Medica EasyStat, Operator'S Manual

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108
p r i n c i p l e s o f o p e r a t i o n
/
t h e o r y
r
%SO2c
The EasyStat analyzer estimates the calculated oxygen saturation (at
normal P50) of available hemoglobin from the measured value of
PO2, pH and PCO2 according to the equation1:
(PO2*)3 + 150 PO2*
(PO2*)3 + 150 PO2* + 23400
where: PO2* = PO2 antilog {0.48 (pH - 7.4) - 0.0013 ([HCO3
-
]-25)}
ctO2
The total oxygen content of blood is expressed as the volume of oxy-
gen (mL per 100 mL or dL of blood. The oxygen content is the sum of
the amount of oxygen bound to hemoglobin and the amount of dis-
solved oxygen. The following equation is used:
ctO2 = ( ) (1.39 [Hb]) + (0.00314 PO2)
where: ctO2 is expressed in mL/dL
1.39 is theoretical amount of oxygen bound to hemoglobin in mL/g
Hb is expressed in g/dL
0.00314 is the amount of dissolved oxygen in blood as mL/(dL
mmHg)
PO2 is expressed in mmHg
Ca++(7.4
)
Ca++(7.4) = Ca++ (pH=x) * 10 exp - 0.24 * (7.4-x)
where: x is the measured pH
(100) %SO
2
c =
%SO
2c
100