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Epidural test dose with levobupivacaine and ropivacaine: determination of ED(50) motor block after spinal administration.
Br J Anaesth. 2004 Jun; 92(6):850-3.BJ

Abstract

BACKGROUND

When a test is required to detect a possible intrathecal catheter, many would seek to use the same local anaesthetic as that used for epidural analgesia. The rapid onset of inappropriate motor block after a local anaesthetic administered epidurally implies intrathecal spread. Because of claims of greater sensory-motor separation, or because of reduced potency compared with bupivacaine, the efficacy of the new local anaesthetics in intrathecal testing has been questioned. The aim of this study was to establish the feasibility of a test dose for an inadvertent intrathecal catheter using ropivacaine and levobupivacaine, and to establish the dose required.

METHODS

Sixty women undergoing elective Caesarean section with a combined spinal- epidural technique were enrolled into this prospective, double-blind sequential allocation study. The women were randomized to receive plain levobupivacaine 0.5% or ropivacaine 0.5% intrathecally. The dose was determined according to up-down sequential allocation. The end-point was any evidence of lower limb motor block within 5 min of injection.

RESULTS

The ED(50) motor block at 5 min was 4.8 mg (95% CI, 4.49, 5.28) for levobupivacaine and 5.9 mg (95% CI, 4.82, 6.98) for ropivacaine (95% CI difference, 0.052, 1.98) (P=0.04). The estimated ED(95) motor block was 5.9 mg (95% CI 5.19, 6.71) for levobupivacaine and 8.3 mg (95% CI, 6.30, 10.44) for ropivacaine. The potency ratio between the two drugs was 0.83 (95% CI, 0.69, 0.99).

CONCLUSIONS

Both local anaesthetics produce evidence of motor block within 5 min of intrathecal injection and could serve as tests of intrathecal administration. Derived ED(95) values suggest 10 mg doses should be effective, but this study did not measure predictive value. Ropivacaine is less potent for motor block than levobupivacaine by a factor of 0.83 (P<0.04).

Authors+Show Affiliations

Department of Anaesthesia, Clinica Città di Roma, Roma, Italy. michela_camorcia@yahoo.itNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

15096445

Citation

Camorcia, M, et al. "Epidural Test Dose With Levobupivacaine and Ropivacaine: Determination of ED(50) Motor Block After Spinal Administration." British Journal of Anaesthesia, vol. 92, no. 6, 2004, pp. 850-3.
Camorcia M, Capogna G, Lyons G, et al. Epidural test dose with levobupivacaine and ropivacaine: determination of ED(50) motor block after spinal administration. Br J Anaesth. 2004;92(6):850-3.
Camorcia, M., Capogna, G., Lyons, G., & Columb, M. (2004). Epidural test dose with levobupivacaine and ropivacaine: determination of ED(50) motor block after spinal administration. British Journal of Anaesthesia, 92(6), 850-3.
Camorcia M, et al. Epidural Test Dose With Levobupivacaine and Ropivacaine: Determination of ED(50) Motor Block After Spinal Administration. Br J Anaesth. 2004;92(6):850-3. PubMed PMID: 15096445.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Epidural test dose with levobupivacaine and ropivacaine: determination of ED(50) motor block after spinal administration. AU - Camorcia,M, AU - Capogna,G, AU - Lyons,G, AU - Columb,M, Y1 - 2004/04/19/ PY - 2004/4/21/pubmed PY - 2004/6/24/medline PY - 2004/4/21/entrez SP - 850 EP - 3 JF - British journal of anaesthesia JO - Br J Anaesth VL - 92 IS - 6 N2 - BACKGROUND: When a test is required to detect a possible intrathecal catheter, many would seek to use the same local anaesthetic as that used for epidural analgesia. The rapid onset of inappropriate motor block after a local anaesthetic administered epidurally implies intrathecal spread. Because of claims of greater sensory-motor separation, or because of reduced potency compared with bupivacaine, the efficacy of the new local anaesthetics in intrathecal testing has been questioned. The aim of this study was to establish the feasibility of a test dose for an inadvertent intrathecal catheter using ropivacaine and levobupivacaine, and to establish the dose required. METHODS: Sixty women undergoing elective Caesarean section with a combined spinal- epidural technique were enrolled into this prospective, double-blind sequential allocation study. The women were randomized to receive plain levobupivacaine 0.5% or ropivacaine 0.5% intrathecally. The dose was determined according to up-down sequential allocation. The end-point was any evidence of lower limb motor block within 5 min of injection. RESULTS: The ED(50) motor block at 5 min was 4.8 mg (95% CI, 4.49, 5.28) for levobupivacaine and 5.9 mg (95% CI, 4.82, 6.98) for ropivacaine (95% CI difference, 0.052, 1.98) (P=0.04). The estimated ED(95) motor block was 5.9 mg (95% CI 5.19, 6.71) for levobupivacaine and 8.3 mg (95% CI, 6.30, 10.44) for ropivacaine. The potency ratio between the two drugs was 0.83 (95% CI, 0.69, 0.99). CONCLUSIONS: Both local anaesthetics produce evidence of motor block within 5 min of intrathecal injection and could serve as tests of intrathecal administration. Derived ED(95) values suggest 10 mg doses should be effective, but this study did not measure predictive value. Ropivacaine is less potent for motor block than levobupivacaine by a factor of 0.83 (P<0.04). SN - 0007-0912 UR - https://www.unboundmedicine.com/medline/citation/15096445/Epidural_test_dose_with_levobupivacaine_and_ropivacaine:_determination_of_ED_50__motor_block_after_spinal_administration_ L2 - https://linkinghub.elsevier.com/retrieve/pii/aeh155 DB - PRIME DP - Unbound Medicine ER -