Abstract
Purpose: Predicting the depth of needle insertion for paravertebral nerve blocks is currently based on patients’ anthropometric characteristics, and the block level. Although preliminary studies report relationships between paravertebral depth and the body mass index (BMI), the number of observations, to date, are inadequate to formulate reliable conclusions. This study was designed to determine which factors may predict the distance between the skin and paravertebral space, for patients undergoing paravertebral nerve block procedures.
Methods: After review of peripheral nerve block procedure records, 559 surgical patients who underwent a total of 1,318 thoracic paravertebral nerve blocks for postoperative pain control, were included in the study. The patients’ gender, age, weight, height, BMI, thoracic level of the performed block, and depth of the needle insertion were analyzed, using stepwise multiple regression models.
Results: With the exception of T5, a linear relationship was established between paravertebral depth and thoracic level, with depth increasing at inferior thoracic levels. The greatest depth was observed in younger patients with higher BMIs. Depth was more variable, and more strongly correlated with age and weight, at levels T4 throughT8, compared to levels T9 through T12. Age had no influence on depth between T9 and T12. In patients who underwent multiple blocks, awareness of depth of one paravertebral space allowed more accurate prediction of the depth of the other paravertebral spaces.
Conclusion: Age, weight and the thoracic level influence the depth of the paravertebral space between spinal levels T4 and T8, while only the thoracic level and body weight are implicated between T9 and T12.
Résumé
Objectif: À l’heure actuelle, la prédiction de la profondeur d’insertion de l’aiguille pour les blocs nerveux paravertébraux se fonde sur les caractéristiques anthropométriques du patient et sur le niveau du bloc. Bien que les études préliminaires rapportent des associations entre la profondeur paravertébrale et l’indice de masse corporelle (IMC), le nombre d’observations est, à ce jour, insuffisant pour émettre des conclusions fiables. Cette étude a été conçue dans le but de déterminer les facteurs pouvant prédire la distance entre l’épiderme et l’espace paravertébral chez les patients traités avec un bloc nerveux paravertébral.
Méthode: Après avoir révisé les dossiers d’interventions de blocs nerveux périphériques, nous avons inclus 559 patients chirurgicaux qui ont subi un total de 1 318 blocs nerveux paravertébraux thoraciques pour la prise en charge de la douleur postopératoire. Le sexe, l’âge, le poids, la taille, l’IMC, le niveau thoracique où le bloc a été réalisé et la profondeur d’insertion de l’aiguille ont été analysés à l’aide de modèles de régression multiple progressifs.
Résultats : À l’exception de T5, une relation linéaire a pu être établie entre la profondeur paravertébrale et le niveau thoracique, la profondeur augmentant à des niveaux thoraciques inférieurs. La profondeur la plus importante a été observée chez les patients plus jeunes présentant un IMC plus élevé. La profondeur était plus variable et plus corrélée à l’âge et au poids, de T4 à T8, par rapport à T9 à T12. L’âge n’a pas eu d’incidence sur la profondeur entre T9 et T12. Chez les patients ayant subi plusieurs blocs, la connaissance de la profondeur d’un espace paravertébral a permis une prédiction plus précise de la profondeur des autres espaces paravertébraux.
Conclusion: L’âge, le poids et le niveau thoracique influencent la profondeur de l’espace paravertébral entre les niveaux rachidiens T4 et T8, alors que dans le cas de T9 à T12, seulement le niveau thoracique et le poids jouent un rôle.
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Research sponsored by the Department of Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
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Chelly, J.E., Uskova, A., Merman, R. et al. A multifactorial approach to the factors influencing determination of paravertebral depth. Can J Anesth 55, 587–594 (2008). https://doi.org/10.1007/BF03021432
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DOI: https://doi.org/10.1007/BF03021432