Table 2. Study characteristics.

ID	Study design	Summary of authors’ conclusions
Adambounou 2014	Pilot study	Satisfactory image results were obtained using a low cost telesonography platform in a low-resource setting.
Adhikari 2014	Feasibility study/simulation	In a simulated disaster triage setting, it was possible to transmit, receive and interpret ultrasound videos of FAST examinations using a pair of mobile phones.
Al-Kadi 2009	User survey	Following a trial of telesonography during resuscitations in a remote hospital, the majority of staff considered telesonography to be a useful clinical and teaching tool, and could provide benefit for trauma patients.
Biegler 2013	Feasibility study	Nurses can effectively detect post-chest tube removal pneumothoraces using telesonography. The essential technical elements are Internet connectivity and a remote expert.
Blaivas 2009	Diagnostic accuracy study	The image quality, detail and resolution of ultrasound pictures recorded by one phone and then sent to another were not significantly different to high-resolution thermal printouts. However, measurements were too small to be read and reviewers had significantly lower confidence in making a diagnosis when using ultrasound images viewed on a phone.
Boniface 2011	Feasibility study/simulation	When given brief teaching on ultrasound use paramedics with no previous experience of ultrasound could successfully perform a tele-mentored bedside FAST examination.
Courreges 2005	Feasibility study	A robotic telesonography was designed and tested by two medical teams on 52 patients. Diagnoses using robotic telesonography were in concordance with results from conventional scans in 80% of cases. Conditions in which legions were small or subtle caused more difficulty
Dyer 2008	Pilot study	A telesonography system for use in major trauma cases in a remote hospital in Canada was found to be technically and clinically feasible, and enabled confirmation of diagnoses of haemoperitoneum and pneumothorax.
Ito 2013	Feasibility study/simulation	A wearable, portable telesonography robot was designed to perform FAST scans in emergency situations. This robot telesonography system was capable of capturing and transmitting ultrasound scans even during body motions such as rough breathing and coughing fits.
Johnson 1998	Pilot study	A telesonography service between remote location and a large hospital in Alberta was found to be feasible. Furthermore, remote supervision was found to be as effective at generating a reliable diagnosis as on site supervision, and the use of telesonography avoided transfer in 42% of cases and influenced management in 59% of cases.
Kim 2015	Diagnostic accuracy study	Telementored telesonography could effectively diagnose paediatric appendicitis, with a comparable degree of accuracy to in person expert ultrasound and a higher degree of accuracy than ultrasound performed by residents without mentoring.
Kim 2016	Diagnostic accuracy/Feasibility study	A smartphone can be used to accurately diagnose of the presence of paediatric appendicitis as well as to remotely interpret left ventricular ejection fraction.
Kolbe 2015	Pilot study	Didactic teaching, practical application and telementoring, can be used to support and disseminate POCUS in remote and rural areas worldwide.
Kwon 2016	Feasibility study/simulation	The provision of minimal training, and support of remote telementors allowed novices acquired diagnostic quality musculoskeletal ultrasound assessments.
Lee 2016	Feasibility/diagnostic accuracy study	Telementoring can allow novice ultrasound operators to perform scans in order to make difficult diagnoses, such as appendicitis, as effectively as onsite mentoring from an expert.
Levine 2015	Feasibility study/simulation	Using a tele-ICU system non-physicians with minimal training, can be telementored to obtain diagnostic quality images. These images can be sent without image degradation, so for most anatomic sites transmitted images are of equivalent clinically utility to those directly from the ultrasound device.
Levine 2016	Feasibility study/simulation	Low cost software can be used to transmit ultrasound images that are of high quality and that are clinically useful. Images transmitted using these methods are equivalent to images directly obtained from the ultrasound device in almost every anatomic location assessed.
Litelpo 2010	Feasibility study/simulation	The use of low cost software is able to facilitate transmission of real-time ultrasound video to an iPhone. Images can be transferred without loss of image quality and with minimal delay. Smaller delays were experienced when Wi-Fi rather than 3G connections were used.
Litelpo 2011	Feasibility study/simulation	The transmission of ultrasound video clips using wireless connections, inexpensive hardware, free videoconferencing software and domestic internet networks is feasible. It is possible to retain a standard of image quality sufficient for interpretation. Wi-Fi transmission results in less image degradation than transmission by a 3G network.
Macedonia 1998	Pilot /feasibility study	The quality of the images recovered from transmitted 3D ultrasound datasets was dependent of factors such as patient morphology and recent meals, but independent of the operator’s level of training. The authors felt that the technique had limited value without the addition of features including Doppler and real time volume acquisition.
McBeth 2011	Case series	It is possible to conduct telesonography using basic, low-cost commercial cellular networks.
McBeth 2013	Feasibility study/simulation	The telesonography system described allowed a remote expert to obtain and interpret ultrasound images so long as an internet connection is available.
Mikulik 2005	Pilot /feasibility study	It is feasible for novice users to perform carotid and transcranial ultrasound examinations when telementored by a remote expert.
Nikolic 2006	Feasibility study/simulation	It is feasible to train marine officers to produce diagnostically quality ultrasound images aboard ships.
Sibert 2008	Feasibility study/simulation	The use of an ambulance based telemedicine system may support rural EMS personnel and patients, although the system may be better suited for intubation than for ultrasound use.
Song 2013	Feasibility study/simulation	A telesonography system can be used to facilitate diagnosis of haemoperitoneum using a FAST scan performed by an emergency medicine technician, and this technique is about 88% accurate.
Strode 2003	Feasibility study/simulation	It is feasible to wirelessly transmit FAST from a field hospital and a moving ambulance to remote experts.
Zennaro 2016	Diagnostic accuracy study	Telementored paediatricians may perform POCUS in the emergency department guided in order to generate swift and reliable and diagnoses.

3G, Third Generation cellular network; 3D, Three dimensional; POCUS, Point of Care Ultrasound; EMS, Emergency services; FAST, Focused Assessment with Sonography for Trauma; ICU, Intensive Care Unit; tele-ICU, tele Intensive care.