Pain Relief in Labour

DR HUSSAIN KARIM, DEAA, MRCAConsultant Anesthetist, Lead Pain Team

Security Forces Hospital, Riyadh

Aim

Is how we can achieve better management of labour pain.

Objectives

Why do we give analgesia for child birth?

1. Humanitarian reason.

2. Economic benefit.

3. Medical reasons.

Medical Effects of Labour Pain

Pain compromises placental blood flow leading to fetal hypoxia and acidosis.

Increase catecholamine secretion leads to increased blood pressure which adversely effects fetal circulation

Releases Adrenocortical hormone which may effect electrolytes, carbohydrates and protein metabolism.

A traumatic labour may lead to post traumatic stress syndrome.

• It is only in the last 100 years that effective methods of pain relief have become available.

• Queen Victoria was given chloroform by John Snow for the birth of her eight child and this did much to popularize the use of pain relief in labour

Background

• Nowadays most women who deliver in modern obstetric units request some kind of pharmaco- logical pain relief.

• Epidural analgesia is the gold standard in obstetric analgesia.

• If an epidural is contraindicated or a woman dose not wish to have epidural, other methods can be used.

1. Entonox (50% Nitrous oxide + 50% Oxygen), Isonox (50% Nitrous oxide + 50% O2 + 0.2% Isoflurane).

2. IV PCA Remifentanil.

3. Parenteral opioids, Morphine, Pethedine, Fentanyl.

Adverse Effects of Parenteral Opioids

The Ideal Analgesic for Labour

Should provide excellent rapid onset

pain relief in both first and second stages .

Without side effects to the

mother or fetus.

Should not effect the ability of mother’s

power and movement during labour.

Pain pathway in Labour

The afferent nerve of the uterus and cervix is via A delta and C fibers, that accompany the thoraco lumbar and sacral dorsal sympathetic chains.

- Pain in first stage mediated through (T10 - L1 ).

- In the second stage mediated through (S2 – S4 ).

PATHOPHYSIOLOGY OF PAIN

Pharmacological Treatments of Pain

History of Epidural (Current therapy in pain, Howard Smith, 2009)

1. First description of Ep. Analgesia dates back to Leonard J. Corning, a neurologist who in 1895 inadvertently injected cocaine in the Epidural space.

2. Since 1900, Epidural analgesia was being used to treat the pain of child birth.

3. In 1931 a continuous technique was described by Italian surgeon, A.M. Dogliotti. He was the first to describe the loss of resistance technique.

4. Philip Bromage published the first text book on Epidural anesthesia in 1978. 5. Bromage introduced the administration of

epidural opioids for post operative analgesia in 1980.

6. 1988: Introduction of PCA with Epidural by many anesthetists, allover the world.

Absolute Contraindications of Epidural

1) Patient refusal.2) Blood Coagulopathy3) Infection at the site of injection4) Sever hypovolemia5) Fixed cardiac out put - Sever aortic stenosis - Sever mitral stenosis - Hypertrophic obstructive cardiomyopathy

Contraindicated In pregnancy

Relative Contraindications of Epidural

1) Systemic sepsis.

2) Uncooperative patient.

3) Preexisting neurological deficits, e.g. demyelinating disease, peripheral neuropathy

4) Sever spinal deformity.

Avoid in pregnancy

The Failing epiduralPattern of pain Possible causes Remedy

Fundal or global pain.

Inadequate top up and infusion rate, orcatheter dislodged

Inspect catheter: if OK, rescue dose, increase subsequent top-ups or increase infusion rate.

Unilateral pain or missed segment

Poor catheter position orEpidural fibrous septa

Withdraw catheter if > 4 cm inside space. Top up with bad side down

Perineal pain or rectal pressure

Occipito-posterior position of fetus, Big baby, oxytocin usage

Sit patient up. Use strong cocktail with opioids.

Complication of Epidural

• Hypotension.

• Tachycardia

• Bradycardia.

• Nausea and vomiting.

• Loss of motor power

• Dural tap. (post dural puncture headache)

In 1993, anaesthetists in Queen Charlotte’s Hospital in London described the CSE technique.

Touhy Needle is advanced in the lumber region.

Then 25 –27 gauge, 120 mm-long pencil point spinal needle.

1 ml of 0.25% Bupivacaine + 25 Micgr Fentanyl injected intrathecally.

Epidural bolus 15 mls 0.1% Bupivacaine + 2 Micgr/ml Fentanyl without test dose.

