Trauma and Critical Care
Luis Pacheco MD, Paul Howell MBChB, FRCA, Edward R. Sherwood MD, PhD
Chapter Outline
The management of critically ill obstetric patients most commonly involves treatment of disease processes that occur as a direct consequence of pregnancy. Although sometimes life threatening, these conditions are usually reversible. Delivery of the infant often attenuates or ablates the disease process, and the mother typically recovers with supportive and resuscitative measures. Primary obstetric disorders account for 50% to 80% of intensive care unit (ICU) admissions for pregnant patients; approximately 80% of these admissions result from preeclampsia, sepsis, and/or hemorrhage (Box 55-1).1,2 The estimated ICU admission rate for obstetric patients is 0.5% to 1% in the United States; the mortality rate in this population is 12% to 20%.3
Trauma accounts for 45% to 50% of all maternal deaths in the United States, and it is the most common nonobstetric cause of maternal death.4 Other common nonobstetric causes of ICU admission are respiratory failure, endocrine disorders, preexisting autoimmune disease, and thromboembolic disorders.5 Ethnic minorities and women with low socioeconomic status have the highest rates of morbidity and mortality. Modern medicine has allowed women with complex medical problems such as congenital heart disease and cystic fibrosis to survive into childbearing age, and these patients are at increased risk for complications during pregnancy and have a higher incidence of ICU admission. Among critically ill obstetric patients admitted to an ICU, the most common cause of death is acute respiratory distress syndrome (ARDS), which can complicate both obstetric and nonobstetric disease processes.6
Critical maternal illness places the fetus at significant risk for morbidity and mortality. Important fetal risk factors include maternal shock, transfusion of blood products, and early gestational age at the time of critical maternal illness.7
Trauma during Pregnancy
Epidemiology
Trauma affects 5% to 7% of pregnancies in the United States and is the leading nonobstetric cause of maternal death; as many as 20% of affected women require emergency surgery.8,9 Motor vehicle accidents are the most common cause of injury-related maternal death (49% to 70%), followed by domestic violence (11% to 25%) and falls (9% to 23%).10–12 Not using a seat belt is a major risk factor for maternal and fetal injury in motor vehicle trauma.13 Penetrating trauma and burns are far less common than blunt mechanisms of injury. The rate of maternal trauma admission to an ICU increases with each trimester: 8% occur in the first trimester, 40% in the second trimester, and 52% in the third trimester.14 Most women are able to continue their pregnancy at home, but up to 38% are hospitalized until delivery.
Risk factors for maternal trauma include age younger than 25 years, low socioeconomic status, minority race, use of illicit drugs or alcohol, and domestic violence.14,15 It is important to remember that any female patient of reproductive age who is a victim of trauma could be pregnant at the time of injury.
Complications and Outcomes
As in the general population, hemorrhagic shock and brain injury are the most common mechanisms of death in pregnant trauma victims.16 Pelvic and acetabular fractures also pose a significant risk. Injuries and complications that are unique to pregnant trauma victims include uterine rupture, placental abruption, preterm labor, and direct fetal injury. Although rare (0.6% of injuries), uterine rupture is a major threat to the life of both the mother (10% mortality) and the fetus (near 100% mortality).17 Placental abruption complicates 1% to 5% of minor injuries and 20% to 60% of major trauma and usually occurs from 16 weeks’ gestation onward.18 Placental abruption can cause major overt and occult hemorrhage and coagulopathy and should be considered as a possible source of bleeding in the unstable pregnant trauma patient. Preterm labor is a common (25%) complication of trauma and can be precipitated even in cases of apparently minor injury.19
Premature rupture of membranes (PROM) increases the risk for both preterm labor and infection. Amniotic fluid embolism is a rare complication of maternal trauma, but it should be considered as part of the differential diagnosis in patients who are refractory to resuscitation.
