaluate the feasibility of the INSIGHT intervention trial design to inform a future adequately powered randomised controlled trial.

Primary Objective: To evaluate the feasibility of a randomised controlled trial of the INSIGHT Scanning Protocol.

Feasibility objectives:

1. Recruitment rate and willingness of approached eligible patients to consent
2. Number of complete scans (i.e., 6/6 windows)
3. Reasons scans not performed/completed
4. Time taken to perform and report INSIGHT scans
5. Proportion of complete scan reports compared to the total number of scans performed
6. Staff perceived feasibility of the INSIGHT Scan on days 1, 3, and 7 of ICU admission

6. Adherence to the INSIGHT Scanning Protocol, measured by the number of INSIGHT scans and reports completed compared to the number required in the INSIGHT protocol design 7. Rate of adverse and serious adverse events

Exploratory clinical objectives:

1. Number of diagnostic tests (chest X-ray, non-INSIGHT ultrasound, CT scans [excluding head]) per patient during ICU stay
2. Radiation exposure (measured in mSv)
3. Duration of mechanical ventilation
4. ICU length of stay
5. Number of nosocomial infections
6. Number and type of incidental clinical findings detected using the INSIGHT scan and time to a clinical intervention to address this incidental clinical finding

Patient participant sample: The investigators will recruit 60 patients during the study.

Randomisation: Participants will be randomised to receive the INSIGHT intervention or standard care (no INSIGHT intervention) on a 1:1 basis.

Patient Inclusion Criteria:

1. Patients 18 years of age or more
2. Critically ill patient requiring level 2/3 care
3. Provides consent to participate (or consent given by substitute decision maker)
4. Anticipated to be admitted to ICU for at least 72 hours from time of admission

Patient Exclusion Criteria:

1. Injuries that prevent probe positioning:

   1. Dressings that restrict the INSIGHT window views
   2. Flail chest
   3. Other unstable fractures that might prevent scanning
   4. Open abdominal/thorax wounds
   5. Surgical emphysema

2. Uncontrolled agitation or pain: this will make scanning more challenging and affect image acquisition

3. Clinical instability requiring prioritisation of stabilising or resuscitative care

4. Allergy to ultrasound gel

5. Anticipated withdrawal of care in the next 24 hours

Staff Inclusion Criteria

i. Nurse, ACCP, physiotherapist, or doctor ii. Completion of an advanced course in ICU nursing, ACCP course, ICU physiotherapy or medicine iii. Working in a participating ICU for a minimum of 6 months before enrolment on training course iv. Competent or undergoing training in the INSIGHT Scan

ICU staff exclusion criteria

i. Any injuries or musculoskeletal conditions that would be exacerbated by performing ultrasound ii. On rotation or planning on leaving ICU role in 6 or less months

The data collected will only be used for publications relating to this trial. Relevant data to the publications will be published. More detailed datasets will be available on request. However these data cannot be used for any other research.