Chapter 35 – Major Trauma Including Road Traffic Accidents




Abstract




Blunt trauma is the most common type of trauma in pregnancy, being caused mainly by road traffic accidents. Different mechanisms of injury give rise to a variety of injury patterns. Blunt forces commonly cause compression injuries, particularly laceration or fracture of solid organs. Sudden deceleration and consequent shearing forces cause avulsion of peritoneal attachments or arteries. Rapid increase in abdominal pressure, for example from a seat belt, can result in hollow viscus rupture or rib or pelvic fractures and cause laceration injuries.





Chapter 35 Major Trauma Including Road Traffic Accidents


Kirsty Crocker and Tim Patel




Key Facts


Trauma is a leading cause of non-obstetric maternal death in the developed world, complicating up to 7% of all pregnancies. The leading cause is road traffic accidents (RTAs) followed by domestic abuse of the obstetric patient [1, 2].


The core principles of trauma management are similar for both pregnant and non-pregnant patients. However, anatomical and physiological changes in the pregnant patient must be appreciated, as they can pose significant challenges for the attending physicians.


Physiological changes can mask normal findings in the trauma patient, leading to inaccurate interpretation of vital signs, while anatomical changes can not only cause differing injury patterns depending on gestational age, but can also cause difficulties with intubation.



Mechanism of Injury



Blunt Trauma


Blunt trauma is the most common type of trauma in pregnancy, being caused mainly by road traffic accidents. Different mechanisms of injury give rise to a variety of injury patterns. Blunt forces commonly cause compression injuries, particularly laceration or fracture of solid organs. Sudden deceleration and consequent shearing forces cause avulsion of peritoneal attachments or arteries. Rapid increase in abdominal pressure, for example from a seat belt, can result in hollow viscus rupture or rib or pelvic fractures and cause laceration injuries.


Pregnancy-specific injuries include




  • Preterm labour



  • Preterm prelabour rupture of membranes; abruption



  • Direct uterine injury; uterine rupture



  • Direct fetal injury



  • Pelvic fractures, fetal mortality 25%


Splenic injury is the most common significant injury in pregnancy secondary to trauma [3]. Maternal shock is the most common cause of death [4], followed by abruption and uterine rupture [5, 6].



Penetrating Trauma


Penetrating trauma, in particular gunshot and knife wounds, accounts for up to 10% of cases and causes a quarter of maternal deaths [7]. Maternal visceral injury is less common than direct fetal injury, 38% versus 70% during the third trimester [8]. During the first trimester the increased uterine density and uterine pelvic position protect the fetus. As the uterus becomes intra-abdominal from 13 weeks of gestation, it displaces bowel and abdominal viscera superiorly. It becomes increasingly vulnerable to direct injury with potential to cause catastrophic haemorrhage when injured. Although the uterus confers some protection to the maternal viscera, upper abdominal wounds can result in significant injury, with a higher likelihood of multiple organ damage.



Issues Relating to Blunt and Penetrating Trauma


Abdominal examination can be unreliable due to the peritoneal distension of pregnancy and neural desensitisation. This can result in atypical pain referral and increased peritoneal pain threshold. Therefore it is important to maintain a high index of suspicion. Abdominal pain with shoulder tip referral should be regarded as a potential liver injury until proven otherwise. It is essential to understand the consequences of organ displacement in the parturient. Haematuria should be evaluated fully, as the displaced bladder is more susceptible to injury and a palpable liver should be deemed abnormal until proven otherwise, as the liver is displaced superiorly by approximately 4 cm in the full-term mother.


The decision to proceed to laparotomy depends on several factors:




  • Gestational age



  • Site of injury



  • Maternal shock



  • Fetal distress


Evidence of intraperitoneal haemorrhage secondary to blunt trauma is treated similarly in both pregnant and non-pregnant patients. Gunshot injury almost always requires an exploratory laparotomy. Conversely, laparotomy in patients with stab wounds is reserved for patients exhibiting signs of shock or radiographic evidence of organ injury or peritoneal injury, bearing in mind that the risk of peritoneal injury increases with increasing abdominal distention of pregnancy. Laparoscopy may be used for lower abdominal penetrating trauma when both mother and fetus are stable; however, exploratory laparotomy is recommended for upper abdominal trauma [9, 10]. Other investigations include performing a fistulogram or amniocentesis. A fistulogram can determine whether the peritoneum has been injured, thus indicating the need for laparoscopy or laparotomy, and amniocentesis can demonstrate a potential uterine injury. However, the presence of bacteria or blood is not an absolute indication for delivery.


