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produced greater maternal sedation when compared with epidural analgesia (Volmanen et al,
2008 Level II). In addition, PCA remifentanil has been associated with maternal apnoea and
there is currently no consensus on the optimal dosing regimen (Hill, 2008 Level IV).
Epidural and combined spinal-epidural analgesia for labour pain
Epidural analgesia provided better pain relief than non‐epidural analgesia (weighted mean
difference [WMD] ‐2.6; CI ‐3.82 to ‐1.38; VAS 0 to 10). Although associated with an increased
use of oxytocin (RR 1.18; CI 1.03 to 1.34) and longer second stage of labour (WMD 15.6
minutes; CI 7.5 to 23.6), there was no increase in the incidence of low neonatal 5‐minute
Apgar Scores (RR 1.18; CI 0.92 to 1.5) (Anim‐Somuah et al, 2005 Level I). Epidural analgesia
increased the risk of instrumental vaginal birth (RR 1.38; CI 1.24 to 1.53), but did not increase
the rate of Caesarean section (RR 1.07; CI 0.93 to 1.23) (Anim‐Somuah et al, 2005 Level I).
Although almost 90% of women can achieve optimal analgesia with epidural techniques,
suboptimal analgesia has been associated with an increased risk of second‐stage outcomes
(Caesarean section, mid‐pelvic procedures and severe perineal tears) (Abenhaim & Fraser, 2008
Level III‐2).
The timing of neuraxial analgesia is based on the degree of cervical dilatation in some centres.
In nulliparous women, on‐demand administration of neuraxial analgesia from early labour
(<4 cm cervical dilation) provided more effective pain relief and did not increase the rate of
Caesarean section or instrumental vaginal delivery when compared with commencement of
epidural analgesia later in labour (Marucci et al, 2007 Level I; Wong et al, 2009 Level II). By
contrast, women receiving early systemic opioid analgesia before late epidural analgesia had a
higher incidence of instrumental vaginal delivery. Infants of mothers receiving early neuraxial
analgesia had improved neonatal acid‐base status, a reduced requirement for naloxone, but
no measurable difference in Apgar scores when compared with infants of mothers receiving
parenteral opioid analgesia (Marucci et al, 2007 Level I). However, it was also noted that many of
the included studies did not score highly for quality, and a lack of blinding may produce bias.
Combined spinal‐epidural (CSE) analgesia in labour had a faster onset of analgesia than
epidural analgesia (Goodman et al, 2009 Level II; Simmons et al, 2007 Level I). Foetal heart rate
abnormalities have been reported following CSE: this has also been associated with increased
uterine hypotonus (Abrao et al, 2009 Level II), high maternal pain scores and older maternal age
(Nicolet et al, 2008 Level IV). As CSE does not improve satisfaction or mobilisation, and increases
the risk of pruritus, clinical advantages over epidural analgesia (either traditional or low dose)
are limited (Simmons et al, 2007 Level I).

Note: reversal of conclusion
This reverses the Level 1 conclusion in the previous edition of this
document, which concluded that maternal satisfaction was CHAPTER 11
increased.

Low dose (0.1%) bupivacaine/opioid infusions in comparison with 0.25% bupivacaine bolus
dose injection reduced motor block and instrumental vaginal delivery rate (Comparative
Obstetric Mobile Epidural Trial (COMET) Study Group, 2001 Level II). There was no significant
difference in any outcome between the use of bupivacaine and ropivacaine (Halpern & Walsh,
2003 Level I).
Combination of epidural fentanyl with levobupivacaine 0.125%, bupivacaine 0.125% or
ropivacaine 0.2% produced effective analgesia, although pain scores were higher in the
levobupivacaine group and motor block was greater with bupivacaine (Atienzar et al, 2008

Acute pain management: scientific evidence 387