Roche cobas b 123 - Ctco 2 (B); Cto; Ph St

Roche Diagnostics
Instructions for Use · Version 13.0 101
cobas b 123 POC system 4 Theoretical foundations
Parameters and calculations
ctO
2
Oxygen content is the sum of oxygen bound to hemoglobin as O
2
Hb and the amount
of oxygen dissolved in the plasma.
[1]
ctO
2
can only be calculated if measured SO
2
is
available.
Unit: [vol%]
Equation 4-15
where
O
2
Hb present: X = O
2
Hb
O
2
Hb not present: X = SO
2(c)
u SO
2(c)
(p. 99)
If PO
2
is not available, ctO
2
is calculated with PO
2
= 90 mmHg.
ctCO
2
(B)
ctCO
2
(B) is the sum of the total CO
2
in plasma and red blood cells (erythrocyte fluid
= ERY).
[5]
Unit: [mmol/L]
Equation 4-16
where
Equation 4-17
SO
2
or if SO
2
not available, see SO
2(c)
(p. 99).
q
Correct calculation of the calculated value is only possible after measuring a whole blood
sample with the sample type setting “blood”.
pH
st
Standard pH value of the blood is defined as the pH value of a blood sample which
has been equilibrated at 37 °C with a gas mixture having a PCO
2
= 40 mmHg.
[3]
Unit: [pH unit]
2
00314.0
100
39.1( OtHb
X
tHb) ,O ,OtO
222
PSPc ⋅+⋅⋅=
()
)
33.8
tHb
(1(P)tCO)10(1tHbCO000768.0
(B)tCO
2
pKpH
2
2
ERYERY
−⋅++⋅⋅⋅
=
−
cP
c
)10lg(16.125pK
)
100
O
(10.0357.4)(pH0.777.19pH
)
100
o
0.067.84(pH
ERY
2
ERY
2
ERY
s
S
⋅−−
+−=
−⋅+−⋅+=