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Anesthesia for the Obstetrical Patient

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Anesthesia for the Obstetrical Patient Fred Rotenberg, MD Dept. of Anesthesiology Rhode Island Hospital Grand Rounds February 27, 2008 Anesthesia for the Obstetrical ... – PowerPoint PPT presentation

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Title: Anesthesia for the Obstetrical Patient


1
Anesthesia for the Obstetrical Patient
  • Fred Rotenberg, MD
  • Dept. of Anesthesiology
  • Rhode Island Hospital
  • Grand Rounds February 27, 2008

2
Anesthesia for the Obstetrical Patient
  • The Pregnant Patient for Nonobstetric Surgery
  • LABOR
  • DELIVERY
  • OBSTETRICAL EMERGENCIES
  • SPINAL HEADACHES AND BLOOD PATCHES

3
Alterations in Maternal Physiology
  • Respiratory
  • Increased O2 consumption
  • Decreased FRC and pCO2 (increased MV)
  • Cardiovascular
  • Increased blood volume and CO
  • Dilutional anemia
  • Possible aorto-caval compression (when supine)
  • GI
  • Reduced gastroesophogeal tone
  • Reduced anesthetic requirements (both GA
    regional)

4
Anesthesia for the pregnant patient undergoing
non-obstetric surgery
5
THE OBVIOUS
  • AVOID MATERNAL HYPOXIA AND HYPOTENSION

6
THE NOT SO OBVIOUS
  • Prevention / Treatment of preterm labor
  • Probably NOT related to anesthetic management
  • Due to SURGERY and/or underlying pathology
  • Tocolytics (indocin or MAGNESIUM, hi dose
    volatile anesthetics)
  • Teratogenic effects of anesthetics
  • Benzodiazepenes? Nitrous oxide?
  • NO GOOD EVIDENCE re risk in humans

7
THE NOT SO OBVIOUS - continued
  • Dose dependent effect of general anesthetics on
    fetal or newborn animals -
  • Apoptotic neurodegeneration
  • Persistent memory/learning impairments
  • Therefore USE AS LITTLE GENERAL ANESTHETIC (iv
    and volatile) as possible

8
Things we can ( should) do
  • If possible delay surgery til 2nd trimester
  • Less risk of teratogenicity, miscarriage, than
  • 1st trimester
  • preterm labor more likely in 3rd trimester
  • Left uterine displacement after 24th week
  • Consider aspiration prophylaxis midazolam
    (reduce maternal stress -gtimprove fetal blood
    flow)
  • Consider Fetal monitoring (but no good data)
  • Consult with obstetrician

9
ANESTHETIC CHOICES
  • GA-preoxygenate, rapid sequence induction, slow
    reversal of relaxants, /- N2O
  • Loss of beat to beat FHR variability is normal
  • Fetal bradycardia is not!
  • Regional anesthesia-minimal effects on fetus
    (assuming normal BP)
  • Cut neuraxial dose of local anesthetic by 1/3rd
    compared to non-pregnant patient
  • NO evidence showing better outcome

10
POST - OP
  • Continue fetal monitoring
  • Because of risk of thromboembolism
  • Early mobilization
  • Consider anticoagulants
  • Post op analgesia (regional is good at this)

11
LABOR ANALGESIA
  • Intravenous
  • Neuraxial
  • Epidural
  • Spinal
  • Combined Spinal-Epidural

12
Goals of Labor Analgesia
  • Adequate Analgesia
  • Allow the mother to participate in birthing
    experience
  • Minimal effect on the fetus
  • Minimal effect on the progress of labor

13
Neuraxial Blockade
  • A well conducted block provides the most
    effective and least depressant analgesic
  • Spinal opiate (single shot) fast onset, limited
    duration
  • Continuous Epidural slower onset, but duration
    is adjustable. Potential motor block.
  • Combined Spinal Epidural best of both

14
Arguments for epidural for Labor
  • Relative risk of maternal mortality during
    C-section was 16x greater with GA compared to
    regional anesthetic
  • Epidural for labor is now used in 2.4m of the 4m
    total births in the US per year

15
Arguments against epidural for Labor
  • Incidence of epidural infection 1/145k
  • Incidence of Epidural bleed 1/150-170k
  • Incidence of persistent neurological injury
    1/237k (transient neurologic injury 1/5,500)
  • Still about 20 of pts w/ labor epidural require
    conversion to GA for C-section

16
Disadvantages of epidural analgesia for labor
  • Slows labor by approximately one hour
  • Questionable effect on Cesarean Section delivery
    rate
  • Increases use of instruments during vaginal
    delivery
  • Increased incidence of maternal fever (and
    subsequent fever workup of mom and child)

17
Effect of Early Neuraxial Analgesia on C-Section
Rate
  • Many older studies show no clear difference in
    section rate comparing neuraxial and parenteral
    opiate analgesia.
  • Wong et al. NEJM 2005
  • Prospective
  • demonstrates no increase in C-section rate
    comparing early vs later epidural opiate
    administration.

