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Symptoms and Signs: Bupivacaine can cause acute toxic effects of a central nervous and cardiovascular nature if it is given in high doses, especially if it is administered intravascularly. However, the dose used in spinal anaesthesia is low (≤20 % of the dose used for epidural anaesthesia) and thus the risk of overdosage is unlikely. In cases of concomitant administration with other local anaesthetics, however, systemic toxic effects may occur, as the toxic effects are additive.
Treatment: In cases of total spinal blockade adequate ventilation must be ensured (patent airways, oxygen, intubation and controlled ventilation if necessary). If there is a fall in blood pressure a vasopressor (preferably with an inotropic effect) should be given, e.g. ephedrine 5-10 mg intravenously.
If signs of acute systemic toxicity occur the administration of local anaesthetics must be stopped immediately. Treatment must be given to maintain good ventilation, oxygenation and circulation. Oxygen must always be given, and assisted ventilation if necessary. If convulsions do not cease spontaneously within 15-20 seconds, thiopentone sodium 1-3 mg/kg should be given intravenously to facilitate ventilation or diazepam 0.1 mg/kg intravenously (acts rather more slowly). Prolonged seizures jeopardise the patient's respiration and oxygenation. Injection of muscle relaxants (e.g. suxamethonium 1 mg/kg) creates more favourable conditions for ventilation and oxygenation of the patient, but requires experience of tracheal intubation and controlled ventilation. In cases of a fall in blood pressure/bradycardia, a vasopressor should be given (e.g. ephedrine 5-10 mg intravenously, which may be repeated after 2-3 minutes).
In the event of circulatory arrest, cardiopulmonary resuscitation should be instituted immediately. It is important to maintain good oxygenation, respiration and circulation, and to treat acidosis.
Children must be given doses in proportion to their age and bodyweight for treatment of systemic toxicity.
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