title: The effect of pH buffering on reducing the pain associated with subcutaneous infiltration of bupivicaine.
abstract: The authors propose that pH buffering of bupivicaine with sodium bicarbonate reduces the pain associated with its local subcutaneous infiltration. In a double-blind, prospective study, 62 healthy adult volunteers received a 0.5 mL subcutaneous infiltration of 0.5% buffered bupivicaine into the dorsum of a randomly chosen hand. The pH was adjusted to 7.0 by adding 0.05 mL of sodium bicarbonate (1 mEq/L [corrected]) to 10 mL vials of commercially available bupivicaine (1:200 dilution). The control hand was injected with the same amount of unbuffered agent. Pain was scored after each infiltration using a nonsegmented visual analogue scale. Student's t-test for paired measurements was used to analyze intergroup pain score differences. Forty-three subjects (69%) reported less pain with buffered bupivicaine and only 17 (27%) noted a modest increase: two subjects (3%) reported no difference. The mean pain score for the buffered agent was 22 mm compared with 30 mm for the control. The mean difference (control-experimental) was 8 mm (t = 4.64, df = 61, P less than .001). The authors conclude that the addition of sodium bicarbonate to bupivicaine reduces the pain associated with its local infiltration.
authors.affiliation: Division of Emergency Medicine, University of New Mexico School of Medicine, Albuquerque 87131.
authors.forename: P R
authors.initials: PR
authors.lastname: Cheney
authors.forename: G
authors.initials: G
authors.lastname: Molzen
authors.forename: D
authors.initials: D
authors.lastname: Tandberg
mesh_terms: D000328:Adult; D001639:Bicarbonates / Q000008:administration & dosage / Q000627:therapeutic use*; D002021:Buffers; D002045:Bupivacaine / Q000008:administration & dosage / Q000009:adverse effects* / Q000600:supply & distribution; D004311:Double-Blind Method; D004338:Drug Combinations; D004355:Drug Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007279:Injections, Subcutaneous; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy* / Q000453:epidemiology; D010147:Pain Measurement; D011446:Prospective Studies; D012964:Sodium / Q000008:administration & dosage / Q000627:therapeutic use*; D017693:Sodium Bicarbonate
chemical_list: D001639:Bicarbonates; D002021:Buffers; D004338:Drug Combinations; D017693:Sodium Bicarbonate; D012964:Sodium; D002045:Bupivacaine