Full text of DOI:10.1080/10903120190939607

AEROMEDICAL TRAUMA SONOGRAPHY BY FLIGHT CREWS
WITH A MINIATURE ULTRASOUND UNIT
Scott W. Melanson, MD, John McCarthy, DO, Christopher J. Stromski, MD,
John Kostenbader, EMT-P, Michael Heller, MD
ABSTRACT
coabdominal trauma and is considered one of the six
primary exams in emergency medicine (EM).8
Backgound. While ultrasound has become an established
diagnostic modality in trauma care, no study has evaluated
its use in the prehospital setting. Objective. To examine the
use of the focused abdominal sonography for trauma
(FAST) exam in the prehospital setting. Methods. After a
three-hour training session in the FAST exam, the nonphysi-
cian flight team of an emergency medical services (EMS) hel-
icopter program attempted a FAST exam on trauma patients
to determine the feasibility of such an intervention. Results.
The majority (83%) of the 71 patients entered suffered blunt
trauma. FAST exams could not be performed in 34 patients
(48%) due to insufficient time (67%), inadequate patient
access, or combativeness. Technical difficulties (difficult
screen visualization due to ambient lighting, battery failure,
and machine malfunction) prevented scanning in seven
(19%) of the 37 in whom it was attempted. In those in whom
scanning was successful, the pelvic view was most com-
monly obtained followed by the right upper quadrant
(RUQ) and left upper quadrant (LUQ). Conclusion.
Significant advances in training, technology, and/or patient
access will be necessary for aeromedical FAST to be feasible.
Key words: focused abdominal sonography for trauma;
FAST; sonography; trauma; ultrasound.
Technological advances have led to the develop-
ment of a hand-held, battery-powered ultrasound
machine that weighs only 33 ounces. This miniatur-
ization of ultrasound technology has created the
potential to perform FAST exams earlier in the evalu-
ation and resuscitation of trauma patients, perhaps
even in the prehospital setting. A Medline search
revealed no prior peer-reviewed studies that have
examined ultrasound evaluation of trauma patients
during transport in the prehospital setting.
The purpose of this study was to evaluate the feasi-
bility of FAST exams’ being performed on trauma
patients using miniature ultrasound technology in a
civilian aeromedical system staffed by nurses and
flight paramedics.
METHODS
Study Design
This was a prospective study involving the use of
miniature ultrasound technology on trauma patients
by a non-physician flight crew in an aeromedical res-
cue unit. The flight crew was instructed to complete a
questionnaire regarding the use of the ultrasound
machine at the conclusion of the flight.
PREHOSPITAL EMERGENCY CARE 2001;5:399–402
Ultrasound has been used in the evaluation of trauma
victims for more than 25 years,1 but its widespread
acceptance and use in North America have occurred
only within the last several years. Many studies have
found that the focused abdominal sonography for
trauma (FAST) exam is a highly accurate, noninvasive
means of evaluating victims of trauma2,3 and have
demonstrated that the FAST exam can be accurately
performed by both emergency physicians and sur-
geons in less than 5 minutes.4–7 Due to these positive
results, the FAST exam has been added to the
Advanced Trauma Life Support (ATLS) course as a
recommended modality in the evaluation of thora-
Population and Setting
The entire flight crew of the University Medevac BK-
117 helicopter system based at the Lehigh Valley
Hospital Trauma Center in Allentown, Pennsylvania,
attended a three-hour training session that included a
one-hour didactic presentation and two hours of prac-
ticing the FAST exam on normal models with both the
hand-held ultrasound unit and a standard portable
ultrasound machine. The flight crews in this aeromed-
ical system typically consist of one nurse and one
paramedic, in addition to the pilot. Historically, the
average flight time with trauma patients was 14 min-
utes. The vast majority, 98%, of the trauma patients
flown in this system had blunt trauma; 2% had pene-
trating trauma.
Received October 26, 2000, from the Emergency Medicine
Residency, St. Luke’s Hospital, Bethlehem, Pennsylvania (SWM,
CJS, MH); and the University Medevac, Lehigh Valley Medical
Center, Allentown, Pennsylvania (JM, JK). Revision received
January 19, 2001; accepted for publication January 22, 2001.
Presented at the American College of Emergency Physicians
Scientific Assembly, Philadelphia, Pennsylvania, October 2000.
Human Subject Review
Address correspondence and reprint requests to: Scott W.
Melanson, MD, Emergency Medicine Residency, St. Luke’s
Hospital, 801 Ostrum Street, Bethlehem, PA 18015.
This study was exempted from institutional review
board (IRB) review as it specifically prohibited any
399

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PREHOSPITAL EMERGENCY CARE OCTOBER/DECEMBER 2001 VOLUME 5 / NUMBER 4
TABLE 1. Ultrasound Scans Not Attempted (34 Patients)*
ing 71 patients in the study. The mechanisms of injury
of the patients were as follows: blunt trauma 83%,
penetrating trauma 4%, and not specified 13%. The
mean age of the patients enrolled was 35 years, with a
range of 3 to 90 years. The average estimated weight
of the patients was 160 pounds, with a range of 34 to
290 pounds.
