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Ultrasound ImageGuided Acoustic Hemostasis of Occult Liver Hemorrhage

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Uncontrolled hemorrhage from high grade hepatic injuries is ... Post HIFU. HIFU Application. incision. interference bands. lesion formation. hyperechoic region ... – PowerPoint PPT presentation

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Title: Ultrasound ImageGuided Acoustic Hemostasis of Occult Liver Hemorrhage


1
Ultrasound Image-Guided Acoustic Hemostasis of
Occult Liver Hemorrhage
Sean Burgess, Vesna Zderic, Frank L. Starr
III, Shahram Vaezy
Department of Bioengineering, University of
Washington, Seattle, WA, USACenter for
Industrial and Medical Ultrasound, Applied
Physics Laboratory, University of Washington
Uncontrolled hemorrhage from high grade hepatic
injuries is highly lethal. Previous studies have
shown that High Intensity Focused Ultrasound
(HIFU) can successfully control visible bleeding
from solid organ injuries. This study
investigates the ability of ultrasound (US)
image-guided HIFU to arrest occult hemorrhaging
in the posterior liver parenchyma using a pig
model. The image-guided HIFU device consisted of
an intraoperative imaging probe and a
spherically-curved HIFU transducer with focal
length of 3.5 cm, frequency of 3.23-MHz, and
focal acoustic intensity of 2350 W/cm2. A total
of 24 incisions (17 HIFU-treated and 7 control
incisions) were made in 5 pig livers. The
incisions, 30 mm long and 7 mm deep, resulted in
a mean blood loss rate of 0.336 mL/s and 0.268
mL/s in the treated and control incisions
respectively. HIFU was applied within 20 seconds
of making an incision. Hemostasis was achieved
in all treated incisions after a mean ? SD of 65
? 15 seconds of HIFU application. After 7
minutes the control incisions had a mean blood
loss rate of 0.231 mL/s. Ultrasound image-guided
HIFU offers a promising method of hemostasis in
surgical settings in which the hemorrhage site is
not accessible.
  • 5 female pigs weighing approximately 30-35 kg
    each were used
  • Animals were anesthetized and administered
    heparin to place in a coagulative state
  • Abdomen was opened allowing access to the liver
  • Incisions were made on the posterior side of
    liver lobe, 30 mm long, 8mm deep, and 5 mm wide
    creating a wedge of tissue which was then removed
  • Blood was collected using gauze pads for blood
    loss rate determination
  • Liver lobe was placed on a bed of gauze
    concealing the incision
  • Image-guided HIFU device placed on anterior side
    of liver lobe
  • Incision was located and targeted using B-mode
    ultrasound
  • HIFU of 2350 W/cm2 was applied for 10-15 seconds
    while scanning at approximately 0.5 mm/s
  • Liver lobe was lifted from gauze bed and incision
    inspected for hemostasis
  • Incision targeting and HIFU treatment continued
    until hemostasis achieved
  • Control incisions were made using same procedure
    except that HIFU was not applied and blood was
    collected immediately after making the incision
    and after 7 minutes
  • The liver has a soft parenchyma which is highly
    vascularized and thinly protected by a fibrous
    capsule which makes it susceptible to injury
    during blunt and penetrating abdominal trauma.
  • Severe liver injury is the most common cause of
    hemorrhagic death after abdominal trauma.
  • Previous studies have shown that HIFU can
    successfully control visible bleeding from solid
    organ. injuries
  • HIFU is an acoustic therapy modality that
    utilizes high power, focused ultrasound waves to
    induce a biological effect.
  • Ultrasound waves can propagate through tissue and
    deposit energy within a millimeter sized focus
    without damaging intervening tissue.
  • Bioeffects are achieved via thermal and
    mechanical mechanisms resulting in coagulative
    necrosis.
  • Thermal effects can result in rapid rise in
    tissue temperature in excess of 70C.
  • Therapeutic uses of HIFU currently under
    investigation include tumor treatment and
    hemostasis.
  • Hemostasis was achieved in all treated incisions
    (n17)
  • Mean ? standard deviation HIFU treatment time was
    66 ? 19 seconds
  • Blood loss rate immediately following making an
    incision was 0.327 ? 0.179 mL/s for the treated
    incisions
  • Blood loss rates for the control incisions were
    0.344 ? 0.284 and 0.274 ? 0.132 mL/s at t0 and
    t7 minutes respectively
  • Control incisions (n7) had a reduction in
    bleeding rate after 7 minutes but were not
    hemostatic
  • Thermal and mechanical effects of HIFU probable
    mechanism of hemostasis

a. Liver section showing normal hepatic
architecture taken from region closest to the
image-guided HIFU device b. Liver section
surrounding treatment site showing sinusoids
congested with red blood cells (arrow) c.
Transition from congested sinusoids towards the
treatment site d. Treated liver having distorted
hepatic structure consistant with coagulative
necrosis (dark smudged nuclei (arrow),
detached individual hepatocytes
  • Ultrasound image-guided HIFU allows targeting and
    treatment below the tissue surface
  • HIFU and ultrasound transducers are mechanically
    coupled such that HIFU focus lies within the
    ultrasound image plane
  • HIFU and ultrasound imaging are electronically
    synchronized producing a visualization window
  • HIFU is powered using a 75 duty cycle,
    ultrasound imaging occurs during HIFU off-time
  • Circulating water pillow provides coupling
    between HIFU transducer and tissue as well as
    cooling to HIFU transducer
  • Image guided HIFU can provide hemostasis of
    occult liver hemorrhage
  • Image-guided acoustic hemostasis may have
    considerable potential in advanced trauma care of
    solid organ injuries
  • Additional studies are needed to improve bleeding
    site targeting to minimize tissue damage during
    HIFU hemostasis

Acknowledgments This work was supported by the
US Army Remote Acoustic Hemostasis Grant and NIH
Organ Hemostasis Grant. Contact
sburgess_at_u.washington.edu
  • HIFU Transducer Frequency 3.23 MHz Focal
    Length 35 mm
  • Imaging Transducer Philips HDI-1000
    Linear Array Bandwidth 5-10 MHz
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