Abdominal Trauma

Published on 22/03/2015 by admin

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208 Abdominal Trauma

The acutely injured patient requires a rapid, systematic, and thorough evaluation.1,2 The goals of this initial evaluation are to detect and treat immediately life-threatening injuries and then to move to a more thorough assessment of less serious injuries and preexisting conditions. Minute-to-minute management must be guided by the patient’s hemodynamic status (physiology) and anatomic injuries. Abnormal physiology kills trauma patients: hypotension, respiratory distress, hypoxemia, and so on. Do not focus on defining every anatomic injury in an unstable patient; find and correct the etiology of the abnormal physiology. The trauma patient admitted to the intensive care unit (ICU) generally has multiple injuries, many of which are threats to life or limb. Prioritization of the management of these injuries is based on treatment of the most immediate threat to life first. In blunt trauma victims, central nervous system injury accounts for 60% of deaths; hemorrhage and its consequences account for 30% of trauma deaths.1 Deaths resulting from penetrating abdominal trauma are from bleeding or sepsis. The most common etiology of hemorrhagic shock in the trauma patient is intraabdominal bleeding. Early deaths from abdominal injury are from bleeding. Late deaths are from intraabdominal sepsis, most often from hollow organ injury.1 Remember that injuries rarely occur in isolation; injuries occur as a component of a pattern of injuries.

image Initial Assessment of the Trauma Patient

Advanced Trauma Life Support (ATLS) course principles should be followed in the assessment of any trauma patient1 (Table 208-1). Immediate threats to life are identified and treated during the primary survey. Do not move beyond the primary survey until the patient has been stabilized. The resuscitation phase of the trauma patient generally occurs simultaneously with the primary survey. Intravenous lines are placed, and fluid resuscitation is initiated. The secondary survey is started after the patient has been stabilized. This is a head-to-toe survey defining all anatomic injuries. Remember that if a trauma patient deteriorates or does not respond as you expect, start over with the primary survey.

TABLE 208-1 Initial Assessment of the Trauma Patient

Primary survey Identify and treat immediate threats to life. This is a physiologic and not a temporal event. Stabilize patient before moving to the secondary survey.
Resuscitation Establish at least two large-bore intravenous lines. Resuscitate to specific endpoints.
Secondary survey Perform head-to-toe examination of patient. Order radiographic studies.
Definitive care Move patient from emergency department to intensive care unit or operating room as quickly as possible.

The trauma patient who arrives in the ICU and later becomes unstable generally has a derangement in circulation. Hypotension, tachycardia, and oliguria are obvious signs of hypoperfusion. On the other hand, even with normal vital signs, as many as 75% of trauma patients in the ICU have compensated shock with tissue hypoperfusion.3,4 Biochemical indices of perfusion such as base deficit or lactate levels should be determined to assess global perfusion.5,6 In the trauma patient, ongoing blood loss is the most common etiology for hypoperfusion. The source of the hemorrhage must be expeditiously identified and stopped. Sources for blood loss in the trauma patient include the abdomen, chest, pelvis, long bones, or externally via open wounds. The gastrointestinal tract is rarely the source of initial blood loss in the trauma patient. Any delay in control of hemorrhage increases morbidity and mortality.

The abdomen is a particularly challenging area to evaluate for several reasons. First, except in cases of evisceration or obvious peritonitis, the history and physical exam findings that suggest intraabdominal injury are usually subtle.7 Second, severely injured patients often have an altered mental status from concurrent brain injury, shock, or intoxicating agents that can mask symptoms and signs. Third, more obvious injuries such as complex open extremity fractures can distract providers and focus attention away from occult torso injuries. Finally, adjuncts to the history and physical, though numerous and ever evolving, still have weaknesses in sensitivity, specificity, and positive or negative predictive value.818

