NOVA BIOMEDICAL Stat Profile PRIME Instructions For Use Manual page 98

Prime CCS Instructions for Use Manual
Arterial Alveolar Oxygen Tension Ratio (a/A)
The arterial alveolar oxygen tension ratio is useful to predict
oxygen tension in alveolar gas and to provide an index of
oxygenation which remains relatively stable when FIO
changes.
** Temperature corrected gas value
Arterial-Mixed Venous O
When the oxygenated blood from the lungs comes into
contact with tissues, it releases oxygen and takes up carbon
dioxide. The quantity of oxygen donated depends on 2 factors:
• The speed of blood flow
• The consumption by tissues
The first factor can be detected from the cardiac output, and
the second depends on the metabolic rate of the patient.
The a – v – DO
content between the arterial blood and the mixed venous
blood (the amount of oxygen donated to the tissues). This
parameter is not an indication of the basic metabolism or
of the cardiac output. It is an nonspecific indication; even if,
in some cases completely relaxed patients with a constant
metabolic rate, it can be related to the cardiac output.
a – v – DO
2
B-12
P
**
a/A = O /A
2
2
is the measurement of the difference in oxygen
2
= CaO2 – Cv – O
Content Difference ( a – v – DO
2
2
Equation 28
)
2
Equation 29