RADIOMETER ABL800 FLEX, Справочное руководство

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ABL800 FLEX Reference Manual 6. Parameters
Oxyhemoglobin dissociation curve (ODC)
These equations account for the effect of
F
COHb on the shape of the
Oxyhemoglobin Dissociation Curve (ODC) in accordance with the Haldane
equation.
ODC equations
Eq. 46
[
16,18
]
:
( )
[ ]
y y x x h tanh k x x
o o o
− = − + × −
( )
o
where k
o
= 0.5343
Eq. Description
46.1
x ln
=
p
46.2
y ln
1-
=
s
s
46.3
y ln
1 -
o
o
o
=
s
s
where
s
o
= 0.867
46.4
x x a b ln( a
o oo oo
= + + = + +
p
) b where
p
oo
= 7 kPa
The actual position of the ODC in the coordinate system (ln(
s
/(1–
s
)) vs ln(
p
)) used in
the mathematical model, is expressed by equations 46.3 and 46.4.
The symbols 'a' and 'b' reflect the ODC displacement from the reference position to
its actual position in this coordinate system:
'a' describes the displacement at 37
°
C.
'b' the additional displacement due to the patient temperature difference from 37
°
C.
The ODC
reference
position
The reference position of the ODC was chosen to be the one that corresponds to the
default value for
p
50(st) = 3.578 kPa, which is traditionally considered the most
likely value of
p
50 for adult humans under standard conditions, namely:
pH = 7.40
p
CO
2
= 5.33 kPa
F
COHb,
F
MetHb,
F
HbF = 0
c
DPG = 5 mmol/L
Continued on next page
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