title: Weight-based determination of spinal canal depth for paediatric lumbar punctures.
abstract: OBJECTIVE
  The aim of this study was to evaluate whether spinal canal depth (SCD), measured using ultrasound, could be estimated from simple body measurements in a sample of children.
  
  
  METHODS
  We measured SCD in a group of 225 children aged 0-18 years in the curved left lateral position using ultrasound. Statistical analysis was performed using Pearson's correlation coefficient at the 5% level of significance. We also performed linear regression analyses (analysis of variance) for mid-spinal canal depth (MSCD), including five potential predictors of age, gender, height, weight and body surface area, in each model.
  
  
  RESULTS
  The mean MSCD was 33.0 mm (18.1-56.4) across the whole cohort. The best linear correlation of MSCD (mm) was found with weight (W; kg), approximating the formula MSCD=0.4W+20 (R(2)=0.72). Body weight accounted for 85% of the variance in the data (adjusted R(2)=0.72). Our formula gives values outside of the actual measured SCD range in 23/225 (10.2%) of cases and estimates MSCD at 24 mm at 10 kg, 32 mm at 30 kg and 40 mm at 50 kg.
  
  
  CONCLUSIONS
  We demonstrate a good correlation between weight and MSCD in a large group of children. Use of the simple formula MSCD (mm)=0.4 W+20 could improve the success rates of lumbar puncture in the paediatric population, but remains to be validated.
authors: Department of Paediatrics, Addenbrooke's Hospital, , Cambridge, UK.
authors: Helen C
authors: HC
authors: Bailie
authors: Owen J
authors: OJ
authors: Arthurs
authors: Matthew J
authors: MJ
authors: Murray
authors: A Wilf
authors: AW
authors: Kelsall
mesh_terms: D000293:Adolescent; D000375:Aging / Q000473:pathology; D000886:Anthropometry / Q000379:methods; D001827:Body Height / Q000502:physiology; D001830:Body Surface Area; D001835:Body Weight / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008297:Male; D013115:Spinal Canal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D013129:Spinal Puncture / Q000379:methods*; D014463:Ultrasonography
keywords: General Paediatrics; Imaging; Measurement