Anesthesia for Normal Labor and Delivery.2003.STIKES

7/28/2019 Anesthesia for Normal Labor and Delivery.2003.STIKES

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Anesthesia for Normal Labor

and Delivery

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McGill Pain Questionnaire

(Melzack R: The myth of painless childbirth. Pain 19:321, 1984)


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John Snow (1853) on Queen Victorias

Anesthetic for the birth of Prince Leopold:

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.


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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


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Pain Pathways in Labor and Delivery

Eltzschi Leiberman Camann NEJM 348 319:2003


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Labor Pain at different Stages of Labor

Eltzschig, Leiberman, Camann, NEJM 348; 319:2003


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Fetal pH during Labor and Delivery

pH


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Analgesia for Vaginal Delivery

Systemic narcotics

Tranquilizers / hypnotics

Inhalation analgesia

Acupuncture

TENS

Psychoanalgesic techniques


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Placental Transfer of Drugs:Maternal, Drug, Placental and Fetal Factors

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


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Differential Protein Binding

Differential maternal and fetal protein binding accounts for

differences in total circulating drug concentrations on both sides

of placenta, when free drug concentrations are actually equal


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UV/MV Fetal-Maternal Drug Ratios

Bupivacaine: 0.25-0.3

Mepivacaine: 0.7

Lidocaine: 0.5

Correlates with degree of protein binding,

but may not reflect total amount of drug in

fetus because of high lipid solubility

leading to significant tissue uptake


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Local Anesthetics - Ionic Trapping

From the American College of Obstetricians and Gynecologists,

Obstet Gynecol 1976; 48:29)

Mother

(normal acid-base)

pH = 7.40

Placental

Membrane

Fetus

(acidosis)

pH = 7.00

(2.4) (1) (1) (6)


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Systemic Opioids in Labor

Easy administration

Inexpensive

No needles

Avoids complications of regional block

Does not require skilled personnel

Few serious maternal complications

Perceived as natural

Advantages:


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Systemic Opioids in Labor

All drugs easily cross placenta

Pain relief inadequate in most cases

Maternal sedation

Nausea, vomiting, gastric stasis

Fetal heart rate effects:

Loss of beat-to-beat variability

Sinusoidal rhythm

Dose-related maternal / neonatal depression

Newborn neurobehavioral depression

Disadvantages:


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Which Systemic Opioid?Pure Agonists

Morphine:

long half-life, neonatal depression

Meperidine:

neonatal depression (normeperidine effect)nausea, vomiting

Fentanyl:

short duration, minimal newborn effects

Alfentanil:

newborn depression

Remifentanil? (what surveillance is needed?)


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IV-PCA Fentanyl during Labor

A suggested regimen:

Loading dose of 50-100 mcg

No background infusion

10-12.5 mcg bolus

8-10 min lockout

4 hour limit - 300 mcg

Pulse oximeter if large doses given


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Visual Analog Pain Scores with

Systemic Opioids During Labor

Visual Analog Pain Scores with

Systemic Opioids During Labor

4-7 cm4-7 cm 8-10 cm8-10 cm00

22

44

66

88

1010

MeperidineMeperidineFentanylFentanyl

VAPS

during

Labor

VAPS

during

Labor

(Data from Rayburn et al.

Obstet Gynecol 1989;14:604)

(Data from Rayburn et al.Obstet Gynecol 1989;14:604)


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Serum Fentanyl Concentrations vs.

Maternal Dose During Labor

Serum Fentanyl Concentrations vs.

Maternal Dose During Labor

5050 100-200100-200 > 200> 20000

0.10.1

0.20.2

0.30.3

0.40.4

0.50.5

MaternalMaternalUmbilicalUmbilical

SerumFentanyl

(ng/ml)

SerumFentanyl

(ng/ml)

Maternal Fentanyl Dose During Labor (g)Maternal Fentanyl Dose During Labor (g)

(Data from Rayburn et al. Am J Obstet

Gynecol 1989;161:202)

(Data from Rayburn et al. Am J Obstet

Gynecol 1989;161:202)


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Which Systemic Opioid?

