Feasibility of remote echocardiography with satellite transmission and real-time interpretation to support medical activities in the austere medical environment.

Echocardiography is an essential tool in the evaluation of patients with cardiac emergencies and chest trauma. The objective of our study was to establish the feasibility and diagnostic accuracy of a portable satellite transmission system in the assessment of cardiac emergencies for the real-time support of mass casualty and humanitarian relief efforts. Twelve patients with various degrees of cardiac structural disease identified by conventional inhospital transthoracic echocardiography were transported to a remote portable field hospital where transthoracic echocardiography was performed with a handheld echocardiographic device. Images were then relayed by a commercial satellite to a level III trauma center where they were interpreted in real time by a cardiologist. Remote studies were recorded at the field hospital before satellite transmission and again on download at the receiving facility. The remotely acquired studies before and after satellite transmission were compared with each other and subsequently compared with conventional hospital transthoracic echocardiograms for technical quality and diagnostic accuracy using a blinded, single-reader, side-by-side comparison. Excellent agreement was found between the recorded field-site and satellite-transmitted images with an overall average of 95% concordance. When the field data acquired with the handheld device and satellite transmission were compared with conventional inhospital echocardiography, a high degree of agreement was demonstrated in overall technical quality (83%) and assessments of left ventricular ejection fraction (100%), pericardial effusion (100%), and left ventricular size (92%). This study demonstrates the feasibility and diagnostic accuracy of remote, real-time echocardiography using satellite transmission for mass casualty triage or humanitarian relief efforts.

Satellite and mobile wireless transmission of focused assessment with sonography in trauma.

OBJECTIVES: Focused assessment with sonography in trauma (FAST) can define life-threatening injuries in austere settings with remote real-time review by experienced physicians. This study evaluates vest-mounted microwave, satellite, and LifeLink communications technology for image clarity and diagnostic accuracy during remote transmission of FAST examinations. METHODS: Using a SonoSite, FAST was obtained on three patients with pericardial and intraperitoneal effusions and two control subjects in a remotely located U.S. Army Combat Support Hospital. A miniature vest-mounted video transmitter attached to the SonoSite sent wireless ultrasound video 20 m to a receiving antenna. The signal was then transferred over VSAT satellite systems at 512 kilobaud per second (kbps), INMARSAT satellite systems at 64 kbps, and over LifeLink on a moving ambulance through a metropolitan wireless traffic-management network. Clarity and absence or presence of effusions were recorded by 15 staff emergency physicians. RESULTS: Average sensitivity, specificity, and accuracy were 87% (95% confidence interval [CI]=79% to 95%), 85% (95% CI=81% to 89%), and 86% (95% CI=82% to 90%) for the Premier Wireless Vest; 98% (95% CI=97% to 99%), 83% (95% CI=75% to 91%), and 86% (95% CI=82% to 90%) for VSAT; 95% (95% CI=94% to 96%), 70% (95% CI=58% to 82%), and 75% (95% CI=70% to 80%) for INMARSAT; and 82% (95% CI=73% to 91%), 83% (95% CI=74% to 92%), and 82% (95% CI=78% to 86%) for LifeLink with clarity of 3.0 (95% CI=2.7 to 3.3), 2.9 (95% CI=2.6 to 3.2), 1.3 (95% CI=1.2 to 1.4), and 2.1 (95% CI=1.8 to 2.4), respectively. CONCLUSIONS: Accuracy correlated with clarity. Roaming vest transmission of FAST provides interpretable, diagnostic imagery at the distances used in this study. VSAT provided the best clarity and diagnostic value with the lighter, more portable INMARSAT serving a lesser role for remote clinical interpretation. LifeLink performed well, and further infrastructure improvements may increase clarity and accuracy.

Wireless and satellite transmission of prehospital focused abdominal sonography for trauma.

OBJECTIVE: As military operations become smaller and more remote and as humanitarian missions increase, ultrasound technology is emerging as a valuable asset for defining injuries in austere settings. This study evaluated the feasibility of focused abdominal sonography for trauma (FAST) examinations in a field environment with real-time images sent wireless to an antenna and over satellite. METHODS: Using a 6-lb SonoSite portable ultrasound device with battery pack, FAST examinations were performed on a healthy volunteer, transferred wireless at distances of 1,000 and 1,500 feet from the receiving antenna using a vest-mounted microwave transmitter, and then redirected over satellite (INMARSAT) to a remote hospital for review by emergency physicians, and a radiologist. RESULTS: Real-time wireless transmissions at 1,500 feet reliably yielded images without quality or interpretability drop compared with those recorded digitally at the examination site. A 32% reduction in image quality and interpretability was seen with still images and a 42% reduction was noted with cine loops using INMARSAT. The authors did not find the upper distance limit of the wireless transmitter used. CONCLUSION: This study suggests 1) that remote FAST examinations are plausible for prehospital care and triage using new-generation portable ultrasound units, 2) that line-of-sight transmission of FAST examinations when compared with on-site images results in no degradation in image quality or interpretability at distances used, 3) that ranges greater than 1,500 feet are feasible for interpretable examinations and therefore line-of-site mass casualty or field triage sites, and 4) that real-time INMARSAT transmission of FAST examinations at 64 kbps may serve a limited role for remote clinical interpretation.

Feasibility of real-time echocardiographic evaluation during patient transport.

Echocardiography is a key diagnostic tool in evaluating patients with cardiac emergencies and chest trauma. The lack of qualified real-time interpretation limits its use by emergency first responders. Early diagnosis of cardiac emergencies has the potential to facilitate triage and medical intervention to improve outcomes. We investigated the feasibility of remote, real-time interpretation of echocardiograms during patient transport. Echocardiograms using a hand-carried ultrasound device were transmitted from an ambulance in transit to a tertiary care facility using a distributed mobile local area network. Transmitted studies were reviewed by a cardiologist for ability to interpret predefined features. Transmission quality and reliability were assessed. Echocardiographic images were successfully transmitted greater than 88% of transport time. The evaluation of left-ventricular size and function, and presence of pericardial effusion were greater than 90% concordant, but only 66% of all echocardiographic features were concordant. Most transmission losses were brief (