Effect of pH-Adjustment of Bupivacaine on Onset and Duration of Epidural Analgesia in Parturients

pH adjustment of mepivacaine decreases the incidence of tourniquet pain during axillary brachial plexus anaesthesia

“…Several studies have shown a decrease in latency to onset of blockade, tr, ls Candido et al 17 demonstrated improved duration of anaesthesia, which could be postulated to be related to improved diffusion into larger nerve fibres. This was confirmed by McMorland et al 26,27 using bupivacaine, who noted prolonged duration of epidural analgesia and anaesthesia with bupivacaine. The influence of alkalinization of local anaesthesia is thought to occur secondary to the considerable increase of the non-ionized form in the solution prior to injection.…”

The air-liquid interface and the pH and PCO2 of alkalinized local anaesthetic solutions

“…Bupivacaine 0.5%, lidocaine 2%, and chloroprocaine 2% were chosen because these were the local anaesthetics and concentrations previously reported to exhibit a hastened onset following alkalinization with NaHCO 3 in parturients. [1][2][3] Five boules of each local anaesthetic were studied and each specific local anaesthetic had the same lot number. Each local anaesthetic solution was alkalinized with NaHCO 3 (8.4%) in a preliminary study at our institution to increase the pH to the maximum value that could be obtained without causing precipitation.…”

Comparative Study of Alkalined Lignocaine, Addition of Potassium Chloride to Lignocaine and Plain Lignocaine on Onset and Duration of Brachial Plexus Block By Supraclavicular Approach

“…Capoga G has shown that concerning brachial plexua block, effects of alkalization were more evident with lidocaine . (15) …”

“…Another possible advantage when alkaliseed solutions are used is the increased analgesic potency of blockwithout increased plasma concentration of local anaesthetic . (15) Mode of action An increase in pH leading to an increase in the unchanged lipid soluble base form. This readily penetrates the nerve and in a relatively acidic intraneural environment is converted to the active form.…”