Management of total spinal block in obstetrics
A high neuraxial block is a sensorimotor block that has reached a spinal segmental level higher than that required to achieve surgical anaesthesia. The terms high, total or complete block are used interchangeably. A sensory level of T3 or above can be associated with significant cardiovascular and respiratory compromise and can hence be considered a high block. Involvement of the cranial nerves signifies intracranial spread of local anaesthetic which can culminate in complete loss of consciousness and cardiorespiratory arrest.
A dose of 10mg hyperbaric bupivacaine plus 10 microgram fentanyl is usually appropriate for caesarean section. If no fentanyl is available, administer hyperbaric bupivacaine 10mg alone.
Prevention.
Unrecognised subdural or intrathecal placement of an epidural catheter and an intended spinal technique after a failed epidural analgesia are two main identified causes of high spinal block. The anaesthetist performing these procedures must be aware of this serious complication and must remain vigilant throughout with continual assessment of progression of the block in a well monitored environment. Any abnormally functioning epidural must be followed up closely. Development of a dense motor block of lower limbs during epidural analgesia using a low dose epidural infusion is abnormal and a high-level suspicion of intrathecal placement must be maintained. This suspicion must be shared with the entire team looking after the patient and emphasised during handover care. Physical barriers in the form of prominent labels must be placed over the epidural catheter to prevent an accidental top up with large volume of LA.
Procedure
After a sub-arachnoid injection or epidural top up, close monitoring of heart rate, blood pressure, oxygen saturations, respiratory rate and level of neuraxial block is necessary. Monitoring should follow clear written protocols.12 The frequency of observations should be determined by normal clinical considerations.12 In hospitals in UK, clinical guidelines suggest that after each epidural bolus or top up for labour analgesia, blood pressure should be recorded for 5 min for the first 20 minutes and thereafter every 30 minutes. Sensory levels can be tested with ice cubes, ice packs, ethyl chloride sprays, alcohol wipes or with pin-prick
During a spinal block, focus on:
• Dose of local anaesthetic required,
• Baricity of drug,
• Position of patient after spinal
During epidural test dose/top up:
• Always aspirate with a 2ml syringe for blood/CSF before any top up.
• For labour analgesia, test dose with a weaker solution, i.e., 10ml of 0.1% Levobupivacaine is enough to rule out sub arachnoid block. But go as per hospital protocol.
• Always check the level of neuraxial block before any epidural top up.
• If possible, top up epidural for procedural anaesthesia in theatre only for ease of managing emergencies.
• Always give local anaesthetic solution in increments.
Post procedure
Written documentation of any difficulty in neuraxial block is of utmost importance. Staffing levels sufficient to provide the necessary standard of care are essential in areas providing care for patients with neuraxial blocks, but the individuals need to be trained to the requisite standard as well, and they must know when (and how) to obtain anaesthetic advice.
MANAGEMENT OF HIGH SPINAL BLOCK:(click to continue)
