Transcript LABOR ANALGESIA - Rhode Island Hospital

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



Cardiovascular




Increased blood volume and CO
Dilutional anemia
Possible aorto-caval compression (when supine)
GI


Increased O2 consumption
Decreased FRC and pCO2 (increased MV)
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



Regional anesthesia-minimal effects on
fetus (assuming normal BP)


Loss of beat to beat FHR variability is normal;
Fetal bradycardia is not!
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
 Incidence
 Incidence
~ 1/237k
1/5,500)


of epidural infection ~ 1/145k
of Epidural bleed ~ 1/150-170k
of persistent neurological injury
(transient neurologic injury ~
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 2.510ug)
 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 (69ml/hr)?
 Must set limits to bolus doses. (4-6ml q 510min; 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 + 50100ug 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–> 10001500ml 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 Csection

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!