Transcript The pregnant trauma patient - UC San Diego Department of

The pregnant trauma patient
Tom Archer MD, MBA
UCSD Anesthesia
Outline
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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
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
Trauma in pregnancy
• Incidence of trauma increases as
pregnancy progresses:
– 8% in first trimester
– 40% in second trimester
– 52% in third trimester
Causes of maternal death
• Most maternal deaths are due to head
trauma or hemorrhagic shock.
Commonest causes of fetal death
• In severe maternal injury, it is maternal
death.
• In “minor” injury, it is placental abruption
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.maternityseatbelt.jp/Seat_belt_photo.gif
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.
Domestic violence
• Think of it as a possibility!
• Look for emotional withdrawal, depression, selfblame.
• Look for other (older) signs of injury.
• Face-to-face, one-on-one interviews. Calm,
matter-of-fact tone helps elicit Hx.
“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
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.
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).
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.
X-ray doses from studies
1 Rad = 10 mGy (“milliGrey”)
Mann FA et al 2000
Risk from X-ray exposure
1 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
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
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
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
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
Lateral pelvic ultrasound: free fluid in cul-de-sac (+ Foley in bladder).
Richards JR 2004
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
Predisposing factors to DIC / ARDS
after trauma in pregnancy:
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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
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.
Umbilical artery (UA)
Umbilical vein (UV)
Fetus
“Lakes” of
maternal blood
Fetal capillaries
in chorionic villi
Uterine veins
Mom
Archer TL 2006 unpublished
Uterine arteries
www.siumed.edu/~dking2/erg/images/placenta.jpg
from Google images
Placental abruption: fetal) asphyxiation
(O2 supply is cut off).
Umbilical vein (UV)
Umbilical artery (UA)
Abruption
Uterine veins
Uterine arteries
Archer TL 2006 unpublished
Placental abruption
Placenta
shears off
Liquid placenta
Elastic myometrium
Abruption separates here
www.simba.rdg.ac.uk
From Google images
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
Miller’s Anesthesia chap. 58
Placental abruption
• Accompanies 1-5% of minor injuries, 20-50% of
major injuries.
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Abdominal tenderness
Uterine tenderness
Uterine contractions
Vaginal bleeding– but hemorrhage may be
hidden.
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?).
Placental disruption: feto-maternal
hemorrhage
)
Umbilical vein (UV)
Umbilical artery (UA)
Chorionic villus
disruption
Uterine veins
Uterine arteries
Archer TL 2006 unpublished
www.siumed.edu/~dking2/erg/images/placenta.jpg
from Google images
Chorionic villus
disruption causing
feto-maternal
hemorrhage
www.simba.rdg.ac.uk
From Google images
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.
Kleihauer-Betke preparation: Massive fetal-maternal hemorrhage
www.cbbsweb.org from Google images
KB prep to diagnose
Feto-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 (?)
Does feto-maternal hemorrhage
promote pre-term labor?
Theory: Kleihauer -Betke test predicts uterine contractions and preterm labor
Muench MV et al 2004
Fetal heart rate monitoring
(for hypoxia) after trauma
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Worry is abruption.
Usually combined with contraction monitoring.
4 hours is routine.
>4 hours if:
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Abruption suspected
Frequent uterine activity
Rupture of membranes
FHR abnormalities present
Mother is in critical condition
Chestnut chap 53
Ruptured uterus
• Life-threatening emergency, 10% maternal
mortality
• Fetus almost always dies.
Ruptured amniotic membranes
• Vaginal fluid leak– avenue for infection.
• By itself, not an emergency.
Maternal / fetal physiology and
anatomy relevant to trauma
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
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
Functional residual capacity (FRC) is our “air tank” for apnea.
www.picture-newsletter.com/scuba-diving/scuba... from Google images
Pregnant Mom has a smaller “air tank”.
Non-pregnant
woman
www.pyramydair.com
/blog/images/scubaweb.jpg
At term, mother has respiratory alkalosis with
metabolic compensation (less HCO3- buffer).
ABGs
Chestnut
At term
PaCO2
Nonpregnant
40
PaO2
100
103
pH
7.40
7.44
HCO3-
24
20
30
At term, mother also has lower
hemoglobin concentration to buffer
acid load:
Hemoglobin
Non-pregnant
At term
12-14 gm / dL
11-12 gm / dL
Compared to non-pregnant state,
pregnant woman has less tolerance for:
• Apnea
• Acidosis
Hematologic changes at
term:
Blood volume increased by 45%
Pregnant woman may tolerate
hemorrhage better than nonpregnant woman, before showing
fall in BP.
Fibrinogen increased.
PT, PTT shortened 20%.
Increased platelet turnover.
Increase in coagulation factors,
immobilization and aorto-caval
compression all increase risk of
DVT.
Vascular congestion
• Swelling of respiratory mucosa (nose, rest
of airway).
• Don’t put anything through the nose if you
can avoid it  prevent bad nose bleed.
GI tract
• Decreased gastric emptying
• Increase GERD
• Full stomach precautions
Avoid aorto-caval compression: use
left uterine displacement (LUD)
• LUD helps venous return. C/S as part of
resuscitation?
• LUD decreases chance of DVT
• LUD increases O2 delivery to fetus:
– Increases uterine artery pressure and decreases
uterine venous pressure.
•Why we don’t do it: It doesn’t look right!
Normal placental function: fetal and maternal circulations separated by thin membrane.
)
Diffusion of O2 and CO2 is +/- complete. Umbilical vessels have no tone.
