Philips M3000A, Руководство по обслуживанию

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Sidestream CO
2
Measurement
48 Introduction to the Instrument
Sidestream CO
2
Measurement
Description
The M3015A Measurement Server Extension has a sidestream carbon dioxide respiratory gas
measurement for the Monitor monitoring device. It is designed to be used with the M3000A/
M3001A Measurement Server for adult, pediatric, or neonatal patients, in a hospital
environment and during patient transport in and outside hospitals by clinical users. The
patients can be intubated or non-intubated.
CO
2
respiratory gas measurements indicate the efficiency of the transfer of oxygen from
alveolar air into pulmonary capillary blood and the elimination of carbon dioxide from
pulmonary capillary blood and its transfer into alveolar air.
CO
2
respiratory gas measurements are evaluated as gas passes through the airway adapter on
the patient’s intubation system. CO
2
respiratory gas measurements are an indication of the
patient’s overall respiratory status.
Blood Gas concepts important to this section are:
• Airway Respiration Rate (AwRR)—The number of inspirations and expirations per
minute.
• End Tidal CO
2
(EtCO
2
)—The highest partial pressure of CO
2
measured during one expi-
ration.
• Inspired Minimum CO
2
(ImCO
2
)—The lowest partial pressure of CO
2
during inspira-
tion.
• Instantaneous CO
2
—The CO
2
measurement at any instant.
• Ventilation—The movement of air in and out of the lungs by inspiration and expiration.
Measurements
The sidestream CO
2
measurement produces respiratory CO
2
gas readings in a real-time CO
2
waveform together with numerics for End-tidal CO
2
(EtCO
2
), Airway Respiration Rate
(AwRR), and Inspired Minimum Carbon Dioxide (ImCO
2
).
Factors affecting accurate measurement of sidestream CO
2
respiratory gas are as follows:
• Proper connection between the Extension and the patient’s respiratory system.
• Temperature of the patient’s breath.
• Amount of water vapour in the patient’s breath.
• Barometric pressure at the site of measurement acquisition.
• Other gases, most notably N2O and O
2
, in the gas mixture.
The EtCO
2
(End Tidal Carbon Dioxide) measurement for Carbon Dioxide uses a technique
based on the absorption of infrared radiation by certain gases.
Infrared light is absorbed by CO
2
. The amount of absorption varies according to the CO
2
concentration in the gas mixture. By using an infrared detector to measure the absorption, the
CO
2
concentration in a gas can be derived.