title: A nomogram for calculating the maximum dose of local anaesthetic.
abstract: Toxic dose limits (mg.kg(-1)) for local anaesthetics based on body weight are well-established, but calculation of the maximum safe volume (ml) of a given agent and formulation is complex, and frequently results in errors. We therefore developed a nomogram to perform this calculation. We compared the performance of the nomogram with a spreadsheet and a general purpose calculator using simulated clinical data. Bland-Altman analysis showed close agreement between the nomogram and spreadsheet, with bias of -0.07 ml and limits of agreement of -0.38 to +0.24 ml (correlation coefficient r(2) = 0.9980; p < 0.001). The nomogram produced fewer and smaller errors compared with the calculator. Our nomogram calculates the maximum safe volume (ml) of local anaesthetic to a clinically acceptable degree of accuracy. It facilitates rapid cross-checking of dosage calculations performed by electronic or other means at negligible cost, and can potentially reduce the incidence of local anaesthetic toxicity.
authors.affiliation: Department of Anaesthetics, Abertawe Bro Morgannwg University NHS Trust, Morriston Hospital, Swansea, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Williams
authors.forename: J D
authors.initials: JD
authors.lastname: Walker
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage*; D006801:Humans; D008508:Medication Errors / Q000517:prevention & control; D049451:Nomograms
chemical_list: D000779:Anesthetics, Local