title: pH-adjustment of 2-chloroprocaine quickens the onset of epidural anaesthesia.
abstract: The effect of pH-adjustment of three per cent 2-chloroprocaine (2-CP, Nesacaine MPF) on the onset, duration, and spread of epidural analgesia and anaesthesia was studied in patients undergoing lower extremity surgery. Forty ASA physical status I and II patients were randomized to two groups. In a double-blinded fashion, patients in both groups received an epidural injection of 15 ml of local anaesthetic (LA) solution via a Tuohy needle at the L3-4 interspace. Local anaesthesia for Group I was prepared by adding 3 mEq NaHCO3 to 27 ml three per cent 2-CP and for Group II was prepared by adding 3 ml 0.9 per cent NaCl to 27 ml three per cent 2-CP. Both solutions contained epinephrine (1:200,000). The pH of commercially prepared Nesacaine MPF was 3.19 +/- 0.02. The pH of the solutions used for Group I and Group II patients were 7.32 +/- 0.01 and 3.27 +/- 0.02, respectively. Times to analgesia and anaesthesia at the L2 dermatome were significantly decreased in Group I patients by 2.5 and 6.6 minutes, respectively. Likewise, pH-adjustment accelerated the attainment of maximum level of block by 2.8 min. No statistical differences were found between groups in the maximum level of epidural block, or in time to 2-segment regression. No precipitation of LA was observed in pH-adjusted solutions of 2-CP after 24 hours. We recommend the use of pH-adjusted three per cent 2-CP (Nesacaine MPF) to accelerate the onset of epidural block.
authors.affiliation: Department of Anesthesiology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814.
authors.forename: R A
authors.initials: RA
authors.lastname: Stevens
authors.forename: W L
authors.initials: WL
authors.lastname: Chester
authors.forename: A
authors.initials: A
authors.lastname: Schubert
authors.forename: D
authors.initials: D
authors.lastname: Brandon
authors.forename: J A
authors.initials: JA
authors.lastname: Grueter
authors.forename: J
authors.initials: J
authors.lastname: Zumrick
mesh_terms: D000328:Adult; D000767:Anesthesia, Epidural; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001639:Bicarbonates; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007866:Leg / Q000601:surgery; D011343:Procaine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D011897:Random Allocation; D012964:Sodium; D017693:Sodium Bicarbonate; D012965:Sodium Chloride; D013997:Time Factors
chemical_list: D000779:Anesthetics, Local; D001639:Bicarbonates; D012965:Sodium Chloride; D011343:Procaine; C004616:chloroprocaine; D017693:Sodium Bicarbonate; D012964:Sodium