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A nomogram to calculate the maximum dose of local anaesthetic in a paediatric dental setting
I N B R I E F
Discusses the correct doses of commonly
used local anaesthetics.
Provides greater ease in calculating safe
doses of local anaesthetics in children.
Describes techniques that will make it
easy to double check calculations.
PRACTICE
J. D. Walker,*1 A. Summers2 and D. J. Williams3
VERIFIABLE CPD PAPER
BACKGROUND
Local anaesthetics are the most commonly used drugs in dental practice, with approximately 300million cartridges used annually in the United States alone.1 Surveys estimate that most practising dentists will use between 1,6001,800cartridges per year, on average.1,2 Problems related to overdose are rare, but can be fatal.3 It is thus surprising that in clinical practice many dentists do not calculate exact safe doses, but rely instead on estimates.4 This may well be because of the complexity of the calculation: maximum doses must be remembered, and are quoted in mg per kilogram body weight; while for historical reasons, agent concentrations are often given in units of percentage weight-in-volume (%w/v).
Recently, Williams and Walker5 developed a nomogram for calculating dose volumes of local anaesthetics used in a hospital setting. For of a number of reasons this is not suitable for use in dentistry: commonly used dental anaesthetic agents such as articaine are not included; the maximum doses used are appropriate for a hospital 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 difculties in remembering the toxic dosage limits, difculties 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 0.0ml, with limits of agreement -0.050.04ml. It was found to be easy to use and suitably accurate for clinical use.
BODY WEIGHT
The British...