Reason
No. Patients
%
Insufficient time
23
6
3
3
2
67
18
9
9
6
Inadequate access
Immobilization/splinting
Crowded conditions
Combative adult
Uncooperative child
1
3
Of the 71 patients entered into the study, ultrasound
scans were not attempted in 34 (48%) (Table 1). The
most common reason for not performing an ultra-
sound exam was insufficient time to complete the
exam given other responsibilities, reported for 23 of
the 34 patients, or 67% of the scans not performed.
Inadequate access to the patient prevented scanning in
six patients; immobilization or splinting of patients
prevented scanning in three, crowded conditions due
to two patients’ being transported simultaneously
prevented scanning in two, and crowding due to extra
flight crew members interfered with scanning in one
patient. Two combative adults and one uncooperative
child also prevented scanning.
Ultrasound scanning was attempted in 37 patients
(52%), but mechanical difficulties prevented scanning
in seven (19%). The reasons included difficulty visual-
izing the LCD screen during bright daylight in four,
battery failure in two, and ultrasound machine mal-
function in one. This malfunction involved an electri-
cal failure of the unit, which necessitated return of the
unit to the manufacturer and resulted in the early ces-
sation of the study.
For the 37 patients in whom scanning was per-
formed by the flight nurse, at least one location was
adequately visualized in 22 (59%) (Table 2). Of the
three images attempted, only one was adequately
visualized in 15 patients, two locations were visual-
ized in five patients, and all three were identified in
only two. In eight patients (22% of those scanned),
none of the three locations were adequately visual-
ized. Overall, 31% (22/71) of the trauma patients had
at least one trauma ultrasound view obtained. The
pelvic view was the location that was most frequently
*Some patients had more than one reason.
TABLE 2. Ultrasound Locations Visualized (37 Patients)
Locations Visualized
n
%
No location
One location
Two locations
Three locations
Mechanical failure
8
15
5
2
7
22
41
13
5
19
interference with standard patient care and the results
of the ultrasound were not used to direct patient man-
agement.
Experimental Protocol
During the return flight to the trauma center, the flight
nurse or paramedic performed an ultrasound exam
evaluating the right and left upper quadrants as well
as the suprapubic region for evidence of hemoperi-
toneum. No attempt was made to identify specific
organ lesions, hemothoraces, or pericardial fluid col-
lections. The interpretation of the flight crew perform-
ing the ultrasound exam was recorded on a data sheet
along with patient information, the flight crew’s confi-
dence in the interpretation, the time available to per-
form the ultrasound exam, and any problems encoun-
tered while scanning. Subsequent care of the patient
was not affected in any way.
All trauma patients transported were eligible for enroll-
ment in the study, regardless of mechanism of injury.
The hand-held ultrasound unit, the Micros Q.V.
(Fig. 1), which utilizes a 3.5-MHz transducer, was pro-
vided by Carolina Medical (King, NC) at no cost. The
Micros Q.V. weighs 33 ounces, measures 10 × 5 × 2.5
inches and is powered by a rechargeable battery pack.
Analytical Methods
We report the problems encountered using a minia-
ture ultrasound unit in an aeromedical rescue unit. As
this was a descriptive study, no statistical analysis was
performed.
RESULTS
A total of 72 patients were entered into the study, but
one involved the flight of a cardiac patient transferred
from another hospital; this patient was excluded, leav-
FIGURE 1. The Micros Q.V.

Melanson et al. AEROMEDICAL FAST
401
TABLE 3. Difficulties Encountered (37 Patients)*
identified. In the 22 patients in whom at least one
image was obtained, the pelvic view was seen in 15
(68%), while the right upper quadrant was visualized
in nine (41%) and the left upper quadrant was visual-
ized in only one patient.
Difficulty
n
%
Time constraints
Screen visualization
Obesity
11
9
7
30
24
19
16
11
3
As this was a feasibility study, significant effort was
made to explore difficulties with the performance of
the FAST exam in the helicopter. For the 37 patients in
whom a scan was attempted, the following difficulties
were listed as interfering with scanning (Table 3): time
constraints (11), difficulty visualizing the screen in
daylight (nine), patient obesity (seven), battery failure
(six), access to the appropriate anatomic areas for
scanning (four), motion of the aircraft (one), and ultra-
sound machine failure (one).
For the 22 patients in whom at least one location was
adequately visualized, the impression of the flight
nurse with regard to the presence or absence of fluid
was that it was present in one, not present in 16, and
indeterminate in four. In one case no interpretation
was noted. In the same group of patients, the flight
nurse reported being “very confident” of the impres-
sion in three patients (Table 4), “somewhat confident”
in 13, “not very confident” in one, and “not at all con-
fident” in five.
Battery failure
Patient access
Motion artifact
Machine failure
6
4
1
1
3
*Some patients had more than one difficulty encountered.
TABLE 4. Confidence of Interpretation (22 Patients)
Confidence Level
n
%
“Very” confident
3
13
1
14
59
4
“Somewhat” confident
“Not very” confident
“Not at all” confident
5
23
personnel and more sophisticated teaching models
such as peritoneal dialysis patients or computer-
assisted simulators. The very abbreviated curriculum
we employed may be simply inadequate.