As noted, both speed and completeness are critical in evaluating the abdomen. Delays in diagnosis and treatment have been shown to affect morbidity and mortality.19 It is essential to recognize that a trauma patient requires a laparotomy with hard signs or positive diagnostic tests (focused assessment with sonography for trauma [FAST] or diagnostic peritoneal lavage [DPL]). It is not necessary, and in fact hazardous to the patient, to persist in defining the specific anatomy injury in a patient with indications for laparotomy. For patients who present in shock, after airway control, support of inadequate ventilation, and control of external hemorrhage, attention should be immediately turned to finding and treating the cavitary hemorrhage. In the majority of patients with torso trauma, the cause of shock will be bleeding. Tension pneumothorax, pericardial tamponade, spinal cord injury, and medical causes of shock will constitute a minority of cases. It is important for the resuscitation team to keep this in mind, and every maneuver should be performed while seeking the most likely causes of shock. Thus, for the critically injured patient, early intubation may be beneficial to avoid the need for emergency intubation further along in the resuscitation. Early chest tube placement should be considered as a potential diagnostic as well as therapeutic maneuver, particularly in patients who present in extremis. Laboratory tests drawn should be routine and performed in order of importance. A specimen for blood for type and crossmatch is vital, since transfusion is highly likely in this group of patients. Arterial blood gas analysis machines are now ubiquitous in resuscitation units and can provide a rapid assessment of the patient’s physiologic status. A specimen should be drawn as early as practical. Venous access must be accomplished expeditiously. Initially, the most experienced personnel should perform these procedures in the critically injured patient. Less experienced providers can provide essential support by procuring and setting up supplies and equipment, coordinating team activities at the direction of the team leader, and providing accurate documentation of the resuscitation.

On occasion, a patient will present in extremis, and some or all of the above regimented activities must be skipped while the patient is taken directly to the operating room (OR) for control of hemorrhage. Even less commonly, an emergency department (ED) thoracotomy may be indicated if vital signs are lost in the ED. The potential benefit of ED thoracotomy in the setting of intraabdominal hemorrhage remains controversial. The exsanguinating patient is best served in the OR, where thoracotomy or laparotomy can be diagnostic and therapeutic.

image Blunt Abdominal Injury

Physical examination alone will miss as many as 45% of abdominal injuries, so for patients who present with evidence of shock but respond to initial resuscitation with fluid replacement, more adjuncts can be employed in initial evaluation. Radiographs of the chest and pelvis are helpful to demonstrate hemothorax, pneumothorax, diaphragmatic rupture, or complex fractures. Abdominal radiographs are not helpful in the evaluation of blunt abdominal trauma. The FAST exam was popularized in the 1990s and has gained acceptance as a screening test for diagnosis of significant hemoperitoneum.13,14 Its major advantage is bedside availability, speed, and noninvasiveness. Because of this ready availability, FAST should be employed in all severely injured blunt trauma patients with a potential abdominal injury. Ultrasound is most helpful for the hypotensive patient with blunt torso trauma and a positive FAST.8,14 In this circumstance, the patient can be taken promptly to the OR for laparotomy. Significant drawbacks remain the relatively low sensitivity for peritoneal blood (68%) and the fact that the test cannot be used to detect diaphragm, hollow viscus, or retroperitoneal injuries.8,14,20 In addition, one cannot use FAST to grade solid-organ injury severity. Ultrasound is less useful in evaluating penetrating trauma. However, because of its ability to detect hemopericardium, it can be useful to direct the initial operative approach and incision placement in thoracoabdominal penetrating trauma.

For hemodynamically stable blunt trauma patients, computed tomography (CT) is the standard diagnostic tool.16,17,21 It is particularly accurate in diagnosis of solid-organ injury. It does lack sensitivity and specificity for pancreatic, hollow viscus, and diaphragm injuries, especially early in the clinical course when the initial study is usually performed.18,2226

DPL is a study used much less frequently since FAST has been shown to reliably detect hemoperitoneum. However, DPL is useful for further evaluation of the abdomen when FAST is negative in unstable patients or in the evaluation of the abdomen in the patient who requires emergency operation for an injury remote from the abdomen.26 The test is relatively simple and rapid, but it is invasive, and complications such as bowel injury are well described. More importantly, similar to FAST, DPL lacks sensitivity for retroperitoneal and diaphragm injuries. In addition, DPL is nonspecific. Thus, exploratory laparotomy based on DPL may be nontherapeutic in 25% of cases.

image Penetrating Abdominal Injury

Any penetrating abdominal injury from the nipple line anteriorly or scapular tip posteriorly to the buttocks inferiorly can produce both a thoracic and abdominal injury.