Fetal-maternal (transplacental) hemorrhage can occur after trauma and result in maternal isoimmunization with the D antigen of the fetal red blood cell Rhesus protein complex (Rh0[D]) in the Rh-negative mother (see Chapter 6). The Kleihauer-Betke test is used to identify fetal blood in the maternal circulation after maternal injury. When fetal-maternal hemorrhage is present, treatment with Rh0(D) immune globulin (RhoGAM) is generally indicated. In a study performed at the R. Adams Cowley Shock Trauma Center of the University of Maryland, more than 50% of evaluated pregnant trauma victims were positive for fetal-maternal hemorrhage as determined by a positive Kleihauer-Betke test.20 Essentially all patients with a positive test had uterine contractions, whereas patients with a negative Kleihauer-Betke test did not have contractions. The investigators concluded that the Kleihauer-Betke test was a sensitive and specific predictor of preterm labor in pregnant trauma patients and should be performed in all victims regardless of blood Rh phenotype.
Fetal Trauma and Outcome
The fetal mortality rate after maternal blunt trauma has been reported to range from 3.4% to 38.0%; placental abruption, uterine rupture, maternal shock, and maternal death are the most frequent factors associated with fetal demise (Box 55-2).15,21 The risk for direct fetal trauma increases with gestational age because the bony pelvis protects the uterus and fetus prior to 13 weeks’ gestation. Pregnant women who sustain blunt trauma have a lower risk for bowel injury than nonpregnant patients because the uterus acts as a shield and pushes the abdominal contents into the upper abdomen.22,23 Maternal pelvic fractures are associated with uteroplacental injury and fetal skull fractures. Skull fracture is the most common direct fetal injury and has a reported fetal mortality rate of 42%.24
The relationship between the Injury Severity Score (ISS) (see later discussion) and fetal outcome is controversial. Some studies have shown a direct relationship between the ISS and the incidence of fetal demise, whereas others have not. Analysis of outcomes from 1195 pregnant trauma victims showed that an ISS of greater than 15 was associated with increased risk for fetal demise.25,26 Evidence suggests that decreased serum bicarbonate, an indicator of systemic hypoperfusion, is associated with fetal demise after maternal trauma. Altered maternal mental status and the presence of head trauma have also been linked to adverse fetal outcomes.
It is crucial to preserve maternal cardiac output, blood pressure, and oxygen delivery to optimize maternal recovery and protect fetal well-being. However, fetal loss can occur even if the mother has not incurred serious injuries. Thus, all pregnant women should be evaluated in a medical setting after trauma, regardless of the apparent severity of injury. The fetus remains at risk for delayed complications after maternal discharge from the hospital. Delayed complications include a twofold increase in the risk for preterm delivery and a ninefold increase in the risk for fetal death.27 Late complications of trauma, such as cerebral palsy, have also been reported in children born to mothers who experienced trauma during pregnancy.28,29
Initial Assessment and Resuscitation
The initial assessment and resuscitation should focus on the mother; it is axiomatic that maternal resuscitation typically facilitates fetal resuscitation. A systematic approach to initial resuscitation and stabilization should be used (Figure 55-1).4 Immediate interventions are initiated to identify and treat life-threatening conditions based on the principles of Advanced Trauma Life Support (ATLS).30 Initial focus should be placed on ensuring adequate airway protection, ventilation (breathing), and circulation (the “ABCs” of resuscitation). Pregnant women experience significant changes in cardiopulmonary and metabolic function that must be considered during resuscitation (Table 55-1).
FIGURE 55-1 Algorithm for management of the pregnant woman after trauma. FHR, fetal heart rate. (Modified from Chames MC, Pearlman MD. Trauma during pregnancy: outcomes and clinical management. Clin Obstet Gynecol 2008; 51:398-408.)
TABLE 55-1
Physiologic Changes of Pregnancy That May Affect Trauma Management
* The reported measurements may fall within the normal range for the hospital laboratory, but the measurements may actually be abnormally high for a pregnant patient.
BUN, blood urea nitrogen.
Airway
Airway patency, stabilization, and protection should be ensured as quickly as possible in all critically injured patients, including those who are pregnant. The status of the patient’s airway can be quickly assessed by eliciting a verbal response. The inability to speak is an indication of severely impaired mental status or the inability to move adequate air to mediate phonation, either of which should prompt interventions to secure and protect the airway. Additional means of assessing airway patency include auscultation of the chest, assessment of chest movement, and assessment of air movement at the oral/nasal openings. Immediate interventions to establish airway patency include head tilt and jaw thrust maneuvers, as well as placement of an oral or nasopharyngeal airway to facilitate bag-mask ventilation and oxygenation.
