The observed unadjusted range of values for the horses in this study was 29 to 42 mmol/L plasma tCO2. These unadjusted values were determined after all manufacturer-provided control and calibrator samples were documented to be within acceptable ranges for the Beckman Synchron EL-ISE instrument (model no446813). In this study, five different horses had at least one unadjusted reading of greater than 39 mmol/L tCO2 after receiving 500 mg furosemide, and one horse had an unadjusted tCO2 reading of greater than 39 mmol/L after receiving 250 mg furosemide. However, after using the slope adjustment based on the NERL standard solutions, none of the 216 duplicate determina- tions of plasma tCO2 values for horses that had received furosemide at least 1 hour before sampling exceeded 39 mmol/L.We evaluated the NERLregression line used to adjust the plasma tCO2 values and found that our aver- age slope for the study was 1.03208178 and our average Y-intercept was 0.55800722.
We evaluated the variation in plasma tCO2 deter- minations between duplicate blood samples and found the CV to be 0.3787/34.6 = 0.0109