Highest daily serum sodium during the intensive care unit stay. Serum sodium (Na) values measured during intensive care unit (ICU) days when desmopressin acetate (DDAVP) was not administered (red dots) and when DDAVP was administered (blue circles). Data reported in the upper part of the plot represent the number of patients under observation on each ICU day of stay (the number decreases from left to right owing to discharge from ICU or owing to patient death). Horizontal dotted line, cut-off level of 145 mmol/l used to define hypernatremia. DDAVP was associated with higher serum Na levels (P < 0.001). The association between DDAVP and hypernatremia was not evident in the latest period of the ICU stay, possibly owing to the lowering effect of DDAVP on serum Na.