Trauma and Pregnancy

AIR CARE & MOBILE CARE

Pregnancy and Trauma

Incidence:
According to the Committee on Trauma of the American College of Surgeons, accidental injury occurs in 6% to 7% of all pregnancies and is the most common cause of death in the gravid patient. The causes of maternal injury are as follows:
- 42% MVCs
- 34% falls
- 18% assaults
- < 1% burns.

Factoids…
- 8 million annual pregnancies in the U.S.
- 6-7% of all pregnancies complicated by trauma.
- 0.3-0.4% of pregnant women hospitalized for trauma.
- 0.3% of trauma patients are gravid.
- trauma is the leading cause of death in women of childbearing age, and is the leading non-obstetric cause of death in pregnant women (22% of deaths).
- maternal mortality is 7% - 24% after major trauma.
- One in twelve inner-city women are battered during pregnancy
- Closed head injury and hemorrhage are the most common causes of traumatic maternal death (85%).
- 8 of 10 pregnancies complicated by maternal traumatic shock result in fetal death.
- placental abruption is the most common cause of traumatic fetal death with maternal survival.

Anatomical and Physiological Changes associated with Pregnancy

Anatomical and Physiological Changes associated with Pregnancy alter the patient's response to traumatic injury, requiring modified assessment, treatment, and transportation strategies.

Gastrointestinal Tract
Gastrointestinal motility may be reduced during pregnancy due to increased levels of the hormone progesterone.. Esophageal peristalsis (movement) is deceased and gastric emptying is slowed. Gastric reflux becomes common because of the slower emptying time and dilatation or relaxation of the stomach's cardiac sphincter. Gastric reflux is more prevalent in later pregnancy due to elevation of the stomach by the enlarged uterus. Besides leading to heartburn, all of these alterations as well as lying in the supine position, increase the possibility of regurgitation and aspiration.

The large and small bowel moves upward and laterally. As noted previously, gastric motility and tone is decreased.

Gallbladder function is altered as well during pregnancy because of the decreased tone of the smooth muscle wall. Emptying time is slowed and often incomplete. Bile can become thick leading to gallstone formation.

Kidneys and Urinary Tract
Renal enlargement, dilatation and position change occurs during pregnancy. The glomerular filtration rate (GFR) increases during pregnancy by about 50% .The renal blood flow increases by as much as 25-50%. Urinary flow and sodium excretion rates in late pregnancy can be altered by posture alone. Even though the GFR increased dramatically during pregnancy, the volume of the urine passed each day is not increased. Thus, the urinary system appears to be even more efficient during pregnancy.

Glucosuria during pregnancy is not necessarily abnormal, may be explained by the increase in GFR with impairment of tubular reabsortion of glucose. Increased levels of urinary glucose also contribute to increased susceptibility of pregnant women to urinary tract infection. Proteinuria changes little during pregnancy and if more than 500mg/24h is lost, a disease process should be suspected.

Levels of the enzyme renine, which is produced in kidney, increase early in the first trimester, and continue to rise until term. This enzyme acts form angiotensin1 and then angiotensin2, which acts as a vasoconstrictor. Normally the pregnant female is resistant to the presser effect of elevated levels of angiotensin2 but those suffering from preeclampsia are not resistant, this is one of the theories to explain this disease and the associated severe high blood pressure.

As the uterus enlarges; the urinary bladder is displaced upward and flattened. Pressure from the uterus leads to increase in urinary frequency. Bladder capacity actually increases (up to 1500ml) as the bladder muscle tone decreases.

Hematologic System
Perhaps the most striking maternal physiologic alteration occurring during pregnancy is the increase in the blood volume. The increases in blood volume progress until term; the average increase in volume at term is 45-50%. The increase is needed for extra blood flow to the uterus, extra metabolic needs of fetus, and increased perfusion of other organs, especially kidneys. Extra volume also compensates for maternal blood loss during delivery. The average blood loss with vaginal delivery is 500-600ml, and with cesarean section is 1000ml.

With the increase in red blood cells, the need for iron for the production of hemoglobin, naturally increases. If supplemental iron is not added to the diet, iron deficiency anemia will result. If iron is not readily available, the fetus uses iron from maternal stores. Thus, the production of fetal hemoglobin is usually adequate even if the mother is severely iron deficient. Anemia in the newborn is rarely a problem; instead, maternal iron deficiency places the mother at risk for preterm labor and late spontaneous abortion.

