GE HEALTHCARE B20, Руководство пользователя

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B40/B20 Patient Monitor
17-16
Basics of airway gases measurement
Airway gases measurement description, CARESCAPE respiratory modules and
Airway Gas Option
With CARESCAPE Respiratory Modules and Airway Gas Option, you can measure and monitor
gases being delivered to the patient and exhaled by the patient through the breathing circuit.
The modules consist of an infrared sensor for measuring CO
2
and N
2
O, and paramagnetic O
2
sensor. The E-sCAiO, N-CAiO modules also include anesthetic agents measurement.
The gas sampling system samples the measured air to the module, and removes water and
impurities from it. The pump of the gas sampling system draws gas at a fixed rate through the
sampling line into the gas measuring units. The side flow creates a slight sub-atmospheric
pressure within the water trap, which causes fluid removed by the hydrophobic filter to collect
in the bottle. After the measurement, gas is exhausted through the sample gas out connector.
Airway gases measurement description, E-miniC
The E-miniC is designed for critical care environment to measure and monitor the expired and
inspired CO
2
concentration (EtCO
2
, FiCO
2
) as well as the respiration rate (RR) up to 80 breaths
per minute. E-miniC has a sample flow of 150 ml/min.
Respiration rate from the CO
2
parameter is counted from the frequency of end-tidal (peak) CO
2
measurements per minute. A sufficient respiration is defined as a difference of at least 1% (at
least 7 mmHg) between the measured inspired fraction and end-tidal CO
2
.
Total sample size volume during one respiratory cycle depends on the respiration rate. The
following table shows different sample size volumes with a 150 ml/min sample flow and I:E
ratio of 1:2.
Sidestream gas sampling
The gas modules use a sidestream gas sampling method. It means that a sample of patient’s
respired gases from the sampling site is transported through a sampling line to the module for
analysis.
A sidestream gas analyzer takes a constant sample from the patient airway adapter at the
following sample rates:
•
CARESCAPE respiratory modules: 120 ml/min
•
E-miniC: 150 ml/min
Total sample size volume during one respiratory cycle depends on the respiration rate.
Respiration rate 10 20 30 40
Duration of inspiration 2.0 seconds 1.0 seconds 0.7 seconds 0.5 seconds
Duration of expiration 4.0 seconds 2.0 seconds 1.3 seconds 1.0 seconds
Volume sampled during
inspiration 5 ml 2.5 ml 1.67 ml 1.25 ml
Volume sampled during
inspiration 10 ml 5 ml 3.33 ml 2.5 ml
Total volume sampled 15 ml 7.5 ml 5 ml 3.75 ml