Fig. 2. Linear regression analysis of 360 paired arterial hemoglobin to pulse hemoglobin (SpHb) measurements obtained from 91 patients undergoing abdominal or pelvic surgery (R 2= 0.48, root mean square error 1.30 g/dl, slope = 0.67, 95% confidence interval 0.60 to 0.74 shown by dashed lines ) (A ). Plot of SpHb to arterial hemoglobin difference (bias) compared with arterial hemoglobin (R 2= 0.18; root mean square error = 1.30 g/dl; slope = −0.33, 95% confidence interval −0.40 to −0.26, shown by dashed lines ). Bias is positive when SpHb is higher than arterial hemoglobin (B ).