White blood cell leukocyte count increases during pregnancy from a prepregnancy level of 4300-4500/mL to 5000-12000/mL in the last trimester.

During pregnancy, levels of several essential coagulation factors increase. Fibrinolytic (anticoagulation) activity is depressed during pregnancy and labor, although the precise mechanism is unknown. The placenta may be partially responsible for this change in clotting mechanisms.

Clearly, coagulation and fibrinolytic (clot busting) systems undergo major alterations during pregnancy leading to two of the more serious problems of pregnancy: hemorrhage and thromboembolic disease (blood clots). A traumatic insult may compound the problem.

Cardiovascular System
As the uterus enlarges the diaphragm becomes elevated, the heart is displaced upward and somewhat to the left. Cardiac capacity increases by 70-80mL; this may be due to increased volume or hypertrophy of cardiac muscle. The size of the heart appears to increase by about 12%

Cardiac output increases approximately 40% during pregnancy, reaching its maximum at 20-24 week's gestation and continuing at this level until term. The increase in output can be as much as 5L/min over the non-pregnant level. Cardiac output is very sensitive to changes in body position. This sensitivity increases with lengthening gestation, presumably because the uterus impinges upon the inferior vena cava, thereby decreasing blood return to the heart.

Systemic blood pressure declines slightly during pregnancy. There is a little change in systolic blood pressure, but diastolic pressure is reduced (5-10mmHg) from about 12-26 weeks. Diastolic pressure increases thereafter to pre-pregnancy levels by about 36 weeks.

As the uterus enlarges it presses on the inferior vena cava. This combined with the pressure of fetal presenting part on the common iliac vein may result in decreased blood return to the heart. This decreases cardiac output, leads to a fall in blood pressure, and causes edema in the lower extremities.

Pulmonary System
Pregnancy produces anatomic and physiologic changes that affect respiratory performance. As the uterus enlarges, the diaphragm is elevated. Lung volumes and capacities change. Respiratory changes include a slight increase in respiratory rate, a 50% increase in minute ventilation, a 40% increase in tidal volume, and a progressive increase in oxygen consumptions of up to 15-20%. With the increase in respiratory tidal volume associated with a normal respiratory rate, there is an increase in respiratory minute volume of approximately 26%. As the respiratory minute volume increases, "hyperventilation of pregnancy" occurs, causing a decrease in alveolar CO2 . This decrease lowers the maternal blood CO2 tension; however alveolar oxygen tension is maintained within normal limits. Maternal hyperventilation is considered a protective measure that prevents the fetus from the exposure to excessive levels of CO2..

Metabolism
As the fetus and placenta grow and place increasing demands on the mother, phenomenal alterations in metabolism occur. The most obvious physical changes are weight gain and altered body shape. Total body fat increases during pregnancy, but the amount varies with total weight gain.

Changes and the Relation to Trauma

All of these anatomical and physiological changes associated with pregnancy alter the patient's response to traumatic injury, requiring modified assessment, treatment, and transportation strategies.

The causes of maternal injury are as follows:
- 42% MVCs
- 34% falls
- 18% assaults
- < 1% burns
These injuries can result in trauma to the gravid uterus and to the maternal bladder, liver, and spleen. Retroperitoneal hemorrhage is also quite common. Maternal bowel injuries are rare. In addition, an injury that results in a pelvic fracture can produce massive hemorrhage and damage to the fetal skull. The severity of any injury depends on many factors, and as in a nongravid patient, severe maternal injury often involves multiple organ systems.

During pregnancy, the fetus is well protected within the uterus; amniotic fluid surrounds the fetus and serves as an excellent shock absorber. Because of this protection, it is extremely rare for a fetus to experience physical trauma except as a result of direct penetrating wounds or extensive blunt trauma to the maternal abdomen. The greatest risk of fetal death is from fetal distress and intrauterine demise caused by trauma to the mother or her death. Uteroplacental circulation does not autoregulate and is strongly influenced by mother's sympathetic tone. The fetus cannot protect itself from maternal hypotension or hypoxia. A mother's compensation for hemorrhage may result in fetal loss. Maternal compensation for hemorrhage may result in 20% fall in uterine blood flow before hypotension becomes evident. Blood flow is shunted away from the fetus as the mother compensates for her loss. When the mother is in trouble, it is obvious that the fetus is in trouble. When the fetus is in trouble, the mother is about to be.

