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1-4 Rad-57 Signal Extraction CO-Pulse Oximeter Operator’s Manual

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Rad-57 Signal Extraction Pulse CO-Oximeter Operator’s Manual

Pulse Oximetry

SpO

GENERAL DESCRIPTION

Pulse oximetry is a continuous and non-invasive method of measuring the level of arterial

oxygen saturation in blood. The measurement is taken by placing a sensor on a patient,

usually on the fingertip for adults, and the hand or foot for neonates. The sensor connects

to the pulse oximetry instrument with a patient cable. The sensor collects signal data from

the patient and sends it to the instrument. The instrument displays the calculated data in

two ways: 1) as a percent value for arterial oxygen saturation (SpO

), and 2) as a pulse

rate (PR). The following figure shows the general monitoring setup.

SpCO GENERAL DESCRIPTION

Pulse CO-Oximetry is a continuous and non-invasive method of measuring the levels of

carbon monoxide concentration (SpCO) in arterial blood. It relies on the same principles

of pulse oximetry to make its SpCO measurement. The measurement is taken by placing a

sensor on a patient, usually on the fingertip for adults. The sensor connects directly to the

pulse CO-Oximetry instrument or with a patient cable. The sensor collects signal data from

the patient and sends it to the instrument. The instrument displays the calculated data as

percentage value for the SpCO. The Rad-57 is a combined SpO

and SpCO monitor with

the same setup as that of a pulse oximeter, shown above, and can display a percentage

value for SpCO as well as SpO

PRINCIPLE OF OPERATION

Pulse oximetry is governed by the following principles:

1. Oxyhemoglobin (oxygenated blood), deoxyhemoglobin (non-oxygenated blood) and

carboxyhemoglobin (blood with carbon monoxide content) species differ in their

absorption of visible and infrared light (spectrophotometry, see figure below).

650 700 750 800 850 905 950 1000

Wavelength (nm)

Absorption (mm-1)

Deoxyhemoglobin

Oxyhemoglobin

Carboxyhemoglobin

overview

Rad-57 Signal Extraction Pulse CO-Oximeter Operator’s Manual

overview

2. The amount of arterial blood in tissue changes with your pulse (photoplethysography).

Therefore, the amount of light absorbed by the varying quantities of arterial blood

changes as well.

The Rad-57 Pulse CO-Oximeter uses a multi-wavelength sensor to distinguish between

oxygenated blood, deoxygenated blood, and blood with carbon monoxide content. Signal

data is obtained by passing various visible and infrared lights (LED’s, 400 to 1000nm)

through a capillary bed (for example, a fingertip, a hand, a foot) and measuring changes

in light absorption during the blood pulsatile cycle. See figure below. The photodetector

receives the light, converts it into an electronic signal and sends it to the Rad-57 for

calculation.

Once the Rad-57 receives the signal from the sensor, it utilizes Masimo Rainbow SET

signal extraction technology to calculate the patient's functional oxygen saturation,

fractional concentration of carboxyhemoglobin, and pulse rate. The SpCO measurement

relies on a multiwavelength calibration equation to estimate the percentage of carbon-

monoxide in arterial blood.

FUNCTIONAL VS. FRACTIONAL SATURATION

The Rad-57 is calibrated to measure and display functional saturation (SpO

): the amount

of oxyhemoglobin expressed as a percentage of the hemoglobin that can transport oxygen.

The Rad-57 does not measure fractional saturation: oxygenated hemoglobin expressed as

a percentage of the four main hemoglobin species, i.e., oxyhemoglobin, deoxyhemoglobin,

carboxyhemoglobin, and methemoglobin. To convert fractional saturation to functional

saturation, the fractional saturation measurements must be converted according to:

Functional saturation =

Fractional saturation

x 100

100 - (% carboxyhemoglobin + % methemoglobin)

MEASURED VS. CALCULATED VALUES

SpO

and SpCO measurements obtained from the Rad-57 are commonly compared to

invasive measurements obtained from blood gas samples. When comparing invasive

and noninvasive measurements and interpreting values, caution should be used, as the

calculated values obtained from the blood gas sample may differ from the SpO

and

SpCO measurements of the Pulse CO-Oximeter. In the case of SpO

, different results

are usually obtained from the arterial blood gas sample if the calculated measurement is

not appropriately corrected for the effects of variables that shift the relationship between

the partial pressure of oxygen (PO

) and saturation, such as: pH, temperature, the partial

pressure of carbon dioxide (PCO

), 2,3-DPG, and fetal hemoglobin. In the case of SpCO,

in addition to the effects of temperature and pH, different results are also expected if

the oxygen saturation and/or concentration of methemoglobin in the blood gas sample

1. Light Emitting Diodes (LEDs)

2. Recessed Photo Detector

1. Instrument

2. Sensor

3. Patient Cable

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