A nomogram to calculate the maximum dose of local anaesthetic in a paediatric dental setting.

While local anaesthetic agents are usually safe and are used ubiquitously, inadvertent overdoses may have potentially fatal consequences. Errors in the dosing of local anaesthetics frequently occur due to inherent difficulties in remembering the toxic dosage limits, difficulties in performing the appropriate calculations correctly, and errors in estimating patient weight. We have developed a simple graphical calculation aid (nomogram) to overcome these problems and facilitate rapid cross-checking of the maximum safe dose for a variety of local anaesthetic agents in common use. Standard mathematical techniques were used to draft the nomogram. A randomised blinded study using simulated patient data and Bland-Altman analysis was used to assess the accuracy and precision of the nomogram. The nomogram was found to have a bias of 0.0 ml, with limits of agreement -0.05-0.04 ml. It was found to be easy to use and suitably accurate for clinical use.