Quality of Spinal Extradural Anaesthesia: The Influence of Spinal Nerve Root Diameter

Abstract

Profiles on the progress of spinal extradural anaesthesia were made in 246 patients using various concentrations of lignocaine, bupivacaine and etidocaine. The advance of analgesia through the different dermatomes showed a consistent and orderly spread on the upper lumbar and thoracic segments. This spread was irregular through the lower lumbar and upper sacral segments. The first sacral segment was especially difficult to block with an overall failure rate of 17.53% with presently available concentrations of various local anaesthetics. This failure was abolished with the use of etidocaine 1.5%. The presence of a delay or failure at the level of L5-S2 is probably related to the larger diameter of these nerve roots as ascertained from measurements in 11 cadavers.

Sensory blockade of S3 dermatome prevents pain during bladder catheterization

“…1 Of the 40 patients in our previous study, only 15 (38%) experienced loss of cold sensation in the S1 dermatome with 33 (83%) reporting loss in the S3 dermatome. 2 However, even in cases of incomplete epidural blockade of the sacral nerves, we often encounter patients who do not complain of unpleasant sensations or pain upon undergoing invasive urogenital or rectal procedures that are expected to cause pain.…”

Concentração analgésica mínima da bupivacaína durante infusão peridural contínua após bloqueio subaracnóideo no período pós-operatório de cirurgias ortopédicas da perna, tornozelo e pé

“…This is in line with other studies where only high local anesthetic concentrations produced a complete sensory block of L 5 and S 1 roots [13][14][15][16] . This is because L 5 and S 1 roots are thicker, thus prolonging sensory and motor block onset and decreasing their intensity 17 . In a previous study, 0.5% bupivacaine, associated or not to epidural or intravenous fentanyl, has not provided total anesthesia and immobility in the territory innervated by L 4 , L 5 and S 1 roots 18 .…”

“…Embora a concentração eficaz em 95% dos pacientes (CE 95 ) seja mais relevante para a prática clínica, a concentração eficaz em 50% dos pacientes (CE 50 ) é uma ferramenta mais útil de pesquisa, dada a sua posição na curva de concentra- -16 . A razão para isto é que as raízes de L 5 e S 1 são mais calibrosas, o que prolonga a latência do bloqueio sensitivo e motor e diminui sua intensidade 17 . Em estudo anterior, a bupivacaína a 0,5%, associada ou não ao fentanil por via peridural ou venosa, não proporcionou anestesia completa e imobilidade no território inervado pelas raízes L 4 , L 5 e S 1 18 .…”

Segmental Levels of Anaesthesia Following the Extradural Injection of 0.75% Bupivacaine at Different Lumbar Spaces in Elderly Patients

“…Fifteen millilitre provides good anaesthesia to the large nerve trunks L5 and SI, with minimal circulatory compromise. Lesser doses may not anaesthetize these nerve roots adequately (Galindo, et al, 1975).…”