Roche Diagnostics
Instructions for Use · Version 13.0 111
cobas b 123 POC system 4 Theoretical foundations
Parameters and calculations
Equation 4-49
PaO
2
= PO
2
Lac
clearance 1h
Lactate Clearance calculates, in percent, the hourly change of measured lactate.
[12],
[13]
. It requires 2 independent measurements.
q
Both measurements must be carried out with the same patient ID.
Define patient ID as an input value.
q
Samples from patients with other patient IDs can be measured between the 2 Qs/Qt partial
measurements.
When calculating lactate clearance, either the current or the previous lactate value has to
be greater than 4 mmol/L.
A minimum of 2 hours, but no more than 8 hours, has to pass between 2 lactate partial
measurements.
Unit: [%]
Equation 4-50
Bibliography
[1] Clinical and Laboratory Standards Institute, Blood gas and pH related measurements,
CLSI document C46-A2; Approved Guideline (2001), Vol. 29 No. 8
[2] Müller-Plathe, Oswald: Säure-Basen-Haushalt und Blutgase/ Breuer, Büttner,
Stamm, Stuttgart; New York: Georg Thieme Verlag, 1982.
[3] Marsoner, Hermann J.: Medequip 82 - Geräte, Instrumente, Materialien,
Diagnostica, Einrichtungen für die Medizin- Jahrgang 1982, Heft 2, Seite 37–42
[4] Marsoner, H. J.; Harnoncourt, K.: The calculation of the oxygen saturation as
function of pO2, pH, temperature and base deviation; Anaesthesist 25, 345–348
(1976)
[5] Siggaard-Anderson. O.; Wimberley. P. D.; Fogh-Anderson. N.; Gøthgen. I. H.:
Measured and derived quantities with modern pH and blood gas equipment:
calculation algorithms with 54 equations; Scand. J. Clin. Lab. Invest. 1988, 48. Suppl.
189: 7–15
PF index
=
P
aO
2
FIO
2
Lac
is the latest measured lactate value
Lac
hist
is the historical lactate value
h
h = 1
Δ
is the time interval between the lactate measurements
LacClear
Lac
hist
Lac–
Lac
hist
-------------------------------- 100
h
Δ
---⋅⋅=
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