For healthcare professionals
SIPA: shock index, pediatric age-adjusted
SIPA is the shock index (heart rate divided by systolic blood pressure) read against a cut point for the child's age. It was built for injured children aged 4 to 16. This calculator is written for clinicians caring for an injured child and is not a diagnosis.
Age and vital signs
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What you will see
The shock index, the cut point for the child's age, and whether SIPA is elevated.
Educational only, not medical advice. Not a diagnosis. Treatment decisions belong to the treating team.
Source
Cut points of the original study (Acker SN and colleagues, Journal of Pediatric Surgery 2015, cited only) as printed in Table 1 of Yoon SH and colleagues, PLOS ONE 2024 (open access, CC BY 4.0). Checked against two more open CC BY 4.0 papers: Cuenca CM and colleagues, Military Medical Research 2020, and Huang KC and colleagues, Frontiers in Pediatrics 2021. Licences were checked in the Europe PMC full text. The tests check every band edge.
Validated in
Children aged 4 to 16 admitted after blunt trauma with an injury severity score above 15, in a multicenter US study from January to June 2014 (as summarised in Yoon 2024). Later studies applied SIPA to children injured in Iraq and Afghanistan (Cuenca 2020) and to children admitted to intensive care without trauma (Huang 2021).
Limits
In a meta-analysis of 12 studies, SIPA at the hospital predicted death with a pooled sensitivity of 0.58 and specificity of 0.72; the authors advise caution because of its limited sensitivity (Yoon 2024). In combat casualties, thresholds that best fit the data varied by age from 1.0 to 1.9, though negative predictive values were all above 0.87 (Cuenca 2020). Children under 4 and over 16 were outside the original age bands.
Formula
Shock index = heart rate / systolic blood pressure. SIPA compares this ratio with a cut point for age. Each cut point comes from the maximum normal heart rate and the minimum normal systolic blood pressure for that age (Yoon 2024) (Huang 2021).
SIPA is elevated when the shock index is above the cut point (Huang 2021).
Worked example: a 10 year old with a heart rate of 110 beats per minute and a systolic blood pressure of 100 mmHg has 110 / 100 = 1.10. That is above the 7 to 12 year cut point of 1.0, so SIPA is elevated. The same numbers in a 5 year old (cut point 1.22) are not elevated.
Cut points by age
| Age | SIPA elevated if above |
|---|---|
| 4 to 6 years | 1.22 |
| 7 to 12 years | 1.0 |
| 13 to 16 years | 0.9 |
Source: the original study's cut points as printed by Yoon and colleagues 2024 (Yoon 2024), from Acker and colleagues 2015 (Acker 2015). Later studies round the 4 to 6 year cut point to 1.2 and use 1.0 for 7 to 12 years and 0.9 for older children (Cuenca 2020) (Huang 2021). Some also apply 1.2 to children aged 1 to 3 (Cuenca 2020); this calculator keeps to the original 4 to 16 year range.
What studies found
A 2024 systematic review and meta-analysis pooled 12 studies of injured children aged 18 or younger. For predicting death, SIPA at the hospital had a pooled sensitivity of 0.58 and specificity of 0.72 (area under the curve 0.693), and SIPA before hospital had 0.61 and 0.67. The unadjusted shock index had 0.71 and 0.45 (Yoon 2024).
In 3,145 children injured in Iraq and Afghanistan, the published cut points gave sensitivities of 0.63 to 0.80 and specificities of 0.35 to 0.62 for massive transfusion across age groups (Cuenca 2020).
In 1,732 children admitted to intensive care without trauma in Taiwan, SIPA 24 hours after admission was associated with higher mortality (Huang 2021).
Related calculators
The shock index calculator gives the same ratio with the adult trauma shock groups. For bleeding in injured patients, see the ABC score for massive transfusion and the RABT score, both studied mainly in adults. For a scored check of six injury findings, see the Pediatric Trauma Score. For a child with a head injury, see the PECARN head injury rule and the Pediatric Glasgow Coma Scale. For a child on a hospital ward, see the Pediatric Early Warning Score. Other bedside scores are listed under For healthcare professionals.
Sources
- Yoon SH, Shin SJ, Kim H, Roh YH. Shock index and shock index, pediatric age-adjusted as predictors of mortality in pediatric patients with trauma: a systematic review and meta-analysis. PLoS One. 2024;19(7):e0307367. doi:10.1371/journal.pone.0307367. PMID 39024206. Open access (CC BY 4.0). Table 1: SIPA cut points of Acker 2015 (4-6 y 1.22; 7-12 y 1.0; 13-16 y 0.9) and study population; methods: cut point from maximum normal heart rate and minimum normal systolic blood pressure; pooled sensitivity and specificity for mortality. pmc.ncbi.nlm.nih.gov/articles/PMC11257222/
- Cuenca CM, Borgman MA, April MD, Fisher AD, Schauer SG. Validation of the age-adjusted shock index for pediatric casualties in Iraq and Afghanistan. Mil Med Res. 2020;7:33. doi:10.1186/s40779-020-00262-8. PMID 32616047. Open access (CC BY 4.0). Methods: published SIPA thresholds by age (1-3 y 1.2, 4-6 y 1.2, 7-12 y 1.0, 13-17 y 0.9); sensitivity, specificity and negative predictive value for massive transfusion and death. pmc.ncbi.nlm.nih.gov/articles/PMC7331217/
- Huang KC, Yang Y, Li CJ, Cheng FJ, Huang YH, Chuang PC, Chiu IM. Shock Index, Pediatric Age-Adjusted Predicts Morbidity and Mortality in Children Admitted to the Intensive Care Unit. Front Pediatr. 2021;9:727466. doi:10.3389/fped.2021.727466. PMID 34650944. Open access (CC BY 4.0). Definition (maximum normal heart rate divided by minimum normal systolic blood pressure by age), Table 1 cut points, elevated defined as above the cut point. pmc.ncbi.nlm.nih.gov/articles/PMC8506146/
- Acker SN, Ross JT, Partrick DA, Tong S, Bensard DD. Pediatric specific shock index accurately identifies severely injured children. J Pediatr Surg. 2015;50(2):331-334. doi:10.1016/j.jpedsurg.2014.08.009. PMID 25638631. Original SIPA study (cited, not quoted). doi.org/10.1016/j.jpedsurg.2014.08.009
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