Childbirth is a natural phenomenon, but it is painful! Some women choose pharmacological pain relief to cope with the challenges that accompany this life experience. Complete analgesia in labour is possible with regional anaesthesia that involves a block in nerve sensation, achieved by introducing a local anaesthetising agent into the lumbar epidural space surrounding the spinal cord. Commonly known as an ‘epidural’, it is only available in obstetric-led units.
An anaesthetist is required to undertake this procedure, during which a catheter is inserted into the epidural space, usually between lumbar vertebrae 3 (L3) and lumbar vertebrae 4 (L4) (Figure 78.1). The anaesthetist must administer the first dose of anaesthetic agent, after which further bolus doses are given to maintain the analgesic effect. How these doses are given may vary as in some hospitals the woman is given the opportunity to control the administration of the maintenance dose herself through a patient-controlled analgesia (PCA) pump, while in other units this is managed by the midwife who will ‘top-up’ the drug via the epidural catheter, which remains in situ.
The anaesthetic agent that is usually given for maintenance is a low concentration of local anaesthetic and opioid solution. In the UK, 0.0625–0.1% bupivacaine with 1–2.0 micrograms/mL fentanyl is recommended. This combination allows some limited sensation and mobility during labour, enabling the woman to feel the urge to push during the second stage. Even though the anaesthetist administers the test dose, it is the midwife’s responsibility to check that this mixture of medication has been correctly labelled and has not passed its expiry date.
The midwife’s role begins antenatally. During follow-up meetings or parent preparation, time should be available to discuss the benefits and risks of this pain relief and this should be reviewed at the onset of labour to ensure informed consent to the procedure. Whilst regional anaesthesia is effective in relieving pain, it is not without risk (Box 78.1).
With this information the woman should be armed with a clear understanding of the choice she is making. The anaesthetist should further explain the procedure, which should better empower her to make a well-informed choice.
Immediately before the procedure the midwife will have made an assessment of the mother and fetus to include her pulse, blood pressure and the fetal heart rate; all of which can be affected by the anaesthetic agents.
In most cases as intravenous access is required prior to initiating the procedure to allow rapid administration of fluid to prevent the risk of hypotension. The midwife may need to cannulate to expedite the whole process.
Due to a limited sensation to urinate and possible urinary retention, once the epidural is established, an indwelling urinary catheter may need to be inserted.
There should be clear documentation of all observations and the stage of labour with an indication of cervical dilation, fetal position and descent. This will all help with monitoring the progress of labour and alert the midwife to any deviation from normal, which may affect the outcome of the labour.
At the insertion of the epidural catheter, it is imperative that the midwife supports the woman and her partner, while assisting the anaesthetist. This would involve:
- Communicating with the woman to ensure that she understands the information from the anaesthetist
- Preparing the equipment and establishing the sterile field with the anaesthetist to enable the sterile technique
- Supporting the woman to maintain an adequate position, which allows maximum curvature of her spine to enable access through the skin and tissues into the epidural space (Figure 78.1)
- Monitoring the fetal wellbeing during the procedure.
The woman’s blood pressure must be recorded every 5 minutes for 15 minutes after the first dose and subsequent bolus doses of anaesthesia for any indication of acute hypotension. This is not uncommon and may be corrected by increasing the rate of the intravenous fluids.
In addition, a change of position to ensure that she is not supine will prevent compression of the inferior vena cava by the uterus. If there is no improvement, guidelines should stipulate that the anaesthetist be urgently summoned to administer a vasopressor.
The analgesic effect of the epidural is monitored, which necessitates observing the woman’s behaviour whilst checking her experience of any existing pain. Furthermore, the midwife is required to monitor the height of sensory block hourly, often by using an approved cold spray or ice on the skin of the abdomen. As the spray or ice is gradually moved upwards the woman’s reaction is observed to ascertain if she can feel the coldness on the skin. The block should be kept at a height between thoracic vertebrae 8 (T8) and thoracic vertebrae 10 (T10).
The impact of the epidural on the woman’s ability to move her legs must also be monitored hourly and according to local policy. The midwife will need to observe the epidural catheter site and record urine output, fetal wellbeing and be vigilant about the possible development of decubitus ulcers.
The aim is provision of adequate comfort and analgesia for the woman who chooses to have regional anaesthesia in labour and provide the care that enables her to safely birth her baby.