Finally, the technology utilized has many limita-
tions that might make imaging difficult even under
ideal conditions and with experienced personnel. The
screen is only 3 inches, a fraction of the size of that on
standard ultrasound devices. Many technical factors,
including the brightness of the screen, the power of
the unit, the choice of focal length, the variability of
the frame rate, and selection of transducer frequency,
are limited.
In addition, other problems we experienced, includ-
ing the limited flight times and cramped space, are
more universal but could vary significantly in other
systems with other flight equipment. The technology,
too, has continued to evolve even in the months fol-
lowing our study. The system we employed has
already been upgraded and at least two new portable
devices (one of which includes Doppler technology)
have already appeared on the market. Such advances
may obviate some of the technical shortcomings that
prevented adequate exams in 10% of our patients and
caused early termination of our study. For example,
battery failure occurred in two cases, but the manu-
facturer has equipped the later versions of the Micros
Q.V. with nickel hydride battery packs, which are said
to provide two hours of scanning on a single charge.
Another mechanical issue was that the unit appeared
susceptible to damage in the back of the helicopter.
Although a sturdy plastic briefcase with foam
padding is provided, the relatively large size of this
case (18 × 13 × 6 inches) prevented its being kept in the
helicopter.
DISCUSSION
Ultrasound has become an accepted modality in the
evaluation of trauma patients, and the role of ultra-
sound in trauma care has been thoroughly evaluated
in the literature.2,3,9 The goal of the current study was
to evaluate the feasibility of flight crews’ performing
trauma ultrasound examinations in the prehospital
setting. The identification of hemoperitoneum in the
prehospital setting could be beneficial, serving as a
marker for potentially severe injury, allowing for a
heightened response in those trauma systems that
have more than one level of personnel response to
trauma patients.
Our feasibility study was negative in the sense that
the FAST exam could be completed in only approxi-
mately half of the trauma patients. There are at least
three variables that no doubt contributed to the disap-
pointing results but that could be modified in subse-
quent studies or actual clinical practice.
First, we utilized non-physician personnel with no
prior ultrasound experience, indeed, with no prior
imaging experience at all. Although successful train-
ing programs have been reported for the FAST exam
utilizing non-imaging specialists, the participants
have been EM or surgical residents (or attendings)
with considerable prior knowledge of both anatomy
and imaging modalities.
Second, the training program itself, a single didactic
hour followed by two hours of hands-on training,
would be minimal even with relatively experienced
Our disappointing results should not be interpreted
as a refutation of the utility of prehospital ultrasound.

402
PREHOSPITAL EMERGENCY CARE OCTOBER/DECEMBER 2001 VOLUME 5 / NUMBER 4
653-7.
Rather, it should serve as a caveat that close attention
to technical issues regarding equipment and timing
will be necessary for even the possibility of success.
2. Melanson SW, Heller M. The emerging role of bedside ultra-
sonography in trauma care. Emerg Med Clin North Am. 1998;
16:165-89.
3. McKenney KL. Ultrasound of blunt abdominal trauma. Radiol
Clin North Am. 1999;37:879-93.
4. Thourani VH, Pettitt BJ, Schmidt JA, Cooper WA, Rozycki GS.
Validation of surgeon-performed emergency abdominal ultra-
sonography in pediatric trauma patients. J Pediatr Surg. 1998;
33:322-8.
5. Boulanger BR, McLellan BA, Brenneman FD, et al. Emergent
abdominal sonography as a screening test in a new diagnostic
algorithm for blunt trauma. J Trauma. 1996;40:867-74.
6. Rozycki GS, Ochsner MG, Schmidt JA, et al. A prospective
study of surgeon-performed ultrasound as the primary adju-
vant modality for injured patient assessment. J Trauma. 1995;39:
492-8; discussion 498-500.
7. Ma OJ, Mateer JR, Ogata M, Kefer MP, Wittmann D,
Aprahamian C. Prospective analysis of a rapid trauma ultra-
sound examination performed by emergency physicians. J
Trauma. 1995;38:879-85.
CONCLUSION
We evaluated the feasibility of using a miniature ultra-
sound unit in an aeromedical system that provided
only brief ultrasound training to non-physician per-
sonnel. FAST exams could be completed in only
approximately half of the patients studied. Prehospital
FAST may be feasible but will require significant
changes in training, personnel, or technology.
The authors are grateful to Carolina Medical for providing the
Micros Q.V. ultrasound unit used in this study. Carolina Medical
provided the ultrasound unit with no stipulations on its use or the
design of this study.
8. Heller M, Jehle D. Ultrasound in emergency medicine.
Philadelphia: W. B. Saunders, 1995, p 236.
References
9. Rozycki GS, Feliciano DV, Davis TP. Ultrasound as used in tho-
racoabdominal trauma. Surg Clin North Am. 1998;78:295-310.
1. Kristensen JK, Buemann B, Kuhl E. Ultrasonic scanning in the
diagnosis of splenic haematomas. Acta Chir Scand. 1971;137:
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