Complications and risks of neuraxial blockade
Unintended high or total spinal block is more common with the use of epidurals because a large volume of local anaesthetic is required to establish a block. The risk of a high or total spinal is 1:10 000. Large doses of local anaesthetic also present the problem of local anaesthetic toxicity. The risk of intravascular injection of local anaesthetic with an epidural is 1:10 000.
Headache occurs due to ongoing cerebrospinal fluid leak after the dura has been breached. If there is an unintentional dural puncture with an epidural needle, the risk of developing a headache is 80%. The risk of a headache after spinal anaesthesia is reduced to roughly 1:200 with the use of small-gauge pencil-point needles.
The risk of obstetric palsy including obturator nerve, femoral nerve and common peroneal nerve injury is 1:3000. The risk of neurological damage with neuraxial blockade is 1:13 000.
A spinal or epidural haematoma or abscess may lead to permanent paralysis as can needle insertion and injection into to the spinal cord. The risk of permanent paralysis with the use of a neuraxial blockade is quoted at 1:1 000 000.
The spinal cord terminates at the level of L1-2 in most adults but may end at L2-3 in some patients. Tuffier’s line is an unreliable as a way of identifying the correct vertebral level, particularly in the obese. One may have miss-judged the level by 2 segments and given that the spinal cord may be at L2-3, one should avoid inserting a needle above L3.
Post operative analgesia
A simple regimen for post-operative analgesia after caesarean section is usually best. There are several options for analgesia. Epidural or spinal morphine is common in some people’s practice and provides good analgesia for up to 24 hours. However, there is an increased risk of itch, nausea and vomiting and most importantly, delayed respiratory depression. Patient controlled intravenous morphine is another option for post-operative analgesia but is cumbersome.
In Melbourne, it is common practice to use a combination of regular paracetamol, rectal or oral diclofenac and rectal or oral oxycodone. Oxycodone is as effective as a neuraxial opioid and far safer. It is simple and inexpensive, with less need for nursing intervention. One does need to bear in mind that other opioids should not be administered within 6 hours of a dose of oxycodone due to the risk of respiratory depression.
In the pre-eclamptic patient, an ongoing epidural infusion will not only provide post- operative analgesia, but will help with blood pressure control. One should check that the coagulation is normal before the epidural catheter is removed.
General anaesthesia
The most common indications for general anaesthesia include: a contraindication to regional anaesthesia, the failure of regional anaesthesia and when there is a need for urgent delivery within 10 minutes such as might occur with severe foetal distress, cord prolapse, and placental abruption.
The advantages of general over regional anaesthesia include a more rapid induction, less hypotension, less maternal anxiety and its application in situations where there is a contraindication to regional anaesthesia.
Potential problems
1. Aspiration pneumonitis
2. Failed intubation (your first responsibility is to the mother)
3. Stress response to intubation
4. Rapid desaturation (pre-oxygenate the patient before induction)
5. Supine hypotension
6. Neonatal depression (Lower APGAR scores at one minute are related to sedation. Regardless of the anaesthetic technique, uterine incision-to-delivery time of greater than 3 minutes produces more asphyxia.)
7. The incidence of maternal awareness is reduced with the use of an increased dose of induction agent and the increased use of volatile agents.
8. Uterine relaxation and maternal bleeding.
Conduct of General Anaesthesia
Reduce the risk of acid aspiration by fasting the patient for at least 6 hours from solids and 3 hours from clear fluids, give antacid prophylaxis as already described and perform a rapid sequence induction with a good assistant to provide cricoid pressure after the loss of consciousness.
Supine hypotension is common at term due to aortocaval compression. This is reduced by left lateral tilt of 15 degrees.
Due to the increased incidence of blood loss under general anaesthesia, it is important to secure large-bore intravenous access. In order to reduce the induction to delivery time, insert a urinary catheter and ask the surgeon to prepare and drape the abdomen before induction of the anaesthetic. Allow the surgeon to start operating as soon at the endotracheal tube is inserted and its position confirmed.
Hypocapnia induces uterine vasoconstriction, therefore avoid hyperventilation of the patient. The patient should be extubated when her airway reflexes return to avoid aspiration of stomach contents on emergence.
Failed intubation is the leading cause of anaesthetic maternal mortality. The incidence is greater than in the general surgical population (up to one in 200). Ensure you have assessed the airway and called for assistance if it looks difficult. Pre-oxygenate the patient in order to allow yourself more time for intubation. Always have a back up plan for failed intubation and know a technique for cricothyroid puncture.
