Non-Invasive Haemoglobin Estimation in Patients with Thalassaemia Major

Objectives: this study aimed to validate pulse co-oximetry-based haemoglobin (hb) estimation inchildren and adults with thalassaemia major (tm) and to determine the impact of different baseline variables on the accuracy of the estimation. methods: this observational study was conducted over a five-week period from march to april 2012. a total of 108 patients with tm attending the daycare thalassaemia centre of a tertiary care hospital in muscat, oman, were enrolled. spot (sp) hb measurements were estimated using a pronto-7® pulse co-oximetry device (masimo corp., irvine, california, usa). these were compared to venous samples of hb using the cell-dyn sapphire hematology analyzer (abbott diagnostics, abbott park, illinois, usa) to determine the reference (ref) hb levels. a multivariable linear regression model was used to assess the impact of baseline variables such as age, gender, weight, height, ref hb and blood pressure on the hb estimations. results: of the 108 enrolled patients, there were 54 males and 54 females with a mean age of 21.6 years (standard deviation [sd] = 7.3 years; range: 2.5–38 years). the mean ref hb and sp hb were 9.4 g/dl (sd = 0.9 g/dl; range: 7.5–12.3 g/dl) and 11.1 g/dl (sd = 1.2 g/dl; range: 7.5–14.7 g/dl), respectively. the coefficient of determination (r2) was 21% with a mean difference of 1.7 g/dl (sd = 1.1 g/dl; range: −0.9–4.3 g/dl). in the multivariable model, the ref hb level (p = 0.001) was the only statistically significant predictor. conclusion: the pronto-7® pulse co-oximetry device was found to overestimate hb levels in patients with tm and therefore cannot be recommended. further larger studies are needed to confirm these results.