RESUMEN
BACKGROUND: The use of regional anesthesia for elective Cesarean section has been demonstrated to be safe for both the mother and new-born. In parturients with an epidural catheter placed previously for labor analgesia, extension of the epidural block may be the preferred option, provided that adequate speed of onset and adequate surgical anesthesia are obtained. We therefore performed a prospective, randomized, double-blind trial to examine the speed of onset and anesthetic quality of 2-chloroprocaine vs. a solution of lidocaine with one additive, epinephrine 5 microg/ml. METHODS: Forty ASA I patients, scheduled for elective Cesarean section, were randomly assigned to two groups: the 2-chloroprocaine group received 2-chloroprocaine 30 mg/ml and the lidocaine group received the same amount (ml) of lidocaine 20 mg/ml with 5 microg/ml epinephrine. The speed of onset was defined as the time taken to loss of cold sensation from 70% ethanol application at thoracic dermatome level 5 (Th5). RESULTS: The time to achieve loss of cold sensation at Th5 was similar in both groups: median of 8 min (range, 4-13 min) in the 2-chloroprocaine group vs. 5 min (range, 2-22 min) in the lidocaine group (NS). Epidural anesthesia was successful for surgery in all but one patient (lidocaine group). There was no significant difference in the need for supplemental intravenous alfentanil between the two groups: 30% vs. 20% of patients in the 2-chloroprocaine and lidocaine groups, respectively; the pain scores (visual analog scale) were also similar. Intra-operative complications occurred with similar frequency, and none was serious. In the patients in the 2-chloroprocaine group, 11 (55%) had episodes of systolic blood pressure less than 90 mmHg vs. 15 (75%) in the lidocaine group (NS). CONCLUSION: Both 2-chloroprocaine and lidocaine have a rapid onset of effect and are suitable local anesthetic agents for Cesarean section. In view of the time taken for preparation and the potential for logistic problems when an additive is used, a pre-prepared solution, such as 2-chloroprocaine, may be preferred.