The accuracy of timed maximum local anaesthetic dose calculations with an electronic calculator, nomogram, and pen and paper

Abstract

Forty anaesthetists calculated maximum permissible doses of eight local anaesthetic formulations for simulated patients three times with three methods: an electronic calculator; nomogram; and pen and paper. Correct dose calculations with the nomogram (85/120) were more frequent than with the calculator (71/120) or pen and paper (57/120), Bayes Factor 4 and 287, p = 0.01 and p = 0.0003, respectively. The rates of calculations at least 120% the recommended dose with each method were different, Bayes Factor 7.9, p = 0.0007: 14/120 with the calculator; 5/120 with the nomogram; 13/120 with pen and paper. The median (IQR [range]) speed of calculation with pen and paper, 38.0 (25.0–56.3 [5–142]) s, was slower than with the calculator, 24.5 (17.8–37.5 [6–204]) s, p = 0.0001, or nomogram, 23.0 (18.0–29.0 [4–100]) s, p = 1 × 10−7. Local anaesthetic dose calculations with the nomogram were more accurate than with an electronic calculator or pen and paper and were faster than with pen and paper.