Combined Lumbar-Plexus and Sciatic-Nerve Blocks: An Analysis of Plasma Ropivacaine Concentrations

Stephanie Vanterpool, Susan M. Steele, Karen C. Nielsen, Marcy Tucker, Stephen M. Klein

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Background and Objectives: Lumbar-plexus and sciatic-nerve blocks are commonly combined for lower-extremity anesthesia using large doses of ropivacaine. Limited information is available about the pharmacokinetics of this practice. We analyzed plasma ropivacaine concentrations after single-injection lumbar-plexus blocks with and without sciatic-nerve blocks. Methods: Twenty patients having lower-extremity surgery using a lumbar-plexus block with 0.5% ropivacaine with 1:400,000 epinephrine (35 mL, n = 10) or the same lumbar-plexus block with the addition of a sciatic-nerve block (25 mL, n = 10, 60 mL total) using the same solution were enrolled. Venous blood samples were collected at 5, 15, 30, 45, 60, 120, and 240 minutes after block placement and analyzed for total ropivacaine concentration by use of gas chromatography. Individual timepoints, maximum concentrations (Cmax), and time to Cmax (Tmax) were compared. Values are mean ± SD. Results: Both groups demonstrated a rapid increase in plasma concentration over the first 30 to 45 minutes. Concentrations were greater for those who received both blocks (P = .0005) at all timepoints. The lumbar-plexus block Cmax was less (986 ± 221 ng/mL) than for the combined blocks (1,560 ± 351 ng/mL, P = .0004). The Tmax was greater for the lumbar plexus (80 ± 49 min) than for the combined blocks (38 ± 22 min, P = .03). There was no relationship between the Cmax and patient age, weight, or body mass index. Conclusions: The results of this study demonstrate that the plasma ropivacaine concentrations increase quicker when a sciatic-nerve block is added to a lumbar-plexus block, but Cmax remains below the toxicity threshold.

Original languageEnglish (US)
Pages (from-to)417-421
Number of pages5
JournalRegional Anesthesia and Pain Medicine
Volume31
Issue number5
DOIs
StatePublished - Sep 1 2006
Externally publishedYes

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Lumbosacral Plexus
Nerve Block
Sciatic Nerve
Lower Extremity
ropivacaine
Gas Chromatography
Epinephrine
Body Mass Index
Anesthesia
Pharmacokinetics
Weights and Measures
Injections

All Science Journal Classification (ASJC) codes

  • Anesthesiology and Pain Medicine

Cite this

Combined Lumbar-Plexus and Sciatic-Nerve Blocks : An Analysis of Plasma Ropivacaine Concentrations. / Vanterpool, Stephanie; Steele, Susan M.; Nielsen, Karen C.; Tucker, Marcy; Klein, Stephen M.

In: Regional Anesthesia and Pain Medicine, Vol. 31, No. 5, 01.09.2006, p. 417-421.

Research output: Contribution to journalArticle

Vanterpool, Stephanie ; Steele, Susan M. ; Nielsen, Karen C. ; Tucker, Marcy ; Klein, Stephen M. / Combined Lumbar-Plexus and Sciatic-Nerve Blocks : An Analysis of Plasma Ropivacaine Concentrations. In: Regional Anesthesia and Pain Medicine. 2006 ; Vol. 31, No. 5. pp. 417-421.
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abstract = "Background and Objectives: Lumbar-plexus and sciatic-nerve blocks are commonly combined for lower-extremity anesthesia using large doses of ropivacaine. Limited information is available about the pharmacokinetics of this practice. We analyzed plasma ropivacaine concentrations after single-injection lumbar-plexus blocks with and without sciatic-nerve blocks. Methods: Twenty patients having lower-extremity surgery using a lumbar-plexus block with 0.5{\%} ropivacaine with 1:400,000 epinephrine (35 mL, n = 10) or the same lumbar-plexus block with the addition of a sciatic-nerve block (25 mL, n = 10, 60 mL total) using the same solution were enrolled. Venous blood samples were collected at 5, 15, 30, 45, 60, 120, and 240 minutes after block placement and analyzed for total ropivacaine concentration by use of gas chromatography. Individual timepoints, maximum concentrations (Cmax), and time to Cmax (Tmax) were compared. Values are mean ± SD. Results: Both groups demonstrated a rapid increase in plasma concentration over the first 30 to 45 minutes. Concentrations were greater for those who received both blocks (P = .0005) at all timepoints. The lumbar-plexus block Cmax was less (986 ± 221 ng/mL) than for the combined blocks (1,560 ± 351 ng/mL, P = .0004). The Tmax was greater for the lumbar plexus (80 ± 49 min) than for the combined blocks (38 ± 22 min, P = .03). There was no relationship between the Cmax and patient age, weight, or body mass index. Conclusions: The results of this study demonstrate that the plasma ropivacaine concentrations increase quicker when a sciatic-nerve block is added to a lumbar-plexus block, but Cmax remains below the toxicity threshold.",
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AB - Background and Objectives: Lumbar-plexus and sciatic-nerve blocks are commonly combined for lower-extremity anesthesia using large doses of ropivacaine. Limited information is available about the pharmacokinetics of this practice. We analyzed plasma ropivacaine concentrations after single-injection lumbar-plexus blocks with and without sciatic-nerve blocks. Methods: Twenty patients having lower-extremity surgery using a lumbar-plexus block with 0.5% ropivacaine with 1:400,000 epinephrine (35 mL, n = 10) or the same lumbar-plexus block with the addition of a sciatic-nerve block (25 mL, n = 10, 60 mL total) using the same solution were enrolled. Venous blood samples were collected at 5, 15, 30, 45, 60, 120, and 240 minutes after block placement and analyzed for total ropivacaine concentration by use of gas chromatography. Individual timepoints, maximum concentrations (Cmax), and time to Cmax (Tmax) were compared. Values are mean ± SD. Results: Both groups demonstrated a rapid increase in plasma concentration over the first 30 to 45 minutes. Concentrations were greater for those who received both blocks (P = .0005) at all timepoints. The lumbar-plexus block Cmax was less (986 ± 221 ng/mL) than for the combined blocks (1,560 ± 351 ng/mL, P = .0004). The Tmax was greater for the lumbar plexus (80 ± 49 min) than for the combined blocks (38 ± 22 min, P = .03). There was no relationship between the Cmax and patient age, weight, or body mass index. Conclusions: The results of this study demonstrate that the plasma ropivacaine concentrations increase quicker when a sciatic-nerve block is added to a lumbar-plexus block, but Cmax remains below the toxicity threshold.

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