Agonist-AntagonistsCeiling effect for respiration and analgesia

Maternal sedation prominent

Nalbuphine

Butorphanol

Buprenorphine


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Potential Fetal/Neonatal Effects

of Maternal Sedation

Low 1 and 5 min Apgar scores

Respiratory acidosis

Naloxone, ventilatory assistance may be needed

Neurobehavioral depression - dose dependent

Prolonged observation in NICU occasionally needed


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Neurologic and Adaptive

Capacity Score (NACS)

(Anesthesiology, 1982)


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Neonatal Neurobehavioral Effects

of Maternal Systemic Medication

Transient, global depression of behavior related

to presence and quantity of drug in newborn

Most effects gone by 3rd day; all by 10 days

Important to differentiate from sinister causes


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Inhalation Analgesia for Vaginal Delivery

Advantages:

Easy to administer (no needles or PDPH)

Satisfactory analgesia variable

Minimal neonatal depression

(N2O 30-50%; very low concentration volatile agents)


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Inhalation Analgesia for Vaginal Delivery

Disadvantages:

Decreased uterine contractility (except N2O)

Rapid induction of anesthesia in pregnancy

Risk of unconsciousness and aspiration

Difficulties with scavenging in labor rooms

(N2O 30-50%; very low concentration volatile agents)


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Analgesia for Labor and Delivery

Local infiltration

Pudendal block

Paracervical block

Paravertebral (lumbar sympathetic block)

Epidural - lumbar (caudal)

Spinal

Combined spinal-epidural (CSE)

Local and regional techniques


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Analgesic Blocks for Labor and Delivery


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Paracervical Block


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Regional Analgesia for Labor

Lumbar epidural

Segmental (T10-L1)

Extended (T10-S5)

Caudal epidural (S5-T10)

Spinal (LA opioids)

CSE (opioids LA)


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Fetal / Neonatal Effects of Regional

Analgesia in Labor

Uterine perfusion maintained

Profound hypotension possible fetalcompromise

LA toxicity - extremely rare

FHR changes:

baseline variability

periodic decelerations (due to maternal catechols?) Apgar scores, acid-base status, unaffected

Neurobehavioral effects absent with current agents


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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


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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


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Analgesia for LaborAnalgesia for Labor

Local AnestheticLocal Anesthetic OpioidsOpioids

Alpha-2-agonistsAlpha-2-agonistsBicarbonateBicarbonate

New spinal agonistsNew spinal agonists


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Choice of Epidural Local AnestheticChoice of Epidural Local Anesthetic

Lidocaine: rapid onset, dense motor block, risk of cumulative toxicity with repeated dosesChloroprocaine:

rapid onset, low toxicity, dense block,

antagonizes bupivacaine and opioids

Bupivacaine: good sensory, minimal motor block, no adverse effect on labor with 0.0625%

Ropivacaine: lower toxicity, ? less motor block, less potentLevobupivacaine: lower toxicity

Lidocaine: rapid onset, dense motor block, risk of cumulative toxicity with repeated dosesChloroprocaine:

rapid onset, low toxicity, dense block,

antagonizes bupivacaine and opioids

Bupivacaine: good sensory, minimal motor block, no adverse effect on labor with 0.0625%

Ropivacaine: lower toxicity, ? less motor block, less potentLevobupivacaine:lower toxicity


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Ropivacaine vs. Bupivacaine in Labor -

What are the Relative Potencies?

Ropivacaine is only 60% as potent as bupivacaine

(2 MLAC studies*)

Claims for reduced toxicity and motor block must

consider relative potency

Do very dilute agents pose risk of toxicity?

Newer agents very expensive

(*Polley et al. Anesthesiology, 1999. Capogna et al. BJA, 1999)


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Relative Analgesic and Motor Blocking Potencies of

Epidural Bupivacaine and Ropivacaine in Labor

(Lacassie et al. Anesth Analg 2002;95:204)


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Relative Motor Blocking Potencies of

Epidural Bupivacaine and Ropivacaine

Motor block potency ratio is the

same as sensory block potency ratio

Ropivacaine is only 0.66 as potent

as bupivacaine

No difference in mode of delivery

(Lacassie et al. Anesth Analg 2002;95:204)

CONCLUSIONS


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Potencies of Levobupivacaine and Bupivacaine in Labor

Lyons et al. Br J Anaesth 1998;81: 899


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Epinephrine Use in Labor

May transiently slow labor

Increases motor block

Improves analgesia ( 1:600K works)

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.


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Epidural Opioids in Labor

Inadequate analgesics 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 Optimal recipe and maximum safe dose not

determined


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WHICH EPIDURAL OPIOID?WHICH EPIDURAL OPIOID?