Combined Spinal Epidural (CSE) Analgesia

Support:

CSE provides more effective analgesia.CSE is faster in onsetCSE has lower failure rate 10% , comparing to 14%

in Epidural only. Miller’s Anaesthesia

Is CSE Better Than Epidural Analgesia?

Disadvantages of CSE

Against

1) Risk of threading epidural catheter intrathecally2) Excessive high block.3) Increase the risk of PDPH.4) Increase the risk of fetal bradycardia from spinal

opioid.5) Increase equipment cost.

• Remifentanil is a novel , ultra short acting synthetic opioid.• It is a selective mu opioid agonist.• Rapid onset; peak effect of blood/brain equilibration time

(1.2 – 1.4 min) .• It has ester linkage rendering it susceptible to rapid

metabolism by non specific blood and tissue esterases.• A short duration of action independent of duration of

infusion ( context sensitive half time 3.7 minutes).

Remifentanil IV PCA

Blair et al, 2001

• Has investigated the efficacy and safety of Remifentanil on 21 women.

• ASA I or II. Patient in active labour, cervix dilated at minimum 3 cm.

• Excluded preeclampsia, multiple pregnancy and allergy to any medications used, or failure to obtain informed consent.

• Bolus dose 0.25 – 1.0 Micgr/kg, with or without background infusion(0.025- 0.05) Micgr/kg/min

Blair et al, 2001 (cont.)

• Monitors mother and fetus.• VAS was used to assess pain score.

• Conclusion • Remifentanil PCA with bolus dose 0.25 – 0.5

Micgr/kg , and lockout time 2 min appears safe and effective to control labour pain.

• The technique appears to be most beneficial with multiparous women ( 73%).

Volikas et al, 2005• Studied maternal and neonatal side effects of

remifentanil in labour.• 50 women enrolled in the study ( 24 multiparous

and 26 primiparous).• Bolus dose 0.5 Micgr/kg, lockout time 2 min.• VAS was used to asses pain, nausea, and itching. • There was no evidence of cardiovascular instability

or respiratory depression.• Pain score decreased significantly.

Conclusion• At the bolus dose the PCA remifentanil has an

acceptable level of maternal side effects and minimal effect on the neonates.

• Remifentanil crosses the placenta and appears to be either rapidly metabolized or redistributed in the neonate.

Balki et al,2007 (Toronto)

Comparing the efficacy of two regimens of Remifentanil PCA

Group A: The infusion was increased from 0.025 to 0.05 , 0.075 , and 0.1 Micgr / kg / min. Bolus was kept constant at 0.25 Micgr/ kg.

Group B: The bolus increased 0.25 to 0.5, 0.75 and 1 Micgr/kg. The infusion was kept constant at 0.025 Micgr/kg/min.

Bolus dose Lockout time Background infusion

0.25 Micgr/ kg 2 min 0.025 Micgr/ kg/min

Result and conclusion1. Pain and patient satisfaction scores were similar in both

groups.2. The over all incidence of side effects was greater in group

B with drowsiness observed in 100% of patients compared to 30% in Group A.

3. The minimum SaO2 was 94.3% Group A, and 92.2 Group B.

4. PCA remifentanil is efficacious for labour analgesia as bolus of 0.25 Micgr/kg with lockout time 2 min, and infusion background of 0.025 to 0.1 Micgr/kg/min.

5. Potential for respiratory depression mandates close respiratory monitoring.

ReferencesI. Journals British Journal of Anaesthesia (V: 95/no. 4, V: 88/no.4 ). Anaesthesia Analgesia (2005;101:1242-1243, 100: 233-238). Anaesthesia Journal of GB and Ireland (V:60 Issue 1, P: 22-27). Acta Anaesthesiologica Scandinavia (V:49,Issue 4, P: 453-458). Current Opinion Anaesthesiology (2008 Jun; Issue 21, P:270- 274) Canadian Journal of Anaesthesia (V 48, N 2, Feb 2001).

II. Text Books Current Therapy in pain ( Howard Smith, 2009). Miller’s Anaesthesia ( Ronald Millers 2009). Clinical Anaesthesia ( Paul Barash 2009). Complication in Anaesthesiology ( Emilio Lobato, 2008). Textbook Of Anaesthesia (Atkenhead, 2007).

Summary

• Pain and suffering in child birth is no longer acceptable in modern delivery suites.

• Epidural analgesia or CSE are the best methods of analgesia available at present .

• We have to find an alternative method for patients in whom epidural analgesia is unsuitable.

• There is a place for PCA Remifentanil in controlling labour pain. But more research is needed.

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