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Labour Epidurals: The New and Old and the Myths

Dr Mary Tan, Dept of Women’s Anaesthesia, KK Women’s and Children’s Hospital 

Labour epidural, long thought of as the gold standard of labour analgesia, was first used in 1942. Much has evolved since then. Today, apart from conventional plain epidural analgesia, many anaesthetists offer combine spinal epidural (CSE). And in addition to continuous epidural infusion, we have patient-controlled epidural analgesia (PCEA) and computer-integrated patient-controlled epidural analgesia (CI-PCEA). 

Each year in KKH, approximately 40-45% of our patients opt for epidural pain relief during labour. This translates to an annual number of more than 5000.

The use of high concentration (0.2-0.25%) of local anaesthetic in the past to maintain labour analgesia has been superseded by the use of low concentration (0.0625-0.125%) of either bupivacaine or ropicavaine. Ropicavaine is a new local anaesthetic that has preferential sensory blockade and less motor blockade compared to bupivacaine. Combined with low doses of opioid (such as fentanyl), the same level of analgesia is achieved while the incidence of side-effects such as maternal hypotension and motor blockade are reduced. At the same time, the incidence of instrumental deliveries is also decreased.1

Apart from conventional epidural analgesia, CSE is fast becoming a popular technique for treating labour pain. One of the disadvantages of plain labour epidural analgesia is the long onset for pain relief to occur (up to 20 minutes).
CSE provides the advantage of a fast onset of pain relief (often within 5 minutes) by allowing the anaesthetist to give an intrathecal component followed by extending the analgesia with the epidural component.

In 1997, KKH became the first hospital in Singapore to adopt the CSE technique for labour pain relief. Today, CSE accounts for more than 80% of our labour epidurals.2 Anaesthetists are more inclined  to use CSE than plain labour epidural for multiparous parturients, and in a more painful or advanced stage of labour. The need for supplemental analgesics is lesser and patient satisfaction higher for CSE compared to the latter. There are also reduced local anaesthetic requirements and less motor block. When compared with plain epidural analgesia, CSE does not appear to result in any difference in duration of labour and mode of delivery. The potential hazards of intrathecal catheter migration with a needle-through needle CSE technique and increase in post-dural puncture headache have not been demonstrated.2

Patient-controlled epidural analgesia for labour (PCEA) was first introduced into clinical practice by Gambling et al in 1988.3 In 1999, KKH became the first hospital in Singapore to offer it to labouring parturients. In a review
of 18 randomized trials, which used PCEA in labour analgesia, PCEA has been shown to offer several advantages over both intermittent nurse-administered dosing and continuous infusion techniques. These include reduced local anaesthetic used, less motor blockade, lower pain scores, improved maternal satisfaction and less anaesthetic interventions with possible decrease in staff workload.4-6

Epidural Analgesia PumpComputer-integrated PCEA (CI-PCEA) is a novel epidural solution delivery system that has been developed and introduced in KKH in the last 2 years. In CI-PCEA, a laptop computer with a programmed algorithm is connected to a standard epidural pump. The computer program automatically adjusts the background infusion rate based on the number of patient’s PCEA demands in the previous hour. The algorithm adjusts the background infusion to 5, 10 or 15ml/h if the patient required one, two, or three demand boluses, respectively, in the previous hour. If there are no bolus demands in the previous hour, the background infusion is cut by 5ml/h. Our studies showed that CIPCEA group had similar local anaesthetic consumption compared with demandonly PCEA but was associated with increased maternal satisfaction. We also found that CI-PCEA reduced the incidence of breakthrough pain without increasing drug consumption when compared with continuous epidural infusion without PCEA for labour analgesia.7,8

Despite being the most efficacious of all labour analgesia nowadays, many women still choose not to have epidural during labour due to the many “myths” surrounding it. We attempt to debunk the more common ones here:

1) Epidural increases the chance of having a cesarean section.
In the late 1980s and early 1990s, several retrospective trials demonstrated an association between the use of epidural and increased caesarean rate.9 However a criticism of these trials was that the women selected for the epidural already represented a population with an increased risk of an unfavourable course of labour such as those with cephalopelvic disproportion or fetal malposition, both of which increased the risk of caesarean section. Recent meta-analyses by Leighton et al and Liu et al found no direct relationship between labour epidural and caesarean section.10,11

2) Epidural prolongs labour and increases chance of instrumental vaginal delivery.
Early studies have suggested that labour epidural prolongs labour and leads to increase in risk of assisted vaginal delivery.12,13 Later studies, however, showed a decrease in assisted births despite an increase in number of women asking for labour epidural.14 This change in incidence of assisted deliveries can be attributed to improved epidural techniques and change in obstetric practice over the years. More obstetricians now recognise the adverse maternal outcomes associated with forcep and vacuum births while anaesthetists have moved towards using dilute local anaesthetic epidural solution to decrease the motor block.