It is essential to consider the possibility of cervical spine injury, facial fractures, and skull base injuries. Excessive head tilt maneuvers can worsen injury if a cervical spine fracture is present.31 Patients who have sustained severe trauma should be suspected of having a cervical spine injury until proven otherwise. Cervical spine injury must be ruled out by radiographic and physical examination criteria.32,33 The cervical spine should be stabilized with a hard collar and in-line stabilization until the severity of injury has been established. In cases of documented cervical spine injury, great care must be taken not to worsen spinal cord injury. A nasopharyngeal airway should not be placed in patients with suspected facial or skull base fractures to avoid further trauma and worsening of preexisting conditions.
Most patients who require interventions to open or support the airway, as just described, will ultimately require tracheal intubation. Indications for tracheal intubation include impaired mental status, airway obstruction, inability to clear secretions or blood from the airway, inadequate spontaneous ventilation, and hypoxemia that is refractory to supplemental oxygen administration.34 Tracheal intubation of pregnant patients is complicated by changes in respiratory system structure and function (see Table 55-1) (see Chapter 30).18 Among the most prominent alterations are airway (including vocal cord) edema, decreased functional residual capacity, and increased oxygen consumption. Airway edema impairs vocal cord visualization, thus complicating laryngoscopy and tracheal intubation. Decreased functional residual capacity and increased oxygen consumption result in more rapid oxyhemoglobin desaturation during periods of apnea. These factors increase the risk for failed tracheal intubation and hypoxemia.
Gastric emptying is normal in pregnant women before the onset of labor. However, lower esophageal sphincter tone is commonly decreased in pregnant women (see Table 55-1). Thus, pregnant women are at increased risk for regurgitation and pulmonary aspiration of gastric contents, although all trauma victims are considered to have a full stomach on arrival in the emergency department or operating room. Therefore, in most cases, rapid-sequence induction of general anesthesia is performed to facilitate tracheal intubation. However, the specific tracheal intubation technique will depend on the practitioner’s skills and resources, as well as on the location of the patient’s injuries. Alternative approaches to rapid-sequence induction include awake tracheal intubation and tracheostomy.
Several factors can complicate tracheal intubation in the trauma patient. The patient may be combative, which complicates awake tracheal intubation strategies. Blood in the airway can also limit the use of a fiberoptic bronchoscope and impair visualization of the glottis when using a standard or video laryngoscope. The presence of facial fractures, direct airway injuries, trauma-induced airway edema, and tracheal deviation can limit access to the airway.
Finally, airway management, including tracheal intubation, is more challenging in the presence of cervical spine injury. If cervical spine injury is present or suspected, it is crucial to avoid flexion, extension, or lateral movement of the neck. The spine is protected using in-line stabilization and/or a hard cervical collar. Airway management devices such as a gum elastic bougie, a video laryngoscope, a lighted intubating stylette, and/or an intubating laryngeal mask airway (LMA), among others, should be available for use if standard laryngoscopy is difficult or impossible. A supraglottic airway device such as an LMA can be used to temporarily provide ventilation in cases in which mask ventilation and tracheal intubation have failed, but an LMA will not provide protection from aspiration and should be replaced by a secure airway device as soon as possible. In some cases, cricothyroidotomy or tracheostomy may be necessary to provide a secure airway.
Breathing
Adequate ventilation and oxygenation should be ensured for the benefit of both the mother and the fetus. Supplemental oxygen should be administered immediately, even if the patient is breathing spontaneously. Mechanical ventilation is often necessary after tracheal intubation in patients with respiratory failure and/or hypoxemia. Ventilation can be compromised by trauma-associated factors such as pneumothorax, hemothorax, lung contusion, mediastinal compression, and chest wall injuries. These problems must be identified during the primary survey and treated to optimize ventilation and oxygenation. In women with advanced pregnancy, it may be necessary to place chest tubes more cephalad than normal owing to the cephalad displacement of the diaphragm and intra-abdominal structures by the gravid uterus. Pregnant trauma patients should be ventilated to maintain PaCO2 at a level that is normal for pregnancy (28 to 32 mm Hg) (see Table 55-1). Positive end-expiratory pressure (PEEP) may be added to improve oxygenation, if indicated; however, PEEP should be titrated carefully in the hypovolemic patient because it may impair venous return and worsen cardiac output and organ perfusion.
