◊ BACKGROUND:
In this prospective, randomized, double-blind study we tested the hypothesis that 50 mg of 1% preservative-free 2-chloroprocaine would provide a faster resolution of spinal block than the same dose of 1% plain lidocaine.

◊ METHODS:
After IV midazolam premedication (0.03 mg/kg), 30 ASA physical status I-II outpatients undergoing knee arthroscopy were randomly allocated to receive 50 mg of either 1% plain lidocaine (n = 15) or 1% preservative-free plain chloroprocaine (n = 15). A blinded observer recorded the evolution of sensory (loss of pinprick sensation) and motor (modified Bromage scale) block until complete regression, as well as times to unassisted ambulation and voiding. A telephone call follow-up was performed 24 h and 7 days after surgery.

◊ RESULTS:
Two chloroprocaine patients (13%) and one lidocaine patient (7%) required fentanyl supplementation (100 microg IV) (P = 0.99) intraoperatively, but no patient required general anesthesia to complete surgery. Median (range) times for recovery of sensory and motor function, and unassisted ambulation were faster with 2-chloroprocaine [95 (68-170) min; 60 (45-120) min; and 103 (70-191) min] than lidocaine [120 (80-175) min; 100 (60-140) min; and 152 (100-185) min] (P = 0.019, P = 0.0005, and P = 0.003, respectively). No differences in first voiding were reported between chloroprocaine [180 (100-354) min] and lidocaine patients [190 (148-340) min] (P = 0.191). Transient neurological symptoms were reported in five lidocaine patients (33%) but no chloroprocaine patients (0%) (P = 0.042).

◊ CONCLUSION:
Intrathecal injection of 50 mg of preservative-free 2-chloroprocaine 1% resulted in quicker recovery of sensory/motor function, and unassisted ambulation, and fewer incidences of transient neurologic symptoms than the same dose of 1% lidocaine.

◊ Reviewed by M. F. Mulroy, MD
Faculty Anesthesiologist,Virginia Mason Medical Center, Virginia Mason Hospital, Seattle, USA

The authors have performed a well-designed and executed randomized, prospective, blinded comparison of 50 mg of 2-chloroprocaine to 50 mg of lidocaine in outpatients with spinal anesthesia for knee arthroscopy. Their findings confirm the previous reports associated with this drug. Specifically Kopacz and colleagues in several studies have shown rapid resolution of spinal anesthesia with 2-chloroprocaine and a faster time for discharge readiness when compared to lidocaine and other local anesthetics. This work also confirms the rapid discharge times that were previously reported by the authors’ own group in performing a dose-ranging study [1]. These characteristics have subsequently been confirmed by a further study by Sell and colleagues [2].

Their significantly faster discharge occurred only if voiding was not considered necessary. As the authors comment, this remains a controversial issue, although their data confirm the absence of difficulty in voiding after short-acting spinal anesthesia. As they point out, Mulroy et al have shown that urinary retention has not been a limiting factor after short-duration spinal or epidural anesthesia for low risk surgical procedures [3]. Further studies will be needed to substantiate the legitimacy of eliminating voiding as a criterion for discharge following short-acting spinal anesthesia. Still, the average time for discharge tended to be shorter in the 2-chloroprocaine group if voiding was included, though not statistically significant.

It is noteworthy that none of the previous volunteer studies, nor the two small clinical series (reported here and by Yoos and Kopacz) report any transient neurologic symptoms (TNS) with 2-chloroprocaine spinal anesthesia, nor any neurological problems. This low incidence of side effects has also been confirmed in a larger (less rigorously studied) series cited in abstract form by the authors. TNS, while not associated with permanent injury, has nevertheless become a source of morbidity for many outpatients and has led to an avoidance of lidocaine spinal anesthesia in this setting. This is unfortunate because of the advantages of outpatient spinal anesthesia. Many of the alternatives proposed, as described by the authors, are associated with longer discharge times or wider variability in efficacy. Taken as a whole, this study and the others suggest the potentially positive role for 2-chloroprocaine as a replacement for lidocaine based on the incidence of TNS. Further studies are clearly needed to confirm the absence of neurotoxicity and of TNS in larger series of patients.

This is an important consideration in the current study. Even if the authors had been unable to confirm faster discharge time with 2-chloroprocaine compared to lidocaine, the absence of TNS in the 2-chloroprocaine group would still suggest that it is a desirable alternative to lidocaine for outpatient spinal anesthesia. This current study adds one more strong piece of evidence to suggest an effective role for 2-chloroprocaine. Overall, this study should help to move this drug to the forefront of anesthetic choices in that setting.

[1] Casati A, Danelli G, Berti M, Fioro A, Fanelli A, Benassi C, Petronella G, Fanelli G.
Intrathecal 2-chloroprocaine for lower limb outpatient surgery: a prospective, randomized, double-blind, clinical evaluation. Anesth Analg. 2006 Jul;103(1):234-8

[2] Sell A, Tein T, Pitkänen M.
Spinal 2-chloroprocaine: effective dose for ambulatory surgery. Acta Anaesthesiol Scand. 2008 May;52(5):695-9.

[3] Mulroy MF, Salinas FV, Larkin KL, Polissar NL.
Ambulatory surgery patients may be discharged before voiding after short-acting spinal and epidural anesthesia. Anesthesiology. 2002 Aug;97(2):315-9