Emergency caesarean section
The rate of emergency CS varies depending on the definition of an emergency but has been reported to be 61%.
The time required for surgical readiness in emergency caesarean section is slightly longer (17min) with a spinal compared with a general anaesthetic. This time is reduced in more experienced hands. In any case, the time difference for surgical readiness for emergency caesarean section does not justify a general where a spinal can be performed.[i] That depends on your definition of an emergency….
The indications for an emergency caesarean section can be grouped into maternal and foetal indications. Maternal indications include a deteriorating medical condition, haemorrhage and trauma. The most common foetal indication is acute severe foetal distress. The other foetal indications are a prolapsed presenting part and foetal injury.
How urgent is urgent?
Anoxia and brain injury in the rhesus monkey
In an early study, hypoxia was deliberately induced in the foetus of the rhesus monkey by clamping the umbilical cord for different periods of time and the severity of foetal brain injury was determined. Less than 10 minutes of anoxia produced no brain injury. With 10-20 minutes of anoxia the foetus survived but had neuronal injury especially in the basal ganglia, thalamus and brain stem. Over 20 minutes of anoxia caused death.
Post mortem caesarean section and neonatal sequelae
Delivery interval Neurological sequelae
< 5 minutes 0%
5-10 minutes 13%
10-15 minutes 17%
>15 minutes 82%
Grading of urgency of caesarean section
I Immediate threat to life of mother or baby 1-10 minutes GA
II Maternal or foetal compromise which is
not life threatening 10-30 minutes Spinal
III Needing early delivery but no maternal or
foetal compromise. 30-60 minutes Regional
IV At a time to suit the patient and staff 1-24 hours Regional
In the UK, the Association of Anaesthetists of Great Britain and Ireland, the Royal College of Obstetrics and Gynaecology and the Royal College of Midwives, recommend that when a decision is made to deliver a baby by caesarean section because of foetal distress, the baby should be delivered within thirty minutes. In a series of audits done in a large obstetric unit in the UK, it was found that delivery within thirty minutes is achievable in only two of three cases but that the delay in delivery made no difference to the rate of admission to special care for babies over 36
Unintended high or total spinal block is more common with the use of epidurals because a large volume of local anaesthetic is required to establish a block. The risk of a high or total spinal is 1:10 000. Large doses of local anaesthetic also present the problem of local anaesthetic toxicity. The risk of intravascular injection of local anaesthetic with an epidural is 1:10 000.
Headache occurs due to ongoing cerebrospinal fluid leak after the dura has been breached. If there is an unintentional dural puncture with an epidural needle, the risk of developing a headache is 80%. The risk of a headache after spinal anaesthesia is reduced to roughly 1:200 with the use of small-gauge pencil-point needles.
The risk of obstetric palsy including obturator nerve, femoral nerve and common peroneal nerve injury is 1:3000. The risk of neurological damage with neuraxial blockade is 1:13 000.
A spinal or epidural haematoma or abscess may lead to permanent paralysis as can needle insertion and injection into to the spinal cord. The risk of permanent paralysis with the use of a neuraxial blockade is quoted at 1:1 000 000.
The spinal cord terminates at the level of L1-2 in most adults but may end at L2-3 in some patients. Tuffier’s line is an unreliable as a way of identifying the correct vertebral level, particularly in the obese. One may have miss-judged the level by 2 segments and given that the spinal cord may be at L2-3, one should avoid inserting a needle above L3.
Post operative analgesia
A simple regimen for post-operative analgesia after caesarean section is usually best. There are several options for analgesia. Epidural or spinal morphine is common in some people’s practice and provides good analgesia for up to 24 hours. However, there is an increased risk of itch, nausea and vomiting and most importantly, delayed respiratory depression. Patient controlled intravenous morphine is another option for post-operative analgesia but is cumbersome.
In Melbourne, it is common practice to use a combination of regular paracetamol, rectal or oral diclofenac and rectal or oral oxycodone. Oxycodone is as effective as a neuraxial opioid and far safer. It is simple and inexpensive, with less need for nursing intervention. One does need to bear in mind that other opioids should not be administered within 6 hours of a dose of oxycodone due to the risk of respiratory depression.
In the pre-eclamptic patient, an ongoing epidural infusion will not only provide post- operative analgesia, but will help with blood pressure control. One should check that the coagulation is normal before the epidural catheter is removed.
