Bayer HealthCare Rapidlab 800 - Manual (Page 651)

Operating Principles IĆ31
sO
2
+
i
+ 7
S
i
+ 0
K
i)1
[(pO
2
S – 27.5)
ń(pO
2
S
) 27.5)] i
K 1
=
51.87074
K 2
=
129.8325
K 3
=
6.82836
8
K 4
=
–223.7881
K 5
=
–27.953
K 6
=
258.5009
K 7
=
21.84175
K 8
=
–119.2322
Total Carbon Dioxide (ctCO
2
)
Total carbon dioxide (ctCO
2
), in combination with pH and pCO
2
, is useful in
distinguishing between metabolic and respiratory acid-base disorders.
Carbon dioxide exists in several forms in blood plasma, but only two forms,
dissolved CO
2
and HCO
3
– , are quantitatively significant. Based on NCCLS
recommendations, 22 the following equation is used:
ctCO
2
= cHCO
3–
+ (0.0307
×
pCO
2
)
Hematocrit
Hematocrit (Hct) is the ratio of the volume of packed red blood cells to the volume
of whole blood.
53 Hematocrit, with other parameters such as total hemoglobin, is
useful in the evaluation of anemia. The hematocrit reference range for a normal
population is 35.0 to 53.0 g/dL.
The estimated hematocrit value is determined using the following equation:
Hct = ctHb x 2.941
where 2.941 is a factor calculated by dividing 100 g/dL by a normal MCHC (mean
corpuscular hemoglobin concentration) of 34%.
Estimated hematocrits should not be used as the sole consideration in the diagnosis
of hematological disorders.