[The importance of the preoperative measurement of hemoglobin concentration. Evaluation of a colorimetric method (Hemocue)].

The present study compares two methods of haemoglobin measurement during surgery in 40 patients aged 1 to 85 years. The reference method is the Coulter STKS based on red cell count and mean cellular content in haemoglobin measurement. The method tested (Hemocue-Diagnostics Transfusion) allows instantaneous determination of haemoglobin on a 10 mu sample by measuring infrared absorption by haemoglobin in the 565 and 880 nm wavelengths. These methods have been compared using the method of assessment of agreement described by Bland and Altman. As previous reports suggested that the precision of haemoglobin measurement by Hemocue could depend on the capillary or venous site of sampling, we assessed agreement of the two methods of measurement of haemoglobin at both sites. In addition, the relationship between hematocrit and haemoglobin measured by either method has been assessed. On venous samples, there was a good agreement between the two methods of measurement of haemoglobin (n = 47), with a mean difference of -0.166 g/dl-1 and agreement limits of -1.041 g/dl-1 and +0.195 g/dl-1. Ninety six percent of the observed differences to two methods were within the 95% confidence interval. On capillary samples, there was a poor agreement between Hemocue and Coulter since the mean difference was -0.272 g/dl-1 with the following limits of agreement: -2.356 g/dl-1 and +1.812 g/dl-1. Only 92% of the observed differences were within the 95% confidence interval, with 17% of these being greater than the clinically accepted limit of 1 g/dl-1. The precision of Hemocue measurement of capillary blood haemoglobin was only +/- 16%.(ABSTRACT TRUNCATED AT 250 WORDS)