Original Contribution

Tele-ultrasound and paramedics: real-time remote physician guidance of the Focused Assessment With Sonography for Trauma examination^?,??

Keith S. Boniface MD, RDMS?, Hamid Shokoohi MD, MPH RDMS,

E. Reed Smith MD, Kari Scantlebury MD

Department of Emergency Medicine, George Washington University Medical Center, Washington, DC 20037, USA

Received 31 August 2009; revised 30 November 2009; accepted 2 December 2009

Abstract

Objectives: The aim of this study was to examine the capability of ultrasound-naive paramedics to obtain interpretable focused assessment with sonography for trauma (FAST) images under the remote direction of emergency physicians (EPs).

Methods: Paramedics without experience using ultrasound participated in a 20-minute lecture covering orientation to the ultrasound machine and the FAST examination. The paramedics subsequently performed FAST examinations on a model patient, whereas the EP remained in another room, out of visual contact. The EP communicated with the paramedic via radio, viewing video from the ultrasound machine on a monitor and directing the probe movements to obtain the views of the FAST examination. We examined the success rate, time to complete the examinations, and adequacy of images from the paramedics’ first FAST examination.

Results: Fifty-one paramedics performed their first FAST examinations and were able to successfully complete 100% of the views of the FAST. The median time from probe placement to examination completion was 262 seconds (interquartile range, 206-343 seconds). The median time to complete right upper quadrant (RUQ) versus left upper quadrant (LUQ) views was 39 and 50 seconds, respectively. The time to complete the LUQ scan took significantly longer than the RUQ (P b .01). Paramedics completed cardiac and pelvic view in a median time of 42 and 25 seconds, respectively.

Conclusions: The study demonstrated that paramedics with no prior ultrasound experience could obtain FAST images under remote guidance from experienced EPs in less than 5 minutes. Given rapidly evolving data transmission technology, this has applicability in battlefield, remote, and rural prehospital settings.

(C) 2011

Introduction

^? This study was presented in the form of an oral presentation at the American Institute of Ultrasound in Medicine National Meeting in San Diego, California, March 2008.

^?? This is a non-funded research project.

* Corresponding author. Tel.: +1 202 741 2907; fax: +1 202 741 2921.

E-mail address: [email protected] (K.S. Boniface).

Bedside ultrasound has become standard of care in emergency medicine in the hospital setting, and has been invaluable in the care of the trauma patient for many years [1]. Deployment of ultrasound in prehospital care and emergency medical services (EMS) could potentially provide critical information about the traumatized patient

0735-6757/$ - see front matter (C) 2011 doi:10.1016/j.ajem.2009.12.001

and thereby optimize triage and transport of patients with multiple injuries. Portability, accuracy, and noninvasiveness of ultrasound create its potential as an effective imagining modality to provide diagnostic information in the prehospital arena, battlefield settings, and scenes of disasters and Mass casualty events [2,3]. It also facilitates medical screening and appropriate decision making in mobile units such as rescue vehicles, ships, aircraft, and the International Space Station [4-8]. In rural areas or battlefield locations remote from hospitals, the identification of free fluid may well lead to use of aeromedical instead of ground transport, or lead to selection of a more distant facility that is more capable of trauma management. Alternatively, paramedics operating in a mass casualty situation could provide a secondary level of triage using Focused Assessment With Sonography for Trauma (FAST), choosing patients with positive FAST examinations over similarly tagged patients with normal FAST examinations for early transport to hospitals.

Despite these potential advantages, ultrasound remains highly operator dependent and necessitates training and practice for providers to produce interpretable images. This training requirement has thus far limited its application in the out-of-hospital setting. Considering current widespread access to advanced data transmission technology, real-time tele-ultrasound is a potentially valuable technique that can leverage the skills of a centrally located ultrasound expert over multiple providers with relatively minimal sonography skills working in multiple Remote locations [9,10].

In recent years, several studies were conducted to examine the use of ultrasound by EMS providers through education and transmitting real-time images [5,7-9]. Real-time tele- guided ultrasound by nonphysician crew members at the International Space Station has been studied in previous research, but this involved prior training in ultrasound and then a prestudy refresher module on the Space Station [4-6]. Measuring the capability of paramedics to perform the ultrasound examination under real-time guidance of emer- gency physician (EP) can facilitate faster deployment of this modality into EMS with limited need for ultrasound training in their already crowded training curriculum.

This study aims to address the feasibility of ultrasound- naive paramedics to rapidly obtain interpretable FAST images under the remote direction of an experienced EP.

Methods

Study design

This was a prospective observational study in which 2 EPs with extensive emergency ultrasound experience and

51 paramedics with no prior training in ultrasound participated in the study. Our institutional review board approved the study. Paramedics provided informed consent before enrollment.

