GE HEALTHCARE E-PSMP, Technical Manual

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Module Frames and Modules
9 - 6
2062973-004
Using inspiratory and expiratory minute volumes MV
i
and MV
e
and volume-weighted
inspiratory concentrations fi and fe, these equations can be rewritten as:
Formula 7
Formula 8
To obtain results which are less sensitive to errors in volume measurements, the so-called
Haldane transformation is used. This means taking advantage of the fact that the patient is not
consuming nor producing nitrogen: the amount of nitrogen inhaled is equal to the amount
exhaled fi
N2
×
MV
i
=fe
N2
×
MV
e
.
VO
2
and VCO
2
can then be written as:
Formula 9
Formula 10
with
f
Hald
= (1-fi
CO2
– fi
O2
– fi
N2O
- fi
Ane1
– fi
Ane2
) / (1-fe
CO2
– fe
O2
– fe
N2O
- fe
Ane1
– fe
Ane2
)
Formula 11
with Un=Urea Nitrogen Excretion = 13 g/day (for adults only).
Formula 12
1.3 Main components
The compact airway modules consist of:
•
Gas sampling system
•
TPX measuring unit
•
OM measuring unit
•
PVX measuring unit
•
CPU board
•
OM board