Hypocalcemia in children with septic shock

Introduction

Ionized calcium is essential for maintenance of myocardial function and vascular tone. Ionized hypocalcemia is seen frequently in critically ill patients and is associated with poorer prognosis. It is unclear whether calcium administration is beneficial in these patients.

Objective

To evaluate the incidence of ionized hypocalcemia (Ca²⁺-level < 1.0 mmol/l), the time course of serum ionized calcium (Ca²⁺) in children with septic shock, the effect of calcium administration and the relationship with survival.

Methods

We retrospectively studied 37 children with septic shock. We analyzed Ca²⁺ levels on admission and after 8 and 24 hours, the dose of intravenous calcium administration in the first 24 hours and survival.

Results

The group consisted of 22 boys and 15 girls with a median age of 2.3 years (0.2–16.1 years). The median PRISM-score was 23. There were nine non-survivors. On admission 26 patients (68%) were hypocalcemic (19 survivors and 7 non-survivors). There was a significant negative correlation between PRISM-score and Ca²⁺ levels on admission (r = -0.46, P < 0.01). On admission there was not a significant lower Ca²⁺level in non-survivors compared to survivors (0.89 mmol/l vs 0.96 mmol/l, NS). During the first 24 hours after admission 14/28 survivors and 8/9 non-survivors received calcium administration intravenously. All 22 patients received calcium in a slow infusion during the first 24 hours, 3/14 survivors and 3/8 non-survivors also received a bolus of 0.1 mmol/kg in 30–60 minutes. There was a significant difference in the Ca²⁺ level on admission between survivors with and without Ca²⁺ administration (0.91 mmol/l vs 1.00 mmol/l, P < 0.05) but no significant increase in Ca²⁺ levels was found 24 hours later in these groups (resp 0.20 mmol/l vs 0.28 mmol/l, NS). For the non-survivors Ca²⁺ levels 8 hours after admission were not significantly higher than Ca²⁺ levels at admission (0.95 mmol/l vs 0.89 mmol/l, NS).The dose of calcium varied between 0.07 and 1.8 mmol/kg/day with a mean of 0.55 mmol/kg/day and in non-survivors the dose was significantly higher compared to survivors (0.64 mmol/kg/day vs 0.2 mmol/kg/day, P < 0.01).

Conclusion

The incidence of ionized hypocalcemia in children with septic shock was high (68%), but Ca²⁺ levels were not related to survival at the time of admission in the PICU. However there was a negative correlation with the PRISM-score. In the survivors 24 hours after admission there was no significant increase of Ca²⁺ levels between children with or without Ca²⁺ administration. Non-survivors received more calcium intravenously compared to survivors, but Ca²⁺ levels 8 hours after admission were not significantly higher compared to Ca²⁺ levels at admission despite calcium administration. The question remains if calcium administration leads to significant changes in Ca²⁺ levels and because of the potential adverse effects of calcium administration this treatment should be reconsidered.