Cerebrospinal Fluid Density Influences Extent of Plain Bupivacaine Spinal Anesthesia

Abstract

These findings indicate an influence of cerebrospinal fluid density on subarachnoid distribution of 3 ml plain bupivacaine 0.5% and show that with higher cerebrospinal fluid densities, a higher spinal block level can be expected.

Bupivacaïne intrathécale pure vs hyperbare pour l’analgésie du travail obstétrical: efficacité et effets secondaires

“…11 Dextrose-free (plain) solutions of bupivacaine and opioids, usually referred to as being isobaric, are actually hypobaric at body temperature, with a density less than 1.00000 g·mL -1 . 3,[12][13][14] The slight hypobaricity of plain solutions relative to CSF (0.00060 g·mL -1 of difference), could explain the rapid, high sensory block observed after administration of plain local anesthetics and lipid-soluble opioids. 10,11,[15][16][17] Moreover, this pattern of cephalad spread might facilitate the antinociceptive effects of intrathecal opioids through dual activation of spinal as well as supraspinal receptor sites of action, 18 which in turn, might augment the quality of analgesia of plain local anesthetics.…”

“…The initial characteristics of the block are mainly determined by the doses of medications (local anesthetic and opioid) and the baricity of the intrathecal solution. 3,4 Compared to plain solutions, hyperbaric solutions might provide a more predictable block with fewer side effects, such as high block, hypotension, nausea, vomiting and pruritus. 5 The use of hyperbaric solutions might risk ineffective analgesia from insufficient cephalad spread, however.…”

<![CDATA[<b>Raquianestesia para cesariana</b>: <b>estudo comparativo entre bupivaca?na isob?rica e hiperb?rica associadas ? morfina</b>]]>

“…É importante a padronização do local de punção entre o terceiro e quarto segmentos lombares, porque a concentração do anestésico local varia inversamente em relação à distân-cia da área de maior concentração, que é geralmente o local de injeção. Mas deve ser salientado que a determinação clí-nica do local de punção está errada em mais de 50% dos casos e em geral ocorrendo em nível mais alto do que o considerado 10 . Diferenças anatômicas individuais, identificadas por exame de ressonância magnética, tem sido responsabilizadas como causa de falha da raquianestesia com soluções hiperbáricas 11 .…”

“…But it should be highlighted that clinical puncture site determination is wrong in more than 50% of cases, and in general it is located at a higher level than the one that is being considered 10 . Individual anatomical variations identified by MRI have been charged as responsible for spinal anesthetic failures with hyperbaric solutions 11 .…”

“…Term pregnant patients exhibit lower CSF density as compared to general population, around from 1.00030 ± 0.00004 g.ml -1 , due to hormonal factors, such as increased estrogen and progesterone concentrations 9, 12,13 . In addition, other components, such as proteins, glucose, chloride and sodium concentrations also influence density and, indirectly, spinal anesthesia extension 10 . Baricity is the ratio between solution's and CSF densities 2,9,14 , being one of the most important influences for local anesthetic spread, though its role in term pregnant women is not clear 13 .…”