General anaesthesia
The most common indications for general anaesthesia include: a contraindication to regional anaesthesia, the failure of regional anaesthesia and when there is a need for urgent delivery within 10 minutes such as might occur with severe foetal distress, cord prolapse, and placental abruption.
The advantages of general over regional anaesthesia include a more rapid induction, less hypotension, less maternal anxiety and its application in situations where there is a contraindication to regional anaesthesia.
Potential problems
1. Aspiration pneumonitis
2. Failed intubation (your first responsibility is to the mother)
3. Stress response to intubation
4. Rapid desaturation (pre-oxygenate the patient before induction)
5. Supine hypotension
6. Neonatal depression (Lower APGAR scores at one minute are related to sedation. Regardless of the anaesthetic technique, uterine incision-to-delivery time of greater than 3 minutes produces more asphyxia.)
7. The incidence of maternal awareness is reduced with the use of an increased dose of induction agent and the increased use of volatile agents.
8. Uterine relaxation and maternal bleeding.
Conduct of General Anaesthesia
Reduce the risk of acid aspiration by fasting the patient for at least 6 hours from solids and 3 hours from clear fluids, give antacid prophylaxis as already described and perform a rapid sequence induction with a good assistant to provide cricoid pressure after the loss of consciousness.
Supine hypotension is common at term due to aortocaval compression. This is reduced by left lateral tilt of 15 degrees.
Due to the increased incidence of blood loss under general anaesthesia, it is important to secure large-bore intravenous access. In order to reduce the induction to delivery time, insert a urinary catheter and ask the surgeon to prepare and drape the abdomen before induction of the anaesthetic. Allow the surgeon to start operating as soon at the endotracheal tube is inserted and its position confirmed.
Hypocapnia induces uterine vasoconstriction, therefore avoid hyperventilation of the patient. The patient should be extubated when her airway reflexes return to avoid aspiration of stomach contents on emergence.
Failed intubation is the leading cause of anaesthetic maternal mortality. The incidence is greater than in the general surgical population (up to one in 200). Ensure you have assessed the airway and called for assistance if it looks difficult. Pre-oxygenate the patient in order to allow yourself more time for intubation. Always have a back up plan for failed intubation and know a technique for cricothyroid puncture.
Emergency caesarean section
The rate of emergency CS varies depending on the definition of an emergency but has been reported to be 61%.
The time required for surgical readiness in emergency caesarean section is slightly longer (17min) with a spinal compared with a general anaesthetic. This time is reduced in more experienced hands. In any case, the time difference for surgical readiness for emergency caesarean section does not justify a general where a spinal can be performed.[i] That depends on your definition of an emergency….
The indications for an emergency caesarean section can be grouped into maternal and foetal indications. Maternal indications include a deteriorating medical condition, haemorrhage and trauma. The most common foetal indication is acute severe foetal distress. The other foetal indications are a prolapsed presenting part and foetal injury.
How urgent is urgent?
Anoxia and brain injury in the rhesus monkey
In an early study, hypoxia was deliberately induced in the foetus of the rhesus monkey by clamping the umbilical cord for different periods of time and the severity of foetal brain injury was determined. Less than 10 minutes of anoxia produced no brain injury. With 10-20 minutes of anoxia the foetus survived but had neuronal injury especially in the basal ganglia, thalamus and brain stem. Over 20 minutes of anoxia caused death.
Post mortem caesarean section and neonatal sequelae
Delivery interval Neurological sequelae
< 5 minutes 0%
5-10 minutes 13%
10-15 minutes 17%
>15 minutes 82%
Grading of urgency of caesarean section
I Immediate threat to life of mother or baby 1-10 minutes GA
II Maternal or foetal compromise which is
not life threatening 10-30 minutes Spinal
III Needing early delivery but no maternal or
foetal compromise. 30-60 minutes Regional
IV At a time to suit the patient and staff 1-24 hours Regional
In the UK, the Association of Anaesthetists of Great Britain and Ireland, the Royal College of Obstetrics and Gynaecology and the Royal College of Midwives, recommend that when a decision is made to deliver a baby by caesarean section because of foetal distress, the baby should be delivered within thirty minutes. In a series of audits done in a large obstetric unit in the UK, it was found that delivery within thirty minutes is achievable in only two of three cases but that the delay in delivery made no difference to the rate of admission to special care for babies over 36
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