Endogenous Na/K ATPase inhibitor ouabain in critically ill children with lung injury.

OBJECTIVE

To measure ouabain, an endogenous adrenocortical Na/K ATPase inhibitor, in critically ill children with acute lung injury and relate it to parameters reflecting epithelial sodium transport.

METHODS

Prospective observational study.

METHODS

Paediatric Intensive Care Unit of Royal Liverpool Children's Hospital.

METHODS

Consecutive children ventilated on a Paediatric Intensive Care Unit.

RESULTS

27 patients were recruited including 11 children with septicemia, 5 patients with localized infections, and 11 patients ventilated for non-infective causes like elective surgery and head injury. Median age of included patients was 5 years (range 1.1-15.5 years). 17 patients had lung injury with radiological evidence of pulmonary edema and/or a paO(2)/FiO(2) ratio of <300 on admission. Ouabain levels were measured in peripheral blood by radioimmunoassay on admission and correlated with sweat sodium levels and renal sodium excretion, paO(2)/FiO(2) ratio and analysis of a chest X-ray on admission. Ouabain levels in all patients had a mean of 23.6pmol/l (SD 13.3, range 10.2-58.2). Ouabain levels were higher in male patients versus female. Children with radiological evidence of septicemia related pulmonary edema, ventilation requirements indicating lung injury or inotrope requirements did not have significantly different ouabain levels compared to patients without lung injury or not on inotropes. There was no significant correlation between sweat sodium or renal sodium excretion and ouabain levels (p=0.91 and p=0.19 respectively).

CONCLUSIONS

Ouabain levels in children ventilated on a Paediatric Intensive Care Unit were not different in patients with lung injury or inotrope requirements. Quabain levels did not relate to parameters reflecting epithelial sodium transport in sweat gland or kidney.