The pregnant trauma patient

1. The pregnant trauma patient Tom Archer MD, MBA UCSD Anesthesia

2. Outline • Epidemiology • General approach to the patient • Anesthesia and diagnostic studies. • Obstetric complications of trauma • (What the obstetrician will be thinking about) • Relevant maternal / fetal physiology • FHR monitoring • Perimortem cesarean section

3. Trauma in pregnancy • Trauma is most common non-obstetric cause of maternal death. • Common major traumas: MVAs, falls and assaults. • 5-10% of pregnancies are marred by some sort of trauma (usually very minor and not seen in hospital). • In one study, 0.2% of all pregnant women were seen in hospital for trauma during a given pregnancy. Chestnut chap 53, El Kady D et al 2004

4. Trauma in pregnancy • Incidence of trauma increases as pregnancy progresses: • 8% in first trimester • 40% in second trimester • 52% in third trimester

5. Causes of maternal death • Most maternal deaths are due to head trauma or hemorrhagic shock.

6. Commonest causes of fetal death • In severe maternal injury, it is maternal death. • In “minor” injury, it is placental abruption

7. Pregnant women need to wear seat belts properly: One strap under uterus, the other between breasts. Many women don’t wear them for fear of hurting the baby. Improper placement can injure fetus. http://www.maternity-seatbelt.jp/Seat_belt_photo.gif

8. Domestic violence • Domestic violence knows no boundaries of race or economic status. • Pregnancy often represents dependency and loss of autonomy and control. • Abusers will take advantage of this. They may feel threatened by pregnancy and attack abdomen as a way of retaliating against fetus.

9. Domestic violence • Think of it as a possibility! • Look for emotional withdrawal, depression, self-blame. • Look for other (older) signs of injury. • Face-to-face, one-on-one interviews. Calm, matter-of-fact tone helps elicit Hx.

10. “What will happen to my baby?” • “Trauma appears to affect the fetus only in the short-term…” • “…if there is no early placental abruption, fetal death, premature rupture of membranes, or urgent delivery, there is no significant difference in pregnancy outcome…” • Shah KH 1998

11. Trauma management in pregnancy • Best way to take care of baby is to take care of mother. All ACLS guidelines apply. • Know how physiological / anatomical changes of pregnancy affect vulnerability of patient to stresses. • Plan for specific obstetric concerns (without getting obsessed). • Common worries (patient, nurse, MD) : radiation, drugs, abruption, anesthesia.

12. Anesthesia in OB trauma • Maintain good anesthesia, oxygenation, normotension, normothermia, normocarbia (PaCO2 = 30) and LUD. Avoid ketamine > 2 mg /kg (uterine hypertonus). • Monitor FHTs if practical. Loss of variability is normal, but fetal tachy- or bradycardia may mean hypoxia. • Defensive medicine: probably avoid benzodiazepines and N2O early in gestation (little to no solid evidence for this).

13. X-ray studies in pregnant patients • Use x-ray studies judiciously– but USE THEM when needed! • Shield uterus when possible. • Consult with radiologist on minimizing exposure.

14. X-ray doses from studies 1 Rad = 10 mGy (“milliGrey”) Mann FA et al 2000

15. Risk from X-ray exposure1 Rad = 10 mGy (“milliGrey”) Benefit of judiciously chosen x-rays far outweighs risks in pregnant trauma patients. Intermediate exposure (50-100 mGy) roughly equivalent to 3 years of natural background radiation exposure and is associated with no increase in anomalies or growth restriction. Mann FA et al 2000

16. X-ray studies in pregnant patients • CT is gold standard for Dx of blunt abdominal trauma. • Transport from ER to CT scanner and radiation risks / fears remain as obstacles to CT. Miller MT 2003

17. MVA, pregnant patient at 27 weeks EGA, lap belt worn across the bulge. CT scan: ruptured uterus with extruded products of conception. Astarita DC et al 1997

18. MVA, pregnant patient at 27 weeks EGA, lap belt worn across the bulge. CT scan: ruptured uterus with extruded products of conception. Astarita DC et al 1997

19. Ultrasound in trauma evaluation • Can ultrasound substitute for CT? Modality is called FAST (“Focused Abdominal Sonography for Trauma”). • Focus of FAST is detecting free fluid, presumed to be blood. • FAST is part of screening process, but can miss injuries (e.g. solid organ). Miller MT 2003

20. Lateral pelvic ultrasound: free fluid in cul-de-sac (+ Foley in bladder). Richards JR 2004

21. Obstetric complications of trauma • Abruption Pre-term labor • Ruptured membranes • Uterine rupture • Direct fetal injury (usually penetrating trauma) • Rare: amniotic fluid embolus, chorionic villus embolus Kingston NJ 2003 Judich A 1998

22. Predisposing factors to DIC / ARDS after trauma in pregnancy: • Abruption. • Dead fetus. • Shock • Sepsis • Traumatic amniotic fluid embolus (rare). • Factors in common are release of abnormal substances into circulation. • Hypothermia and acidosis exacerbate coagulopathy. Ferrara A 1990

