Abstract

Background: Spinal anesthesia is very safe, effective, and economical technique in anesthesia for a regional block. Various drugs are used for spinal anesthesia from which lignocaine is very popular since several decades. The discovery of opioid recep- tors in the central nervous system especially in spinal cord initiated interest in using them as intrathecal and extradural uses.
Objective: To evaluate the efficacy of intrathecal pethidine as a sole anesthetic agent and as a postoperative analgesia in the surgical procedure below the umbilicus. It was compared with commonly used drug like lignocaine.
Materials and Methods: The present study was carried out in patients of either sex belonging to American Society of Anesthesiology (ASA) grade I or II, in the age group of 16–70 years. Patients were undergoing elective lower abdominal, genitourinary or lower extremity surgery under spinal anesthesia at our hospital. Patients were divided into 2 groups of 50 patients each. Patients in group 1 (study group) were given 1 mg/kg preservative-free injection pethidine hydrochloride (5%) diluted up to 2cc with 0.9% normal saline intrathecal. Patients in group 2 (control group) were given 2 ml injection lignocaine (5%) in 7.5% dextrose intrathecal. Anesthesia was given in subarachnoid space in lateral or sitting position between L3–L4 interspace by using 25 gauge needles with all aseptic precautions. Sensory block was tested by using pin prick method. Time to onset of motor blockage was determined by modified Bromage scales of grade II. The degree of postoperative analgesia was carried out by visual analog scale. Result: There was no incidence of sensory block failure in either group. Time of onset of sensory block was significantly (p < 0.01) faster in the case of lignocaine group (group 2). The difference between the time to regress sensory block by two segments was significant between 2 groups ( p < 0.01). Duration of analgesia at L1 level was significantly different between both groups (p < 0.05). The difference between the total duration of sensory block was not significantly different between both groups (p > 0.05). The onset of motor block at knee joint was significantly prolonged in group 1 as compared to group 2 ( p < 0.01). The mean duration of motor block was shorter in group 1 as compared to group 2 (p < 0.01). In group 1, 4 out of 50 patients developed incomplete motor block. In this study mean duration of analgesia was 14 hours in group 1 and 2 hours in group 2. This showed a significant difference ( p < 0.01). The patients in group 1 required analgesia once in 24 hours postoperatively while in group 2 patients required analgesia two to three times in 24 hours postoperatively. Conclusion: This study showed that intrathecal pethidine in the dose of 1 mg/kg produced comparable effects produced by suba- rachnoid administration of local anesthetics such as lignocaine including sensory, motor, and sympathetic block. It also showed fewer side effects than lignocaine. It also showed lesser requirements of analgesics postoperatively and early ambulation.