Oridion Capnostream 20p, Руководство оператора

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Technology Overview
20 Portable Bedside Capnograph/Pulse Oximeter
Infrared spectroscopy is used to measure the concentration of molecules that absorb infrared light. Because the
absorption is proportional to the concentration of the absorbing molecule, the concentration can be determined
by comparing its absorption to that of a known standard.
The Microstream
®
etCO
2
consumables deliver a sample of the inhaled and exhaled gases from the ventilator
consumable or directly from the patient (via an oral/nasal cannula) into the monitor for CO
2
measurement.
Moisture and patient secretions are extracted from the sample, while maintaining the shape of the CO
2
waveform.
The 50 ml/min. sampling flow rate reduces liquid and secretion accumulation, decreasing the risk of obstruction
in the sample pathway in humid ICU environments.
Once inside the Microstream
®
CO
2
sensor, the gas sample goes through a micro-sample cell (15 microliters).
This extremely small volume is quickly flushed, allowing for fast rise time and accurate CO
2
readings, even at
high respiration rates.
The Micro Beam IR source illuminates the micro-sample cell and the reference cell. This proprietary IR light
source generates only the specific wavelengths characteristic of the CO
2
absorption spectrum. Therefore, no
compensations are required when different concentrations of N
2
O, O
2
, anesthetic agents and water vapor are
present in the inhaled and exhaled breath. The IR that passes through the micro-sample cell and the IR that
passes through the reference cell are measured by the IR detectors.
The microprocessor in the monitor calculates the CO
2
concentration by comparing the signals from both
detectors.
What is Pulse Oximetry?
Pulse oximetry is based on the following:
•
The difference in the absorption of red and infrared light (spectrophotometry) by oxyhemoglobin and
deoxyhemoglobin
•
Changes in the volume of arterial blood in tissue during the pulse cycle (plethysmography), and hence,
light absorption by that blood.
A pulse oximeter determines Spot Oxygen Saturation (SpO
2
) by passing red and infrared light into an arteriolar
bed and measures changes in light absorption during the pulsatile cycle. Red and infrared low power light
emitting diodes (LEDs) in the oximetry sensor serve as light sources; a photodiode serves as the photo detector.
Because oxyhemoglobin and deoxyhemoglobin differ in light absorption, the amount of red and infrared light
absorbed by blood is related to hemoglobin oxygen saturation. To identify the oxygen saturation of
arterial
hemoglobin, the monitor uses the pulsatile nature of arterial flow. During systole, a new pulse of arterial blood
enters the vascular bed and blood volume and light absorption increase. During diastole, blood volume and light
absorption reach their lowest point. The monitor bases its SpO
2
measurements on the difference between
maximum and minimum absorption (measurements at systole and diastole). The focus of light absorption by
pulsatile arterial blood eliminates the effects of nonpulsatile absorbers such as tissue, bone, and venous blood.