Skin-to-epidural distance in the Southeast Asian paediatric population: multiethnic morphometrics and international comparisons.

INTRODUCTION Paediatric epidurals can present technical challenges due to wide variations in age and weight among children, ranging from neonates to teenagers. This study evaluated the skin-to-epidural distance in the thoracic and lumbar regions to determine the relationship between age, weight and ethnicity and depth to the epidural space in our Singapore paediatric population. METHODS Data from the Acute Pain Service was prospectively collected over 16 years. Details included patient demographics, level of epidural performed and distance from skin to epidural space. Multivariable regression analysis was performed to determine the association of weight, age, ethnicity and gender with the depths to the thoracic and lumbar epidural spaces. A simple linear regression was calculated to predict the depth to both thoracic and lumbar epidural spaces based on body weight. Equations were formulated to describe the relationship between weight and depth of epidural space. RESULTS A total of 616 midline epidurals were studied. Regression analysis was performed for 225 thoracic epidurals and 363 lumbar epidurals. Our study revealed a clear correlation between skin-to-lumbar epidural distance and weight in children. The best correlation was demonstrated between skin-to-lumbar epidural distance and body weight (R-2 = 0.729). This relationship was described by the formula: depth (mm) = (0.63 x weight [kg]) + 9.2. CONCLUSION Skin-to-lumbar epidural distance correlated with weight in children. Our results highlighted the clinical significance of differences between Southeast Asian paediatric populations when compared to other populations.