Morphine

(2 mg)

Morphine

(2 mg)

Risk of respiratory depression

Pruritus ++ Ineffective alone

Risk of respiratory depression

Pruritus ++ Ineffective alone

Meperidine

(25-100 mg)

Meperidine

(25-100 mg)

Neonatal effects with larger

doses. Local anesthetic effect

Neonatal effects with larger

doses. Local anesthetic effect

Butorphanol(1-2 mg)Butorphanol(1-2 mg)Somnolence, dysphoria withlarger doses

Somnolence, dysphoria with

larger doses


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Which Epidural Opioid in Labor?

Fentanyl and Sufentanil

Rapid onset, few side effects

Sufentanil slightly more effective

No significant fetal drug accumulation (? less

with sufentanil)

No serious adverse neonatal effects with either


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Light or Ultra-light AnalgesicTechniques

Bupivacaine

Ropivacaine + OPIOID

Levobupivacaine


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Continuous Infusion Epidural

A larger volume of a more dilute agent is more

effective for labor analgesia than a smaller

volume of higher concentration

PCEA

Good analgesia Patient autonomy

Less need for MD interventions

Cost effective

Effect of Low-Dose Mobile vs. Traditional


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Epidural Techniques on mode of delivery:

A randomized Trial

0

10

20

30

40

50

"Traditional" CSE Low-doseInfusion

Spontaneous

InstrumentalC/Section

%

Patients**

(Comet Study UK , Lancet 2001;358:19)

Bupivacaine

0.25%

Bupivacaine

0.1% + fentanyl

Bupiv 2.5 mg

+ Fent 25 mcg

*


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Effect on Instrumental Vaginal Delivery Rate

of Continuing Epidural Infusion During the

Second Stage of Labor

Effect on Instrumental Vaginal Delivery Rate

of Continuing Epidural Infusion During the

Second Stage of Labor0.125% bupivacaine vs. 0.0625% bupivacaine + 2 g/ml fentanyl0.125% bupivacaine vs. 0.0625% bupivacaine + 2 g/ml fentanyl

% Instrumental

Delivery

% Instrumental

Delivery

(Chestnut et

al. 1987, 1990)

(Chestnut et

al. 1987, 1990)

5353

2828

2121

1515

0.125%Bup0.125%Bup 0.0625% Bup

+ fentanyl

0.0625% Bup

+ fentanyl

00

2020

4040

6060

Infusion continuedInfusion continued

Infusion discontinuedInfusion discontinued

**

Ultra-Light Bupivacaine-Sufentanil


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Ultra-Light Bupivacaine-Sufentanil

PCEA technique for Labor Analgesia(Stanford Technique)

Block initiated with 15-20 ml bolus:

0.125% bupivacaine + sufentanil 10 mcg

PCEA solution:

0.0625% bupivacaine + sufentanil 0.3-0.4 mcg/ml

PCEA settings:

Basal infusion: 10-15 ml/hour

Bolus: 12 ml

Lockout: 15 min


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Physician Administered Boluses

0

20

40

60

80

100

% Pts

Gp A Gp B Gp C Gp D

No boluses 1 bolus >1 bolus


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IT Opioid Analgesia (CSE)


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Advantages of CSE (opioids local

anesthetic) for Labor Analgesia

Rapid onset ofintense analgesia (the

patient loves you immediately! ) Ideal in late or rapidly progressing labor

Very low failure rate

Less need for supplemental boluses

Minimal motor block (walking epidural)

Side effects vs standard epidural?

M di U d L L l f D d


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10 g

Median Upper and Lower Level of Decreased

Pinprick Sensation after Intrathecal Sufentanil 10 g

(Cohen et al. Anesth Analg, 1993)


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Duration of Intrathecal Opioid

Analgesia in Labor

Duration of Intrathecal Opioid

Analgesia in Labor

188188

114114

148148

108108

9090

100100

9090

134134

114114

Sufentanil + Bup + EpiSufentanil + Bup + Epi

Fentanyl + Bup + EpiFentanyl + Bup + Epi

Sufentanil + BupSufentanil + Bup

Fentanyl + BupFentanyl + Bup

Sufentanil + EpiSufentanil + Epi

SufentanilSufentanil

FentanylFentanyl

Morphine + SufentanilMorphine + Sufentanil

Morphine + FentanylMorphine + Fentanyl

00 5050 100100 150150 200200

(Data from multiple sources)(Data from multiple sources)(min)(min)


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Onset of Analgesia: CSE vs. EpiduralCollis et al. Lancet 1995;345:1413

0

25

50

75

100

Baseline 5 10 15 20

Time (minutes)

CSE

Epidural

VAPS(0-100)


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Severe hypotension

Respiratory depression

High sensory block

Severe fetal bradycardia

Infection

Severe hypotension

Respiratory depression

High sensory block

Severe fetal bradycardia

Infection

Complications of IT Opioid or CSE

Analgesia in Obstetrics



Rare but Serious Problems


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The Problem

QuickTime and aGraphics decompressor

are needed to s ee this picture.

