Mindray VS-900 - 11 Monitoring CO; Overview; Safety; Measurement Limitations

11-1
11 Monitoring CO
2
11.1 Overview
CO
2
monitoring is a continuous, non-invasive technique for determining the
concentration of CO
2
in the patient’s airway by measuring the absorption of infrared (IR)
light of specific wavelengths. CO
2
has its own absorption characteristic and the amount of
light passing the gas probe depends on the concentration of the measured CO
2
. When a
specific band of IR light passes through respiratory gas samples, some of IR light will be
absorbed by the CO
2
molecules. The amount of IR light transmitted after it has been
passed through the respiratory gas sample is measured with a photodetector. From the
amount of IR light measured, the concentration of CO
2
is calculated.
The CO
2
measurement is to monitor the patient’s respiratory status.
CO
2
monitoring is intended for adult, pediatric and neonatal patients.
11.2 Safety
WARNING
 Remove the airway sampling line from the patient’s airway while nebulized
medications are being delivered.
 Leakage in the breathing or sampling system may cause the displayed EtCO
2
values to be significantly low. Always make sure that all components are
securely connected.
 EtCO
2
values measured from the CO
2
module may differ from those of from the
blood gas analysis.
 Route all tubing away from the patient’s throat to avoid strangulation.
 Inspect the airway for a tight connection and make proper settings before
attaching it to the patient.
 Squeezing or bending the sampling line during the CO
2
measurement may
cause inaccurate CO
2
reading or no reading.
11.3 Measurement Limitations
The following factors may influence the measurement accuracy:

Leaks or internal venting of sampled gas

Mechanical shock

Cyclic pressure up to 10 kPa (100 cmH
2
O)

Other sources of interference, if any