EMS should promptly assess and intervene on behalf of the mother. Severe abdominal injury may result in premature separation of the placenta (abruption), premature labor or abortion, rupture of the uterus, and fetal death. Causes of fetal death from maternal trauma include death of the mother, separation of the placenta, maternal shock, uterine rupture, and fetal head injury.

Complications of Trauma Related to the Pregnant Patient

Placental Abruption:
Premature separation of the placenta may occur as the result of trauma. This condition occurs in 1 - 5% of minor injuries and 40 - 66% of patients with life-threatening injuries. Direct abdominal trauma is the most common cause, but not required. Placental Abruption Occurrence may be delayed 24 - 72 hours after the traumatic event.

Symptoms:
- uterine contractions
- uterine tenderness
- fetal tachycardia
- late decelerations (detected with fetal monitoring)
- vaginal bleeding present in < 50% of the cases

Risk factors increasing possibility of abruption:
- trauma
- hypertension
- diabetes
- smoking
- advanced maternal age
- drug abuse
- multiparity

Consequences of premature separation of placenta:
- Fetal death (inevitable if > 50% of placenta involved, overall fetal mortality 30-68%)
- Maternal hemorrhage
- Consumptive coagulopathy/DIC/Disseminated Intravascular Coagulation (severe coagulation disorder leading to massive hemorrhage)
- Amniotic fluid embolism
- Fetal-maternal hemorrhage

Uterine Rupture
- Rare, complicates < 0.6% of traumatic episodes in pregnancy.
- Fetal loss approaches 100%.
- Maternal mortality < 10% when rupture occurs, and often results from other injuries.
- Vaginal bleeding often does not occur with rupture.

Fetal distress occurs with reduction of fetal oxygen delivery < 50% of baseline. Causes may be maternal hypoxia and or blood loss from trauma or complications of trauma. Fetus itself may be traumatized as well as mother.
Signs of fetal distress include:
- bradycardia or tachycardia
- decreased fetal movement

The next two items are noted with fetal monitoring equipment:
- reduced or absent variability in heart rate
- repetitive late decelerations.

Assessment and Management

Priorities in assessing and managing a pregnant trauma patient are the same as for a nongravid patient: the ABCs, adequate airway, ventilatory, and circulatory support with spinal precautions; hemorrhage control; and rapid assessment, stabilization, and transport to a medical facility. Resuscitating the mother is the key to survival of both mother and fetus. Therefore during the initial stages of assessment and management, efforts should be directed toward the mother's status. Regardless of the severity of injury, all pregnant trauma patients should be transported for physician evaluation.

The secondary assessment should be thorough. Injuries that would contribute to hypovolemia or hypoxia must be detected, identified, and treated early. With the normal increase in maternal blood volume, the mother can tolerate more blood loss, but the fetus is at risk. A 30% to 35% reduction in blood volume can produce minimal changes in blood pressure but will reduce uterine blood flow by 10% to 20%. Thus the mother may achieve homeostasis at the expense of the fetus, and the true magnitude of blood loss may be difficult to discern. Fetal monitoring is the best available indicator of fetal well being after trauma. However, assessment of fetal heart rate should never delay patient transport. Accelerations of fetal heart rate above baseline are associated with fetal movement and contractions but may also be an early sign of fetal distress. Decreased fetal movement and increased fetal heart rate can indicate impending maternal shock. Decelerations of fetal heart rate below the baseline are associated with a decrease in cardiac output and the presence of hypoxia. A hypoxic fetus in metabolic acidosis cannot accelerate his or her heart rate and thus becomes bradycardic (a heart rate of less than 120 beats/mm). Sustained fetal bradycardia can only be tolerated for a short time before the fetus becomes acidotic. Fetal bradycardia is usually a late occurrence from maternal hypoxia and hemhorage.

Special Management Considerations:

Special considerations in managing the pregnant trauma patient include airway protection, oxygenation, volume replacement, and hemorrhage control. Premature labor is also a complication of trauma in pregnancy, so the EMS crew should be prepared to manage imminent delivery or spontaneous abortion. A fetus is considered viable if gestational age is > 23 weeks. Estimation of gestational age can be made based on fundal height. The diagram to the right illustrates gestational age based on fundal height.

If cardiac arrest occurs, cardiopulmonary resuscitation (CPR) should be instituted in the usual fashion. An aggressive resuscitation effort is justified in patients near term to allow for emergency cesarean delivery at the emergency department. Fetal survival is good if the interval between maternal death and delivery is less than 5 minutes and poor if longer than 20 to 25 minutes. Advance notice to the receiving emergency department of impending emergency cesarean delivery is paramount.

