Age- and sex-specific normal values for shock index in National Health and Nutrition Examination Survey 1999-2008 for ages 8 years and older

Published:March 13, 2013DOI:



      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.

      Basic procedures

      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.

      Main findings

      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.


      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.
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        • Allgower M.
        • Burri C.
        Shock index.
        Deutsch Med Wochenschr. 1967; 92: 1947-1950
        • King R.W.
        • Plewa M.C.
        • Buderer N.M.
        • Knotts F.B.
        Shock index as a marker for significant injury in trauma patients.
        Acad Emerg Med. 1996; 3: 1041-1045
        • McMahon C.G.
        • Kenny R.
        • Bennett K.
        • Little R.
        • Kirkman E.
        The effect of acute traumatic brain injury on the performance of shock index.
        J Trauma. 2010; 69: 1169-1175
        • Vandromme M.J.
        • Griffin R.L.
        • Kerby J.D.
        • McGwin Jr., G.
        • Rue 3rd, L.W.
        • Weinberg J.A.
        Identifying risk for massive transfusion in the relatively normotensive patient: utility of the prehospital shock index.
        J Trauma. 2011; 70 (discussion 388–390): 384-388
        • Bircan A.
        • Karadeniz N.
        • Ozden A.
        • et al.
        A simple clinical model composed of ECG, shock index, and arterial blood gas analysis for predicting severe pulmonary embolism.
        Clin Appl Thromb Hemost. 2011; 17: 188-196
        • Sankaran P.
        • Kamath A.V.
        • Tariq S.M.
        • et al.
        Are shock index and adjusted shock index useful in predicting mortality and length of stay in community-acquired pneumonia?.
        Eur J Intern Med. 2011; 22: 282-285
        • Birkhahn R.H.
        • Gaeta T.J.
        • Terry D.
        • Bove J.J.
        • Tloczkowski J.
        Shock index in diagnosing early acute hypovolemia.
        Am J Emerg Med. 2005; 23: 323-326
        • Birkhahn R.H.
        • Gaeta T.J.
        • Van Deusen S.K.
        • Tloczkowski J.
        The ability of traditional vital signs and shock index to identify ruptured ectopic pregnancy.
        Am J Obstet Gynecol. 2003; 189: 1293-1296
        • Jaramillo S.
        • Barnhart K.
        • Takacs P.
        Use of the shock index to predict ruptured ectopic pregnancies.
        Int J Gynaecol Obstet. 2011; 112: 68
        • Talmor D.
        • Jones A.E.
        • Rubinson L.
        • Howell M.D.
        • Shapiro N.I.
        Simple triage scoring system predicting death and the need for critical care resources for use during epidemics.
        Crit Care Med. 2007; 35: 1251-1256
        • Cannon C.M.
        • Braxton C.C.
        • Kling-Smith M.
        • Mahnken J.D.
        • Carlton E.
        • Moncure M.
        Utility of the shock index in predicting mortality in traumatically injured patients.
        J Trauma. 2009; 67: 1426-1430
        • Rady M.Y.
        • Smithline H.A.
        • Blake H.
        • Nowak R.
        • Rivers E.
        A comparison of the shock index and conventional vital signs to identify acute, critical illness in the emergency department.
        Ann Emerg Med. 1994; 24: 685-690
        • Rady M.Y.
        • Rivers E.P.
        • Nowak R.M.
        Resuscitation of the critically ill in the ED: responses of blood pressure, heart rate, shock index, central venous oxygen saturation, and lactate.
        Am J Emerg Med. 1996; 14: 218-225
        • Keller A.S.
        • Kirkland L.L.
        • Rajasekaran S.Y.
        • Cha S.
        • Rady M.Y.
        • Huddleston J.M.
        Unplanned transfers to the intensive care unit: the role of the shock index.
        J Hosp Med. 2010; 5: 460-465
        • Chen L.
        • Reisner A.T.
        • Gribok A.
        • Reifman J.
        Exploration of prehospital vital sign trends for the prediction of trauma outcomes.
        Prehosp Emerg Care. 2009; 13: 286-294
        • Guyette F.
        • Suffoletto B.
        • Castillo J.L.
        • Quintero J.
        • Callaway C.
        • Puyana J.C.
        Prehospital serum lactate as a predictor of outcomes in trauma patients: a retrospective observational study.
        J Trauma. 2011; 70: 782-786
        • Stone T.J.
        • Riesenman P.J.
        • Charles A.G.
        Red blood cell transfusion within the first 24 hours of admission is associated with increased mortality in the pediatric trauma population: a retrospective cohort study.
        J Trauma Manag outcomes. 2008; 2: 9
        • Newgard C.D.
        • Cudnik M.
        • Warden C.R.
        • Hedges J.R.
        The predictive value and appropriate ranges of prehospital physiological parameters for high-risk injured children.
        Pediatr Emerg Care. 2007; 23: 450-456
        • Kline J.A.
        • Corredor D.M.
        • Hogg M.M.
        • Hernandez J.
        • Jones A.E.
        Normalization of vital signs does not reduce the probability of acute pulmonary embolism in symptomatic emergency department patients.
        Acad Emerg Med. 2012; 19: 11-17
        • Paladino L.
        • Subramanian R.A.
        • Nabors S.
        • Sinert R.
        The utility of shock index in differentiating major from minor injury.
        Eur J Emerg Med. 2011; 18: 94-98
        • Ott R.
        • Kramer R.
        • Martus P.
        • Bussenius-Kammerer M.
        • Carbon R.
        • Rupprecht H.
        Prognostic value of trauma scores in pediatric patients with multiple injuries.
        J Trauma. 2000; 49: 729-736
        • Zarzaur B.L.
        • Croce M.A.
        • Fischer P.E.
        • Magnotti L.J.
        • Fabian T.C.
        New vitals after injury: shock index for the young and age x shock index for the old.
        J Surg Res. 2008; 147: 229-236
        • Fuchs S.
        • Yamamoto L.
        • American Academy of Pediatrics
        • American College of Emergency Physicians
        APLS: the pediatric emergency medicine resource. 5th ed. Jones & Bartlett Learning, Burlington, MA2012
        • Kleinman M.E.
        • Chameides L.
        • Schexnayder S.M.
        • et al.
        Pediatric advanced life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
        Pediatrics. 2010; 126: e1361-e1399
        • Tschudy M.M.
        • Arcara K.M.
        Johns Hopkins Hospital. Children's Medical and Surgical Center. The Harriet Lane handbook: a manual for pediatric house officers. 19th ed. Elsevier Mosby, Philadelphia, PA2012
        • National Center for Health Statistics
        National Health and Nutrition Examination Survey Data.
        in: Centers for Disease Control and Prevention. U.S. Department of Health and Human Services, Hyattsvile, MD1999–2008
        • National Center for Health Statistics
        National Health and Nutrition Examination Survey: Physician Examination Procedures Manual. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, Hyattsville, MD2007
      1. Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: methods and development. Vital and health statistics. Series 11, Data from the national health survey. May 2002(246):1–190

        • Cole T.J.
        Using the LMS method to measure skewness in the NCHS and Dutch National height standards.
        Ann Hum Biol. 1989; 16: 407-419
      2. R: A Language and Environment for Statistical Computing [computer program]: R Foundation for Statistical Computing; 2011.

        • Park M.K.
        Blood pressure tables.
        Pediatrics. 2005; 115 ([author reply 827]): 826-827