Medica EasyStat, Operator'S Manual

Page: 112 / 158

106
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
HCO3
-
The following equation is used to calculate the bicarbonate concentra-
tion
1
:
where: log [HCO3
-
] = pH - 7.608 + log PCO2
HCO3
-
is expressed in mmol/L
BE
b
The base excess of blood, or in vitro base excess, is calculated using
the following equation
1
. This parameter is defined as the titratable base
of blood which may be determined by titration with strong acid or base
to (plasma) pH = 7.400 and PCO2 = 40 mmHg at 37.0°C.
BEb = (1 - 0.014 [Hb]) ([HCO3
-
] - 25 + (1.43 [Hb] + 7.7) (pH - 7.4))
where: Hb is expressed in g/dL
HCO3
-
is expressed in mmol/L
BEb is expressed in mmol/L
The hemoglobin value used is either preset (14.5 g/dL), entered or
calculated. When entered, the value is input from the
PATIENT
INFORMATION
screen.