[Unilateral spinal anesthesia with low 0.5% hyperbaric bupivacaine dose.].

BACKGROUND AND OBJECTIVES Unilateral spinal anesthesia may be advantageous, especially for outpatient procedures. Low anesthetic doses, pencil point or cutting point needles, slow injection rate and the lateral position have been reported as helping unilateral spinal anesthesia technique. This longitudinal study aimed at investigating the depth of unilateral spinal anesthesia with 5 mg of 0.5% hyperbaric bupivacaine injected with 27G Quincke needle with patients in the lateral position and limb to be operated on facing downward. METHODS Spinal anesthesia with 0.5% bupivacaine and 27G Quincke needle was induced in 30 patients physical status ASA I-II submitted to orthopedic surgeries. Spinal puncture was performed with patients previously placed with the side to be operated on facing downward and 5 mg of 0.5% hyperbaric bupivacaine were injected at 1 mL.15s-1. Sensory and motor blocks (pinprick and 0 to 3 scores) were compared between operated and contralateral sides. RESULTS Motor and sensory blocks between operated and contralateral sides were significantly different in all moments. Unilateral spinal anesthesia was obtained in 85.7% of patients. There has been hemodynamic stability in all patients. No patient has developed post dural puncture headache. CONCLUSIONS In the conditions of our study, 0.5% hyperbaric bupivacaine (5 mg) has provided predominantly unilateral block. Twenty minutes were enough for blockade installation. Major unilateral spinal anesthesia advantages are hemodynamic stability, patients satisfaction and faster anesthetic recovery.