[Early evaluation of anaemia in patients with acute gastrointestinal bleeding: venous blood gas analysis compared to conventional laboratory].

BACKGROUND AND OBJECTIVE: Evaluation of patients with acute gastrointestinal bleeding (AGB) requires early clinical evaluation and analysis. The aim of this study is to evaluate early concordance of hemoglobin (Hb) and hematocrit (HTC) levels determined by conventional venous blood gas analysis (VBG) and by conventional Laboratory in Emergencies (LAB).

PATIENTS AND METHODS: Observational and prospective study of patients admitted in the Gastrointestinal Haemorrhage Unit with both high and low AGB. Demographic and clinical variables and simultaneous venous blood samples were obtained to determine Hb and HTC by VBG and LAB. Concordance in both methods was analysed by intra-class correlation coefficient (ICC) and Bland-Altman analysis.

RESULTS: One hundred and thirty-two patients were included: 87 (65.9%) males, average age 66.8 years. VBG overestimated Hb in 0.49 g/dl (95% confidence interval: 0.21-0.76) with respect to LAB. Concordance was very high in Hb (ICC 0.931) and high in HTC (0.899), with the Bland-Altman graphs showing both concordance and overestimation of Hb levels determined by VBG. In 19 patients (14.39%), Hb by VBG exceeded in more than 1g/dL the final determination obtained by LAB.

CONCLUSIONS: Early determination of Hb and HTC in patients with AGB by VBG provides reliable results in the initial evaluation of anaemia. VBG systematically overestimates Hb values by less than 0.5 g/dl, and therefore clinical and hemodynamic evaluation of the bleeding patient should prevail over analytical results.