Table 3

 Agreement between arterial and venous pH, bicarbonate, lactate, and base excess (cluster analysis)

VariableNo. of samplesMean difference (venous – arterial)95% limits of agreement
pH110−0.03 mmol/l−0.07 to 0.01
Bicarbonate1100.32 mmol/l−1.75 to 2.40
Lactate1090.07 mmol/l−0.31 to 0.45
Base excess1070.24 mmol/l−1.63 to 2.10