Laparotomy is not an indication for performing caesarean section. Provided that maternal injury can be correctly identified and safely managed, the gravid uterus should be left undisturbed and the pregnancy allowed to proceed to term. However, a caesarean section should be considered if the uterus interferes with treatment of the mother. Other indications for a caesarean section include near-term, irreparable uterine damage, maternal shock, unstable thoracolumbar injury, and maternal death.



Key Pitfalls




  • Massive haemorrhage. Uterine blood flow increases from 60 mL/minute to 750 mL/minute with resultant massive haemorrhage in blunt or penetrating trauma.



  • Unreliable abdominal examination. Peritoneal distension of pregnancy and neural desensitisation lead to atypical pain referral and an enhanced peritoneal pain threshold.



  • Burns: Maternal outcome with respect to burn injury is not affected by the pregnancy; however, fetal survival parallels the percentage of burns, with spontaneous abortion being more common in the first trimester. This is due to septicaemia, hypoxia, and the intensely catabolic state of the burn victim [11, 12]. It is generally accepted that urgent delivery is required if the patient has more than 50% burns in the second or third trimester. Treatment priorities are the same as for the non-pregnant woman, but attention should be paid to fluid resuscitation and airway management.



  • Fetal mortality is as high as 70% with electrical burns due to the fetus sitting in a bag of low-resistance fluid; fetal monitoring is essential even when the injury appears minor.



Key Pearls




  • Increase fluid requirements. Fluid volumes are greater than in the non-pregnant patient.



  • Intubate early. Airway oedema can make a difficult pregnant airway extremely challenging.



Key Actions


A multidisciplinary approach involving emergency department physicians, obstetricians, neonatologists, anaesthetists and surgeons is essential. The initial management approach for the parturient remains the same as for the non-pregnant patient, remembering that fetal outcomes are intimately dependent on adequate resuscitation of the mother prior to early fetal assessment. The initial sequence of trauma resuscitation follows the standard ABCDE approach to trauma [13]. The most recognisable additions are early left lateral tilt and fetal assessment. During the primary survey, life-threatening injuries are identified and managed simultaneously. The primary survey includes




  • Airway maintenance with cervical spine protection



  • Breathing and ventilation



  • Circulation with haemorrhage control



  • Disability: neurological status



  • Exposure and environmental control



Airway with Cervical Spine Control


If a cervical spine injury is suspected, the neck should be immobilised with three-point immobilisation, which should include a well-fitting cervical collar, blocks and tape. All patients should receive high-flow oxygen through a high concentration mask. Any airway compromise should give rise to early consideration of securing the airway with a definitive airway. The potential for a difficult intubation secondary to anatomical changes, airway oedema and delayed gastric emptying should be anticipated. Therefore gastric prophylaxis and rapid sequence induction are essential if a general anaesthetic is required; however, regional anaesthesia is preferable. It is essential to aim for normal physiological parameters to reduce any chance of fetal hypoxia and acidosis. A ‘light anaesthetic’ causes increased catecholamine release, reducing placental flow; therefore ensure adequate anaesthetic doses during a general anaesthetic. The increased risk of failed intubation in the pregnant patient mandates the immediate availability of appropriate difficult-airway equipment.



Key Pitfall


Increased risk of difficult intubation and gastric aspiration.



Breathing and Ventilation


Attention should be given to the physiological respiratory changes that can affect assessment and management in trauma. Respiratory changes are secondary to the effects of progesterone on the respiratory centre, compounded by the raised diaphragm compressing the lungs. This results in a physiological dyspnoea, increased metabolic demands and oxygen consumption and therefore a decreased respiratory reserve.


These changes can result in rapid oxygen desaturation if ventilation is impaired; hence all patients must receive high-flow oxygen through a high-concentration mask. Tidal volumes are increased, resulting in a slightly lower PaCO2 of 4 kPa. ‘Normal’ PaCO2 levels should raise concerns, indicating possible ventilatory compromise. The diaphragm is raised by up to 4 cm; therefore thoracostomy should be placed 1–2 intercostal spaces higher.



Key Pitfalls




  • Decreased functional residual capacity and increased oxygen consumption can lead to rapid desaturation; therefore oxygenate all patients.



  • Thoracostomy placement should be one to two spaces higher.



Circulation and Haemorrhage Control


Insert two large-bore cannulae, take blood for full blood count, coagulation studies, X-Match, Rh status, Kleihauer–Betke test for fetal cells and urea and electrolytes. Evidence of cardiovascular compromise may be masked or mimicked by both cardiac and vascular changes of normal pregnancy. The physiological increase in intravascular volume means that pregnant patients can lose a significant volume of blood before exhibiting any signs of hypovolaemia. Thus fetal hypoperfusion and distress can manifest well in advance of maternal compromise becoming apparent. Physiological changes to be mindful of include a reduction in systolic and diastolic blood pressure of 10–20 mm Hg and a 10–20 beats per minute rise in heart rate. These changes are at their ‘peak’ at 28 weeks’ gestation, returning to prepregnancy levels at term. Arrhythmias or palpitations are also common, as are ECG changes such as nonspecific ST changes and inferior Q waves.


