Brazilian Journal of Anesthesiology
Brazilian Journal of Anesthesiology
Original Investigation

Rider sitting position widens lumbar intervertebral distance: a prospective observational study

A posição sentada montada amplia a distância intervertebral lombar: um estudo observacional prospectivo

Melike Korkmaz Toker, Basak Altıparmak, Ali ˙Ihsan Uysal, Mustafa Turan, Semra Gumus Demirbilek

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Reduced lumbar lordosis may make the process of identifying the intervertebral distance easier. The primary aim of this study was to measure the L3 L4 intervertebral space in the same patients undergoing spinal anesthesia in three different sitting positions, including the classic sitting position (CSP), hamstring stretch position (HSP) and rider sitting position (RSP). The secondary aim was to compare ultrasonographic measurements of the depth of the ligamentum flavum and intrathecal space in these three defined positions.

This study is a single-blinded, prospective, randomized study. Ninety patients were included in final analysis. the patients were positioned on the operating table in three different positions to perform ultrasonographic measurements of the spinal canal. The intervertebral distance (IVD), the distance between the skin and the ligamentum flavum (DBSLF) and the intrathecal space (IS) were measured in the L3 L4 intervertebral space in three different positions.

The RSP produced the largest mean distance between the spinous processes. The RSP yielded a significantly larger IVD than did the CSP (p < 0.001) and HSP (p < 0.001). The DBSP was larger in the CSP than in the HSP (p = 0.001). The DBSLF was significantly larger in the RSP than in the HSP (p = 0.009).

Positioning the patient in the RSP significantly increased the intervertebral distance between L3 L4 vertebrae compared to the CSP and HSP, suggesting easier performance of lumbar neuraxial block.


Anesthesia, spinal,  Ultrasonography,  Spinal column



A lordose lombar reduzida pode facilitar o processo de identificação da distância intervertebral. O objetivo principal deste estudo foi medir o espaço intervertebral L3-L4 nos mesmos pacientes submetidos à raquianestesia em três posições sentadas diferentes, incluindo a posição sentada clássica (PSC), posição de alongamento dos isquiotibiais (PAIT) e posição sentada montada (PSM). O objetivo secundário foi comparar as medidas ultrassonográficas da profundidade do ligamento amarelo e do espaço intratecal nessas três posições definidas.


Este estudo é um estudo simples-cego, prospectivo e randomizado. Noventa pacientes foram incluídos na análise final. os pacientes foram posicionados na mesa cirúrgica em três posições diferentes para realização de medidas ultrassonográficas do canal medular. A distância intervertebral (DIV), a distância entre a pele e o ligamento amarelo (DBSLF) e o espaço intratecal (EI) foram medidos no espaço intervertebral L3-L4 em três posições diferentes.


A PSM produziu a maior distância média entre os processos espinhosos. A PSM rendeu um DIV significativamente maior que a PSC (p < 0,001) e a PAIT (p < 0,001). A DBSP foi maior na PSC do que na PAIT (p = 0,001). A DBSLF foi significativamente maior na PSM do que na PAIR (p = 0,009).


O posicionamento do paciente na PSM aumentou significativamente a distância intervertebral entre as vértebras L3-L4 em comparação à PSC e à PAIT, sugerindo uma realização mais fácil do bloqueio neuroaxial lombar.


Raquianestesia; Ultrassonografia; Coluna vertebral


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