Circulation
Once respiratory stabilization has been achieved, it is essential to assess cardiovascular function and to determine whether the patient is in shock. Two large-bore peripheral intravenous catheters should be placed in the upper extremities to facilitate resuscitation. Central venous access facilitates rapid resuscitation but may be difficult to obtain. Intraosseous cannulation should be considered if it is difficult or impossible to obtain peripheral or central venous access.
Fluid resuscitation should be initiated using crystalloid solution, but blood transfusion should be considered if significant blood loss is apparent or suspected. Left uterine displacement should be initiated immediately to prevent or minimize aortocaval compression by the gravid uterus. The adverse effects of aortocaval compression may be exacerbated during periods of trauma-associated hypovolemia. The use of the pneumatic antishock garment to stabilize fractures or control hemorrhage is relatively contraindicated in pregnant women owing to its adverse effects on venous return.
The hallmark clinical signs of shock are listed in Box 55-3. The presence of these signs indicates a need for timely and appropriate fluid resuscitation. A rapid assessment of sources of blood loss should be performed. In trauma victims, the most common locations of exsanguinating blood loss are the chest, abdomen, retroperitoneum, long bones, and external sites. In the pregnant trauma patient, placental abruption and uterine rupture are also potential sources of hemorrhage. A brief physical examination will identify fractures of the long bones and external sites of bleeding. Thoracic blood loss and pelvic fractures can be identified by chest and pelvic radiographs, respectively. Focused abdominal sonography in trauma (FAST) or diagnostic peritoneal lavage can be used to identify intra-abdominal bleeding. However, diagnostic peritoneal lavage may be difficult to perform safely in advanced pregnancy. FAST can be rapidly performed to assess the hepatorenal, splenorenal, and pelvic spaces, which are the most common sites of major hemorrhage in trauma patients. FAST can also be used to assess uteroplacental integrity and the presence of intrauterine bleeding. Finally, ultrasonography facilitates assessment of cardiac filling and recognition of cardiac tamponade in patients with thoracic trauma.
It is important to recognize that pregnant trauma patients may lose a significant amount of blood before the development of hypotension. Pregnant patients have a 40% to 50% increase in blood volume by the third trimester. Classic signs of hypovolemia such as tachycardia, hypotension, and poor capillary refill may not be evident until blood loss approaches 1.5 to 2 liters. Therefore, it is likely that a pregnant trauma victim will have lost significantly more blood volume and oxygen-carrying capacity than a comparable nonpregnant patient when signs of cardiovascular deterioration become evident. Resuscitation should be guided by apparent blood loss to maintain adequate maternal cardiac output and uteroplacental perfusion. Because of the physiologic anemia of pregnancy, oxygen-carrying capacity may be significantly impaired at the time that hypovolemia becomes evident. In addition, maternal perfusion of vital organs is often sustained at the expense of uteroplacental perfusion. Uterine blood flow may decrease by as much as 30% before the mother shows signs of hypovolemia. Therefore, a nonreassuring fetal heart rate (FHR) pattern may be the first sign of significant intravascular volume loss. Fluids should be warmed to minimize the risk for hypothermia, which can contribute to coagulopathy, arrhythmias, and altered drug responses.
Fluid Resuscitation.
Current practice supports the use of crystalloid solutions to resuscitate the hypovolemic trauma victim. However, the crystalloid versus colloid debate remains to be fully resolved. The Saline versus Albumin Fluid Evaluation (SAFE)35 did not show any difference in survival in nonpregnant trauma patients randomized to receive resuscitation with either colloid or crystalloid, with the exception of patients with head trauma, who had worse outcomes when resuscitated with albumin. However, colloid solutions are anecdotally preferred in some trauma centers. The current ATLS guidelines advocate the use of lactated Ringer’s solution for initial fluid resuscitation.30 Lactated Ringer’s solution has significant buffering properties and is less likely to cause hyperchloremic metabolic acidosis during high-volume resuscitation than normal saline solution. Other buffered salt solutions such as Plasma-Lyte, Ringer’s ethyl pyruvate, and Ringer’s hydroxybutyrate also may have value. Currently, no evidence supports the use of one buffered isotonic crystalloid solution over another.
