Comparing the Effects of Levobupivacaine and Bupivacaine in Anorectal Surgery Under Saddle Spinal Anesthesia

This study was completed in the General Surgery operating room within the Department of Anesthesiology and Reanimation in Gazi University Faculty of Medicine after receiving permission from Gazi University, Faculty of Medicine Local Ethics Committee (dated 28.05.2007, numbered 172). After receiving informed consent forms, the study included 60 patients aged 18-50 years in ASA I-II risk group with planned elective anorectal surgery. Those with known hypersensitivity to amid-type local anesthetics, who did not accept regional anesthesia administration, with preoperative motor and sensory loss, who did not accept participation in the study and with contraindications for spinal anesthesia method were not included in the study.

Patients did not have premedication before the operation. Patients were divided into two groups with Group B given 7.5 mg (1.5 mL) hyperbaric bupivacaine (Marcaine® Spinal Heavy, 0.5%, 4 mL ampoule, AstraZeneca/England, Eczacıbaşı/Turkey, dextrose content 80 mg/mL), while Group L were administered 7.5 mg (1.5 mL) hyperbaric levobupivacaine. In order to obtain hyperbaric levobupivacaine, 1 mL 0.75% isobaric levobupivacaine (Chirocaine® 75 mg/10mL ampoule Abbott/Turkey, Nycomed Pharma/Norway) was added to 0.24 mL 50% Dextrose (dextrose 120 mg) (Eczacıbaşı/Turkey) and 0.26 mL distilled water. While mixing hyperbaric levobupivacaine, in order to obtain accurate doses of levobupivacaine, it was measured with 50% dextrose and 1 mL distilled water in an insulin injector. The hyperbaric bupivacaine and hyperbaric levobupivacaine had specific gravity values measured in Gazi University, Central Biochemistry Laboratory (solutions were heated before measurements and set with an electronic thermometer - Microlife gold-tipped thermometer MT 3001, importer Trimpeks - İstanbul, Made in P.R.C.) at 37 ºC as 1.026 (URISYS 2400, Serial No:1744-017 part No:614-0010, Roche Diagnostics Germany, Made in Japan Production year 2005). Based on specific gravity, mean density in water at 37 ºC was accepted as 0.993 g/mL (51,72) and we calculated the solution density used in our study as 1.0188 g/mL (1.026 x 0.993 g/mL = 1.0188 g/mL).

Local anesthetics to be used for spinal anesthesia were prepared by another anesthesiologist so the researcher who would administer and monitor the patient, and the patient, did not know which was used. Sixty patients had the random double-blind study method applied according to order until each group contained 30 patients. Before administering spinal anesthesia, IV cannulation was performed on the nondominant hand with an 18-gauge (G) branule and patients were administered 8-10 mL/kg Ringer lactate solution over 10-15 minutes. The fluid amounts before anesthesia and in total were recorded. Patients taken to the operating room had ECG (II derivation), SpO2, and noninvasive blood pressure (NIBP) monitoring performed (NIHON KOHDEN, Model: BSM4113K, SN:01236, 2004 - Japan). The 4 L/min O2began to be administered through a mask and basal hemodynamic parameters for patients with preoperative motor and sensory examination were recorded as control values on the monitoring form prepared for the study.

All patients had spinal anesthesia performed in the sitting position in the L4-5 or L5-S1 interspinous space. The number of spinal puncture attempts and the successful interval were recorded. If puncture was unsuccessful on the third attempt, the case was excluded from the study. All drugs were prepared for single use under sterile conditions.

After necessary skin disinfection, the interval for the intervention had local anesthesia provided by 2 mL 2% lidocaine administered with a 22 G fine needle to infiltrate the ligamentum flavum from the skin. The appropriate interval first had a 20 G 35 mm needle introducer (guide needle) inserted from the spinal needle set. Within the introducer, a 26 G atraumatic spinal needle (Atraucan®, B.Braun, Melsungen AG) was inserted parallel to the dura fibers on the midline until the dura was passed and then the chuck of the spinal needle was removed and after clear cerebrospinal fluid (CSF) was observed the needle opening was turned toward sacral. For Group B 7.5 mg hyperbaric bupivacaine (1.5 mL) and for Group L 7.5 mg (1.5 mL) hyperbaric levobupivacaine was administered into the intrathecal space over 30 seconds and the end of drug administration was accepted as 0 minutes. Supported by an assistant, the patients were left in sitting position for 5 min and then laid supine. The break region of the operating table was placed equivalent to the iliac crista of the patient and they were given the prone jack-knife position.