3) Epidural leads to post-partum chronic backache.
Mechanical and structural changes in the spine as a result of normal physiological changes of pregnancy often lead to back pain after pregnancy.15 Studies have also shown the incidence of antenatal backache to be as high as 76-80%.16,17 Those who experienced back pain during pregnancy are more likely to have back pain after they have delivered.18 Other factors include high BMI, hypermobility of joints and young age.19 It is normal and anticipated to have a tender area and small bruise over the location of epidural injection up to a few days after delivery. This has led to one of the biggest myths about epidural analgesia that it is to be blamed for the development of chronic back pain post delivery. As a matter of fact, opting for epidural analgesia does not position the mothers at higher risk for long term back pain compared to those without.12,20

References
1) Comparative Obstetric Mobile Epidural Trial (COMET) Study Group UK. Effect of lowdose mobile versus traditional epidural techniques on mode of delivery: a randomized controlled trial. Lancet 2001; 358:19-23. Comment in: Lancet 2001; 358:2, Lancet 2001; 358:1725; author reply 1726.
2) Sia AT, Camann WR, Ocampo CE, et al. Neuraxial block for labour analgesia – is the combined spinal epidural (CSE) modality a good alternative to conventional epidural analgesia? Singapore Med J 2003; 44:464-70.
3) Gambling DR, Yu P, Cole C, McMorland GH, Palmer L. A comparative study of patient controlled epidural analgesia (PCEA) and continuous infusion epidural analgesia (CIEA) during labour. Can J Anaesth. 1988 May;35(3 ( Pt 1)):249-54.
4) D’Angelo R. New techniques for labour analgesia: PCEA and CSE. Clin Obstet Gyynecol 2003; 46: 623-32
5) American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Practice guidelines for obstetric anesthesia: an updated report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology 2007;106: 843–63.
6) Halpern SH. Maintenance of epidural analgesia for labor— continuous infusion or patient control. In: Halpern SH, Douglas MJ, eds. Evidence-based obstetric anesthesia. Malden, MA: Blackwell publishing, 2004:23–9
7) Lim Y, Sia AT, Ocampo CE. Comparison of computer integrated patient controlled epidural analgesia vs. conventional patient controlled epidural analgesia for pain relief in labour. Anaesthesia 1006;61:339-44.
8) Sia AT, Lim Y, Ocampo CE. Computer-integrated patient controlled epidural analgesia: a preliminary study on a novel approach of providing pain relief in labour. Singapore Med J 1006;47:951-6.
9) Sharma SK, Leveno KJ. Regional analgesia and progress of labor. Clin Obstet Gynecol 2003; 46:633-45.
10) Leighton BL, Halpern SH. The effects of epidural analgesia on labor, maternal, and neonatal outcomes: a systematic review. Am J Obstet Gynecol 2002; 186 (5 Suppl Nature):S69-77. Comment in: Am J Obstet Gynecol 2002; 186 (5 Suppl Nature):S78- 80, J Fam Pract 2002; 51:786.
11) Liu EH, Sia AT. Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opioid analgesia: systematic review. BMJ 2004; 328:1410. Comment in: BMJ 2004; 329:293
12) Howell CJ, Kidd C, Roberts W, et al. A randomised controlled trial of epidural compared with non-epidural analgesia in labour. BJOG 2001;108:27-33. Comment in: ACP J Club 2001; 135:65, BJOG 2001; 108:1-2.
13) Leighton BL, Halpern SH. The effects of epidural analgesia on labor, maternal, and
neonatal outcomes: a systematic review. Am J Obstet Gynecol 2002; 186 (5 Suppl Nature):S69-77. Comment in: Am J Obstet Gynecol 2002; 186 (5 Suppl Nature):S78- 80, J Fam Pract 2002; 51:786.
14) Roberts CL, Algert CS, Douglas I, Tracy SK, Peat B. Trends in labour and birth interventions among low-risk women in New South Wales. Aust N Z J Obstet Gynaecol 2002; 42:176-81.
15) MacEvilly M, Buggy D. Back pain and pregnancy: a review. Pain 1996; 64:405-414.
16) Patel RR, Peters TJ, Murphy DJ. Is operative delivery associated with postnatal back pain at eight weeks and eight months? A cohort study. Acta Obstet Gynecol Scand. 2007;86(11):1322-7.
17) To WW, Wong MW. Factors associated with back pain symptoms in pregnancy and the persistence of pain 2 years after pregnancy. Acta Obstet Gynecol Scand. 2003 Dec;82(12):1086-91.
18) Russell R, Dundas R, Reynolds F. Long term backache after childbirth: prospective search for causative factors. BMJ 1996;312:1384-8.
19) Wijnhoven HA, de Vet HC, Smit HA, Picavet HS. Hormonal and reproductive factors are associated with chronic low back pain and chronic upper extremity pain in women--the MORGEN study. Spine (Phila Pa 1976). 2006 Jun 1;31(13):1496-502.
20) Loughnan BA, Carli F, Romney M, Dore J, Gordon H. Epidural analgesia and backache: a randomized controlled comparison with intramuscular meperidine for analgesia during labour. Br J Anaesth 2002; 89:466-72. 




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