2.1 Prevention of Inadequate Block
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Women who are unable to speak English:
The Trust’s current provider of translation services should be contacted to assist with communication to assess effectiveness of epidural or adequacy of block in women who do not speak English.
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Consent:
Women should be made aware of the likely sensations that should be anticipated during caesarean section under neuraxial block, but also of the risks of block failure.
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Monitoring of effectiveness of labour epidurals:
The anaesthetist responsible for labour ward must regularly monitor the effectiveness of labour epidurals once sited, especially in women with risk factors that make a surgical delivery more likely. The most reliable predictor of failure of epidural top up is the requirement of more than one unscheduled clinician top up in labour.(1) In an obstetric emergency, valuable time may be lost by attempting to top up an ineffective epidural.
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Topping up a labour epidural:
A labour epidural that has been recognised as inadequate should not be topped up for surgery. The anaesthetist should ensure that the patient and obstetric team are aware that block development of an epidural top up is likely to take at least 10-15 minutes, depending on drugs used.(2)
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Testing the block:(3)
A block to light touch which includes T5 is likely to provide adequate anaesthesia. A second sensory modality, such as block to cold, should be assessed if there is any difficulty in ascertaining the block height using light touch. Inability to bilaterally straight leg raise against gravity indicates adequate motor block. Warm, dry feet indicate a sympathetic block and demonstrate that the block has reached T10. An epidural top up that has resulted in uneven motor or sympathetic block should be carefully evaluated for sensory adequacy as it indicates a difference between the effectiveness of the two sides. The lower limit of the block can be assessed by sensory assessment of the undersides of the legs or sacrally-supplied plantar aspects of the feet.
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The impact of positioning on block development must be considered. Alterations in positioning may improve ability to achieve adequate block height or bilateral spread if the block is still developing or if further epidural top ups are feasible within limits of local anaesthesia doses.
2.2 Management of Inadequate Block Prior to Surgery Commencing
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Combined spinal-epidural (CSE): (3)
Requires familiarity with the technique. Allows extension of block height with use of the epidural component.
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Single shot spinal: (3)(4)
Spinal anaesthesia after partial or failed epidural block may cause concerns about high spinal block. No consensus exists on dose in this situation with some clinicians advocating dose reduction by 20-30%, and some a normal dose with meticulous attention to patient positioning.
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General anaesthesia: (3)
This depends on surgical urgency, the wishes of the patient, and the assessment of risks of general anaesthesia for the individual patient.
2.3 Management of Inadequate Block After Surgery Has Started (3)
- Pause surgery, if appropriate (not between uterine incision and delivery of the baby), and assess the patient. Establish what the woman is feeling and whether communication is needed regarding usual sensations to be expected. However, even if the anaesthetist views the sensations as “normal”, if they continue to distress the patient then this situation must still be managed as a failed block.
- Do not attempt to use sedation or anxiolytics to manage intraoperative pain.
- General anaesthesia must always be clearly stated as an option and documented.
- If only the skin has been incised, consider covering the wound and performing a neuraxial technique in the lateral position.
- If an epidural catheter is in place, assess block and consider top up, remembering not to exceed maximum doses of local anaesthesia, and recheck block prior to recommencement of surgery.
- Pain early in the procedure is unlikely to be effectively managed for a prolonged duration with analgesic adjuncts. Later in surgery, analgesia may be sufficient to allow surgery to be completed if the woman does not want to have a general anaesthetic.
- Nitrous oxide. Use 50:50 oxygen and nitrous oxide via anaesthetic machine.
- Alfentanil. Give incrementally in 250 microgram boluses. Monitor for sedation and respiratory depression, use face mask oxygen if required. Advise the midwife and paediatrician that an opioid has been given, if prior to delivery.
- Fentanyl. Give incrementally in 25 microgram boluses. Monitor for sedation and respiratory depression, use face mask oxygen if required. Advise the midwife and paediatrician that an opioid has been given, if prior to delivery.
- Ketamine. Give incrementally in 10mg boluses but note that ketamine is contraindicated in hypertension and hypertensive conditions of pregnancy. The amnesic, hallucinatory and sedative effects of ketamine should be considered prior to its use. A small dose of midazolam should be used in conjunction with ketamine to reduce its hallucinatory effect. (5)
- Midazolam. In the event of severe maternal anxiety, a small dose of up to 2mg midazolam intravenously may be considered after delivery of the baby. Benzodiazepines are not a treatment for pain.
- Local anaesthetic infiltration. This may be performed by the surgeon if nearing completion of surgery.
- Communication with the obstetric surgeons throughout is necessary. They should aim to minimise surgical stimulation in the event of a wish by the woman to complete surgery with a suboptimal block with the use of analgesic adjuvants only.
2.4 Follow Up (3)(6)
- Communicate events with the surgeon and the multi-disciplinary team.
- Ensure documentation accurately reflects the events that have taken place, including all offers of analgesia or anaesthesia.
- Debrief with patient at end of surgery, then later on ward prior to discharge and ensure a clinic appointment is offered if distress has been significant.
- A letter giving details of the intraoperative pain and how it was managed should be sent to the patient and the patient’s GP. It should include the phone number of the anaesthetic department in case a debrief appointment is required. This is the responsibility of the anaesthetist involved in her case, with supervision of the duty consultant if the anaesthetist is not a consultant/NCCG.