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Labour analgesia
1.
2. Analgesia for Labor and Delivery
ALWAYS controversial !
“Birth is a natural process”
Women should suffer!!
Concerns for mother’s safety
Concerns for baby
Concerns for effects on labor
3. Garden of Eden
History
Original Sin
God punished Eve: “In sorrow thou shalt bring forth children.”
Genesis 3:16
Formed the basis of 1800 years of opposition to pain relief in
labor.
1591
Lady Euframe MacAlyane of Edinburgh, Scotland: was Burned
at the Stake because asking for labor analgesia.
4. HISTORY
1847 – James Young Simpson; ETHER
1853 – John Snow ; CHLOROFORM
- Queen Victoria, 8th child
5. Chloroform a’ la reine
“The inhalation lasted fifty-three minutes.
The chloroform was given on a
handkerchief in fifteen minim doses; the
Queen expressed herself as greatly
relieved by the administration.”
6. Chloroform a’ la reine
“Dr Snow gave me the blessed
chloroform and the effect was soothing,
quieting and delightful beyond measure”
7. History contd..
1855
Religious acceptance
Archbishop of Canterbury's (leader of
the Anglican/Episcopal Church) daughter received
chloroform for labor pains. He refused to criticize.
1860-1940 : Dark ages of obstetric anesthesia
8. History
August Bier ,……………..,
Virginia Apgar ,…
1900 :
Oskar Kreis , used spinal anesthesia for
childbirth for the first time
10. DEFINITION OF PAIN
ISAP - AS AN UNPLEASANT SENSORY
AND EMOTINAL EXPERIENCE
ASSOCIATED WITH ACTUAL
POTENTIAL TISSUE DAMAGE (OR)
DESCRIBED IN TERMS OF SUCH
DAMAGE.
17. CENTRAL MECHANISMS
NOCICEPTIVE AFFERENTS
DORSAL ROOT
GANGLION
DORSALHORN
C&SOME A-DELTA SUPERFICIAL LAMINA(1&2)
SOME A-FIBERS —LAMINA - 5
30% -C-FIBERS
—DOUBLE BACK THROUGH
VENTRAL ROOT
1&5 -------THALAMUS
LAMINA 2—SUBSTANTIA GELATINOSA (INHIBITORY)
“THE GATE CONTROL THEORY OF PAIN”
22. PAIN PATHWAYS
1st stage of labor – mostly visceral
Dilation of the cervix and distention of the
lower uterine segment
Dull, aching and poorly localized
Slow conducting, C fibers, T10 to L1
2nd stage of labor – mostly somatic
Distention of the pelvic floor, vagina and
perineum
Sharp, severe and well localized
Rapidly conducting, A-delta fibers,S2 to S4
33. ACUPUNTURE
Generally two local points and two distal points on the
arms or on the legs are selected.
Begin Acupuncture 4 weeks before the expected time of
delivery.
Needles are placed once a week using the specific points.
Points
LI.4 Hegu, SP.6 Saninjiao, Extra Neima
PC 6 (Neiguan), Du.20,Du.2,Du6, GB.21,
He.7(shenmen)
34. TENS
Beneficial in patients with moderate to severe
contraction pains in an otherwise reasonably
normal labor.
Very popular in Europe.
Easy to apply, non-toxic and frequently
effective.
4 electrodes are placed one on either side of
the
spine in the lower thoracic region (T 10) and
one
on either side of the spine in the sacral area.
The patient may control up to 3 levels of
intensity
of stimuli, and she can switch it off if she
wishes.
36. Factors Determining Fetal Drug Levels
Lipid solubility
Molecular size
Total dose of drug
Concentration gradient
Maternal metabolism and excretion
Degree of ionization
pKa of drug, maternal and fetal pH
Protein binding - mother and fetus
Uterine blood flow
Time for equilibrium to occur
37. Systemic Opioids in Labor
Advantages:
Easy administration
Inexpensive
No needles
Avoids complications of regional block
Does not require skilled personnel
Few serious maternal complications
Perceived as “natural”
45. Inhalation Analgesia
Disadvantages:
Decreased uterine contractility (except N2O)
Rapid induction of anesthesia in pregnancy
Risk of unconsciousness and aspiration
Difficulties with scavenging in labor rooms
47. Paracervical Block
Local bilateral injection near the cervix
Given during 1st stage of labor
Lasts about 2 hours
Disadvantage
fetal bradycardia
Lidocaine toxicity
51. Indications
PAIN EXPERIENCED BY A WOMAN IN LABOR
ACOG and ASA stated
“ in the absence of a medical contraindication,
maternal request is a sufficient medical
indication for pain relief…”
Points of controversy
When?
