• Dr Peter Chew

Epidural anaesthesia

I intend to have epidural anaesthesia for pain relief during labour. I would like to know more about it. Is it effective? Any side effects or risks? What can be done if the pain relief is not complete?

Answer: Epidural anaesthesia is done by anaesthetist for pain relief during labour. It is done by introducing a fine tube (epidural catheter) into a space at the back of the spine called epidural space. A local anaesthetic agent is then given via this epidural catheter and can be topped up intermittently or continuously, with the dosage adjusted accordingly, till the baby is delivered.

If Caesarean section is required, the dosage can be topped up to provide anaesthesia throughout the operation.

The side effects and risks of epidural anaesthesia are as follows:

a) Common side effects:

1) Shivering – harmless and self-limiting.

2) Transient drop in blood pressure – correctable with intravenous infusion.

3) Nausea and vomiting – short term.

b) Less common side effects

1) Infection – This is very rare as epidural and spinal procedures are done under strict aseptic conditions.

2) Puncture into vessels giving rise to haematoma (blood clot) that may press on the nerves causing persistent paralysis. This is very rare (0.001%) and will require surgical procedure to remove the clot and reverse the paralysis. If an aberrant nerve is injured during the epidural procedure foot drop may result. This will require supportive and sometimes prolonged physiotherapy.

3) Severe drop in blood pressure and difficulty in breathing when the effect of the local anaesthetic goes too far up the spine to affect the respiration. This can be damaging.

4) Delayed recovery of part of the numbness of the lower limbs caused by the anaesthesia – may take weeks or months. This incidence risk is about 0.001%

5) Puncturing of the dura membrane during the epidural procedure (0.5%). Patient will suffer severe post-delivery headache. This usually takes about a week to recover with the help of painkillers. Relief of headache can be achieved by a procedure instilling a blood patch to the same epidural space the next day to seal up the puncture in the dura membrane.

6) Persistent foetal heart rate changes requiring some intervention such as caesarean section.

7) Rapid absorption of the local anaesthetic, usually through a vein to cause a seizure – very, very rare.

8) Respiratory and cardiac arrest leading to fatality has been reported but is again extremely rare.

80% of patients who have had an epidural successfully inserted will get complete nerve block and pain relief. 15% of patients may get one-sided or partial nerve block and about 5% may not get any pain relief at all. This may be due to some anomaly of the patient’s spine, causing the epidural to be deviated to one side or even be displaced in the course of labour. Sometimes when the labour is too advanced or cervical dilatation is too rapid, epidural anaesthesia given at this stage may not act in time to alleviate pain.

If the pain relief is not complete, the following steps can be taken to try to rectify it: 1) Adjust the posture of the patient, e.g. turn the patient to one side or sit the patient in a more upright position. 2) Adjust the epidural catheter, and 3) If above procedures fail the final solution is to re-do the epidural at a new space. This usually gives good results but still there is no guarantee of 100% success.

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