Study setting and population

Paramedics participated in 1 of 5 didactic sessions lasting 20 minutes covering orientation to the ultrasound machine and to the FAST examination, including 1 normal example of each of the 4 FAST examination views as well as 1 photograph of each of the probe locations. This length of time was chosen to be a minimal burden on valuable training time and was felt to be of a brief enough duration that would allow easy integration into routine ongoing continuing Education sessions. There was no hands-on scanning component to these sessions before the study examination.

The study population represented a sample of 51 paramedics with varying years of EMS experience who were recruited to participate in the study. Participation was voluntary and had no influence on their standing at work. Inclusion criteria included current active duty in EMS and lack of prior experiences with ultrasound. There was no limitation on years of experience for participation. Emer- gency physicians involved in directing the ultrasound examination were credentialed in FAST examination and had experience teaching the use of bedside ultrasound as well as providing online medical direction for EMS.

Study protocol

The paramedic and a model patient were placed in an examination room with the ultrasound machine (Sonosite Micromaxx and Sonosite M-Turbo, Bothell, Wash). The EP remained in another room out of visual contact and communicated with the paramedic via 2-way radio, viewing the real-time (cable) video feed from the ultrasound machine on a monitor. There was no visual monitoring of scanning site, patient, or paramedic by the EP instructor during the examinations. The paramedic took direction from the EP to obtain the 4 views of the FAST examination. The FAST examination was initiated with the probe in the “horizontal subxiphoid line landmark.” The landmark consists of the intersection between a horizontal line through the xiphoid process and the right midaxillary line (in RUQ) and the left posterior axillary line (in LUQ). The horizontal subxiphoid line landmark was validated in a previous research study by the authors [11].

The FAST protocol includes coronal planes of the RUQ and LUQ, a subxiphoid view of the heart, and transverse and longitudinal planes of transabdominal pelvic view. In a subgroup of models with difficult subxiphoid view, the medics were instructed in real time to obtain an alternative parasternal long-axis view of the heart, although this was not included in the didactics.

The EPs viewed the transmitted ultrasound images and verbally instructed the medics through the necessary repositioning, system setting adjustment, and probe place- ment and orientation modifications to obtain the optimal

images. When the EP felt the image was adequate, the image was saved and the time elapsed was recorded. The use of a “cue card” describing probe movements, locations of probe placement on the torso, and an ideal example of each of the four ultrasound views assisted in communications [5,12]. If paramedic was not able to obtain an acceptable image for a particular view in 5 minutes, the view was listed as incomplete and the paramedic moved on to the next view. Time to obtain the images and paramedics’ perfor- mances on following EP instruction were monitored by second investigator in the scanning room without any communication with participants.

Another EP with ultrasound expertise subsequently reviewed the scans for completeness and image adequacy.

Data analysis

Data collection forms, including data points such as years of EMS experience and time breakdown of the FAST examination, were completed by second investigator. The successful acquisition of the requisite images was documen- ted by saving the images electronically.

Time to obtain the images, time to complete the examination, and ability of paramedic to follow the direction were recorded by an investigator in the scanning room, who did not communicate at all with the paramedic. Data analysis was performed on only the first FAST examination performed by each paramedic, and no practice scanning occurred. Time obtaining unacceptable images was included in the analysis and was recorded by an investigator in the scanning room. Visualizing the target organs and saving representative images completed the examination.

Continuous variables including the time of obtaining images are expressed as median with interquartile ranges because the data are nonnormally distributed. To test the mean difference for scanning duration in each view and total elapsed time to complete the test, a paired t test was used. For all comparisons, P value b .05 was considered to indicate a statistically significant difference. Statistical significance for intergroup differences was assessed by ?2 test for categorical variables and Mann-Whitney U test for continuous variables. Statistical analyses were performed by using SAS software (SAS 9.0; SAS Institute, Cary, NC) and SPSS software (SPSS Statistics Base 17, Chicago, Ill).

Results

Fifty-one paramedics with median EMS experience of 12 +- 11.0 years (range, 2-47) performed their first tele- guided FAST examination on volunteers. Paramedics completed all 4 views of FAST examination with a success rate of 100%. One paramedic obtained suboptimal subxiphoid cardiac windows but was subsequently able to be directed through a parasternal long-axis examination

Scanning view	Median time (s)	Interquartile range
RUQ	39	26-73
LUQ	50	33-94
Subxiphoid	42	21-74
Pelvic	25	15-36
Total scanning	187	139-263
Total elapsed time	262	206-343
(includes time between views)

within the time allotted. The median time to complete the FAST examinations (measured from time probe is placed on body to time probe is off the body) was measured as 262 seconds (interquartile range, 206-343 seconds). There was no difference in the median examination time of the paramedics with the EMS experience above the median (258 seconds) as compared with those with less than the median EMS experience (271 seconds). There was no significant difference in the median examination time of the first 26 paramedics to enroll in the study (271 seconds) compared with the second 25 paramedics in the study (260 seconds). The median time needed to complete LUQ scanning was significantly longer than RUQ (50 seconds versus 39 seconds; P b .01). The median times required for each of the 4 views assessed are shown in Table 1.

