Effects of commercial (pH approximately 3.5) and freshly prepared (pH approximately 6.5) lidocaine-adrenaline solutions on tissue pH.
Differences in the effects of commercially available, sodium bisulfite-containing (pH 3.5-4), and freshly prepared (pH 6.5) lidocaine-adrenaline solutions on tissue pH and tissue oxygenation were studied experimentally. In rabbits, a 5 x 5 cm area under the panniculum was infiltrated with 0.9% NaCl, plain lidocaine, plain adrenaline or one of the two lidocaine-adrenaline solutions. Tissue pH was measured continuously as well as intermittently in the infiltrated area with monocrystalline antimony needle electrodes. Infiltration of the tissue with the 4 ml volume of a test solution did not seem to induce any significant tissue injury. Tissue pH was decreased for 30 min following plain lidocaine and for 90 min or more following lidocaine-adrenaline infiltration. With the exception of the first few minutes, no significant differences in the effects on tissue pH between commercial and freshly prepared lidocaine-adrenaline solutions could be seen. Tissue hypoxia occurred only following infiltration with plain adrenaline. It may thus be concluded that in spite of the low pH and the O2-reducing properties of commercial lidocaine-adrenaline solutions, a rapid buffering occurs in the tissues. The use of commercial lidocaine-adrenaline solution for local infiltration thus seems as safe as that of freshly prepared lidocaine-adrenaline solutions.
D000818:Animals; D002021:Buffers; D004837:Epinephrine / Q000008:administration & dosage / Q000009:adverse effects*; D006863:Hydrogen-Ion Concentration; D008012:Lidocaine / Q000008:administration & dosage / Q000009:adverse effects*; D011817:Rabbits; D012996:Solutions
D002021:Buffers; D012996:Solutions; D008012:Lidocaine; D004837:Epinephrine