Figure 2: Bland-Altman plot of the average TcpCO2 and blood pCO2 values. Bland-Altman plot of the average TcpCO2 and blood pCO2 values (-axis) and difference between TcpCO2 and blood pCO2 values (-axis). . Mean bias = −0.93 kPa and 95% confidence limit of agreement = −4.05 to +2.16 kPa.