The use of hypertonic crystalloid solutions such as 3% sodium chloride is controversial; currently no evidence supports their use in pregnant trauma victims. Hypernatremia is a risk in patients resuscitated with hypertonic saline, and some studies have shown increased mortality in patients resuscitated with hypertonic crystalloid solutions.36
Some practitioners have advocated hypovolemic resuscitation in patients with major hemorrhage after trauma.37 This technique employs permissive hypotension (systolic blood pressure of 80 to 90 mm Hg) until hemorrhage can be controlled in the operative setting. The underlying premise of hypovolemic (hypotensive) resuscitation is that over-resuscitation worsens ongoing blood loss as a result of higher perfusion pressure and dilution of clotting factors. Small boluses of fluids are administered to maintain perfusion in patients without evidence of closed head injury. The use of hypotensive resuscitation is likely to be detrimental in patients with closed head injury because it is crucial to maintain adequate cerebral perfusion pressure (CPP) in patients with elevated intracranial pressure (ICP).38 (CPP is the difference between mean arterial pressure [MAP] and ICP.) No definitive published data support the use of hypotensive resuscitation in pregnant trauma patients. Current guidelines do not support this approach because it may compromise uteroplacental perfusion.
Damage Control Principles and Resuscitation.
The traditional approach to treatment of traumatic life-threatening injuries has been definitive operative repair. However, some patients experience progressive physiologic decline during long surgical procedures and develop severe derangements such as hypothermia, metabolic acidosis, and coagulopathy, a combination that has become known as the deadly triad.39 These pathologic alterations require rapid and effective treatment to prevent severe morbidity and death. More recently, some practitioners have advocated the use of a more targeted approach, termed damage control, which is initiated to control hemorrhage without providing early definitive repair of injuries.40 Major surgical bleeding is controlled, and the thoracic and abdominal cavities are packed to provide hemostasis. Gastrointestinal diversion is performed, and body cavities are temporarily closed, often using vacuum-type closure systems. Active volume resuscitation is performed to achieve metabolic homeostasis. On achievement of stable hemodynamic and acid-base status, coagulation function, and temperature, the patient is taken back to the operating room for definitive repair of injuries.
Blood Products.
All trauma centers should have rapid access to type O, Rh-negative blood for emergency use before type-specific or crossmatched blood is available. Recently, some trauma specialists have advocated damage-control resuscitation using packed red blood cells and fresh frozen plasma mixed in equal proportions (1 : 1) (see Chapter 38). Several investigators have reported the value of this approach in military practice, and they have specifically observed that this approach results in more effective resuscitation, less coagulopathy, and improved survival than more traditional approaches.41 It remains unclear whether this approach will be advantageous in civilian practice, but many centers are investigating its use.
In the setting of uncontrolled hemorrhage, recombinant activated factor VII (rFVIIa) has been shown to be effective in treating severe coagulopathy in a small number of observational studies. Case reports and case series have described the efficacy of rFVIIa during massive hemorrhage in trauma and obstetric patients (see Chapter 38).37 A multidisciplinary group in Israel reported that rFVIIa was effective in decreasing severe bleeding in 36 trauma patients.42 European consensus guidelines also advocate the use of rFVIIa in trauma patients with massive uncontrolled hemorrhage that is refractory to conventional transfusion of blood products.43 However, further research is needed before rFVIIa can be endorsed for treatment of massive hemorrhage, owing to its high cost and an incomplete risk-benefit analysis. A major concern is the potential increased risk for thromboembolism in patients treated with rFVIIa.
