CO Measurements
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þ Fetal hemoglobin may cause falsely high CO levels (up to 8% in newborns)
  when measured with the usual method (spectrophotometric co-oximetry) [Vreman
  HJ et al. Interference of fetal hemoglobin with spectrophotometric
  measurement of carboxyhemoglobin.  Clin Chem 1988;34:975.]