title: Measuring skin to subarachnoid space depth in Egyptian population: A prospective cohort study.
abstract: BACKGROUND
  Lumbar puncture is a difficult medical skill and is used for administering subarachnoid anesthetic medications. Estimation of skin to subarachnoid space depth (SSD) helps to reduce post spinal anesthetic complications.
  
  
  OBJECTIVE
  To measure the SDD in overall Egyptian population and to find a formula for predicting SSD in Egyptian patients.
  
  
  METHODS
  Four hundred patients of American Society of Anesthesiologist class I and II adult Egyptian patients undergoing surgery using spinal anesthesia in general and obstetric surgery unit, Mansoura University main hospital, were included in this prospective, observational study.
  
  
  METHODS
  Patients were divided into three groups: Males (Group M), nonpregnant females (Group F), and pregnant females (Group PF). SSD was measured after performing lumbar puncture. The relationship between SSD and patient characteristics was studied; correlated and statistical analysis was used to find a formula for predicting SSD.
  
  
  METHODS
  Statistical analysis was done using Statistical Package for Social Sciences (SPSS 19.0, Chicago, IL, USA). One-way ANOVA withpost hoc(Bonferroni correction factor) analysis was applied to compare the three groups. All the covariates in the study further were taken for multivariate analysis. Multivariate regression analysis was performed to evaluate important covariates influencing SSD for each group separately.
  
  
  RESULTS
  Mean SSD was 4.99 ± 0.48 cm in the overall population. SSD in adult males (4.93 ± 0.47 cm) was significantly longer than that observed in females (4.22 ± 0.49 cm) but was comparable with SSD in parturient (4.32 ± 0.47 cm). Formula for predicting SSD in the overall population was 2.1+ (0.009 × height) + (0.03 × weight) + (0.02 × body mass index [BMI]) + (0.15 × body surface area [BSA]). Craig's formula when applied correlated best with the observed SSD.
  
  
  CONCLUSIONS
  SSD in adult males was significantly longer than that in both pregnant and nonpregnant females, but it was nearly the same in pregnant and nonpregnant females. SSD in Egyptian population can be calculated based on height, weight, BMI, and BSA. Craig's formula was the most suitable to be applied to Egyptian population.
authors.affiliation: Department of Anesthesia and Surgical Intensive Care, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt.
authors.forename: Hani Ibrahim
authors.initials: HI
authors.lastname: Taman
authors.affiliation: Department of Anesthesia and Surgical Intensive Care, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt.
authors.forename: Ahmed Mohamed
authors.initials: AM
authors.lastname: Farid
authors.affiliation: Department of Gynecology and Obstetrics, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt.
authors.forename: Waleed Mohamed
authors.initials: WM
authors.lastname: Abdelghaffar
keywords: Intrathecal; lumbar puncture; predictive formulae; subarachnoid space depth