Pressure-Volume Characteristics of the Intact and Disrupted Pelvic Retroperitoneum

Abstract

Hemorrhage is a major cause of mortality in pelvic fractures. Bleeding can be controlled in hypotensive patients by direct ligation, angiographic embolization, pelvic packing, and acute external fixation. Acute application of an external fixator can reduce pelvic volume and reduce bleeding fractures to effect tamponade. This therapy assumes that the pelvis represents a closed space, which clearly is not true anatomically. However, the premise may hold functionally. This study explored the relationship between pressure and volume in the intact and disrupted pelvic retroperitoneum. In cadaveric specimens, the external iliac vein was dissected, ruptured, and cannulated. This method allowed controlled flow of fluid, with simultaneous measurement of pressure, into the intact retroperitoneum. Open book pelvic fractures were created by applying external rotation to the pelvis through the femoral heads. The pressure-volume measurements, without and with external fixation applied, were repeated after the fracture, as well as after a laparotomy. In the intact retroperitoneum, pressures rapidly rose to an average of 30 mm Hg after infusion of 5 liters of fluid. After fracture, up to 20 liters of fluid could be infused at pressures not exceeding 35 mm Hg. External fixation increased pressures approximately 3 mm Hg at low fluid volumes, and approximately 11 mm Hg at the highest fluid volumes. Laparotomy decreased retroperitoneal pressure from approximately 35 mm Hg to approximately 15 mm Hg. The results of the study suggest that low-pressure venous hemorrhage may be tamponaded by an external fixator, given that enough fluid volume is present in the pelvic retroperitoneum. However, external fixation may not generate sufficient pressure to stop arterial bleeding. In any case, it seems that a large volume of fluid must be lost into the pelvis before an external fixator can have much effect on retroperitoneal pressures.

Can a Modified Anterior External Fixator Provide Posterior Compression of AP Compression Type III Pelvic Injuries?

“…Reduction of the pelvic ring results in decreased volume and improved stability [17,22,35]. The benefit of anterior external fixators in AP compression pelvic ring instability is well described [21,28], but they lack the capacity to produce posterior compression across the sacroiliac joint [15].…”

“…First, we used synthetic bone models imitating human pelvic geometry but without soft tissues. The absence of a soft tissue envelope, including ligaments and muscles, can influence the biomechanical behavior of pelvic ring instability and reduction [22]. The pelvic ring is mainly stabilized by the osseous and ligamentous structures.…”

“…In the case of a partial disruption of the sacroiliac joint, the sacrospinous and sacrotuberous ligaments and the muscles of the pelvic floor can modify the degree of instability. Clinically, this may result in a partial reduction and close to normal appearance of pelvic structures on the initial radiograph [12,22]. It was our aim to explore the basic mechanical behavior of different pelvic frame constructs and applications in a simplified mechanical experiment and reduce other variables such as soft tissues or soft tissue injuries.…”

Spontaneous Retroperitoneal Hemorrhage and Hemothorax After Intravenous Heparin Treatment

“…7) In the past, open surgical repair has been considered the only option in uncontrollable hemodynamic collapse, 8) but removal of the hematoma may increase rebleeding by releasing the tamponade effect. 9) Recently, many reports have discussed successful endovascular interventions using microcoils, gelform, or stent grafts. Microcoils are probably the most widely used and safest form of treatment, but it should be remembered that proximal coiling of the bleeding artery may not be sufficient when there is a rich network of collateral arteries and new arteries may develop after embolization of the bleeding artery.…”

Noninvasive Reduction of Open-Book Pelvic Fractures by Circumferential Compression

“…In addition, ORIF may release the evolving pelvic hematoma. Anterior external fixation has inherent deficiencies in reducing and stabilizing posterior pelvic disruptions (15,20,24). Pelvic antishock clamps may be difficult to apply and have caused severe complications (14,19).…”