Oxygenation
· Adequate airway maintenance and oxygenation are essential to prevent fetal hypoxemia. The pregnant trauma patient is prone to vomiting and aspiration due to the decreased gastric motility described earlier.
· Oxygen requirements are 10% to 20% greater than in the nongravid patient. Fetal hypoxia may occur with even small changes in maternal oxygenation.
· If available, pulse oximetry should be used to monitor oxygen saturation.

Volume Replacement
· Signs and symptoms of hypovolemia may not be present until a blood loss is large.
· Blood is preferentially shunted away from the uterus to preserve maternal blood pressure.
· Bleeding may also occur inside the uterus. The pregnant uterus can hide up to 2000 ml of blood following separation of the placenta with little or no evidence of vaginal bleeding.
· Crystalloid fluid replacement should be initiated even in normotensive patients.
· Vasopressors are generally not recommend because they decrease uterine blood flow and fetal oxygen delivery; fetal hypoxia ensues.

Hemorrhage Control
· External hemorrhage is controlled.
· Vaginal bleeding may indicate placental separation or uterine rupture
· A vaginal examination should be avoided as it may increase bleeding and precipitate delivery.
· The amount and color of vaginal bleeding should be documented.
· Any expelled tissue should be collected a transported with the patient to the hospital

Transportation Strategies
After 3 to 4 months gestation, pregnant patient should not be transported in a supine position. There is a potential for supine hypotension. Supine hypotension syndrome:
- decreased venous return due to pressure of the uterus on the inferior vena cava in supine position.
- will cause hypotension even in the absence of injury in a significant proportion of third-trimester pregnancies.
- shifting patient 15 degrees to left, or manual displacement of uterus to the left, can increase uterine blood flow and systolic blood pressure by 20-30%.

If spinal injury is not suspected, the patient should be transported in a left lateral recumbent position If spinal injury is suspected, the EMS provider prepare the patient for transport in the following manner:
1 . Fully immobilize the patient on a long spine board.
2 . After immobilization, carefully tilt the board on its left side by logrolling the secured patient 10 to 15 degrees.
3 . Place a blanket pillow or towel under the right side of the board to move the uterus to the left.

Reference
DeCherney,Pernoll-Obstetric & Gynecologic Diagnosis & Treatment
Pregnancy & Trauma by Steve Carlteon MD. PhD

Case Study:

A 23 year old female driver was involved in a T-bone MVC where her driver’s side was struck by another vehicle going about 40 mph. She was restrained and her air bags deployed. Due to severe damage to the woman’s car, it took twenty minutes to extricate her. On the arrival of EMS personnel, she complained of severe left hip and back pain and had an obvious deformity of her left arm. She was crying and asking about her baby. She reported that she was 35 weeks pregnant with her second baby. She states that she has had no problems with this pregnancy, but she may be having contractions now.

Upon extrication, her spine was immobilized using a backboard, rigid c-collar, and CID blocks. On a primary survey, she was maintaining an airway without difficulty. Her respirations were slightly fast at 28/minute, but symmetrical. Bilateral breath sounds were clear and equal. There was no crepitus to her chest and her trachea was midline. Her O2Sat was 95%. Mucosa was moist and pink. O2 was started at 15L/min via a non-rebreather mask to increase O2 content for both mother and child.

The woman’s pulse was thready and fast. A monitor revealed sinus tachycardia at 122 beats/minute and a blood pressure of 106/62. Due to her tachycardia and relative hypotension, two large bore IVs were stated and an infusion of normal saline was given. Her backboard was tipped to the left to displace her uterus and provide for better venous return to her heart. Her Glascow Coma Scale was 15. Both pupils were equal and briskly reactive to light.

On secondary survey, the young woman was found to have irregular contractions, no external vaginal bleeding or fluid, and fetal heart tones at a rate of 137/minute by Doppler. An OB pack was made ready in case of a precipitous delivery. Her left arm was splinted.

During her transport to a trauma center, repeat vital signs were:

Pulse-106, B/P-132/74, Respiratory Rate-20, and O2Sat-100. The patient still complained of hip and back pain, but stated that contractions seemed to be decreasing. Treatment priorities of airway, breathing, and circulation were addressed for both the mother and the baby.

Upon her safe arrival at the trauma center, she was found to have a pelvic fracture with bleeding into her retroperitoneal space and a fractured left humerus. The baby was not in distress and no injuries were found by ultrasound. With timely and appropriate care, both mother and baby survived without serious complications.

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