Fig. 2

Bland-Altman analysis of the difference in potassium between the three sampling sites when analysed by blood gas analyser. For each comparison, the mean value between the two sites is plotted against their difference. Red dash lines represent the ±0.5 mmol/L upper and lower limits of standard criteria for acceptable performance for potassium. CV = central vein; FA = femoral artery; K + =potassium; PV = peripheral vein