Relationship between Lactate levels and Shock Index in pediatric patients with sepsis at a tertiary care Hospital in Karachi, Pakistan.

Abstract

Background & Objectives: Septic shock is common in children and is linked to high rates of
mortality and morbidity. Early identification of severe sepsis can improve outcomes. The Shock
Index (SI), which is the ratio of heart rate (HR) to systolic blood pressure (SBP), could serve as
a valuable noninvasive indicator of hemodynamic instability; however, it has been inadequately
studied in pediatric populations. The objective of this study was to assess the potential of SI as
an early prognostic marker for septic shock in children.
Methods: A cross-sectional study was conducted on children aged 1 to 60 months who
presented with septic shock at the pediatric intensive care unit of Civil Hospital Karachi. Heart
rate (HR) and systolic blood pressure (SBP) were recorded for Shock Index (SI) calculation,
along with lactate concentrations, at 0, 2, 4, and 6 hours after admission. The outcome (death or
survival) was documented for all patients. We calculated the Pearson correlation coefficient (r)
between SI and lactate levels and assessed the area under the curve (AUC) to determine the
sensitivity and specificity of both SI and lactate levels in predicting mortality.
Results: This study enrolled 153 children admitted with septic shock, with an almost equal
distribution of males and females. The mortality rate was 63.4%, with significant differences
observed in survival rates across age groups, particularly between 1-2 years and 2-4 years
(p=0.049). Gastroenteritis was the most common diagnosis, while myocarditis was more
prevalent in deceased patients (p<0.0001). A strong correlation between serum lactate levels
and Shock Index (SI) was found (r=0.910 to 0.942, p<0.001), with both markers showing high
sensitivity and specificity for predicting mortality across various time intervals. The Shock
Index demonstrated strong diagnostic performance across all age groups, making it a reliable
prognostic tool for pediatric septic shock.
Conclusions: In our cohort of children with septic shock, the Shock Index (SI) proved to be a
clinically significant and easily calculated predictor of mortality. It may provide a more accurate
assessment of hemodynamic status than heart rate (HR) and systolic blood pressure (SBP)
alone, enabling earlier detection of severe sepsis.
KeyWords: sepsis, severe sepsis, septic shock, shock index, prognostic, lactate level