title: Age- and sex-specific normal values for shock index in National Health and Nutrition Examination Survey 1999-2008 for ages 8 years and older.
abstract: OBJECTIVE
  Shock index (SI), the ratio of heart rate to systolic blood pressure, has found to outperform conventional vital signs as a predictor of shock. Although age-specific vital sign norms are recommended in screening for shock, there are no reported age- or sex-specific norms for SI. Our primary goal was to report age- and sex-specific SI normal values for a nationally representative population 10 years and older by 5-year age groups. A secondary goal was to report SI normal values for children ages 8 to 19 years by 1-year age groups.
  
  
  METHODS
  Weighted data from the National Health and Nutrition Examination Survey 1999-2008 data sets were used to generate age- and sex-specific percentile curves of SI for subjects 8 years and older.
  
  
  RESULTS
  The primary analysis included 33906 subjects (101837 weighted) 10 years and older. The secondary analysis included 13393 subjects (37983 weighted) 8 to 19 years old. Normalized SI values for each percentile decreased with increasing age and were higher for females across all ages. The most commonly cited SI threshold of 0.9 exceeded the 97th percentile for males younger than 25 years and for females younger than 40 years.
  
  
  CONCLUSIONS
  This first report of age- and sex-specific normal values for SI indicates that SI norms vary by age and sex. Just as age-specific vital sign norms are recommended in screening for shock, our findings suggest that age- and sex-specific SI norms may be more effective in screening for shock than a single-value threshold.
authors.affiliation: Children's Hospital Colorado, Aurora, CO, USA. lara.rappaport@childrenscolorado.org
authors.forename: Lara D
authors.initials: LD
authors.lastname: Rappaport
authors.forename: Sara
authors.initials: S
authors.lastname: Deakyne
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Carcillo
authors.forename: Kim
authors.initials: K
authors.lastname: McFann
authors.forename: Marion R
authors.initials: MR
authors.lastname: Sills
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D012015:Reference Standards; D012016:Reference Values; D012189:Retrospective Studies; D017678:Sex Distribution; D012769:Shock / Q000175:diagnosis* / Q000503:physiopathology; D014481:United States; D055815:Young Adult