Who?
How?
54. Contraindications
ABSOLUTE
Patients refusal
Inability to cooperate
Increased intracranial
pressure
Infection at the site
Frank coagulopathy
Hypovolemic shock
RELATIVE
Systemic maternal infection
Preexisting neurological
deficiency
Mild coagulation
abnormalities
Relative hypovolemia
Poor communication
55. GOALS OF LABOR ANALGESIA
Dramatically reduce pain of labor
Should allow parturients to participate in birthing
experience
Minimal motor block to allow ambulation
Minimal effects on fetus
Minimal effects on progress of labor
56. How to Achieve Goals:
What you put in:
Drugs, concentrations, combinations
How you deliver it:
Intermittent boluses, Continuous, PCEA
How much you give:
Low Vs. High infusion rates
58. Neuraxial Blocks
Spinal opioids alone: very high risk pts
Epidural opioids alone: High doses
Spinal LA alone: Saddle block, 6mg bupivacaine
Epidural LA alone
Epidural LA + Opioid ± Adjuvants
Combined Spinal & epidural – LA+Opioid
± Adjuvants
Continuous spinal – LA ± Opioids
59. Choice Of Local Anesthetic
Rapid onset with minimal motor block
Minimal risk of maternal toxicity
Negligible effects on uterine activity and
uteroplacental perfusion
Limited uteroplacental transfer
Long duration of action
60. Choice of Epidural LA
Lignocaine: Rapid onset, Dense motor block, Risk of
cummulative toxicity, UV/MV ratio – 0.6
Chlorprocaine:Rapid onset, Low toxicity, Dense block,
Antagonises bupivacaine &poioids
Bupivacaine( 0.0625%): Good sensory, Minimal motor
block, 2hrs, No adverse effects on labor, UV/MV – 0.3
Ropivacaine: Lower toxicity, ?Less motor block, Less
potent
Levobupivacaine: Lower toxicity
61. Epinephrine Use in Labor
May transiently slow labor
Increases motor block, Improves analgesia
Epinephrine test dose often avoided in labor
Low specificity - maternal heart rate very variable
Low sensitivity - ↓ response to sympathomimetics
Increases motor block - prevents ambulation
Potential for ↓ UBF with repeated doses
Very dilute agents - “whole first dose is test dose.”
62. Epidural Opioids in Labor
Inadequate analgesics if used alone
Synergize with local anesthetics
Speed onset of analgesia
Improve quality of analgesia
Permit use of very dilute LA solutions
Help relieve persistent perineal pain and
unblocked segments
63. Effect of low conc LA + opioid
(Comet Study UK , Lancet 2001;358:19)
50
%
Patients
40
*
*
*
30
20
10
0
"Traditional"
Bupivacaine
0.25%
Low-dose
Infusion
Bupiv 2.5 mg
+ Fent 25 mcg
Bupivacaine
0.1% + fentanyl
Spontaneous
Instrumental
C/Section
64. Which Epidural Opioid ?
Fentanyl and Sufentanil
Rapid onset, few side effects
Sufentanil slightly more effective
No significant fetal drug accumulation
No serious adverse neonatal effects
68. Continuous epidural infusion
“A larger volume of a more dilute agent is more
effective for labor analgesia than a smaller
volume of higher concentration”
Good pain releif
Less motor block
Increased maternal hamodynamic stability
Safe drug concentrations
No change in neonatal outcome
69. PCEA
Good analgesia
Patient autonomy
Less anaesthetist interventions
Cost effective
Lower total dose
Bupivacaine 0.125% + Fentanyl 2µg/ml – 6ml basal
infusion, 3ml bolus, 10min lockout interval, max
24ml/hr
70. From Gambling DR et al. Comparison of patient-controlled epidural
analgesia and conventional intermittent top up injections during labor.
