Introduction Intrapartum caesarean delivery (CD) is a common obstetric intervention. Published cohorts report up to 31,2% of intrapartum CD among parturients admitted to delivery room.¹ It also represents 60 to 70% of total cases of CD in several countries.^2,3 Most frequent indications are a failure to progress or non-reassuring foetal heart rate, which don’t require a fast response. However, obstetric emergencies like umbilical cord prolapse, uterine rupture or other maternal and/or foetal distress may require an immediate reaction from the obstetricians, so the anaesthetic technique must be adapted consequently.³

When an emergency CD is indicated (category I or II according to Lucas Classification)⁴, some authors have described a risk for a poorer outcome if foetal extraction is delayed (OR: 1.8, 95% confidence interval (1.2–6.5)).⁵Decision to Delivery Time (DDT) is a good indicator for this possible delay in the foetal extraction, and it was progressively integrated into the protocols of management of emergency CD. A recent consensus document of the Scientific SubCommittee-4 of the European Society of Anaesthesia and Intensive Care (SSC4-ESAIC) and the European Board of Anaesthesiology of the UEMS (EBA-UEMS) showed that recommended DDT varied between 15 and 30 minutes for a category I CD, depending on the European country.⁶ The anaesthetic technique employed to attend these patients is conditioned by the level of emergency of the caesarean delivery, the goal being to provide the best and safest possible anaesthesia in the shortest time. For this purpose, several options can be offered depending on the situation.

Could epidural top up not work for emergency intrapartum CS?

In European maternities, despite a certain disparity between and even within countries, labour epidural analgesia (LEA) is the gold standard technique that provides the best comfort to labouring women.⁶ Many recent cohorts of patients describe a LEA rate which has increased drastically in the last 20 years in high income countries, with values usually above 60 to 80%.⁷ On top of comfort and analgesia, LEA offers a significant advantage in terms of safety, since it permits to convert the analgesic to an anaesthetic block when an intrapartum CD is indicated, and so it avoids a general anaesthesia in almost 90% of the cases,⁸ with an acceptable time difference in terms of DDT.⁹ In fact the administration of a top up dose of concentrated local anaesthetic prior to intrapartum CD has been an extended practice for a very long time now,¹⁰ and can be considered the gold standard of care in obstetric anaesthesia practice. Many studies have been published concerning the best top up local anaesthetic solution to obtain a surgical epidural block,¹¹ and it seems that Lidocaine 2% plus adjuvants (bicarbonate and/or norepinephrine and/or fentanyl)¹² and 2-Chlorprocaine 3%¹³ have a faster onset. Although the latency of Ropivacaine 0.75% is longer, this local anaesthetic confers more stability to the block and is associated less requirements for intraoperative supplementation, with no synergic effect of fentanyl.¹⁴

Most authors recommend invigilating parturients at risk of intrapartum CD with special care, especially if they present risks for a failed LEA.¹⁵ This permits to administer an early top up conversion dose when an emergency CD is indicated, which increases the chance of successful surgical block.¹⁶ It is sometimes challenging for the obstetric team to choose whether to allow time for the regional block to become effective, or to perform a general anaesthesia in case of emergency CD. In fact, the DDT for CD performed under general anaesthesia was measured to 24.7 minutes, versus 32.6 minutes if an extension of the epidural block is performed (P < 0.001).¹⁷ This difference of almost 8 minutes can make a huge difference in a compromised foetus and must be considered. On the other hand, a worse Apgar score at birth¹⁷ and a higher rate of admission of the neonate to the ICU¹⁸ were observed when general anaesthesia was required. So, time for a correct extension of the block may not be the only factor to consider, and epidural extension remains the best option in most of the cases.

Despite those strategies to decrease the rate of general anaesthesia for intrapartum CD, the epidural conversion proved to be incomplete for intrapartum CD in up to 21% of the cases.¹⁶ In case of category-I intrapartum CD, time becomes a limiting factor: it was associated with an increased risk of failure of the epidural conversion, when compared to non-emergency CD (Odds Ratio: 40.4 , 95% CI [8.8–186] ),¹⁹ even if LEA was well-functioning during labour. In this situation, many authors agree that this dilemma is difficult to solve, especially when there is no best practice guideline.²⁰

What are the anaesthetic options after an epidural block failure for emergency intrapartum CD?

When epidural conversion is not efficient enough and/or fast enough to provide a rapid surgical block, various options have been proposed to continue with CD. Those include a manipulation or replacement of the catheter, a withdrawal of the epidural and performance of a combined spinal-epidural or a spinal anaesthesia, or a general anaesthesia.¹¹ The most important constraints of category-I CD is time and any technique which would prolong DDT is not convenient, so only few strategies seem acceptable ³:

- epidural conversion. Cautious conscious sedation can be offered until completion of the block, but it might increase the risk of aspiration and can cause neonatal respiratory depression so a benefit-risk balance should be appreciated.²¹ Moreover, emotional distress and posttraumatic stress disorders have recently been described secondary to pain during CD,²² so intraoperative pain should not be permitted.

- general anaesthesia. All obstetric anaesthesiologists avoid general anaesthesia due to the increased risk of maternal and foetal morbidity.

- new spinal anaesthesia after withdrawal of the epidural catheter. It can be an option, but the anaesthesiologist must agree with the obstetrician that he disposes of enough time.

