Page 109 - JSOM Winter 2018

FIGURE 1 Abdominal Aortic Junctional Tourniquet with associated https://www.biotimeinc.com) at initial intervention if the
prototype torso plate modification. mean arterial pressure (MAP) was less than 50mmHg and sys-
tolic blood pressure (SBP) was less than 90mmHg. For animals
randomly assigned to the AAJT-TP, the plate was positioned
in the epigastric area and the AAJT-TP was secured and in-
flated to an abdominal pressure of approximately 40mmHg.
The AAJT-TP was then deflated 20 minutes after application.
In addition, these animals received the same fluid treatment as
the control group. Animals in both groups were then observed
for 60 minutes in a simulated prehospital phase.
Sixty minutes after injury, the animals underwent damage con-
trol surgery and up to 3L of whole-blood resuscitation. Upon
opening the abdomen, manual control of the liver was imme-
diately achieved, and shed blood was collected. Atraumatic
liver clamps were placed on the transected edge of the liver
and the liver was packed to control any additional bleeding.
The abdomen was closed with a Bogota bag made from a 1L
bag originally containing normal saline and the animal was
Oregon Health and Science University, Portland, Oregon. An- observed for an additional 240 minutes of intensive care unit
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imals were used in accordance with Guide for the Care and (ICU) time. During the ICU phase of the experiment, a criti-
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Use of Laboratory Animals. A pilot study of the AAJT-TP cal care algorithm was used to maintain a normotensive state
in swine of similar weights was performed before this experi- and to correct any electrolyte abnormalities. If the animal’s
ment for model development. In that study, there was a 50% SBP was less than 90mmHg, and hemoglobin concentration
increase in survival of animals that received AAJT-TP (unpub- was at least 7g/dL, it received fresh frozen plasma (FFP). If
lished data). the animal’s hemoglobin concentration was less than 7g/dL,
it received packed red blood cells. If the animal’s pressures
Twenty-four male Yorkshire swine (75kg–85kg) were anes- were unresponsive to two subsequent boluses of either FFP
thetized with tiletamine via intramuscular injection and main- or packed red blood cells and its systemic vascular resistance
tained with isoflurane after orotracheal intubation. Vascular was less than 80% of baseline, norepinephrine was initiated
access was achieved by percutaneous technique and included at 0.02μg/kg/min. Insulin and 50mL of 50% dextrose was ad-
a right external jugular pulmonary artery catheter, left carotid ministered if the potassium level was 5.5mEqL or higher.
artery catheter, left external jugular venous catheter, and fem-
oral arterial and venous catheters. Cut down was performed At the completion of the experiment, animals were euthanized
for right carotid flow-probe monitor placement. Animals were and underwent necropsy and gross pathology assessment. Tis-
monitored using telemetry, electrocardiogram, invasive arte- sue samples were collected from the terminal ileum, kidney,
rial pressures, cardiac output, systemic vascular resistance, liver, pancreas, lung, and heart. These samples were sent for
end-tidal carbon dioxide, venous oxygen saturation, oxygen histological analysis by a certified veterinary pathologist.
consumption, near-infrared spectroscopy, carotid flow, and in-
traabdominal pressures. Data Collection and Study End Points
Arterial blood samples were taken before surgery (baseline),
Laparotomy and devascularization of the spleen were per- at end of preparation and stabilization (T0), and at the fol-
formed to eliminate autotransfusion and create a standardized lowing times (in minutes) after T0: 30 minutes (T30), T60,
degree of soft-tissue injury. After this, laparoscopic ports were T90, T120, T150, T180, T210, T240, T270, and T300 or at
placed and included two 12mm ports in the right lower quad- the time of euthanasia. Data collected for primary end points
rant, one 5mm port in the left lower quadrant, and one 12mm included survival, indices of cardiovascular and cardiopulmo-
port in the left lower quadrant. Three intraabdominal balloon nary function, intraabdominal pressure changes, indices of tis-
transducers were placed in the left paracolic gutter, mesentery, sue oxygenation and oxygen consumption, and blood gas and
and left subdiaphragmatic areas. The abdomen was then closed chemistry values. Secondary end points included clotting and
and the animal underwent a 10-minute stabilization period. coagulation status and histopathological examination of lung,
apex of the heart, kidney, liver, pancreas, and bowel.
After stabilization, the abdomen was insufflated to 15mmHg
and laparoscopic liver injury was created by transecting ap- Statistical Analysis
proximately 80% of the left lateral lobe of the liver. We chose Baseline data points were compared using Student t test. Cate-
this model to show an injury complex for which the AAJT gorical data were analyzed with the Fischer exact test. Clinical
is currently not indicated. The abdomen was desufflated, all and laboratory values were measured and analyzed by analysis
ports were removed, and the skin was quickly reapproximated of variance with post hoc pairwise comparisons where appro-
using staples. The animal was allowed to bleed freely for 10 priate (Holm-Sidak method). Kaplan-Meier analysis was per-
minutes and then underwent intervention. During the free formed for analysis of survival.
bleeding period, animals were randomly assigned into one of
two groups: control or AAJT-TP.
Results
Animals randomly assigned to the control group underwent There were no statistical differences in baseline characteris-
infusion of up to two boluses of 500mL of Hextend (Biotime, tics, preparation time, physiologic values, and viscoelastic

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