High Ionized Calcium Concentration Is Associated With Prolonged Length of Stay in the Intensive Care Unit for Postoperative Pediatric Cardiac Patients

Objective: There has been controversy regarding the beneficial effects of calcium on myocardial contractility and the harmful effects on myocardial cells, especially in children. The aim of this study was to investigate an association between ionized calcium concentration (iCa) and outcomes for pediatric patients after cardiac surgery. Design: A retrospective, single-center study from May 2013 to December 2014. Setting: Referral high-volume pediatric cardiac center in a tertiary teaching hospital. Patients: Patients <72 months old with congenital heart disease who underwent palliative or definitive surgery. Interventions: None. Measurements and Main Results: The association between pH-corrected iCa within 24 hours after surgery and intensive care unit (ICU) length of stay (ILOS) was defined as the primary outcome. The highest iCa (iCa_max), lowest iCa (iCa_min), and time-weighted average iCa (iCa_ave) were stratified and compared with the outcomes. The authors reviewed 5,468 ionized calcium measurements from 357 consecutive pediatric patients during the study period. One patient died at postoperative day 34 in the ICU. Significant differences in ILOS were observed among patients after cardiopulmonary bypass (CPB) according to iCa_ave, iCa_max, and iCa_min but not among patients without CPB. Patients with CPB and an iCa_ave value of 1.31-to-1.40 mmol/L, 1.41-to-1.50 mmol/L, 1.51-to-1.60 mmol/L, and >1.60 mmol/L stayed in the ICU for 7 (interquartile range [IQR] 4-10) days, 8 (IQR 6-16) days, 10 (IQR 8-14) days, and 19 (IQR 12-38) days, respectively, which was significantly longer than the ILOS of 5 (4-8) days for patients with an iCa_ave of 1.21-to-1.30 mmol/L. Even after adjustment for other predictors of ILOS using multivariable analyses, there were significant relationships of ILOS with iCa_ave and iCa_min values of >1.50 mmol/L among patients with CPB. Conclusions: Higher iCa within 24 hours after congenital cardiac surgery using CPB was independently associated with longer LOS in the ICU.