Study Design:
This study was designed as a feasibility trial of tele-POCUS in a physician provided emergency medical service in Vienna, Austria. Ethical approval (Number:1771/2020) was obtained by the Ethics Committee of the Medical University of Vienna (Martin Brunner, MD) before patient enrolment. The study conformed to the Declaration of Helsinki guidelines regarding research on human subjects and followed the tenets of Good Clinical Practice. The trial was registered before enrolment at ClinicalTrials.gov by the principal investigator Martina Hermann (11/2020 ClinTrials.gov NCT04612816). During a period of 8 months, 24 prehospital performed POCUS examinations were live transmitted (audio and video) to an expert located at the Medical University of Vienna. Subsequent to the rescue mission, the physician evaluated the feasibility and quality of POCUS and reported technical problems using a questionnaire.
Emergency Physicians:
The participating rescue physicians (n = 4) were residents and specialists at the Department of Anaesthesia, General Intensive Care and Pain Management of the Medical University of Vienna with clinical experience of a least 3 years and moderate experience in in-hospital POCUS (daily clinical routine examinations at intensive care units and in the perioperative setting in anaesthesia).
The supervisor was a specialist in anaesthesia and critical care medicine at the Medical University of Vienna with the European Diploma in advanced critical care echocardiography.
Patients:
Patients treated by the participating emergency physicians were included, if prehospital POCUS was performed due to at least one of the following criteria: trauma, acute dyspnea or circulatory failure. Informed consent was obtained post hoc. CONSORT diagram is available online as suppl 1.
Prehospital Ultrasound and data transmission:
POCUS was performed with the portable ultrasound device Lumify™ (Philips Ultrasound, Inc., 22100 Bothell-Everett Hwy Bothell, WA 98021 − 8431 USA). For transthoracic echocardiography, the transducer S4-1 (4 − 1 mHz) and for transabdominal sonography, the transducer C5-2 (5 − 2 mHz) were used. POCUS was performed on-scene according to standardized protocols of emergency ultrasound (e.g. Focus-assessed transthoracic echocardiography, FATE; Extended Focused Assessment with Sonography for Trauma, eFAST). The examination was chosen according to the leading clinical symptom (e.g. dyspnea, cardiac arrest). Concomitant to the start of POCUS, remote data transmission was initiated utilizing the interactive audio-video platform Reacts (Remote Education, Augmented Communication, Training and Supervision, Philips Ultrasound, Inc., 22100 Bothell-Everett Hwy Bothell, WA 98021 − 8431 USA), which offers secure data transfer and live communication with the expert (Image 1). To establish connection, a mobile 4G-SIM-card was used, which links to the strongest signal for a defined region regardless of the provider.
Data collection:
Data collection was performed by the emergency doctor at end of mission as well as by the remote supervisor concerning image quality and sonography findings. Demographic data of the patients (age, BMI, gender) as well as inclusion criteria for POCUS (trauma, acute dyspnea or circulatory failure) and additionally other symptoms and comorbidities were recorded. Image quality of POCUS as well as quality of communication were rated on a numeric scale (1 = excellent to 10 = poor). Ultrasound specific variables (performed scans, duration of POCUS and transmission), the availability of the expert on time, delay of POCUS due to problems with data transmission as well as the occurrence of technical problems were evaluated. The questionnaire is found as online suppl 2.
Statistical analysis:
Statistical analysis was performed using Prism 9.0 software (GraphPad, San Diego, CA, USA). Demographic data are presented as mean ± standard deviation (SD) or median (25-75th percentile).