In a recent observational study, Wiskott et al.²¹ described 403 patients with epidural labour analgesia in whom an emergency intrapartum CD was indicated. Surgical conversion of labour epidural analgesia failed in 20 (4,9%) parturients: 9 (2,2%) patients required a conversion to spinal anaesthesia and 11(2,7%) required general anaesthesia after a failed epidural conversion, 4 (1,0%) of whom had a well-functioning epidural analgesia during labour. This study shows that all the options are used in clinical practice. We will address here the advantages and conditions to perform this last technique for an emergency intrapartum CD.

Why and how to perform a new spinal when the epidural is failing?

In case of an emergency intrapartum CD, the most important factor is the speed of conversion of analgesia to anaesthesia. Rapid sequence spinal anaesthesia was described in category-I CD and is an interesting option. It provides a surgical block in 8 (Range [6–8]) min, with a DDT of 23±6 min.²³ Another study in category III intrapartum CD showed an interval between injection and skin incision of 12 (10–15) min for spinal anaesthesia versus 18 (16–19) min for epidural conversion (p=<0,001).²⁴ These shorter delays to obtain an effective surgical neuraxial block make of this technique an interesting alternative when epidural conversion failed. However, DDT it is still longer for spinal anaesthesia than general anaesthesia.

Spinal anaesthesia for CD presents a very high success rate, with better results than epidural anaesthesia: Kinsella described a rate of block failure of 6% when using a spinal block, versus 24% with epidural top up in an audit among 5080 patients operated of CD.¹⁰ Even though this audit didn’t register specifically patients who received a spinal anaesthesia after LEA, this result supports the use of spinal for emergency CD, especially when general anaesthesia should be avoided. A recent study by Yoon et al.²⁴ showed a lower incidence of pain during intrapartum category-III CD, if a new spinal anaesthesia was performed (Spinal: 2,5% vs Epidural: 15,3%, P < 0,001), with no difference in the requirement for a secondary conversion to general anaesthesia. These results confirm the low rates of failure of spinal anaesthesia for intrapartum CD in patients with LEA of 5,0 to 10,2% described in other studies.^10,19,25,26

The doses of local anaesthetic administered via an epidural catheter for an intrapartum CD expose patients to a risk of local anaesthetic systemic toxicity (LAST). The total dose of local anaesthetic administered is minimized if the catheter is removed and a new spinal block is performed, and this represent a great advantage of spinal over epidural surgical anaesthesia.³

When performing a spinal anaesthesia after removing LEA catheter, high-spinal blocks can occur. Lower doses of intrathecal local anaesthetic are recommended.^16,23,27 Two reasons to explain this phenomenon are that dural sac is submitted to an extrinsic compression by epidural local anaesthetic, and that there could be a leakage of local anaesthetic from the epidural space to the intrathecal space.³ To decrease the risk of total spinal block, some authors also recommended not to perform a new spinal anaesthesia if a top up epidural dose has been administered in the 30 min before the rescue spinal anaesthesia.²⁷ Other authors are in favour of performing a combined spinal-epidural technique to decrease the dose of intrathecal local anaesthetic, and to be able to administer epidural top ups in case of insufficient block.¹⁵ However, in the context of a Category-I CD, the time frame is not favourable for this technique.

Other data suggest that a new spinal anaesthesia might increase the risk of hypotension. In a recent study, the authors report an incidence of hypotension of 14,6% in patients who received a new spinal, versus 6,7% among those with an epidural top up (p<0,05). In this study, the protocol for prevention of hypotension consisted of ephedrine and atropine.⁸ This rate of hypotension is acceptable and would probably be less with the preventive use of phenylephrine or noradrenaline recommended in patients with a spinal anaesthesia.²⁸

While respecting these precautions, this practice has demonstrated to be safe.²⁵ In a recent survey among all the Obstetric Anaesthetists’ Association in the UK, the respondents considered to use a spinal anaesthesia after a conversion failure (no objective sensory block or below a T10 level or unilateral block), and to decrease the dose of spinal anaesthesia.²⁰ An algorithm published by Vaida et al.²⁹ also considered the level of emergency of the CD to indicate a spinal block: the authors only recommended a spinal anaesthesia for category-2 CD, when parturients presented an epidural analgesia failure.

Finally, false identification of intradural space due to the presence of local anaesthetic in the epidural space is one of the cause of failed rescue spinal block.³ For this reason, new spinal anaesthesia should be performed by an experienced anaesthesiologist, to decrease the risk of failure in emergency situations.

Conclusions Even though a new spinal anaesthesia should not be the first-line anaesthetic technique for intrapartum caesarean delivery in a patient with well-functioning labour epidural analgesia, it is a safe and efficient rescue technique to avoid general anaesthesia in case of failing labour epidural analgesia for emergent caesarean delivery.

Its indications must always be discussed with the obstetricians because onset time to establish a surgical block is longer than for general anaesthesia. Although decision to delivery time is acceptable in many cases with spinal anaesthesia, the situation does not always allow to wait before foetal extraction.

So, YES, For Emergency caesarean delivery, a Labour Epidural Analgesia catheter should be removed, and a Spinal Anaesthetsia used instead, but only for failed epidural conversion and not in all the situations.

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