RESEARCH Open Access

The relationship between serum potassium, potassium variability and in-hospital mortality in critically ill patients and a before-after analysis on mortality from 23.3 % before introduction of GRIP-II to 19.9 % afterward (P <0.001) was not related to a specific potassium Hessels et al. Critical Care (2015) 19:4 DOI 10.1186/s13054-014-0720-9Center Groningen, Hanzeplein 1, Groningen 9700 RB, the Netherland