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 45degrees toward the operative side before threading the epidural catheter (45degrees-rotation group, n = 24) as compared to a conventional insertion technique with the tip of the Tuohy needle oriented at 90degrees cephalad (control group, n = 24) on the distribution of 10 mL of 0.75% ropivacaine with 10 mug 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 45degrees-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 45degrees-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 45degrees-rotation group (P = 0.0005). Complete motor blockade of the operative limb was achieved earlier in the 45degrees-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 45degrees-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 45degrees-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 45degrees 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.