Scandinavian journal of clinical and laboratory investigation. Supplementum
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Scand J Clin Lab Invest Suppl · Jan 1984
A quality control simulator for design and evaluation of internal quality control procedures.
A computer simulation program has been developed to aid clinical chemists in the design and theoretical evaluation of statistical control procedures. This "QC simulator" permits the user to study the effects of different parameters characterizing the measurement procedure (method standard deviation, components of variation, rounding of results) and parameters of the control procedure (decision criteria, control limits, number of observations). The performance of control procedures is characterized by the probability for rejection, estimated at several different levels of random and systematic error. ⋯ The relative performance of different control procedures can be compared based on these performance characteristics. Another important application of the program is the design of control procedures to assure that a specified level of analytical quality is achieved in routine analyses. Various optimization criteria may be applied, e.g., in terms of test yield and cost.
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The Henderson-Hasselbalch equation has always occupied a central place in the description of the acid-base status of the blood. An equation of similar importance is the equation for the CO2 equilibration curve of blood in vitro. It is proposed to name this the Van Slyke equation: a - 24.4 = - (2.3 X b + 7.7) X (c - 7.40) + d/(1 - 0.023 X b), where a = bicarbonate concentration in plasma/(mmol/l), b = hemoglobin concentration in blood/(mmol/l), c = pH of plasma at 37 degrees C, d = base excess concentration in blood/(mmol/l). These two equations provide an arithmetic algorithm for calculation of the various acid-base variables of the blood after measuring the pH, the pCO2, and the hemoglobin concentration.