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Is shock index associated with outcome in children with sepsis/septic shock?*
Yuki Yasaka1, Robinder G Khemani, Barry P Markovitz
11Division of Pediatric Critical Care Medicine, Department of Pediatrics, Okinawa Prefectural Nanbu Children's Medical Center, Okinawa, Japan. 2Department of Anesthesiology and Critical Care Medicine, Children's Hospital Los Angeles, Los Angeles, CA. 3Keck School of Medicine, University of Southern California, Los Angeles, CA.
Insights
The pediatric intensive care unit (PICU) shock index, a ratio of heart rate to systolic blood pressure, is associated with mortality in children with sepsis/septic shock. Elevated shock index may indicate a need for aggressive resuscitation and higher care levels.
Area of Science:
- Pediatric critical care medicine
- Pediatric cardiology
- Pediatric emergency medicine
Background:
- Sepsis and septic shock are leading causes of mortality in children admitted to the pediatric intensive care unit (PICU).
- Early identification of children at high risk for mortality is crucial for timely and effective intervention.
- The shock index (SI), calculated as heart rate divided by systolic blood pressure, is a simple, non-invasive bedside tool that has shown potential in predicting outcomes in adult sepsis.
Purpose of the Study:
- To investigate the association between the pediatric shock index (SI) and mortality in children with sepsis/septic shock.
- To explore potential cutoff values for SI in predicting ICU mortality.
- To examine the impact of changes in SI within the first 6 hours of ICU admission and the influence of vasoactive therapy on the SI-mortality relationship.
Main Methods:
- A retrospective cohort study was conducted at a single-center tertiary PICU.
- Data from 544 children diagnosed with sepsis/septic shock between January 2003 and December 2009 were analyzed.
- The study assessed the association of hourly SI with mortality, explored age-specific SI cutoff values, and evaluated the effect of SI changes and vasoactive therapy on outcomes.
Main Results:
- Overall mortality in the cohort was 23.7%.
- Hourly SI was significantly associated with ICU mortality across all time points (0-6 hours), with increasing odds ratios.
- SI at admission was a fair predictive marker for mortality in children aged 1-3 and ≥12 years. Improvement in SI within 6 hours was linked to lower mortality in these age groups when SI was initially elevated. SI at 6 hours remained associated with mortality even after controlling for vasoactive therapy.
Conclusions:
- The pediatric shock index shows promise as a mortality marker in pediatric sepsis/septic shock.
- While no definitive cutoff value for SI reliably predicts mortality across all pediatric age groups, a rising SI correlates with increased mortality risk.
- Children with an elevated SI may benefit from more aggressive resuscitation strategies and a higher level of care to improve outcomes.
Objectives:
To investigate the association between PICU shock index (the ratio of heart rate to systolic blood pressure) and PICU mortality in children with sepsis/septic shock. To explore cutoff values for shock index for ICU mortality, how change in shock index over the first 6 hours of ICU admission is associated with outcome, and how the use of vasoactive therapy may affect shock index and its association with outcome.
Design:
Retrospective cohort.
Setting:
Single-center tertiary PICU.
Subjects:
Five hundred forty-four children with the diagnosis of sepsis/septic shock.
Interventions:
None.
Measurements And Main Results:
From January 2003 to December 2009, 544 children met International Pediatric Sepsis Consensus Conference of 2005 criteria for sepsis/septic shock. Overall mortality was 23.7%. Among all patients, hourly shock index was associated with mortality: odds ratio of ICU mortality at 0 hour, 1.08, 95% CI (1.04-1.12); odds ratio at 1 hour, 1.09 (1.04-1.13); odds ratio at 2 hours, 1.09 (1.05-1.13); and odds ratio at 6 hours, 1.11 (1.06-1.15). When stratified by age, early shock index was associated with mortality only in children 1-3 and more than or equal to 12 years old. Area under the receiver operating characteristic curve in age 1-3 and more than or equal to 12 years old for shock index at admission was 0.69 (95% CI, 0.58-0.80) and 0.62 (95% CI, 0.52-0.72) respectively, indicating a fair predictive marker. Although higher shock index was associated with increased risk of mortality, there was no particular cutoff value with adequate positive or negative likelihood ratios to identify mortality in any age group of children. The improvement of shock index in the first 6 hours of ICU admission was not associated with outcome when analyzed in all patients. However, among patients whose shock index were above the 50th percentile at ICU admission for each age group, improvement of shock index was associated with lower ICU mortality in children between 1-3 and more than or equal to 12 years old (p = 0.02 and p = 0.03, respectively). When controlling for the use of vasoactive therapy within the first 6 hours with logistic regression analysis, shock index at hour 6 remained significantly associated with mortality (odds ratio, 1.09; 95% CI, 1.05-1.14).
Conclusions:
Shock index may have promise as a marker of mortality in children with sepsis/septic shock. Although there is no clear cutoff shock index to identify risk of mortality, given the higher risk of mortality as shock index increases, children with elevated shock index may benefit from more aggressive resuscitation and higher level of care.