18
Epidural analgesia increases rate of instrument
assisted deliveries
  • Rate of instrument assisted vaginal deliveries is
    at least doubled by epidural analgesia
  • Etiology of this effect?
  • Motor block from neuraxial local anesthetic
  • Epidural analgesia is associated with increased
    rate of occiput posterior presentation (does this
    painful presentation promote increased demand for
    epidural analgesia?)
  • The presence of a block might lower
    obstetricians threshold for using instruments

19
LABOR EPIDURAL
  • Continuous combined dilute local anesthetic plus
    opiate.
  • Better pain relief when combined less motor
    block. Less instrumented deliveries. Minimal
    absorbtion by Mom or baby.
  • Eg Bupivicaine 0.0625 plus 2ug/ml fentanyl (/-
    epinephrine) _at_ 10-12 ml/hr.

20
Notes on epidural cath placement
  • Sterile technique
  • Loss of resistance to fluid (not air)
  • Prevent intrathecal placement (0.5-3 incidence)
  • Prevent intravenous placement (3-15 incidence)
    (use Arrow Flex-Tip inject 10 ml dilute local
    through needle prior to cath placement).
  • Aspiration of blood or csf is quite reliable

21
Notes on epidural cath placement - 2
  • Epinephrine test dose is not sensitive for
    intravenous location.
  • Local anesthetic (eg 45mg of Lido w/ epi) as test
    for intrathecal placement is somewhat better.
  • Wait 5 min after test to see motor changes.
  • Seek subjective change in pts ability to feel
    normal contraction of muscles controlling
    micturation.
  • Rapid profound analgesia suggests intrathecal
    dose.

22
Notes on epidural cath placement - 3
  • Safety is determined by the above careful
    placement AND
  • DOSE FRACTIONATION give 3ml every 1-2 minutes.
  • patience is wisdom and wisdom is patience

23
Notes on epidural cath placement -4
  • For a wet tap consider
  • Thread the epidural cath intrathecally and use it
    for continuous spinal. (Then leave it in place
    for 24 hrs to reduce the risk of spinal HA.)
  • Spinal catheter dosing Bupiv 0.1 plus
    sufentanil 0.5ug/ml. Start with 3 ml bolus
    infuse a basal rate of 2 ml/hr allow PCEA
    boluses of 1 ml q 30min prn.

24
Combined Spinal Epidural Analgesia
  • Most beneficial in early or late labor
    (especially the multiparous patient)
  • 27 spinal needle through epidural needle
    followed by epidural catheter insertion
  • Almost immediate pain relief with spinal opiate
    (fentanyl 10-25ug or sufentanil 2.5-10ug)
  • 2-3 hour duration of analgesia with the spinal
    opiate
  • Patient may ambulate

25
Combined Spinal Epidural Analgesia
  • In early labor (lt4 cm dilation) CSE promotes more
    rapid cervical dilation than IV hydromorphone.
  • Also, high concentrations of local anesthetic
    slow labor.

26
Combined Spinal Epidural Analgesia
  • For severe pain in the late stages of labor may
    need to add local anesthetic to spinal mixture.
  • Rx Sufentanil 2.5-5ug plus bupivicaine 2.5 mg
    -gt
  • Rapid profound analgesia without significant
    motor block.
  • Longer duration of analgesia than opiate alone.

27
Problems with Intrathecal Opiates
  • Pruritus usually mild and short lived
  • Nausea and vomiting best treatment?
  • Hypotension Rx ephedrine.
  • Urinary retention
  • Uterine hyperstimulation and fetal bradycardia?
    (studies show no increased risk)
  • Maternal respiratory depression monitor for at
    least 20 minutes post injection

28
Technical Problems with CSE
  • Post dural puncture headache
  • (Incidence is 1 or less)
  • Subarachnoid migration of epidural catheter?
  • Risk is remote especially with separate port in
    epidural needle for spinal needle.
  • Still use small incremental epidural doses

29
Patient Controlled Epidural Analgesia
  • May minimize drug doses, less motor block, but
    may provide inferior analgesia should we add a
    basal infusion rate (6-9ml/hr)?
  • Must set limits to bolus doses. (4-6ml q 5-10min
    max 4-6doses/hr)
  • Although less demands on anesthesia personnel,
    must still make periodic assessments.

30
Continuous Spinal Analgesia?
  • Microcatheters are they associated with cauda
    equina syndrome?
  • 28g microcatheters seem safe (Arkoosh et al
    2003) but are still not FDA approved.
  • Clearly increased risk of headache with larger
    catheters, but advantage of controlled
    incremental dosing (cf epidural) may justify its
    use.

31
Anesthesia for delivery Vaginal
  • Epidural Perineal dose for imminent delivery
    (10-12 ml of 0.062bupiv 50-100ug of fentanyl)
    to allow the pt to push
  • For forceps delivery or episiotomy repair
    epidural 8-12 ml of 2 lido.