Anesth Analg 1990;70:256-61.
71. Combined spinal-epidural
Faster onset - intense analgesia
Additional flexibility - epidural
Very low failure rate
Minimal motor block if only opioid used for spinal
Less need for supplemental boluses
IT opioids: Fentanyl 5-25 μg, sufentanil 5-10 μg
Early labor : opioid ± 0.125 mg bupivacaine;
Advanced labor: opioid ± 2-2.5 mg bupivacaine
72. COMBINED SPINAL EPIDURAL
Needle” through “Needle”
“ Back “ eye”
Needle” through “Needle” technique is the best
Can be placed in lateral or sitting position
Walking Epidural possible
73. Onset of Analgesia: CSE vs.
Epidural
Collis et al. Lancet 1995;345:1413
100
CSE
Epidural
75
VAPS
(0-100)
50
25
0
Baseline
5
10
Time (minutes)
15
20
74. Combined spinal-epidural
Not recommended - morbidly obese, difficult airway
or non-reassuring fetal heart rate
Two interspace techniques
Needle through needle
-PDPH: 1% or less, small bore atraumatic needles.
-Subarchanoid migration of epidural catheter - No added
risk with CSE
75. Continuous Spinal Analgesia
28 or 32-G catheters for 22 or 26-G spinal needles
Bupivacaine 2.5mg+25µg fentanyl,
1-2ml/hr of bupivacaine 0.125% + 2µg/ml fentanyl
Cauda Equina Syndrome
Restricted by FDA in 1992
Ongoing multi-institutional study – 28-G catheters
sufentanil ± bupivacaine
Appears safe
76. Side effects of IT opioids
Nausea, Vomitting
Pruritis
Sedation
At very high doses - Resp depression
- Fetal bradycardia
Stratergy to ↓ side effect - Add LA
- Lowest dose opioid
77. We are All Ready…Now What?
Obstetrician is consulted
Pre-anesthetic evaluation
Pt’s informed consent
Fetal well-being assessed and reassured
(obstetrician?, midwife?, yourself?)
Stage of labor/ Cervical dilatation
Resuscitation equipment and drugs are
immediately available
Aspiration prophylaxis
78. Conduct of Labour analgesia
Baseline BP, HR, FHR
IV access, Preload 500 -1000ml
Perform epidural / CSE
Pregnancy – Physiologic changes
Left lateral / sitting
R/O intrathecal/ IV placement
3-5cm catheter inside space
4ml of the drug
79. Conduct of Labour analgesia
Monitoring:
BP every 1 to 2 min , 20 min
Continuous maternal HR during induction
(pulseoximetry)
Continuous FHR monitoring
Continual verbal communication
After 5mins, 4-8ml of drug » T10-L1 block
Alternatively continuous infusion /PCEA
Assess progression of labor
Treat every bolus as test dose
80. Conduct of Labor analgesia
Nursed in lateral position
Second stage of labor – S2 -4
Head end elevation, 4-8ml drug bolus
Intermittent techniques – 10-15ml drug
Prolonged for instrumental delivery /
C.section
85. Controversial areas
Maternal pyrexia:
↑0.1 C/hr, No infection, No neonatal sepsis
Progress of Labor:
?only minimally prolongs
Rate of C/S: Not increased
Epidural test dose:
? Adrenaline, ?isoprotenerol
Careful aspiration
86. Avoiding Epidural Disasters
Maintain constant verbal contact
Always aspirate before each injection
Observe for passive return through the catheter
Do not inject more than 4 ml of LA at a time
Observe the patient at least 1.5-2 min between boluses
If in doubts, repeat test dose. Still in doubts? Replace it
i
After all, be mentally prepare to treat
1. Convulsions
2. Total spinal
3. Cardiovascular collapse and arrest
87. Conclusions
Individualize technique to patient’s goals and
stage of labor
Optimize management for spontaneous delivery
Provide safe, cost-effective analgesia
88. The Ideal Labor Analgesic
Good pain relief
No autonomic block (no hypotension)
No adverse maternal or neonatal effects
No motor block
No effect on labor and delivery:
No increase in C/S rate
No increase in forceps/vacuum delivery
Patient can ambulate
Economical: cost and personnel