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LABOR ANALGESIA

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LABOR ANALGESIA Powered By Docstoc
					Anesthesia for the Obstetrical
           Patient

 Fred Rotenberg, MD
 Dept. of Anesthesiology
 Rhode Island Hospital


   Grand Rounds February 27, 2008
Anesthesia for the Obstetrical Patient
   The Pregnant Patient for Nonobstetric
    Surgery

 LABOR
 DELIVERY
 OBSTETRICAL EMERGENCIES
 SPINAL HEADACHES AND BLOOD
  PATCHES
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)
Anesthesia for the pregnant patient
undergoing non-obstetric surgery
THE OBVIOUS


AVOID MATERNAL HYPOXIA
 AND HYPOTENSION
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
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
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 ->improve fetal blood
    flow)
   Consider Fetal monitoring (but no good data)
   Consult with obstetrician
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
POST - OP
 Continue fetal monitoring
 Because of risk of thromboembolism:
       Early mobilization
       Consider anticoagulants
       Post op analgesia (regional is good at this)
LABOR ANALGESIA
       Intravenous


       Neuraxial:
        Epidural
         Spinal
 Combined Spinal-Epidural
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
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
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
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
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)
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.
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
        obstetrician’s threshold for using instruments
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) @ 10-12
    ml/hr.
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
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 pt’s ability to feel
        normal contraction of muscles controlling
        micturation.
       Rapid profound analgesia suggests intrathecal
        dose.
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”
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.
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
Combined Spinal – Epidural Analgesia
 In early labor (<4 cm dilation) CSE
  promotes more rapid cervical dilation than
  IV hydromorphone.
 Also, high concentrations of local
  anesthetic slow labor.
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 ->
 Rapid profound analgesia without
  significant motor block.
 Longer duration of analgesia than opiate
  alone.
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
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
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.
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.
Anesthesia for delivery – Vaginal
 Epidural “Perineal dose” for imminent
  delivery (10-12 ml of 0.062%bupiv + 50-
  100ug of fentanyl) to allow the pt to push
 For forceps delivery or episiotomy repair:
  epidural 8-12 ml of 2% lido.
Anesthesia for delivery
(Cesarian)
 GETA
 Spinal
 Epidural
 CSE
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)
Spinal
 Fast onset; profound anesthesia; avoid
  airway risks associated with GA
 Recipe:Bupivicaine 6-12mg + 0.1mg MS
  or 20ug fentanyl (setup in 5 min; 2-4 hr
  duration)
 Acute Hypotension prevention–> 1000-
  1500ml crystalloid immediately before
  spinal; left uterine displacement.
 Tx of hypotension: Ephedrine (10mg) +/-
  phenylephrine
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
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)
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
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
ASA Guidelines - 3
 Labor/delivery units should be equipped
  with difficult airway, fluid resuscitation
  and ACLS equipment
 For maternal cardiopulmonary arrest (>4
  min) consider emergent operative delivery
  of the fetus in addition to maternal
  resuscitation
 Uterine displacement improves maternal
  venous return and should be routinely
  utilized
Anesthetic Management for
 Obstetrical Emergencies
“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.
“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.
PLACENTAL ABRUPTION
 Premature separation of normally
  implanted placenta
 May occur pre- or intrapartum (incidence
  ~ 1:80 deliveries)
 Associated with maternal hypertension,
  heavy EtOH use or cocaine use.
 Leads to maternal blood loss, neonatal
  neurologic damage or asphyxia
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 FSP’s
 For severe abruption consider immediate
  C-section under GA.
 Consider oxytocin and other uterotonic
  drugs and aggressive transfusion.
PLACENTA PREVIA
 Abnormal implantation of placenta close to
  or over the cervical os.
 Incidence: 1:200-250 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
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.
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
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
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.
THE END


   THANKS FOR YOUR ATTENTION!

				
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