Secondary Survey
As in all trauma cases, it is crucial to evaluate the mother for significant abdominal, thoracic, orthopedic, and neurologic injuries. A head-to-toe examination should be performed to determine the presence of injuries and the need for intervention. A more detailed evaluation of neurologic function, as well as examination of the head and neck, should be performed. This survey includes examination of posterior structures that may be obscured by the supine position and the presence of a cervical collar. The torso should be examined to identify thoracic and abdominal injuries. The thoracic examination should include chest auscultation, inspection, and palpation. Palpation of the abdomen should be performed to evaluate abdominal tenderness, and a rectal examination should be performed to identify evidence of intraluminal bleeding. The extremities must be examined to identify deformities, and each joint should be manipulated. Distal perfusion of the extremities must be continuously monitored, especially in limbs that show signs of significant injury. This is accomplished by evaluation of distal pulses and capillary refill. In cases of penetrating injury, the sites of entry and exit should be identified. It is especially important to examine carefully the areas that are difficult to access such as the oral cavity, perineum, axilla, scalp, and back. Once the secondary survey has been performed, more targeted assessments of suspected injuries can be performed using radiologic imaging.
Fetal Survey.
After initial stabilization of the mother, information about the pregnancy should be gathered through a focused history and physical examination. The history should include the date of the last menstrual period, expected date of delivery, and status of the pregnancy. In cases in which there is uncertainty regarding fetal age, an approximate determination can be made by measuring fundal height. The fetal age is estimated to be 1 week for each centimeter of fundal height above the symphysis pubis. In addition to the assessment of fundal height, the abdominal examination should include an assessment of uterine tenderness and consistency, the presence or absence of uterine contractions, and fetal position and movement.
A pelvic examination should be performed to evaluate cervical dilation and effacement, fetal station, and the presence of amniotic fluid and blood. The FHR is assessed by Doppler auscultation or ultrasonography. If maternal stability permits, ultrasonography facilitates estimation of fetal age and assessment of uteroplacental injury.
If no fetal cardiac activity is identified, fetal resuscitation should not be attempted (see Figure 55-1). In a series of 441 pregnant trauma patients, the absence of a detectable FHR was associated with fetal death in all cases.9 When a FHR is detected, an assessment of fetal viability should be performed. An estimated gestational age of 24 to 25 weeks and an estimated fetal weight of 500 g are common thresholds for extrauterine fetal viability. The FHR should be monitored in cases in which the fetus is determined to be viable. In cases in which a nonviable fetus is present, the importance of FHR monitoring is unclear. However, alterations in FHR and FHR variability may signal maternal deterioration and serve as a good monitor of the effectiveness of maternal resuscitation.
FHR monitoring is generally performed with external Doppler auscultation, and a tocodynamometer is used to assess uterine contractions. Adverse fetal outcomes are unlikely in cases with a reassuring FHR tracing and no early warning signs of uteroplacental injury (bleeding, abdominal pain).44 In contrast, an abnormal FHR tracing or evidence of uteroplacental injury (vaginal bleeding, uterine contractions, uterine tenderness, presence of amniotic fluid on vaginal examination) predicts poor fetal outcome in approximately 50% of cases.45
Fetal Monitoring
Continuous electronic FHR monitoring is the current standard of care for pregnant trauma victims with a viable fetus.9,14 FHR monitoring should be initiated as soon as maternal stabilization is complete, because placental abruption can occur early during the course of resuscitation. Continuous electronic FHR monitoring is more sensitive for placental abruption than ultrasonography, physical examination, or Kleihauer-Betke testing. Occasional uterine contractions are common after trauma and are usually not associated with poor fetal outcome.11,45,46 Random uterine contractions usually resolve within a few hours of the accident. However, regular and prolonged uterine contractions (eight contractions per hour for more than 4 hours) are associated with placental abruption, which has a high fetal mortality rate.46 The diagnosis of placental abruption should trigger immediate cesarean delivery; a large percentage of viable fetuses can be rescued if expedited delivery is performed. The presence of fetal bradycardia and frequent late FHR decelerations should also prompt delivery if the mother is stable and adequately resuscitated.
The ideal duration of FHR monitoring has not been determined. However, a common practice, based on a prospective study of 60 pregnant trauma patients at more than 20 weeks’ gestation, is to monitor the FHR for 4 hours.47 If maternal-fetal abnormalities are not detected within 4 hours, it is generally considered safe to discontinue FHR monitoring because a normal FHR tracing has a negative predictive value of 100% when combined with a normal maternal physical examination. However, the presence of abnormalities such as vaginal bleeding, spontaneous rupture of membranes, category II and III FHR patterns, persistent uterine contractions, uterine tenderness, abdominal pain, and/or need for maternal analgesia should prompt further FHR monitoring. The sensitivity of ultrasonography for placental abruption ranges from 50% to 80%, but ultrasonography is a safe and effective means of assessing fetal viability, FHR, placental location, gestational age, and amniotic fluid volume. It is particularly valuable in the presence of maternal tachycardia, when it can be difficult to differentiate maternal and fetal heart rates using Doppler auscultation.
