Roche cobas b 123 - Nca; Shunt Estimated (Qs;Qt Est )

Roche Diagnostics
Instructions for Use · Version 13.0 105
cobas b 123 POC system 4 Theoretical foundations
Parameters and calculations
Shunt estimated (Qs/Qt
est
)
To calculate an estimated shunt value, a fixed value of 5.15 vol% (=2.3 mmol/L) is
used for avDO
2
.
[5]
To determine this, 1 independent measurement of arterial blood is
required.
o Select “arterial” blood type. The desired value for Qs/Qt
est
is determined.
Additional information Calculating shunt requires the following measurement and calculation values:
o tHb, SO
2
(arterial)
o PO
2
(arterial)
o PAO
2
(arterial)
Unit: [%]
Equation 4-26
nCa
2+
The ionized calcium value is standardized to pH = 7.40.
[7]
Unit: [mmol/L]
Equation 4-27
Blood: F5 = 0.22
This equation is valid for pH values between 7.2 and 7.6.
AG
The anion gap is a calculated parameter used to express the difference in
concentration of major cations and anions in the blood sample.
[2]
Unit: [mmol/L]
Equation 4-28
Q
s
shunt flow
Q
t
heart minute volume
Q
s
/Q
t (est)
estimated fraction of shunted cardiac output
SaO
2
arterial oxygen saturation fraction
(a)
arterial measurement value
ܳ
௦
ܳ
௧
(
݁ݏݐ
)
=
100 ή
൤
1.39 ήݐܪܾ
(
ܽ
)
ή൬1 െ
ܱܵ
ଶ
(ܽ)
100
൰+
൫
ܲܣܱ
ଶ
(
ܽ
)
െܱܲ
ଶ
(
ܽ
)
൯
ή0.00314
൨
൤
5.15 + 1.39 ήݐܪܾ
(
ܽ
)
ή൬1 െ
ܱܵ
ଶ
(
ܽ
)
100
൰+
൫
ܲܣܱ
ଶ
(
ܽ
)
െܱܲ
ଶ
(
ܽ
)
൯
ή0.00314
൨
7.4)(pHF
10Ca7.4)pHnCa
−⋅++
⋅==
522
(
−
++
+=
3
-
HCO - Cl -K NaAG c