Absolute overdose if the dose used is excessive. Reducing the risk of toxicity Decide on the concentration of the local anaesthetic that is required for the block to be performed. Calculate the total volume of drug that is allowed according to the table below. Use the least toxic drug available. Use lower doses in frail patients or at the extremes of ages.
Most nerve blocks are more dependent on volume of drug injected than the total dose .
The addition of adrenaline will make no difference to the toxicity of the local anaesthetic if it is injected intravenously. Make sure that the patient is monitored closely by the anaesthetist or a trained nurse during the administration of the local anaesthetic and the following surgery. The systemic toxic effects due to local anaesthetic overdose primarily involve the central nervous and cardiovascular systems. Therefore CNS manifestations tend to occur earlier. Brain excitatory effects occur before the depressant effects.