Low hyperbaric bupivacaine doses for unilateral spinal anesthesia for open inguinal herniorrhaphy. a pilot study with 20 patients

Abstract

Background : Unilateral spinal anesthesia may have advantages over bilateral spinal anesthesia. Low doses of local anesthetic, slow injection speed and lateral position are facilitators to produce unilateral spinal anesthesia. The aim of this study was to perform inguinal hernia repair with unilateral spinal anesthesia and low doses of bupivacaine associated with morphine in a pilot study with 20 patients. Material and methods : Spinal anesthesia with 0.5% bupivacaine and 26G Quincke needle was induced in a prospective pilot study in 20 patients physical status ASA I-II submitted to inguinal hernia repair. 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 plus 80 µg of morphine were injected at 1 mL/30 s. Sensory and motor blocks (pinprick and 0 to 3 scores) were compared between operated and contralateral sides. Hemodynamic changes, nausea and vomiting, pruritus and urinary retention were evaluated. Results : All 20 patients were operated on using the technique employed, with no need for supplementation with sedation or general anesthesia. Unilateral block was induced in 100% of patients at 15 minutes and the end of the surgery. There has been hemodynamic stability in all patients. Urinary retention occurred in 8 patients (40%), pruritus in 4 patients (20%) and nauseas and vomiting in 4 patients (20%). No patient has developed post dural puncture headache. Conclusion: This prospective pilot study with 0.5% hyperbaric bupivacaine (5mg) associated with morphine (80 µg) has provided predominantly unilateral block. Fifteen minutes were enough for blockade installation. Major unilateral spinal anesthesia advantages are hemodynamic stability, patients ’satisfaction and faster anesthetic recovery.