Selenium in critically ill children with cardiac dysfunction

Introduction

Selenium (Se) and selenocysteine residues are essential for the activity of glutathione peroxidase enzyme (GPX). GPX plays an important role in antioxidant defense. Se deficiency is reported in critically ill patients due to deficient dietetic intake, unsupplemented parenteral nutrition, catabolic state and increased losses. The objective of the study was to study the Se and GPX status in critically ill children with cardiac dysfunction and the effects of Se supplementation.

Methods

Thirty-five critically ill cardiac children (mean age: 2.82 ± 3.41 years) with different cardiac disorders (15 with myocarditis, 15 with cardiomyopathy and five with rheumatic heart disease) were investigated for blood Se and GPX levels and echocardiographic parameters at admission and after 3 days of parenteral Se supplementation (initial dose of 2 μg/kg/day on the first day followed by 1 μg/kg/day). Fifteen healthy children were included as controls.

Results

At admission, Se and GPX levels were significantly decreased in patients (6.61 ± 1.16 μg/l and 10.8 ± 1.14 U/l) compared with controls (16.06 ± 2.08 μg/l and 20.64 ± 2.13 U/l) (P < 0.001). Se levels did not differ between studied cardiac diseases (P > 0.05). Se levels correlated positively with corresponding ejection fraction values (EF) (r = 0.57 and P < 0.05) and fractional shortening values (FS) (r = 0.45 and P < 0.05), and negatively with left ventricular end-diastolic diameter (r = -0.50 and P < 0.05). After Se supplementation, Se and GPX were raised (16.53 ± 2.25 μg/l and 19.71 ± 2.63 U/l). Clinical examination revealed that orthopnea improved in 88.6% of cases and dys-rhythmia disappeared in 65.7%. Echocardiography showed that EF and FS were also significantly improved (admission values for EF and FS were 34.6 ± 7.4 and 16.8 ± 4.1, compared with 52.6 ± 11.4 and 27.7 ± 6.8 after Se supplementation; P < 0.05).

Conclusion

Se deficiency is one of the mechanisms of worsening cardiac dysfunction in critically ill patients regardless of the underlying cardiac etiology. Se supplementation can reverse such a mechanism and improve cardiac performance.