Figure 1. Cardiotocogram (1 cm/min) showing: 1) typical uterine hyperactivity with fetal distress, 2) administration of

intravenous nitroglycerin (arrow, 90 g administered), 3) resolution of the hyperactivity with normalization of fetal heart

rate, and 4) r apid rea ppearance of regular uterine activity.

Anesth Analg 1997; 84 :1117 20

Journal Conte nt Copyright 1991-Present, ASA, IARS, BJA, CAS. All Rights Reserv ed. Repr oduction of

said material, without prior permission from the Proprietor holding the copyright to the material, is illegal.

Epinephrine Levels after Analgesia


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Epinephrine Levels after AnalgesiaCascio et al. Can J Anaesth 1997; 44:605-609

Fetal Bradycardia


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Fetal BradycardiaAfter Labor Analgesia

Pain ReliefDecreased Circulating Epinephrine

Increased Uterine Tone

Decreased Uterine Blood Flow

Fetal Bradycardia

Fetal Heart Rate Changes after Analgesia:


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Nielsen et al. Anesth Analg 1996; 83:7426

Palmer et al. Anesth Analg 199;88(3):577-81

Riley et al. Anesthesiology 1999; A1054

Eberle et al. Am J Obstet Gynecol 1998; 179:150-155

0

10

20

30

Nielsen Palmer Riley Eberle

CSE

Epidural

%

Fetal Heart Rate Changes after Analgesia:

CSE vs. Epidural


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Greater Pain Scores and Cervical Dilation

Before Analgesia May Contribute to Bias

0

2

4

6

8

10

Cervical Dilation Baseline Pain Score

Epidural

CSE

*

*

Riley...Cohen et al. Anesthesiology 1999; A1054

(n = 196)

M t f FHR Ch


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Management of FHR Changes

Left uterine displacement

Maternal position change

O2 administration

STOP OXYTOCIN!

Fetal scalp stimulation

Nitroglycerin: 400 g sublingual X 2 (or more)

100 g IV repeated as needed

Terbutaline 0.25 mg, subcutaneous

Treat hypotension

Ephedrine - epinephrine level; UBF


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Analgesic failure:

needle too short needle deviates from midline drug inadequate

Drug mixing errors

Post dural puncture headache

Pruritus

Nausea/vomiting

Analgesic failure:

needle too short needle deviates from midline drug inadequate

Drug mixing errors

Post dural puncture headache

Pruritus

Nausea/vomiting





Other Problems

S i l N dl D i


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Spinal Needle DesignRiley, Cohen et al.

Obtain

CSF? 120 mm Needle 127 mm Needle

Success 83% 100%Failure 17% * 0%

*Longer needle subsequently successful in all these cases.


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CSE vs Epidural Labor Analgesia:


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CSE vs. Epidural Labor Analgesia:

Risk of Headache

0.0

0.4

0.8

1.2

1.6

2.0

% Patients

DuralPuncture

Headache EBP

CSE

Epidural

Norris et al, Anesthesiology 2001;95:913

(n=2183)

Strategies to Decrease


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Strategies to Decrease

Complications with CSE

Decrease dose of opioid:

Fentanyl 15-20 g

Sufentanil 2.5-5 mg

Combine with:

Local anesthetic (bupivacaine 1.25-2.5 mg)

Epinephrine?

Clonidine?

(Neostigmine?)


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Current Recommendations for CSE

Use lowest effective dose of opioid, dont repeat

Monitor BP, FHR, Respiration, (SpO2 if indicated)

Expect potentiation of epidural doses

All mixtures hypobaric - avoid prolonged sitting

position after block

Treat hypotension and uterine hypertonus

Naloxone and resuscitation equipment available

Same or greater surveillance as after epidural


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Controversial Areas

Effects on labor and delivery process

Maternal temperature elevation

Drug choice - are new agents better?

Epidural vs. CSE


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Conclusions

Individualize technique to patients goals

and stage of labor

Optimize management for spontaneous

delivery

Provide safe, cost-effective analgesia

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Anesthesia for Normal Labor and Delivery.2003.STIKES