Estudio radiológico para evaluar la difusión de dos volúmenes (10 vs. 20 ml) de contraste radiopaco en el bloqueo de las ramas cutáneas de los nervios intercostales en la línea medio axilar (BRILMA) en un modelo experimental porcino

Objective Interfascial blocks of the thoracic wall are being developed as an alternative to central blocks in breast surgery. However, there are few studies that have evaluated the anatomical extension of the local anaesthetic. The objective of this study was to analyse, using fluoroscopy, the spreading of two volumes (10 vs. 20 ml) of radiological contrast in the serratus-intercostal plane block in an experimental pig model. Material and methods Ten Large-White breed pigs were selected to have a bilateral ultrasound serratus-intercostal plane block performed, with the administering of 10 ml and 20 ml of iopamidol in the right and left hemithorax, respectively. The spreading of contrast was analysed by fluoroscopy. The Spearman test correlation was used to evaluate the relationship between the administered volume and radiological spreading. A value of P < .05 was considered significant. Results Twenty anaesthetic blocks were performed, being able to analyse 18 of them. The administration of 10 ml of contrast was associated with a mean spreading of 2.28 ± 0.31 (95% CI; 2.01-2.54) intercostal spaces, while the administration of 20 ml showed a spreading of 3 ± 0.25 (95% CI; 2.81-3.18) intercostal spaces. There was a significant correlation between the injected volume and the spreading of the contrast (Spearman correlation coefficient of 0.81; P = .0001). Conclusion The results showed a spreading of volume subject to the serratus-intercostal plane block, although not maintaining a 1:1 ratio. Doubling the volume increased the blocked segments by 31%. These findings, if corroborated in the clinical practice, would allow a more precise adjustment in the anaesthetic volume administered.