Oxford Handbook of Midwifery (63 page)

method of pain relief for women.
¹

The
Midwives Rules and Standards
²
outline the midwife’s responsibilities in the administration of pain relief.

1. Rosen MA (2002). Nitrous oxide for relief of labor pain: a systematic review.
   American Journal of Obstetrics and Gynecology
   186
   (5), S110–S26.
   
2. Nursing and Midwifery Council (2004).
   Midwives Rules and Standards, Rule 7
   . London: NMC, p. 19.
   

OPIATES

259‌‌

Opiates

Considerations for the use of opiates during labour

The use of opiates for the relief of pain during labour has been somewhat superseded by the growing popularity of epidural analgesia. There does remain a place for an alternative to epidurals, and midwives do need to be able to advise mothers about a range of choices.

In discussion, clients need to be made aware of the following issues:

The commonly used opiates are pethidine and morphine derivatives, for example diamorphine. Meptazinol, a drug introduced in the 1980s is less commonly offered, probably due to its cost.

Pethidine

Diamorphine

1. Tsui MHY, Kee WDN, Ng FF (2004). A double blinded randomized placebo-controlled study of intra-muscular pethidine for pain relief in the first stage of labour.
   BJOG International Journal of Obstetrics and Gynaecology
   111
   (7), 648–55.
   
2. Wood C, Soltani H (2005). Does pethidine relieve pain?
   Practising Midwife
   8
   (7), 16, 18–20, 22–5.
   
3. Hunt S (2002). Pethidine: love it or hate it?
   MIDIRS Midwifery Digest
   12
   (3), 363–5.
   
4. Sosa CG, Buekens P, Hughes JM,
   et al
   . (2006). Effect of pethidine administered during the first stage of labor on the acid-base status at birth.
   European Journal of Obstetrics and Gynecology and Reproductive Biology
   129
   , 135–9.
   

   CHAPTER 13
   Pain relief: pharmacological
   

   260‌‌
   

   Lumbar epidural analgesia
   

   This is a very effective method of pain relief which has gained in popularity since its use in obstetrics became more widespread in the 1970s.
   

   A senior anaesthetist must be present or readily available during administration of lumbar epidural anaesthesia. This limits the use of this technique in units or centres that cannot provide 24h anaesthetic cover. However, recently ODAs and nurses have begun to insert epidurals for labouring women.
   

   What is an epidural?
   

   • A local anaesthetic, usually bupivacaine hydrochloride (Marcain
     ^®
     ) injected into the epidural space between the second and third lumbar vertebrae.
     
   • This drug acts on the spinal nerves at this level to produce a sensory and partial motor block.
     
   • The sensory block produces excellent pain relief, as it affects the uterine and cervical nerve plexuses, which are the main transmitters of pain sensation during uterine contractions.
     
   • The partial motor block leaves the woman unable to walk around, so she is cared for in bed.
     
   • There is a reflex relaxation of the blood vessels in the lower body, leading to increased warmth and a feeling of heaviness in the lower limbs.
     
   • This haemodynamic shift results in rebound hypotension, improved circulation in the lower body, and relaxation of the pelvic floor.
     
   • As labour advances, contraction pain is centred on the rectum and pelvic floor, and the sacral nerve plexus is then involved in the transmission of pain. A stronger dose of bupivacaine can be administered with the woman in a more upright position to give
     

effective pain relief at this time (referred to as a second-stage top-up).

Types of epidural

An epidural anaesthetic can be administered in several ways.

Standard
: 10mL of bupivacaine 0.25–0.5% via an epidural cannula. Each dose lasts 1–2h, therefore the drug is readministered as required (epidural top-up).

Combined epi-spinal
: a combination of low-dose bupivacaine (0.15%) into the epidural space, with a small dose of opiate (3micrograms fentanyl) into the subarachnoid space, is used to produce a less-dense motor block, allowing the woman more mobility. This is sometimes referred to as a

mobile epidural, but it does not mean the woman can walk about! She will have improved motor control so she will be able to move around in bed

more easily. Regular injections every 1–2h of bupivacaine into the epidural space will still be required.

Continuous lumbar epidural infusion
: once the epidural block is estab- lished, 10–15mg/h of a 0.1 or 0.125% solution of bupivacaine (with or without opiate) is administered via an infusion pump attached to the epi- dural cannula. This can be combined with a patient-controlled device that allows the woman to top up the dose, within a strict limit (a very popular option with mothers and midwives!).

LUMBAR EPIDURAL ANALGESIA

261

Choice between the above methods depends on availability (midwives to administer the top-ups), unit protocol, and the mother’s preference.

Before asking for consent, explain the risks and benefits of the procedure to the woman who is considering epidural analgesia.

Indications

Contraindications

formation in the epidural space.