Hemodynamic Instability associated with pelvic fracture
| Estimated fluid and blood losses* based on patient's initial presentation** | ||||
| Parameters | Class I | Class II | Class III | Class IV |
| Blood loss (ml) | Up to 750 | 750 to 1,500 | 1,500 to 2,000 | >2,000 |
| Blood loss (% BV) | Up to 15% | 15% to 30% | 30% to 40% | >40% |
| Pulse rate | <100 | >100 | >120 | >140 |
| Blood pressure | Normal | Normal | Decreased | Decreased |
| Pulse Pressure (mm HG) | Normal or increased | Decreased | Decreased | Decreased |
| Respiratory rate | 14 to 20 | 20 to 30 | 30 to 40 | >35 |
| Urine output (ml/hr) | >30 | 20 to 30 | 5 to 15 | Negligible |
| CNS/mental status | Slightly anxious | Mildly anxious | Anxious and confused | Confused and lethargic |
| Fluid replacement (3:1 rule) | Crystalloid | Crystalloid | Crystalloid and blood | Crystalloid and blood |
* For a 70-kg male ** The guidelines in Table 1 are based on the "three-for-one" rule. This rule derives from the empiric observation that most patients in hemorrhagic shock require as much as 300 ml of electrolyte solution for each 100 ml of blood loss. Applied blindly, these guidelines can result in excessive or inadequate fluid administration. For example, a patient with a crush injury to the extremity may have hypotension out of proportion to his blood loss and require fluids in excess of the 3:1 guideline. In contrast, a patient whose ongoing blood loss is being replaced requires less than 3:1. The use of bolus therapy with careful monitoring of the patient's response can moderate these extremes. | ||||
The patient's admission vital signs (Table 1) indicate the severity of the hemorrhagic state. A 3% mortality was noted in pelvic fracture patients admitted hemodynamically normal compared to a 38% mortality rate for patients admitted hypotensive.{15} Aggressive resuscitation is initiated to obtain an adequate tissue perfusion. The search for the hemorrhagic site evaluates the thoracic cavity, the intraperitoneal cavity, and the retroperitoneal space. Before assuming that hypotension in a pelvic fracture patient is secondary to the fracture, other bleeding sources must be ruled out. Knowledge of intraperitoneal pathology is critical in deciding the best management of the unstable patient. As soon as possible after admission, ultrasound or a supraumbilical peritoneal lavage should be performed. Aspiration of 10 to 20 cc of blood confirms significant intraperitoneal injury and emergency exploratory laparotomy should be performed. If the peritoneal aspiration is negative, the trauma team should assume that the cause of the patient's hemodynamic instability is not from an intra-abdominal source and bleeding into the retroperitoneal space must be a primary concern. Efforts to identify the retroperitoneal bleeding site and control the blood loss are initiated.
Bleeding due to the pelvic fracture is from three sources: cancellous bone at the fracture sites, retroperitoneal lumbar plexus venous injury, and pelvic arterial injury. The bleeding sources can be considered as low-pressure and high-pressure systems.
In most cases, blood loss from pelvic injury is from a low-pressure source. Major arterial injury has been associated with only 20% of pelvic hemorrhage related deaths.{14} Arterial injury was noted (in order of decreasing frequency) from the superior gluteal, the internal pudendal, the obturator, and the lateral sacral artery. Active bleeding was most commonly found at the internal pudendal artery.{16}
Because of complexity and the acuity of the decision making process in the polytrauma patient, an institutional protocol that outlines the suggested management guidelines is useful to direct the treatment team to the evaluation and intervention sequences (Fig. 2).
A hemodynamically abnormal patient with a pelvic fracture and a positive peritoneal aspirate or ultrasound is emergently explored to identify and control the intraperitoneal bleeding site. The orthopaedic surgeon must be present at the laparotomy to assess the abdominal injury and the size and stability of the retroperitoneal hematoma. Provisional control of an unstable pelvic injury can be obtained prior to laparotomy by application of an external fixator,{3,17} a pelvic clamp,{18} MAST trousers, or a bean bag in the trauma admitting area. The provisional pelvic fixation can be modified or definitive fixation applied at the conclusion of the laparotomy, depending on the patient's response to resuscitation and laparotomy and the dynamics of the retroperitoneal hematoma.
