Abstract ID: A4
Abstract Title: Double-blind Randomized Study of 2-chloroprocaine Versus Low Dose Bupivacaine for Spinal Anesthesia in Healthy Volunteers
Poster Type: Either
ABSTRACT BODY
Introduction:
As ambulatory surgical procedures continue to increase, interest in a short-acting spinal anesthetic with minimal side effects increases. Historically, lidocaine has been the primary agent used due to its predictable regression time and adequacy of surgical anesthesia, but lidocaine is associated with undesirable side effects, namely transient neurologic symptoms (TNS) (1). Because of this, many clinicians have switched to low-dose bupivacaine, but its unpredictable regression time and often inadequate surgical anesthesia are problematic (2).
When preservative-free 2-chloroprocaine (2-CP) was first introduced in 1952 it appeared to have a desirable profile for short acting local anesthetics. As preservatives were then added, it became unsuitable for spinal anesthesia and was primarily used for epidural anesthesia in obstetrics (3). As preservative and antioxidant-free formulations are again available, 2-CP has re-entered the ambulatory surgical setting as an alternative for spinal anesthesia.
Recent volunteer studies and a clinical chart review illustrate that preservative-free 2-CP is safe and provides excellent surgical anesthesia with predictable regression. Like bupivacaine, it is rarely associated with TNS. This double-blind randomized volunteer study was designed to directly compare 40mg of preservative-free 2-CP with low dose (7.5mg) bupivacaine in a simulated ambulatory surgical setting.
Materials and Methods:
After IRB approval and informed consent, 8 volunteers received 2 spinal anesthetics, one each with 40mg preservative-free 2-CP and 7.5mg preservative-free bupivacaine. Using previously described methodology, motor strength, tolerance to thigh tourniquet, pinprick level of anesthesia and tolerance to transcutaneous electrical stimulation were assessed. To assess simulated discharge criteria, volunteers were evaluated for time to ambulation and voiding. Volunteers were followed for 48 hours for side effects associated with each spinal anesthetic.
Results:
All subjects had uncomplicated spinal anesthesia with both 2-CP and bupivacaine. No subjects reported TNS or other side effects with either spinal. The peak dermatomal block for 2-CP averaged T7 (range T3-T10) and for bupivacaine averaged T9 (T4-L1), p=0.15. Regression to the L1 dermatome for 2-CP was 64±10 min (55-80) and for bupivacaine 87±41 min (5-140), p=0.124. Tourniquet tolerance for 2-CP and bupivacaine was 52±11 min (29-65) and 60±27 (24-106) respectively, p=0.40. Full motor movement of the lower extremity was regained at 69±16 min (40-90) for 2-CP and 89±50 min (0-140) for bupivacaine, p=0.20. Complete regression of block (with ambulation and voiding) for 2-CP was at 113±14 min (90-130) and for bupivacaine at 191±30 (160-240), p=0.0009 (Fig 1).
Discussion:
40mg of spinal 2-CP has significantly faster block resolution and return to ambulation when compared to 7.5mg of bupivacaine, while producing similar quality of surgical anesthesia. Therefore, while neither agent is associated with TNS, 2-CP may have better characteristics of an ideal spinal anesthetic for ambulatory surgical procedures of short duration.
References:
1) Reg Anesth Pain Med 27:581-6.
2) Anesth 85:729-36.
3) Anesth Analg 59:452-4.
ATTACHED FILES
Reg Anesth Pain Med 2004; 29(2):A4