A Prospective, Randomized Evaluation of the Effects of Epidural Needle Rotation on the Distribution of Epidural Block

We evaluated the effects of turning the tip of the Tuohy needle 45° toward the operative side before threading the epidural catheter (45°-rotation group, n = 24) as compared to a conventional insertion technique with the tip of the Tuohy needle oriented at 90° cephalad (control group, n = 24) on the distribution of 10 mL of 0.75% ropivacaine with 10 μg sufentanil in 48 patients undergoing total hip replacement. The catheter was introduced 3 to 4 cm beyond the tip of the Tuohy needle. A blinded observer recorded sensory and motor blocks on both sides, quality of analgesia, and volumes of local anesthetic used during the first 48 h of patient-controlled epidural analgesia. Readiness to surgery required 21 ± 6 min in the control group and 17 ± 7 min in the 45°-rotation group (P > 0.50). The maximum sensory level reached on the operative side was T10 (T10-7) in the control group and T9 (T10-6) in the 45°-rotation group (P > 0.50); whereas the maximum sensory level reached on the nonoperative side was T10 (T12-9) in the control group and L3 (L5-T12) in the 45°-rotation group (P = 0.0005). Complete motor blockade of the operative limb was achieved earlier in the 45°-rotation than in the control group, and motor block of the nonoperative side was more intense in patients in the control group. Two-segment regression of sensory level on the surgical side was similar in the two groups, but occurred earlier on the nonoperative side in the 45°-rotation group (94 ± 70 min) than in the control group (178 ± 40 min) (P = 0.0005). Postoperative analgesia was similar in the 2 groups, but the 45°-rotation group consumed less local anesthetic (242 ± 35 mL) than the control group (297 ± 60 mL) (P = 0.0005). We conclude that the rotation of the Tuohy introducer needle 45° toward the operative side before threading the epidural catheter provides a preferential distribution of sensory and motor block toward the operative side, reducing the volume of local anesthetic solution required to maintain postoperative analgesia.