Abdominal Aortic Junctional Tourniquets: Clinically Important Increases in Pressure in Aortic Zone 1 and Zone 3 in a Cadaveric Study Directly Relevant to Combat Medics Treating Non-Compressible Torso Hemorrhage.

Background: "Non-compressible" torso hemorrhage (NCTH) is the leading cause of preventable battlefield death, requiring rapid surgical or radiological intervention, which is essentially precluded close to the point of injury. UK Joint Theatre Trauma Registry (JTTR) analysis 2002-2012 showed 85.5% NCTH mortality. JTTR vascular injury data 2003-2008 revealed 100% mortality in named truncal vessel injuries. Gas insufflation and hyper-pressure intraperitoneal fluid animal studies have demonstrated significant reductions in blood loss in splanchnic injuries. We hypothesized that the noninvasive Abdominal Aortic Junctional Tourniquet - Stabilized ( AAJT-S) would be a forward combat medic-delivered intervention to tamponade bleeding from vessels of the celiac trunk in descending aorta zone 1 by generating clinically significant proximal epigastric compartment pressure.

Methods: Four cadaveric donors each had two manometric water-filled balloons placed intra-peritoneally (1 epigastric, 1 retropubic), con- nected to manometer tubing. Baseline pressures of 8cmH2O were set (equating mean intra-abdominal pressure (IAP). AAJT-S was applied and inflated to 250mmHg. Pressures were contemporaneously recorded. AAJT-S was removed, along with the epigastric manometer. We added 500mL of water to simulate blood through the epigastric aperture. The manometer was replaced and reset to 8cmH2O. AAJT-S was reapplied to 250mmHg, and IAP steady pressures were again recorded.

Results: Proximal compartment pressures reached a mean of 54.6cmH2O (40.2mmHg); distal compartment pressures achieved a mean of 46cmH2O (34mmHg.) With 500mL intra peritoneal fluid, proximal compartment achieved a mean of 52.25cmH2O (38.4mmHg); distal compartment achieved a mean of 35cmH2O (25.7mmHg.) BMI had a statistically significant inverse effect on epigastric pressure, in this study range (BMIs, 16.7-22.9kg/m2). This proved clinically insignificant, with sufficient pressure still achieved in all tests.

Conclusion: The AAJT-S at 250mmHg achieves proximal epigastric compartment pressures of 40mmHg, with or without 500mL simulated free blood in the abdomen. This represents a highly significant and titratable reduction in blood flow within the celiac trunk branches. BMI does not have a clinically significant effect. AAJT-S application also produces zone 3 aortic and inferior vena cava occlusion. AAJT-S may be a point-of-injury intervention for forward medics that contributes to non-surgical hemorrhage control and likely clot stabilization for zone 1 vascular and solid organ injuries.