32
Anesthesia for delivery (Cesarian)
  • GETA
  • Spinal
  • Epidural
  • CSE

33
Regional anesthesia for C-section
  • Supplementation of Indwelling Epidural
  • 10-15ml of 1 lido or 0.125 bupiv, ropiviacaine
    or levobupivicaine.
  • Spinal (fast onset, dense block)

34
Spinal
  • Fast onset profound anesthesia avoid airway
    risks associated with GA
  • RecipeBupivicaine 6-12mg 0.1mg MS
  • or 20ug fentanyl (setup in 5 min 2-4 hr
    duration)
  • Acute Hypotension preventiongt 1000-1500ml
    crystalloid immediately before spinal left
    uterine displacement.
  • Tx of hypotension Ephedrine (10mg) /-
    phenylephrine

35
Post Dural Puncture Headache
  • Caused by decreased ICP, cerebral vasodilation
  • Dx Postural component and cervical muscle spasm
  • Not always self limited, not always benign
  • Abducens N. palsy (visual problems)
  • Auditory disturbances
  • Subdural hematoma / hygroma

36
blood patch
  • Autologous blood patch is warranted
  • Risk is small
  • Effective
  • Avoid in coagulopathy or febrile patient
  • Keep pt recumbent for 2 hrs after patch
  • Pts should avoid heavy lifting or Valsalva
  • Rx stool softener and/or cough suppressant
  • Prophylactic blood patch is not warranted (blood
    patch is less effective if done in 1st 24 hours)

37
ASA Guidelines
  • Fetal Heart Rate monitoring before and after
    labor epidural
  • For elective cases, clear liquids acceptable up
    to 2 hrs preop no solids for 6-8 hrs.
  • Timely administration of non-particulate
    antacids, H2 blockers and/or metoclopramide.
  • Pencil point spinal needles should be used rather
    than cutting needles to reduce PDP headache

38
ASA Guidelines - 2
  • For urgent delivery GA is faster than SAB which
    is faster than epidural
  • GA is associated with lower APGAR scores
  • Phenylephrine for maternal hypotension may cause
    less fetal acidosis than ephedrine infusions.
  • Cell saver should be considered for massive
    hemorrhage

39
ASA Guidelines - 3
  • Labor/delivery units should be equipped with
    difficult airway, fluid resuscitation and ACLS
    equipment
  • For maternal cardiopulmonary arrest (gt4 min)
    consider emergent operative delivery of the fetus
    in addition to maternal resuscitation
  • Uterine displacement improves maternal venous
    return and should be routinely utilized

40
Anesthetic Management for Obstetrical Emergencies
41
Nonreassuring Fetal Heart Rate (ie Fetal
Distress)
  • FHR deceleration related to uteroplacental
    insufficiency.
  • Prolonged / repeated deceleration of FHR may lead
    to fetal acidosis.
  • Lack of fetal heart rate variability may be due
    to fetal hypoxemia.

42
Nonreassuring Fetal Heart Rate (ie Fetal
Distress)
  • Profound variable or late decelerations
    especially if associated with decreased FHR
    variability dictates consideration of immediate
    delivery.
  • Fetal pulse oximetry, used in conjunction with
    FHR monitoring decreases emergent C-section rate
    related to nonreassuring FHR.

43
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44
PLACENTAL ABRUPTION
  • Premature separation of normally implanted
    placenta
  • May occur pre- or intrapartum (incidence 180
    deliveries)
  • Associated with maternal hypertension, heavy EtOH
    use or cocaine use.
  • Leads to maternal blood loss, neonatal neurologic
    damage or asphyxia

45
PLACENTAL ABRUPTION
  • May lead to consumptive coagulopathy and progress
    to DIC.
  • For suspected abruption type and crossmatch
    blood send H/H, plt count, fibrinogen and FSPs
  • For severe abruption consider immediate C-section
    under GA.
  • Consider oxytocin and other uterotonic drugs and
    aggressive transfusion.

46
PLACENTA PREVIA
  • Abnormal implantation of placenta close to or
    over the cervical os.
  • Incidence 1200-250 deliveries (more common in
    multipara, prior C-section or previous placenta
    previa).
  • Common cause of 3rd trimester bleeding
  • For ongoing bleeding may require C-section

47
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48
UTERINE RUPTURE
  • Often related to previous uterine scar from
    previous C-section
  • Sx Vaginal bleeding, severe uterine pain,
    shoulder pain, disappearance of FH tones,
    hypotension.
  • Requires urgent delivery and abdominal
    exploration.

49
VBAC
  • In a prospective study between 1999-2002 18k
    women attempted VBAC 16k had elective repeat
    C-section
  • Symptomatic uterine rupture occurred in 124
    (0.7) of VBAC women
  • Hypoxic-ischemic encephalopathy occurred in 12
    infants in VBAC cases none in elective section
  • Lower incidence of maternal complications in
    elective section

50
POST PARTUM HEMORRHAGE
  • Retained placenta
  • Occurs in about 1 of deliveries
  • Requires manual exploration of uterus
  • 1 MAC of GA provides uterine relaxation
  • NTG (100 ug) also provides uterine relaxation

51
POST PARTUM HEMORRHAGE - 2
  • Uterine Atony
  • Seen following 2-5 of deliveries
  • Associated with over distention of uterus,
    retained placenta, excessive oxytocin use during
    labor, and operative interventions.
  • Rx Fluids, uterine massage and uterotonics.

52
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53
THE END
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