Neutralizing (buffering) lidocaine 1%/epinephrine 1:100,000 solution (Lido/Epi) with sodium hydrogen carbonate (NaHCO3) (also called sodium bicarbonate) is widely used to reduce burning sensations during infiltration of Lido/Epi. Optimal mixing ratios have not been systematically investigated.
To determine whether a Lido/Epi:NaHCO3 mixing ratio of 3:1 (investigational medicinal product 1) causes less pain during infiltration than a mixing ratio of 9:1 (IMP2) or unbuffered Lido/Epi (IMP3).
Double-blind, randomized, placebo-controlled, crossover trial (n = 2 × 24) with 4 investigational medicinal products (IMP1-4).
The 3:1 mixing ratio was significantly less painful than the 9:1 ratio (P = .044). Unbuffered Lido/Epi was more painful than the buffered Lido/Epi (P = .001 vs IMP1; P = .033 vs IMP2). IMP4 (NaCl 0.9% [placebo]) was more painful than any of the anesthetic solutions (P = .001 vs IMP1; P = .001 vs IMP2; P = .016 vs IMP3). In all cases, the anesthesia was effective for at least 3 hours.
Results of this trial cannot be generalized to other local anesthetics such as prilocaine, bupivacaine, or ropivacaine, which precipitate with NaHCO3 admixtures.
Lido/Epi-NaHCO3 mixtures effectively reduce burning pain during infiltration. The 3:1 mixing ratio is significantly less painful than the 9:1 ratio. Reported findings are of high practical relevance, given the extensive use of local anesthesia today.Le texte complet de cet article est disponible en PDF.
Key words : 3:1, admixture, bicarbonate, burning sensation, controlled, double-blind, epinephrine, lidocaine, local anesthesia, placebo, randomized, ratio, sodium hydrogen carbonate, trial, unbuffered
Abbreviations used : IMP, Lido/Epi, NaCl, NaHCO3, NRS
| Funding sources: Supported by the JH Rahn Foundation and Bruno Bloch Foundation.
| Conflicts of interest: None disclosed.
| IRB approval status: This study has been approved by the local ethical committee (KEK-ZH, Nr2015-0531) and by Swissmedic.