The usefulness of non‐invasive co‐oximetry haemoglobin measurement for screening pre‐operative anaemia
Yuhe Ke, Kyu-Sic Hwang, Thiri Naing Thin, Yilin Eileen Sim, Hairil Rizal Abdullah
Abstract
Summary Pre‐operative anaemia (haemoglobin < 13.0 g.dl −1 ) is a modifiable peri‐operative risk‐factor. This is screened for using formal laboratory testing. A non‐invasive finger‐probe sensor that can accurately measure haemoglobin is a possible alternative. This study considers the accuracy of non‐invasive haemoglobin measurement using the Rad‐67™ Rainbow (Masimo Corp., Irvine, CA, USA) compared with formal laboratory testing and its usefulness in detecting pre‐operative anaemia. A total of 392 patients had measurements taken for non‐invasive haemoglobin and perfusion index values using the Rad‐67 Rainbow, alongside further peri‐operative parameters and a formal laboratory haemoglobin test. Bland–Altman and sensitivity analysis showed that the limits of agreement between non‐invasive and formal laboratory haemoglobin testing were between −1.95 g.dl −1 and 2.23 g.dl −1 (p < 0.001). The overall performance of non‐invasive haemoglobin measurement was better in men than women (ROC 91.1% vs. 78.2%) and less biased in men, mean −0.08 (SD 1.09, 95%Cl −0.23–0.07) compared with women (mean 0.38 (SD 0.99, 95%CI 0.24–0.52)). Pre‐operative anaemia was more prevalent in women than men (50.3% vs. 14.4%). The sensitivity of non‐invasive anaemia detection (haemoglobin < 13 g.dl −1 ) was 66% for women and 52% for men. A non‐invasive haemoglobin value of 14.0 g.dl −1 had an overall 91% sensitivity for detecting pre‐operative anaemia (82% in men and 93% in women). The Rad‐67 Rainbow is inadequate for the estimation of formal laboratory haemoglobin and lacks sensitivity for detecting pre‐operative anaemia, especially in women. Further advancement in technology and accuracy is needed before it can be recommended as a routine pre‐operative screening test.