3-11. High central neuraxial block

START

❶ Reassure the patient – remember that they may be fully aware.

• Plan to ensure hypnosis as soon as clinical situation permits.

❷ Call for help and inform theatre team of the problem.

❸ Treat airway and breathing:

• Give 100% oxygen.
• Chin lift / jaw thrust may suffice.
• Consider supraglottic airway or tracheal intubation (Box A).

❹ Treat circulatory insufficiency:

• Give i.v. fluid by rapid infusion.
• Elevate the legs. Do not use head-down tilt.
• In obstetrics, relieve aorto-caval compression.
• Bradycardia: give atropine or glycopyrrolate (Box B).
• Hypotension: give metaraminol, phenylephrine or ephedrine (Box B).
• CPR may be necessary to circulate drugs.

❺ If the case is obstetric, consider expedited delivery of the baby to manage:

• Risk to mother of unrelieved aorto-caval compression
• Risk to fetus of impaired feto-placental oxygen delivery

❻ Consider other causes that may mimic signs and symptoms, including (Box C):

• Obstetric aorto-caval compression.
• Local anaesthetic toxicity.
• Vasovagal event.

❼ Plan ongoing care in a suitable location.

Box A:  INDUCING ANAESTHESIA

• Consider reduced dose of hypnotic drug to avoid further hypotension. A full induction dose will not be necessary if the patient’s consciousness is already impaired.
• Neuromuscular blockade may not be necessary for tracheal intubation if the patient is unconscious, paralysed and apnoeic.

Box B:  DRUG DOSES

Bradycardia:

• Atropine: 0.6-1.2 mg
• Glycopyrrolate: 0.2-0.4 mg

Hypotension:

• Metaraminol: 1-2 mg boluses repeated
• Phenylephrine: 50-100 μg boluses repeated or by infusion
• Ephedrine: 6-12 mg boluses repeated  up to max 30 mg (tachyphylaxis limits further usefulness)

Box C:  CRITICAL CHANGES

• Cardiac arrest → 2-1
• Hypotension → 2-4
• Bradycardia → 2-6
• Local anaesthetic toxicity → 3-10