Bosenberg and Grouws developed equations for estimating the skin to epidural depth in children. The authors are from the University of Natal and South African Medical Research Council in South Africa.

Patient selection: 0.5 to 10 years of age


Position: L3-4 interspace with patient in the left lateral position



(1) body weight in kilograms

(2) age in years


skin to epidural distance in mm =

= (0.8 * (body weight)) + 3.93


A rough estimate for depth is 1 mm per kilogram for body weight.


skin to epidural distance in mm =

= (1.76 * (age in years)) + 9

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