23. Normal placental function: fetal and maternal circulations separated by thin membrane (syncytiotrophoblast). Diffusion of O2 and CO2 is +/- complete. Fetal O2 uptake limited by uterine blood flow. ) Umbilicalartery (UA) Umbilical vein (UV) Fetus “Lakes” of maternal blood Fetal capillaries in chorionic villi Mom Uterine veins Uterine arteries Archer TL 2006 unpublished

24. www.siumed.edu/~dking2/erg/images/placenta.jpgfrom Google images

25. Placental abruption: fetal asphyxiation (O2 supply is cut off). ) Umbilicalartery (UA) Umbilical vein (UV) Abruption Uterine veins Uterine arteries Archer TL 2006 unpublished

26. Placental abruption Placenta shears off Liquid placenta Elastic myometrium

27. Abruption separates here www.simba.rdg.ac.uk From Google images

28. Placental abruption from “minor” trauma Usually happens within 4-6 hours (if it’s going to happen). Incidence of abruption from minor trauma is low (1.6%), but… Minor trauma is common, so minor trauma causes many abruptions. Major trauma is uncommon, but incidence of abruption is high (37.5%). Pearlman MD 1997

29. Miller’s Anesthesia chap. 58

30. Placental abruption • Accompanies 1-5% of minor injuries, 20-50% of major injuries. • Abdominal tenderness • Uterine tenderness • Uterine contractions • Vaginal bleeding– but hemorrhage may be hidden.

31. Placental trauma (+/- abruption):Feto-maternal hemorrhage • More common with anterior placenta? (Pearlman 1990) • Chorionic villi break, releasing fetal RBCs into lakes of maternal blood. • Dangers: • Iso-immunization of Rh- mother by Rh+ fetal cells. • Fetal exsanguination / anemia / hydrops / brain damage. • Premature labor (due to release of thrombin, lysozymes or prostaglandins into maternal circulation?).

32. Placental disruption: feto-maternal hemorrhage ) Umbilicalartery (UA) Umbilical vein (UV) Chorionic villus disruption Uterine veins Uterine arteries Archer TL 2006 unpublished

33. www.siumed.edu/~dking2/erg/images/placenta.jpgfrom Google images

34. Chorionic villus disruption causing feto-maternal hemorrhage www.simba.rdg.ac.uk From Google images

35. Kleihauer- Betke preparation • Maternal blood smear eluted with acid wash. • Adult hemoglobin washed away • Fetal hemoglobin stays behind– a few brightly stained fetal cells amongst a sea of ‘”ghostly” maternal cells.

36. Kleihauer-Betke preparation: Massive fetal-maternal hemorrhage www.cbbsweb.org from Google images

37. KB prep to diagnoseFeto-maternal hemorrhage • One dose of RhoGam (anti-D antibody to destroy fetal Rh+ RBCs) is routine with trauma to Rh- mother (regardless of KB results). • Kleihauer – Betke prep sometimes used to assess: • Need for repeated RhoGam doses (large FMH) • Probability of pre-term labor (?)

38. Does feto-maternal hemorrhage promote pre-term labor?

39. Theory: Kleihauer -Betke test predicts uterine contractions and preterm labor Muench MV et al 2004

40. Fetal heart rate monitoring (for hypoxia) after trauma • Worry is abruption. • Usually combined with contraction monitoring. • 4 hours is routine. • >4 hours if: • Abruption suspected • Frequent uterine activity • Rupture of membranes • FHR abnormalities present • Mother is in critical condition Chestnut chap 53

41. Ruptured uterus • Life-threatening emergency, 10% maternal mortality • Fetus almost always dies.

42. Ruptured amniotic membranes • Vaginal fluid leak– avenue for infection. • By itself, not an emergency.

43. Maternal / fetal physiology and anatomy relevant to trauma

44. Mom 4 ml O2 / kg / min Feto-placental unit 12 ml O2 / kg / min Mother is consuming and delivering oxygen for two! www.studentlife.villanova.edu

45. Physiological changes of pregnancy at term: • Maternal-fetal O2 consumption increases 40-50% over non-pregnant state. • Cardiac output increases by 50%. • Functional residual capacity (apneic reserve of O2) decreases by 20% Pregnant patient has diminished capacity to tolerate apnea! Chestnut chap. 53

46. Functional residual capacity (FRC) is our “air tank” for apnea. www.picture-newsletter.com/scuba-diving/scuba... from Google images

47. Pregnant Mom has a smaller “air tank”. Non-pregnant woman www.pyramydair.com/blog/images/scuba-web.jpg

48. At term, mother has respiratory alkalosis with metabolic compensation (less HCO3- buffer). Chestnut

49. At term, mother also has lower hemoglobin concentration to buffer acid load:

50. Compared to non-pregnant state, pregnant woman has less tolerance for: • Apnea • Acidosis