Gunshot Wounds

Gunshot wounds which violate the peritoneal cavity generally mandate exploratory laparotomy. The likelihood of visceral injury requiring repair is 80% to 95%.27,28 After a rapid primary survey, the entire body must be inspected for penetrating wounds by rolling the patient on both sides. Special attention must be paid to hidden areas such as the axillae, skin folds, body creases, and the perineum. The number of bullet wounds should be noted. Radiographs are taken of any body areas which may have been in the path of bullet trajectory. This is a critical maneuver to identify all bullets, possible trajectory, and thus structures at risk. Remember that bullets often do not travel in a straight line and may ricochet off bony structures; trajectory cannot be determined with complete confidence. The number of external wounds plus bullets found within the patient (usually on radiographs) must equal an even number; an odd number means that a bullet has not been found and other body cavities are at risk.

Abdominal Stab Wounds

The likelihood of finding an injury which requires operative repair in a patient with an anterior stab wound is only 25% to 33%.29 Indications for immediate exploration include hypotension, peritonitis, and evisceration. In the absence of these signs, selective management is appropriate, provided a surgeon and an OR are immediately available. In the stable patient with a reliable physical examination, the surgeon may simply decide to perform serial abdominal examination (selective management). The need for exploratory laparotomy is then based on change in abdominal examination, vital signs (especially temperature or heart rate), or white blood cell count.29,30

In the setting of anterior abdominal stab wounds, local wound exploration (LWE) can be helpful.31,32 This is a formal surgical procedure usually performed in the resuscitation room. Using sterile technique and under local anesthesia, the anterior abdominal stab wound is elongated with a scalpel, and the underlying fascia is exposed with sharp dissection. Penetration of the anterior fascia suggests the possibility of peritoneal penetration and usually warrants further operative intervention, usually laparotomy or DPL. A recent multicenter trial suggested that anterior abdominal stab wounds without evisceration, hemodynamic instability, or peritonitis could be triaged based upon the results of LWE.32 In some centers, diagnostic laparoscopy is performed when FAST, DPL, or LWE are equivocal. Laparoscopy in this setting has been challenged because of the difficulty in detecting small intestinal injuries, but it can be very helpful in evaluating the diaphragm in left thoracoabdominal stab wounds. In the stable patient, knife wounds of the flank and back may be evaluated by CT to assess trajectory of the weapon and possible visceral injury.

image Solid-Organ Injury

Liver

The majority of liver injuries do not require an operation.3335 Indeed, 86% of all isolated liver injuries were managed nonoperatively in a recent National Trauma Data Bank review.35 The speed and accuracy of CT has greatly enhanced the ability to detect and accurately grade solid-organ injuries. The key decision point is hemodynamic stability for CT imaging. If they are stable enough for CT, the majority of these patients can be observed. Conversely, 25% of liver injuries will require an intervention for a complication (bleeding, abscess, bile leak, biloma). Thus, interventional radiology has a critical role in the management of solid-organ injury.36 This has facilitated the study of the natural history of liver injuries treated nonoperatively. It has been shown that the grade of injury is an important predictor of success of nonoperative management, but even high-grade liver injuries can be successfully managed in this way.

The key to favorable outcomes in liver injury is recognition of failure of nonoperative management, as evidenced by ongoing bleeding. Signs of bleeding such as progressive anemia, hypotension, tachycardia, and failure to correct base deficit with volume resuscitation must be addressed in the setting of known liver injury. Angiographic embolization of hepatic arterial branches may avoid laparotomy if utilized immediately following recognition of arterial bleeding on the initial CT or early in the resuscitation phase.37 It must be emphasized that the hemodynamically unstable patient with a liver injury must undergo immediate operation.

Operative treatment of liver injuries has evolved over time to minimal necessary intervention to control bleeding. This usually entails simple packing of the liver with sponges and temporarily leaving the abdomen open as discussed in more detail later. On occasion, débridement of non-viable tissue with suture control is employed. A number of coagulation devices are also available, as are a variety of hemostatic products that can be applied directly to the injured liver surface.

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