The relationship between epidural analgesia and instrumental delivery needs careful interpretation.
Editor - I was interested to read the article by Roberts and
colleagues 1. I would like to make a few comments on the relationship
between epidural analgesia and instrumental delivery.
Roberts et al observed that the epidural analgesia began a cascade of
obstetric interventions leading to a low probability of a non-operative
birth. They also noted that the private patients had higher age adjusted
rates of instrumental delivery, especially after an epidural. Another
important observation was that the use of augmentation or induction
without epidural did not noticeably increase the probability of an
instrumental birth. Do these observations really mean that the epidural
analgesia is responsible for increasing the incidence of instrumental
birth? I feel to express my reservation on this matter because of the
following reasons.
This study was based on statistical analysis of the data collected
retrospectively 1. There are other prospective randomised double blind
trials which investigated the effect of epidural analgesia on the outcome
of labour 2 3. One of the previous investigations found that the epidural
analgesia did increase the incidence of instrumental delivery and also
prolonged the duration of labour 2. However, a more recent study has
proved that the use of regional analgesia was not associated with increase
in either instrumental delivery or operative delivery 3. These
contradictory outcomes from these studies prove the complexity of the
issue 2 3. The decision on delivery by instrumentation depends upon many
factors. These factors often based on clinician's subjective judgement.
Epidurally administered local anaesthetic solution provides labour
analgesia, obtunds physiological reflexes and produces motor blockade
depending on the concentration of the solution. The method of epidural
analgesia varies from place to place or even from person to person too. A
high concentration of local anaesthetic solution in the epidural space is
thought to responsible for severe motor blockade leading to a prolonged
labour and a higher instrumental delivery rate. Epidural analgesia based
on lower concentration of a local anaesthetic solution with an opioid
provides good analgesia, less motor blockade and lower instrumental
delivery rate 4. Based on this concept, some maternity units provide
"mobile epidural" service.
A mixture of low concentration of local anaesthetic and opioid for
epidural analgesia during labour is commonly used in modern obstetric
anaesthesia practice. This mixture provides good pain relief without
significant motor weakness. Thus, it is unlikely that the duration of
labour would be significantly longer or the instrumental delivery rate
would be higher.
Roberts et al detected different outcomes between the private and the
public patients with epidurals in respect to instrumental delivery and
caesarean section rate. This may indicate that the clinician's decision
varies according to social circumstances too. Thus, the relationship
between epidural analgesia and instrumental delivery may not be
straightforward. Before making any conclusion on this relationship several
other factors should be kept in mind.
References
1. Roberts CL, Tracy S, Peat B. Rates for obstetric intervention among
private and public patients in Australia: population based descriptive
study. BMJ 2000; 321: 137-41.(15 July)
2. Thorp JA, Hu DH, Albin RM, McNitt J, Meyer BA, Cohen GR, Yeast
JD. The effect of intrapartum epidural analgesia on nulliparous labour: a
randomised controlled prospective trial. Am J Obstet Gynecol 1993; 169:
851-8.
3. Loughnan BA, Carli F, Romney M, Dore CJ, Gordon H. Randomised
controlled comparison of epidural bupivacaine versus pethidine for
analgesia in labour. Br J Anaesth 2000; 84: 715-9.
4. Olofsson CH, Ekblom A, Ekman-Oreberg G, Irestedt L. Obstetric
outcome following epidural analgesia with bupivacaine-adrenaline 0.25% or
bupivacaine 0.125% with sufentanil - a prospective randomized controlled
study in 1000 parturients. Acta Anaesthesiol Scand 1998; 42: 284-92.
Dr Nanda Gopal Mandal, Specialist Registrar, Department of
Anaesthesia, Southampton General Hospital, Tremona Road, Southampton, SO16
6YD, UK.
Rapid Response:
The relationship between epidural analgesia and instrumental delivery needs careful interpretation.
Editor - I was interested to read the article by Roberts and
colleagues 1. I would like to make a few comments on the relationship
between epidural analgesia and instrumental delivery.
Roberts et al observed that the epidural analgesia began a cascade of
obstetric interventions leading to a low probability of a non-operative
birth. They also noted that the private patients had higher age adjusted
rates of instrumental delivery, especially after an epidural. Another
important observation was that the use of augmentation or induction
without epidural did not noticeably increase the probability of an
instrumental birth. Do these observations really mean that the epidural
analgesia is responsible for increasing the incidence of instrumental
birth? I feel to express my reservation on this matter because of the
following reasons.
This study was based on statistical analysis of the data collected
retrospectively 1. There are other prospective randomised double blind
trials which investigated the effect of epidural analgesia on the outcome
of labour 2 3. One of the previous investigations found that the epidural
analgesia did increase the incidence of instrumental delivery and also
prolonged the duration of labour 2. However, a more recent study has
proved that the use of regional analgesia was not associated with increase
in either instrumental delivery or operative delivery 3. These
contradictory outcomes from these studies prove the complexity of the
issue 2 3. The decision on delivery by instrumentation depends upon many
factors. These factors often based on clinician's subjective judgement.
Epidurally administered local anaesthetic solution provides labour
analgesia, obtunds physiological reflexes and produces motor blockade
depending on the concentration of the solution. The method of epidural
analgesia varies from place to place or even from person to person too. A
high concentration of local anaesthetic solution in the epidural space is
thought to responsible for severe motor blockade leading to a prolonged
labour and a higher instrumental delivery rate. Epidural analgesia based
on lower concentration of a local anaesthetic solution with an opioid
provides good analgesia, less motor blockade and lower instrumental
delivery rate 4. Based on this concept, some maternity units provide
"mobile epidural" service.
A mixture of low concentration of local anaesthetic and opioid for
epidural analgesia during labour is commonly used in modern obstetric
anaesthesia practice. This mixture provides good pain relief without
significant motor weakness. Thus, it is unlikely that the duration of
labour would be significantly longer or the instrumental delivery rate
would be higher.
Roberts et al detected different outcomes between the private and the
public patients with epidurals in respect to instrumental delivery and
caesarean section rate. This may indicate that the clinician's decision
varies according to social circumstances too. Thus, the relationship
between epidural analgesia and instrumental delivery may not be
straightforward. Before making any conclusion on this relationship several
other factors should be kept in mind.
References
1. Roberts CL, Tracy S, Peat B. Rates for obstetric intervention among
private and public patients in Australia: population based descriptive
study. BMJ 2000; 321: 137-41.(15 July)
2. Thorp JA, Hu DH, Albin RM, McNitt J, Meyer BA, Cohen GR, Yeast
JD. The effect of intrapartum epidural analgesia on nulliparous labour: a
randomised controlled prospective trial. Am J Obstet Gynecol 1993; 169:
851-8.
3. Loughnan BA, Carli F, Romney M, Dore CJ, Gordon H. Randomised
controlled comparison of epidural bupivacaine versus pethidine for
analgesia in labour. Br J Anaesth 2000; 84: 715-9.
4. Olofsson CH, Ekblom A, Ekman-Oreberg G, Irestedt L. Obstetric
outcome following epidural analgesia with bupivacaine-adrenaline 0.25% or
bupivacaine 0.125% with sufentanil - a prospective randomized controlled
study in 1000 parturients. Acta Anaesthesiol Scand 1998; 42: 284-92.
Dr Nanda Gopal Mandal, Specialist Registrar, Department of
Anaesthesia, Southampton General Hospital, Tremona Road, Southampton, SO16
6YD, UK.
Competing interests: No competing interests