Spinal and intravenous midazolan anesthetic effects on fentanyl/ ligdocaine regional anesthesia following back minor orthopedic surgery

Abstract

OBJECTIVES: the present study was designed to evaluate the usefulness of intravenous and intrathecal midazolan as an adjunct to intrathecal ligdocaine, with or without intrathecal fentanyl. METHODS: double-blind study, institutional approval and informed consent; 40 patients scheduled for minor lumbar orthopedic surgery were randomly assigned to one of five groups (n=8). Patients were premedicated with a 4 mL final intravenous volume (saline or midazolan). Spinal anaesthesia was administered to a 3 mL final volume - 75 mg of lidocaina plus either 33 mg fentanyl or 500 mg midazolan diluted in saline (0,9%) - with the patient in sitting position. The latency time for onset of the block (LT), time to progress to T10 sensory level (TT10), duration of the block (Bl), duration of effective analgesia (An), the subjective degree of intraoperative sedation, level of alertness, concentration level and degree of anxiety were specifically measured. P<0.05 was considered significant. RESULTS: the addition of midazolan to the intrathecal injection in the absence of fentanyl was the only procedure which caused a statistically significant reduction in LT (p<0.002) and TT10 (p<0.001). Intrathecal midazolan increased the blockade time both with (p<0.05) and without (p<0.02) intrathecal fentanyl, but, when given intravenously, this effect failed to reach statistical significance (p>0,05). Both intrathecal fentanyl and midazolan increased the duration of analgesia (p<0.01). With respect to the subjective measures, group 1 served as the control group, demonstrating an alert, fully awake patient who was able to concentrate but showed some anxiety. CONCLUSIONS: while all additional treatments resulted in a relaxed patient, only those given intrathecal midazolan remained fully awake, alert and able to concentrate. Intrathecal fentanyl with saline premedication or intravenous midazolan premedication resulted in decreased alertness and inability to concentrate, as well as sleepiness, which was more extreme in the case of those patients given intravenous midazolan.