Prospective randomized study comparing the use of lidocaine 2% with epinephrine buffered with sodium bicarbonate and lidocaine 2% with epinephrine as epidural top-up for extremely urgent cesarean section during labour.

General anesthesia in pregnant women remains burdened by a significant maternal-fetal morbidity and mortality. An increased risk of orotracheal intubation difficulty, gastric inhalation syndrome and neonatal respiratory depression is described.

The rate of epidural analgesia during labor is about 85% in France. In addition to the comfort provided, epidural analgesia allows emergency Caesarean sections to be performed by converting epidural analgesia to epidural anesthesia, a technique known as "epidural extension" or "epidural top-up". The effectiveness and the time necessary to obtain this surgical anesthesia depends on the protocols used and determines the possibility of performing fetal extractions, even the most urgent ones, without resorting to general anesthesia.

We define an extremely urgent cesarean delivery as a delivery required in the event of an immediate threat to maternal or fetal vital prognosis, with a target of less than 15 minutes between the extraction decision time and birth.

In France, the latest recommendations date from 2007 and recommend the practice of epidural extension with 15 to 20 ml of 2% adrenaline lidocaine. With this technique, surgical anesthesia is typically obtained within 10 to 15 minutes. This time remains too long in certain obstetrical emergency situations, notably extremely urgent cesarean sections, which require frequent recourse to general anesthesia to compensate for this length of nerve block installation.

The alkalinization of local anesthetics with sodium bicarbonate has been experimentally studied since the 1970s and makes it possible to accelerate the time of action of local anesthetics. Alkalinization of local anesthetics is practiced in 35% of epidural extensions in Denmark and 12% of epidural extensions in the United Kingdom.

Since 2016, this technique has been used in the anesthesia departments of maternity units of Bayonne and Bordeaux hospitals. In the former, a retrospective study of 51 cases from January 2019 to July 2019 showed a decrease of more than 80% in the rate of recourse to general anesthesia in extremely urgent caesarean sections (4/4 vs 0/7) and a 50% decrease in the time required to obtain adequate epidural anesthesia (5 min vs 10 min).

The main objective of the current prospective study is to prospectively confirm the decrease in the use of general anesthesia in extremely urgent cesarean sections.

Inclusion Criteria:

• Adult patients, affiliated to social security
• Informed consent signed by the participant and the investigating physician at the latest after the therapeutic intervention
• Initial indication for vaginal delivery
• Benefiting from emergency caesarean section during labour for fetal extraction with a maximum 15-minute decision-to-delivery delay (i.e. extremely urgent caesarean section)

Exclusion Criteria:

• Opposition to participation in research before delivery
• Refusal or impossibility of informed consent
• Lack of understanding or significant language barrier
• Initial indication for general anaesthesia defined by the following situations: non-functional epidural analgesia, altered consciousness, eclampsia, suspicion of amniotic embolism, confirmed or suspected severe haemorrhage occurring before birth
• Contraindication to the use of the products defined in the protocol : adrenalized lidocaine ; sodium bicarbonate.
• Persons placed under judicial protection