Bailie et al used body weight to estimate the spinal canal depth in pediatric patients. This can help to gauge the needle length required for a lumbar puncture. The authors are from Addenbrooke's Hospital in Cambridge, England.
Patient selection: age 0 to 18 years
Outcome: mid-spinal canal depth from ultrasonography in mm with patient in a curved left lateral position (L3-L4 intervertebral space, MSCD midway between the anterior and posterior spinal canal depth in ultrasonography).
Parameter:
(1) body weight in kilograms, from 5 to 80 kg
mid-spinal canal depth (MSCD) in mm =
= (0.4 * (weight in kilograms)) + 20
= (0.38 * (weight in kilograms) + 20.6
Performance:
• The correlation coefficient (r-squared) was 0.72 which was better than age, height or body surface area.
For the lines in Figure 2, the following line estimates were generated.
MSCD in mm =
= (1.33 * (age in years)) + 20.9
= (0.38 * (weight in kg)) + 21.1
= (0.21 * (height in cm)) + 5.3
= (16.54 * (BSA in square meter)) + 15.7
