EFFECTS OF SPINAL NEEDLE TYPE ON LATERAL DISTRIBUTION OF 0.5-PERCENT HYPERBARIC BUPIVACAINE

To evaluate the influence of needle type on the lateral distribution o f 0.5% hyperbaric bupivacaine, 30 patients undergoing lower limb surge ry were placed in the lateral position with the side to be operated on dependent and underwent dural puncture by either a 25-gauge Whitacre (n = 15) or a 25-gauge Quincke (n = 15) spinal needle. The needle hole was turned toward the dependent side and 8 mg of 0.5% hyperbaric bupi vacaine was injected over 30 s. The lateral position was maintained fo r 15 min while a blind observer recorded loss of pinprick sensation an d degree of motor block on both the dependent and nondependent sides e very 5 min until regression of motor block by 1 degrees on the depende nt side. Thirty minutes after the patients were placed in the supine p osition, unilateral sensory block was observed in 10 patients in the W hitacre group (66%) and in 2 patients in the Quincke group (13%) (P < 0.05). No differences in the rate of unilateral motor block were obser ved (73% and 40% in Whitacre and Quincke groups, respectively). We con clude that when a small dose of 0.5% hyperbaric bupivacaine is injecte d slowly into patients in the lateral position for 15 min, the Whitacr e spinal needle provides a more marked differential block of sensory n erve roots between dependent and nondependent sides compared with the Quincke needle. Implications: Because unilateral spinal anesthesia can be advantageous for lower limb surgery, we evaluated the influence of the Whitacre and Quincke spinal needle types on the lateral distribut ion of small-dose 0.5% hyperbaric bupivacaine injected slowly into adu lt patients.