Abstract ID: A28

Abstract Title: Lumbar Plexus Block at the End of Total Hip Replacement Performed Under Epidural Anesthesia

Poster Type: Poster

ABSTRACT BODY

Introduction:
Lumbar plexus block (LPB) provides excellent analgesia following total hip replacement (THR) but has been associated with a higher proportion of complications than other blocks including total spinal anesthesia in 3 of 396 patients [1]. This report reviews the experience of a single practitioner (NES) who has performed LPB on all patients undergoing THR over the last 16 months. LPB was performed at the end of surgery, which was conducted under hypotensive epidural anesthesia.

Materials and Methods:
The technique of LPB used was a modification of Winnie's technique with needle entry 6-8 mm lateral to the L3-4 interspace angled medially 20-30o to detect the transverse process, then redirected caudally and medially using a 10 cm 21# insulated needle at 2 mAmps. Upon eliciting a thigh twitch, 30 ml of 0.5% bupivacaine plain (150 mg) was injected in 5 ml aliquots. Injections were performed in the lateral decubitus position at the end of surgery conducted under hypotensive epidural anesthesia using 25-35 ml of 0.75% bupivacaine injected at L1-T10 interspace. The duration between epidural injection and LPB was 140 + 10 minutes. The mean dose of epidural bupivacaine was 287 mg (262 mg - 299 mg). 39 patients underwent bilateral hip replacement and received a total of 40 ml 0.5% bupivacaine, 20 ml on each side.

Results:
From July 2002 until November 2003, 527 of 544 patients undergoing THR received LPB (Table 1). 388 were performed by NES alone and 139 were performed by residents or fellows under supervision of NES. Elicitation of a twitch was obtained in all but 5 cases (patients who had L3-sacrum spinal fusion were excluded, n = 5). No patients developed frank hematuria postoperatively. There were no seizures. One patient developed an ileus requiring surgery but no evidence of perforation of the colon was noted. One patient developed a total spinal, which was recognized within minutes. The patient was ventilated for 3 hours and made an uneventful recovery. There were no clinically manifested retroperitoneal hematomas nor persistent neurological sequelae.

Conclusion:
The L3-L4 nerve roots in the paravertebral space are responsive to nerve stimulator at 2 mAmps two hours following epidural anesthesia performed at L1-T10 with 25-35 ml 0.75% bupivacaine. The risk of seizures is negligible injecting 150 mg bupivacaine for the LBP 1.5 - 3 hours following epidural injection of at least 262 mg bupivacaine. Total spinal anesthesia remains a potential risk of LPB in spite of a modified technique designed to reduce the risk.

References:
1. Auroy, Y., M.D., et al., Major complications of regional anesthesia in France. Anesthesiology, 2002. 97(5): p. 1247-1280.

ATTACHED FILES

A28_Table1.doc

Reg Anesth Pain Med 2004; 29(2):A28