A new indicator dilution method for the estimation of surgical blood loss.

The principles of using indicator dilution techniques for the estimation of blood loss on swabs are explained. The feasibility of an intrinsic indicator such as intracellular and extracellular potassium ions was investigated. An empirical mathematical relationship between the total potassium content per litre of whole blood and the haemoglobin concentration of whole blood was established. The correlation between these two variables is statistically highly significant. The derived total potassium content per litre was then used with the indicator dilution technique to calculate the volume of blood lost. The accuracy, sources of error and advantages of the technique are discussed.