Table 1 Distribution of median scanning time in seconds by different views of FAST ultrasound examination

Discussion

This study demonstrated that paramedics with no previous experience with ultrasound could successfully perform and complete a bedside FAST examination instructed by an experienced EP via tele-ultrasound after a very brief introduction. Tele-guided ultrasound can virtually link minimally trained paramedics with a remote experienced EP and allow the paramedics to be an extension of the centrally located sonographer physician. This use of technology can enable deployment of ultrasound technology in locations otherwise limited by need for ultrasound education and training. Existing technology that enables transfer of ultrasound images in real time to a content expert in a remote location has the potential to substantially reduces the need for initial and refresher paramedic training requirements by allowing EP input during the conduct of the examination.

Establishing simple and reliable landmarks and prede- termined starting point for probe placement, aided by topologic reference cue cards for various protocols, may improve the remote instruction and facilitate communication. We used the “horizontal subxiphoid line” as a landmark for the RUQ and LUQ views, which was an effective, easy to use landmark for the paramedics [11].

Have patient take deep breath

Flatten the angle of probe Not able to visualize Slide toward feet to pubic the bladder symphasis

Pelvic

Subxiphoid Visualize liver

but do not see heart

Slide toward head

Slide and fan posteriorly

LUQ

Slide toward head

Fan posteriorly

Visualize liver but do not see kidney Visualize kidney but do not see liver Visualize spleen

but do not see kidney Visualize kidney

but do not see spleen

Solution

Trouble

Scanning view

RUQ

Table 2 Troubleshooting guidelines during remote-guided FAST examination

In completing the FAST protocol, the LUQ view took substantially longer than the RUQ view. However, both views scanning were completed within times comparable to FAST examination conducted in the emergency department, as demonstrated in prior studies [3,6].

Finding a common language to communicate probe movements is crucial to the remote guidance of ultrasound scanning. The EPs had some difficulty communicating “fanning of the probe,” which then had to be explained using different verbiage. Also, switching the location and adjust- ment to visualize the cardiac view was one of the most difficult facets of the examination to communicate.

Communication and streaming of video information are at the heart of proposed tele-ultrasound-guided scanning. In this study we used a secure cable connection and analog radio that provided smooth communication. Transferring real-time ultrasound images and simultaneous verbal com- munication needed to provide real-time tele-ultrasound guidance require advanced digital technology, which is currently available and is likely to improve in the near future [13,14].

Some lessons learned from this project have broad applicability to any physician providing bedside instruction in ultrasound. This study confirmed our impression that one does not need to watch the probe to guide the novice, but rather respond to the images on the screen. It also reinforced the utility of certain anatomic relationships in communicat- ing how to improve an ultrasound view (see Table 2). These anatomic relationships are essential for improving a view when an acoustic window has been obtained, and an abdominal organ has been visualized but not the proper anatomic relationship sought in the particular examination.

Limitations

This was a limited feasibility study focusing on the interaction between a remote expert and an on-scene novice

provider and did not evaluate other variables involved in real-time tele-ultrasound. In this study, ultrasound scanning was performed under ideal controlled conditions. None of the models had abnormal findings because the models were healthy volunteers. In addition, there was no blinding of the timer or the reviewer of images in this study. Images obtained were assessed only as “adequate” or “not adequate.” The study methods do not necessarily reflect a prehospital or austere environment, where space limitation, background noise, vehicle movement, and need to simultaneously perform procedures may interfere with scanning. In this study, we used a secured cable connection and analog radio that provided smooth transmission of data and communica- tion between EP and the paramedics, which does not take into consideration the data dropout that happens with voice and data transmission over a wireless or satellite link. Prior studies have evaluated the ability of images to transmit wirelessly, and this technology is expected to continue to rapidly evolve. Our study focused on the interaction between a centrally located EP sonographer and an ultrasound-naive paramedic onsite to test the ability of this sonographer/ paramedic team to rapidly attain interpretable images.

Conclusions

This study demonstrated the feasibility of performing a remotely guided FAST ultrasound examination with mini- mally trained paramedics. This method may allow integration of ultrasound technology in EMS systems for limited scanning protocols and appropriate clinical indications. Rapidly evolving technology likely will result in widespread implementation of tele-ultrasound procedures in distant scenes and prehospital setting. Further investigation of real- time image transfer and communication paradigms in actual prehospital scenes and practical applications is warranted.

Acknowledgments

The authors wish to thank the paramedics of Arlington Fire and EMS and Fairfax County Fire and EMS for their talent, enthusiasm, dedication, and hard work in providing the best of emergency care for their patients. We would also like to thank Mary Pat McKay, MD, MPH, for her invaluable assistance in data analysis.

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