Sodium Bicarbonate to Augment Lidocaine’s Intravesical Activity: A Randomized, Crossover Study
Michael E. Goltzman, MD1, Brendan Gontarz, MD1, Suzanne Roman, LPN2, Gerard Pregenzer, MD2.
1UConn Health, Farmington, CT, 2Saint Francis Hospital, Trinity Health of New England, Hartford, CT.
BACKGROUND: There are multiple indications for intravesical botulinum toxin-A (BTX-A) injections. Local anesthetic has been used to improve discomfort experienced during intradetrusor injections. Alkalization of local anesthetic has improved its efficacy in other areas of the human body. We sought to study its effects in the naturally acidic environment of the bladder. The purpose of the study was to determine if there is a difference in pain perception during intradetrusor BTX-A injection when utilizing alkalinized lidocaine versus lidocaine alone. METHODS: This study was an IRB-approved, prospective, randomized controlled trial with a crossover design conducted by a single urologist in the office setting. Patients with indications for intravesical BTX-A injections and possessing the cognitive ability to report subjective pain scores were eligible. On the first procedure, patients were randomized to either the control or intervention group. Controls received 50mL of 2% lidocaine alone, whereas the intervention group received a mix of 50mL of 2% lidocaine with 5mL of 8.4% sodium bicarbonate. On the second visit, 4-6 months later, participants would be switched to their opposite group to act as their own controls. On the third visit all patients received the intervention (Figure 1). Subjective pain, regarded as the primary outcome, was measured prior to the procedure, at time of first injection and throughout the procedure. Pain levels were assessed by identical pain questionnaires, including a qualitative measure of pain as per a visual analog pain scale (VAS). Demographic information was collected prior to intervention including age, sex, race, and prior analgesic use. RESULTS: Twenty-six of the 33 patients (13 men, 20 women; mean age: 59.5 years) received 2 procedures and 16 received a 3rd procedure . Of the 68 procedures, 26 were in the control arm and 42 intervention. Subjective pain score at first injection was significantly lower in the intervention arm (2.31 vs 3.81; p=0.028). Pain throughout the procedure was lower in the intervention arm although not significant (2.08 vs 2.75; p=0.258). There were no adverse events noted during the study. CONCLUSIONS: In our cohort, those who received the sodium bicarbonate experienced less pain at first injection compared to those subject to lidocaine alone. Although subjective pain scores vary between patients, acting as their own controls limits this bias. With no adverse events and no significant alterations to the office-based procedure, we found sodium bicarbonate is an effective and cost-conscious augmentation to lidocaine instillation for intradetrusor BTX-A therapy. Buffering of lidocaine has a greater likelihood of achieving successful anesthesia which may promote further treatment adherence. 
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