From 20 weeks’ gestation the uterus can compress the inferior vena cava and aorta, causing a significant reduction in cardiac output, exacerbating a potential shock state. Early displacement of the uterus to the left either manually or via tilting the patient to 15–30 degrees with a pillow or wedge is essential. If a spinal injury is suspected, the patient should be immobilised on a spinal board and the whole board tilted. Left lateral tilt should be maintained at all times, including during transport, as failure to do so may result in a fall in cardiac output of up to 30%.



Damage Control Resuscitation


Resuscitation of the trauma patient requires proactive concurrent treatment of the ‘the lethal triad’ of




  • Coagulopathy



  • Hypothermia



  • Acidosis


Damage control resuscitation is the systematic approach to major trauma, combining a series of clinical techniques:




  • Rapid control of bleeding



  • Fluid resuscitation



  • Haemostatic resuscitation



Rapid Control of Bleeding




  • Direct pressure



  • Tourniquets



Fluid Resuscitation


Minimise crystalloid-based resuscitation to avoid dilutional coagulopathy and acidosis. Excessive crystalloid can lead to oedema, compartment syndrome and acute lung injury as well as possible clot disruption and exacerbation of bleeding.


The use of vasopressors will contribute to fetal hypoxia by reducing uterine blood flow and should be used only to support maternal blood pressure if absolutely necessary, for example, in spinal shock.



Haemostatic Resuscitation


Very early use of blood and blood products as primary resuscitation fluids, for example,




  • 2–4 units of packed red blood cells



  • 2–4 units of fresh frozen plasma (FFP)



  • 1 pool of platelets



  • 1–2 pools of cryoprecipitate (8–10 units)


Haemostatic resuscitation is moving to a higher ratio of FFP and platelets to red blood cells. Randomised controlled trial (RCT) evidence is limited for a 1:1:1 ratio of RBC: FFP: platelets, most being from observational non-civilian, non-obstetric trauma in the military setting. For this reason, many units use a ratio of 2:1:1 [14, 15].



Haemostatic Agents


Haemostatic agents can be used as an adjunct to prevent or control bleeding and should be considered in the obstetric trauma setting.



Fibrinogen Concentrate


Fibrinogen concentrate has been used in the obstetric trauma setting. FFP is still first line in many countries to replace fibrinogen, as the concentrate is expensive and not yet proven in RCTs. However, its advantages over FFP/cryoprecipitate are as follows:




  • Rapid reconstitution



  • Lower volume



  • Standardised fibrinogen concentration



  • Virally inactivated



Tranexamic Acid


Tranexamic acid has been shown in large multicentre RCTs to decrease mortality if given to major trauma patients within 3 hours of injury as well as reducing death due to bleeding in women with postpartum haemorrhage with no adverse effects [16, 17].



Calcium Replacement


Massive blood transfusion can lead to acute hypocalcaemia due to the calcium binding effect of the citrate in stored blood.


Ionised calcium levels <1 mmol/L can impair coagulation and should be replaced.



Recombinant Factor VIIa


Recombinant factor VIIa (rFVIIa) has been used off label in the obstetric setting or as part of clinical trials. However, lack of RCT evidence, expense and concerns with regards to the potential to cause thromboembolism have limited its use.



Point of Care Testing


Pregnancy is a naturally occurring prothrombotic state thought to be a protective mechanism for decreasing blood loss following the delivery of the placenta. Physiological changes in the coagulation system during pregnancy include




  • Increase in a number of coagulation factors including fibrinogen



  • Decreased fibrinolysis



  • Decreased platelet count


However, this normal decrease in activated partial thromboplastin time (aPTT), prothrombin time (PT)/international normalised ratio (INR), thrombin time (TT) and a fibrinogen level >300 mg/dL can lead to delayed recognition and treatment of coagulopathy.



Viscoelastic Coagulation Monitoring





  • Thromboelastography (TEG)



  • Rotational thromboelastometry (ROTEM)



Real-time, rapid bedside assessment of the viscoelastic properties of a clot is a useful means to rapidly diagnose coagulopathy and guide transfusion requirements in major trauma.


TEG/ROTEM provide a global and functional assessment of coagulation in terms of time to clot initiation, clot strength, and fibrinolysis in comparison to traditional testing that inform on clot initiation.


Both tests used in parallel decrease transfusion requirements in comparison to the traditional ‘blind’ approach.

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May 9, 2021 | Posted by in OBSTETRICS | Comments Off on Chapter 35 – Major Trauma Including Road Traffic Accidents
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