If after addressing the abdominal injury the patient and the retroperitoneal hematoma stabilize, extension of the midline laparotomy incision will allow for plating of a pubic symphysis diastasis, if required. After closure of the abdomen, percutaneous iliosacral screw fixation of a reduced posterior pelvic injury can be considered. If the patient's condition prohibits additional operating room time or wound extension, control of the anterior pelvis is obtained with a external fixation frame. Supplemental, ipsilateral femoral traction is added, if necessary, to control cephalad migration in fractures with complete instability.
If the patient has a large or rapidly expanding or pulsatile retroperitoneal hematoma at the initiation of the abdominal exploration, angiographic evaluation is imperative. The intraventional radiologist is emergently called and an angiography suite is placed on immediate stand-by. At the conclusion of the laparotomy, an external fixator or pelvic resuscitation clamp is applied to the pelvis (if the fracture pattern requires and the frame has not been previously applied in the emergency room) and the patient is transported to the angiography suite. Resuscitation with appropriate blood product continues.
In some cases, laparotomy decompresses the abdominal content and allows for rapid expansion of the pelvic hematoma. The pressure rapidly falls and massive fluid volumes are required. Closure of the abdomen is sometimes impossible. If the patient is "in extremis" and cannot be stabilized for transport to the angiography suite, temporary cross clamping of the abdominal aorta must be considered to allow for transport and initiation of the angiography procedure or for immediate exploration and packing of the retroperitoneal space.
Although the practice of exploration of the hematoma and ligation of bleeding sites and packing of the retroperitoneal space has been largely abandoned in the United States, reports indicate that a growing series of hemorrhagic patients have been successfully controlled with this technique.{10,19} The injury is approached in a manner similar to the management of a massive liver injury. The retroperitoneal space is opened and the hematoma is evacuated. Accessible bleeding sites are ligated. The space is packed and closed and packings are changed every 2 to 3 days.
After the patient's pelvic bleeding is controlled and the hemipelvis is stabilized, intensive care monitoring, pulmonary and vascular support, and normalization of coagulation parameters are the major elements needed for patient survival.
Control of Retroperitoneal Bleeding: Modality Overview
The control of retroperitoneal hemorrhage has focused on three interventions: (1) decreasing blood loss from the fracture sites and lacerated soft tissue by stabilizing the fracture and the forming hematoma, (2) limiting of low-pressure bleeding by normalization of the pelvic volume and evoking a retroperitoneal tamponade effect, and (3) localizing and controlling arterial bleeding sites via therapeutic angiography or surgical exploration.
External Fixation
Although it has not been validated by prospective randomized trials, many clinical series have advocated the use of immediate external fixation to stabilize the pelvis, reduce the pelvic volume, and initiate a retroperitoneal tamponade effect.{20,21} One author reported that the external fixator was more successful in controlling hemorrhage than the MAST trousers (95% vs 71%) and noted that blood replacement was reduced from 7.4 to 3.7 units with application of the fixator.{22} Another author noted a decrease in the mortality rate (from 41% to 21%) in patients with pelvic fracture who were admitted with a systolic blood pressure < 100 mm Hg after initiation of an early external fixation protocol.{17} In one study at the Maryland Shock Trauma Center, the author reported a 28% incidence in the use of external fixation.{3} The recent development of "resuscitation clamps" allows for potentially rapid and effective stabilization of the pelvic fracture in the emergency room.{18,23}
Noninvasive external fixation is used in the emergency room in some centers. Deflatable, deforming bean bags are placed under the patient and conformed around the pelvis as it is manually reduced. The bags are deflated and the provisional cast mold helps maintain reduction and limit pelvic motion. The pneumatic antishock garment (PASG) has application in the treatment of pelvic injuries. It can be utilized as a field stabilization and transport device as a method of "tamponade" for patients with persistent hypotension, pending the availability of an operating suite or angiography.
Therapeutic Angiography
Continued, unexplained blood loss, despite fracture stabilization and aggressive resuscitation, mandates angiographic exploration. In one study, 8% of the 162 patients reviewed by the authors required angiography. Embolization was needed in 20% of APC and VS injuries and CMIs, but in only 1.7% of LC injuries.{3} In a series of 63 patients referred for angiography, the authors reported 123 arterial injuries in 49 patients.{16} Angiography successfully stopped arterial bleeding in 86% of patients in another study.{24} One author advocates "preemptive embolization," stressing that if an artery is found at angiography to be transected, it should be embolized to avoid the risk of delayed hemorrhage than can occur with clot lysis.{25}
Annotated References