Effects of incrementally increasing tidal volume on the right internal jugular vein in pediatric patients

Purpose: The aim of the present study was to evaluate the effects of incremental increases of tidal volume (TV) on the cross-sectional area (CSA) and size of the right internal jugular vein (RIJV), and the relationship between RIJV and the carotid artery (CA). Methods: This prospective study included 23 pediatric patients aged between 7 and 12 years who were anesthetized. Using a standard anesthesia protocol, the TV was increased from 6 to 10 mL/kg in 1 mL/kg increments. For each TV, images of the RIJV and CA at the level of the cricoid cartilage were recorded at the end of the inspiration. From these results, the CSA and size of the RIJV and the percentage of CA overlap were calculated. Results: The median (interquartile range) RIJV CSA was 0.82 (0.52-1.07) cm2 at a TV of 6 mL/kg and significantly increased to 0.86 (0.58-1.05), 0.88 (0.55-1.08), 0.95 (0.62-1.17) and 1.02 (0.70-1.20) cm2 at TVs of 7, 8, 9 and 10 mL/kg, respectively. There were no significant differences in the percentage overlap of the CA between all TVs. The median (interquartile range) transverse diameter was 1.16 (0.99-1.36) cm at a TV of 6 mL/kg and significantly increased to 1.20 (1.10-1.41), 1.26 (1.05-1.45), 1.28 (1.10-1.49) and 1.35 (1.12-1.52) cm at TVs of 7, 8, 9 and 10 mL/kg, respectively. The median (interquartile range) anteroposterior diameter was 0.77 (0.72-0.90) cm at a TV of 6 mL/kg and significantly increased to 0.81 (0.72-0.94), 0.85 (0.74-0.99), 0.88 (0.75-1.02) and 0.89 (0.79- 1.06) cm at TVs of 7, 8, 9 and 10 mL/kg, respectively. Conclusions: This study reveals that a TV of 10 mL/kg in anesthetized children achieved the greatest size in the RIJV, and caused no difference in the CA overlap. These results suggest that a TV of 10 mL/kg is the optimal choice when facilitating catheterization and in the avoidance of complications in anesthetized children connected to mechanical ventilator that are required to undergo RIJV catheterization.