Laboratory Studies
Laboratory evaluation in pregnant trauma patients does not differ from the evaluation for nonpregnant patients, with a few exceptions. As for all trauma patients, the laboratory evaluation will be driven by the type and severity of injury. For most patients with significant injury, standard analysis includes a complete blood cell count with a platelet count, coagulation studies, serum electrolyte measurements, blood glucose and lactate levels, liver function tests, arterial blood gas analysis, urinalysis, and toxicology screening, as well as sending a blood sample for typing and crossmatching for compatible blood products (Box 55-4).
The presence of disseminated intravascular coagulation (DIC) and low blood bicarbonate levels is associated with poor fetal outcome.10,25 Both abnormalities reflect severe maternal injury and should prompt aggressive maternal resuscitation. Of special consideration in pregnant trauma patients is maternal-fetal hemorrhage. The Kleihauer-Betke acid elution assay is used to detect the entry of fetal blood into the maternal circulation.20 It is typically performed in Rh0(D) antigen–negative mothers to detect transplacental hemorrhage and the potential for developing Rh0(D) sensitization, which can be prevented in 99% of cases by early treatment with Rh0(D) immune globulin (RhoGAM). However, this test may help predict adverse fetal outcomes in all pregnant trauma patients (see earlier discussion).
Imaging
The pregnant trauma patient often requires imaging to evaluate orthopedic, head, thoracic, and abdominal injuries. Although many patients and physicians are concerned about the fetal effects of ionizing radiation, the risks for teratogenesis, malignancy, and gene mutation are small with a radiation exposure less than 5 to 10 rads (see Chapter 17).48 Less than 1% of trauma patients receive more than 3 rads of radiation exposure. When possible, the fetus should be shielded with lead. Intravenous pyelography subjects the fetus to as much as 1.4 rads of exposure, but the test can be invaluable in diagnosing injuries to the kidneys, ureters, and bladder. Computed tomography (CT) is associated with greater radiation exposure than plain radiography, but exposure levels are generally below that considered to be dangerous to the fetus. Modern multidetector (multislice) CT results in higher fetal radiation exposure, but it has significant advantages in speed and image resolution. Overall, the small risk for fetal radiation exposure is outweighed by the benefits to the injured mother and, by extension, the fetus.
Injury Scoring
Several injury scoring scales have been developed over the past 40 years. The scoring systems provide a framework for standardizing clinical management, benchmarking outcomes, and planning research. Presently, no reliable scoring tool exists for predicting maternal or fetal outcome after trauma. Currently used scoring systems include (1) anatomic injury scales that rely on physical examination and diagnostic procedures, (2) physiologic injury scales that rely on assessment of physiologic responses and function, and (3) combination injury scales.
One of the first anatomy-based injury scales was the Abbreviated Injury Scale (AIS) developed by the Association for the Advancement of Automotive Medicine.49 Each of nine body regions is given an injury severity score that ranges from 1 (minor) to 6 (maximal [currently untreatable]). Although the AIS effectively describes the severity of injuries at specific locations, it provides a limited assessment of the overall pathophysiologic impact of all injuries. The Injury Severity Score (ISS), which was developed to address this issue, is obtained by summing the square of the three highest severity scores from the AIS. The ISS ranges from 1 to 75. Minor injuries are classified as an ISS of less than 9; moderate, from 9 to 15; serious, from 16 to 25; and severe, greater than 25. The ISS correlates with the risk for preterm delivery after trauma, but its value in predicting fetal death, placental abruption, and other adverse outcomes is controversial.15 The American Association for the Surgery of Trauma developed the Organ Injury Scale (OIS)50; this is an organ-based severity scale designed to facilitate clinical investigation and outcomes research. The value of the OIS in predicting adverse maternal and fetal outcomes remains to be established.
