Siemens Rapidlab 1200 - Respiratory Index

Rapidlab 1200 Operator’s Guide: System Overview and Intended Use 1-61
02087462 Rev. V
Respiratory Index
The respiratory index (RI(T)) is the ratio of the alveolar-arterial blood
oxygen-pressure difference to arterial pO
2
, when both values are corrected
for patient temperature. This index is also a means of as
sessing the degree of
pulmonary shunting.
19
The system determines respiratory index as follows:
RI(T) = pO
2
(A-a)(T) / pO
2
(a)(T) × 100
where pO
2
(A-a)(T) is the temperature-corrected alveolar-arterial oxygen tension
difference and pO
2
(a)(T) is the temperature-corrected oxygen tension of arterial
blood.
Arterial-Venous (a-v) Study
This section describes the parameters associated with an a-v study.
Arterial Oxygen Content
The oxygen content of arterial blood [ctO
2
(a)] is a determination of the total
oxygen carried by the arterial blood, including the oxygen bound to hemoglobin
and the oxygen dissolved in plasma and in the fluid within the red blood cells.
The system determines the oxygen content
of arterial blood, based on CLSI
recommendations
19
as follows:
ctO
2
(a) = (OBF × tHb × FO
2
Hb) + (0.00314 × pO
2
)
where OBF is the O
2
binding factor. The system uses the default value of 1.39, or
whatever value is entered as the default value in Setup. FO
2
Hb is in decimal
format.
Mixed Venous Oxygen Content
The oxygen content of mixed venous blood [ctO
2
( )] is a determination of the
total oxygen carried by the mixed venous (pulmonary artery) blood, including the
o
xygen bound to hemoglobin and the oxygen dissolved in plasma and in the fluid
within the red blood cells.
The system determines the oxygen content of mixed venous
blood, based on CLSI
recommendations
19
as follows:
ctO
2
( ) = (OBF × ctHb × FO
2
Hb) + (0.00314 × pO
2
)
where OBF is the O
2
binding factor. The system uses the default value of 1.39, or
whatever value is entered as the default value in Setup. FO
2
Hb is in decimal
format.