Low dose spinal anesthesia for knee arthroscopy

Objective: to evaluate the nature of unilateral spinal anesthesia using various modes of administration of low doses of hyperbaric bupivacaine. Materials and Methods. Prospectively, the randomized study included 56 patients undergoing knee arthroscopy. In the control group bupivacaine of 5mg was administered simultaneously, in the main group — fractionally by 2.5 mg. The development of thermal and pain blocks from different sides was investigated. The data were statistically processed. Results. In the control group, the positioning of the patient usually began after the entire dose of anesthetic had been administered. In the case of temperature paresthesia in the area of the sacral segments of the full anesthesia throughout underlying limb was not always achieved. In 6 cases of block was not sufficient. In the main group patient positioning was performed after the administration of 2.5 mg of anesthetic and evaluate temperature paresthesia and in 2 cases the total dose was increased to 7.5 mg. The successful development of sensory block at fractional administration was significantly higher than in the single-step introduction. Conclusion. Temperature paresthesia occurs within the first minute and is an early predictor of developing spinal anesthesia. The area of arising paresthesia shows preferential distribution of the anesthetic. In the application of low dose local anesthetic the desired upper level of anesthesia via the patient positioning and dose adjustment may be achieved.