Anatomic scoring systems have value in describing the extent and severity of injuries to specific organ systems. However, physiologic scoring systems may add prognostic value. The Glasgow Coma Scale, which is among the most widely used physiologic scoring systems, evaluates the neurologic status of the trauma patient. The Glasgow Coma Scale evaluates eye opening, verbal response, and motor activity; scores range from 3 to 15, with 3 indicating the absence of neurologic activity and 15 representing intact neurologic function. A Glasgow Coma Scale score of less than 9 reflects severe impairment, whereas as a score of 9 to 12 reflects moderate disability. However, concerns have been raised about inter-rater reliability and lack of prognostic utility for the Glasgow Coma Scale. Some researchers have proposed that a simplified motor score would be more reliable. Evidence suggests that the Glasgow Coma Scale has a poor correlation with fetal outcome.15
Traumatic Brain Injury
Brain injury is the most common severe injury in patients who suffer from motor vehicle accident, and it is a major cause of mortality among pregnant trauma victims.51 It is important to perform a thorough neurologic examination with particular attention to level of consciousness. Altered mental status may be an indicator of evolving intracranial pathology, intoxication, hypoperfusion, and/or metabolic disturbances. Mental status should be reevaluated frequently because intracranial pathologic processes may not be apparent on initial evaluation and may evolve during the course of resuscitation.
Elevated ICP is a common finding in patients with traumatic brain injury and may be a significant threat to life. Head CT is the imaging study of choice for identifying the site and severity of intracranial pathologic processes in trauma patients, and it should be performed within 1 hour of arrival in the emergency department.
Crystalloid fluid resuscitation should be used for resuscitation in patients with traumatic brain injury; resuscitation with albumin is deleterious in patients with traumatic brain injury (see earlier discussion).35 Hypotensive resuscitation is contraindicated in patients with traumatic brain injury and elevated ICP. It is crucial to maintain CPP to minimize the risk for brain ischemia and permanent brain injury. The extent of brain injury will worsen if CPP is not maintained. It is also important to maintain cerebral oxygen delivery by optimizing maternal cardiac output and blood oxygen-carrying capacity.
It may be necessary to intubate the trachea of patients with deteriorating mental status for airway protection and provision of ventilatory support. Hypoventilation should be avoided because it increases ICP. Hyperventilation to a PaCO2 between 25 and 30 mm Hg will provide a transient decrease in ICP and may be useful until definitive treatment can be initiated. However, hyperventilation can be disadvantageous for the fetus because it can decrease uteroplacental blood flow by decreasing maternal cardiac output and blood pressure, and perhaps by causing uteroplacental vasoconstriction. Therefore, it is prudent to maintain PaCO2 at levels that are normal in pregnant females (28 to 32 mm Hg). Additional maneuvers to decrease ICP include treatment with a diuretic such as mannitol or furosemide and elevation of the head 30 to 45 degrees.
Corticosteroids are no longer recommended for patients with traumatic brain injury because their administration in this setting is associated with increased mortality. Barbiturates decrease cerebral oxygen use and blood flow and may provide cerebral protection in patients with severe impairment. Both mannitol and furosemide cross the placenta and could cause alterations in fetal plasma osmolality and decrease fetal intravascular volume. However, concern regarding adverse fetal effects should be overridden by the needs of the mother in cases of traumatic brain injury.
Cardiopulmonary Resuscitation
The incidence of cardiac arrest in pregnancy is reported to be 1 : 20,000 to 1 : 30,000 patients in industrialized countries.52 The most frequent causes are trauma, peripartum hemorrhage, embolic phenomena, stroke, preeclampsia/eclampsia, sepsis, status asthmaticus, and anesthesia-related complications.53 Cardiopulmonary resuscitation should be initiated immediately (see Chapters 17 and 42). The 2010 American Heart Association (AHA) guidelines highlight the importance of initiating high-quality chest compressions to facilitate circulation.52,54 The hands should be placed slightly above the center of the sternum because the diaphragm and abdominal contents are displaced cephalad during the third trimester of pregnancy (Box 55-5). In the hospital setting, the airway should be secured and the mother ventilated with 100% oxygen. Intravenous or intraosseous access should be secured to facilitate resuscitation. Advanced Cardiac Life Support (ACLS) guidelines should be followed to identify and treat causes of cardiopulmonary arrest.52