Fetal O2 uptake limited by uterine blood flow.
pH = 7.37
pO2 = 28
Umbilical artery (UA)
300 ml / min
Umbilical vein (UV)
Fetus
pH = 7.33
pO2 = 15
pCO2 = 44
pCO2 = 35
Uterine artery
Uterine vein
700 ml / min
pH = 7.35
pH = 7.45
pO2 = 33
pO2 = 96
Mom
pCO2 = 37
pCO2 = 28
Data from Chestnut chap.4
Ohm’s Law of the placenta: O2 delivery = Placental blood flow = (P1 – P2) / R
Aorto-caval compression decreases P1 (“aorto”) and increases P2 (“caval”)
Therefore, aorto-caval compression decreases O2 delivery to fetus.
R = placental resistance
(fixed in short term)
P1 = uterine
Placenta blood flow
(O2 delivery) =
artery pressure
(P1 – P2) / R
P2 = uterine vein pressure
Archer TL 2006
Colman-Brochu S 2004
http://www.manbit.com/OA/f28-1.htm
http://www.manbit.com/OA/f28-1.htm
Manbit
images
Chestnut chap. 2
What happens if fetus doesn’t get enough oxygen?
(What is the mammalian diving response?)
www.doc.govt.nz/.../images/diving-whale-tail.jpg
FIGURE 6. Nonreassuring pattern of late decelerations with preserved beatto-beat variability. Note the onset at the peak of the uterine contractions and
the return to baseline after the contraction has ended. The second uterine
contraction is associated with a shallow and subtle late deceleration.
http://www.aafp.org/afp/990501ap/2487.html
Humans have diving responses too!
Univ of Lund Thesis
Johan Andersson
http://www.biol.lu.se/zoof
ysiol/Johan/Avhandling.h
tml#Sv
The human diving response. The changes in mean arterial blood pressure
(MAP), heart rate (HR) and skin capillary blood flow (SkBF) during apnea with
face immersions are shown. The heart rate and skin capillary blood flow are
reduced while the MAP increases during apnea.
Univ of Lund Thesis Johan Andersson
http://www.biol.lu.se/zoofysiol/Johan/Avhandling.html#Sv
The mammalian diving reflex shuts down blood flow
to all organs except the heart and brain, in order to
conserve oxygen.
The fetus’ response to hypoxia is related to this reflex.
See Univ of lund thesis Johan Andersson
http://www.biol.lu.se/zoofysiol/Johan/Avhandling.html#Sv
Perimortem cesarean section – 5 minute rule
Chestnut chap. 53
Summary
• MVAs, falls and assaults are the
commonest traumatic mechanisms in
pregnancy.
• Think of the possibility of domestic
violence / partner abuse.
• Pregnant women need to wear seat belts
properly.
Summary
• Don’t over-react to the fact that patient is
pregnant.
• ACLS and all usual diagnostic studies
should be performed. Ultrasound may be
useful, but perform needed x-ray studies!
• Management of pregnancy is part of
secondary survey.
Summary
• Abruption is commonest cause of fetal
death in non-life-threatening trauma to
mother.
• Abruption most likely with abdominal
trauma.
• Abdominal trauma can also cause fetomaternal hemorrhage, uterine rupture,
rupture of membranes and pre-term labor.
Summary
• Feto-maternal hemorrhage may be a
cause of pre-term labor.
• KB prep may have value in screening for
severe feto-maternal hemorrhage and risk
of pre-term labor.
• One dose of RhoGam is routine in trauma
to Rh- mother, regardless of KB results.
Summary
• Pregnant women are vulnerable to apnea and
have swollen airways.
• They may be tolerant of blood loss, with
delayed fall in BP.
• LUD is important for 3 reasons:
– Maternal hemodynamics
– Fetal oxygenation
– DVT prophylaxis
Summary
• Fetal oxygen uptake is proportional to
placental blood flow.
• The fetus will drop heart rate in response to
hypoxia. This is the basis for FHR monitoring
after maternal trauma.
• This response is related to the “mammalian
diving reflex.”
Summary
• To deliver an intact newborn, perimortem
cesarean section should deliver baby
within 5 minutes of cessation of maternal
circulation and oxygenation.
My Website
• You can download this talk from:
• www.archeranesthesia.info
Thank you!
The End
References
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Astarita: J Trauma, Volume 42(4).April 1997.738-740
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Chestnut DH, Obstetric Anesthesia, Principles and Practice, third edition.
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Colman-Brochu S American Journal of Maternal Child Nursing. 29(3):186-92, 2004
May-Jun.
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El Kady D et al American Journal of Obstetrics and Gynecology (2004) 190, 1661e8
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Elovitz MA American Journal of Obstetrics & Gynecology. 185(5):1059-63, 2001 Nov.
•
Ferrara A American Journal of Surgery. 160(5):515-8, 1990 Nov.
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Judich A Injury, Vol. 29, No. 6, 475-477, 1998.
•
Kingston NJ Am J Forensic Med Pathol 2003;24: 193–197
References
Mann FA et al The Journal of Trauma (2000) Vol. 48, No. 2, pp.354-357
Miller MT Journal of Trauma Volume 54(1), January 2003, pp 52-60
Muench MV J Trauma. 2004;57:1094–1098.
Pearlman MD et al American Journal of Obstetrics & Gynecology. 162(6):1502-7;
discussion 1507-10, 1990 Jun.
Pearlman MD International Journal of Gynecology & Obstetrics 57 (1997) 127-132
Richards JR Radiology 2004; 233:463–470
Shah KH J Trauma Volume 45(1), July 1998, pp 83-86
Warner MW ANZ J. Surg.2004;74: 125–128