RADIOMETER ABL90 FLEX - Chco (P,St); List of Equations

ABL90 FLEX reference manual 8. Parameters
8-23
List of equations
All definitions and equations are based on SI units. If "T" for patient
temperature is not stated, the calculation is based on a temperature of 37.0 °C.
The following SI units are used:
concentration in mmol/L
temperature in °C
pressure in kPa
fractions (not %)
The following symbols are used in the equations:
log(x) = log
10
(x)
ln(x) = log
e
(x)
Eq. 1 [13]:


pH( ) pH(37) 0.0147 0.0065 pH(37)-7.40 -37TT

 





NOTICE: The formula is different from previous Radiometer analyzers. The
constant 0.0146 is now changed to 0.0147, to be in accordance with NCCLS
(CLSI)-approved guidelines [24].
The change corresponds to –0.1 mpH/°C.
Eq. 2:


9pH ()
+
H()=10c
 T
T
Eq. 3 [4]:

0.019 -37
22
CO ( ) CO (37) 10
T
pTp






NOTICE: The formula is different from previous Radiometer analyzers. The
constant 0.021 is now changed to 0.019, to be in accordance with NCCLS (CLSI)-
approved guidelines [24].
The change corresponds to 2%/5 °C.
Eq. 4 [24]:


p
pH-pK
-
32
HCO (P) 0.23 CO 10cp 
where
095.6pK
p

cHCO
3
–
(P) includes ions of hydrogen carbonate, carbonate and carbamate in the
plasma.
NOTICE: The formula is different from previous Radiometer analyzers. The pK
p
is
now constant, to be in accordance with NCCLS (CLSI)-approved guidelines [24].
The change corresponds to 5% in the pH range 7-7.8.
Units and
symbols
pH(T)
cH
+
(T)
pCO
2
(T)
cHCO
3
–
(P)