Training novice users to assess stroke aetiology in remote settings using transcranial ultrasound: pilot study

Emergency care delivery to patients in remote and rural areas is limited by diagnostic restrictions and long transport times to major centres of care. People with suspected acute stroke living long distances from a hospital are unlikely to receive time-critical reperfusion therapy for these reasons. Basic brain imaging assessing blood flow in the major intracranial arteries could facilitate such care in remote settings. A 3-hour training package for novice transcranial ultrasound users has been piloted on a small group of volunteers to investigate whether they could acquire transcranial ultrasound images and video clips to potentially allow remote interpretation and optimise pre-hospital management of acute stroke.

A pilot training project was set up in a university setting in Inverness, Scotland. Volunteer clinicians and students of nursing or medicine with no practical experience in transcranial ultrasound were recruited. Participants received three 1-hour training sessions combining theoretical aspects and hands-on practice on healthy volunteers provided by a qualified neurologist with more than 2 years of experience in transcranial ultrasound. Transcranial greyscale and colour-coded duplex sonography was performed to visualise midline structures and major intracranial vessels, and to measure blood flow velocity in the middle cerebral artery, followed by an unsupervised assessment. Qualitative analysis of the anonymised feedback from participants on the training experience and its potential application was also performed.

A total of 11 volunteers were recruited in the current pilot study. The average time to complete transcranial ultrasound assessment was approximately 40 minutes. The brain midline and cerebral peduncles were correctly labelled by 64% (7/11) and 91% (10/11) of volunteers, respectively. Participants demonstrated a good performance in detecting major intracranial vessels. The correct labelling rate for the middle cerebral artery was 73% (8/11), and 64% (7/11) for the anterior and posterior cerebral arteries. There was agreement between the trainer and the participants on rating the quality of scans as assessed using a visual analogue scale. All participants gave positive feedback on the provided training and time allocated for each session. Generally, volunteers thought that operating the ultrasound machine and the probe simultaneously was difficult. It was also suggested that further follow-up training, with possible supervision, would be useful to retain the acquired skills.

Transcranial ultrasound scans of a quality to allow expert interpretation can be acquired by inexperienced transcranial ultrasound operators after receiving a brief training. This could potentially be used by medical staff working in remote and rural areas to facilitate acute care for stroke patients, but further work with a larger sample is needed.