[Hypernatremic alkalosis. Possible counterpart of hyperchloremic acidosis in intensive care patients?].

BACKGROUND: With broad acceptance of Stewart's acid-base model "hyperchloremic acidosis" is regarded as an independent form of metabolic disorder. It is unknown whether hypernatremia plays a corresponding role with respect to the development of alkalosis.
METHODS: A total of 201 artificially ventilated, critically ill patients were monitored for hypernatremic episodes. Inclusion criterion was a serum sodium concentration above 145 mmol/l.
RESULTS: In 20 patients a total of 78 periods of elevated plasma sodium levels lasting at least 24 h were observed. In 86% of these cases sodium and chloride concentrations were simultaneously increased. The development of alkalosis correlated with the strong ion difference (r=0.80, p<0.01) but not with the serum sodium concentration (r=-0.031, p=0.78). In cases without accompanying hyperchloremia (13%) metabolic alkalosis regularly occurred and a correlation between serum sodium concentration and base excess could be verified (r=0.66, p=0.03). Alkalosis occurred in 84.8% of cases where the strong on difference exceeded 39 mmol/l.
CONCLUSION: From the available data hypernatremic alkalosis could not be defined as an independent metabolic disorder. In would seem more appropriate to use the term "strong ion alkalosis" in this context.