Masimo Radical Signal Extraction Betreibershandbuch PDF herunterladen (Seite 10)

1-6 Radical-7 Color Display Signal Extraction Pulse Oximeter Operator’s Manual Radical-7 Color Display Signal Extraction Pulse Oximeter Operator’s Manual 1-7

overview

FUNCTIONAL VS. FRACTIONAL SATURATION

The Radical-7 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 Radical-7 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 SATURATION

SpO

, SpCO and SpMet measurements that can be obtained from the Radical-7 are

commonly compared to invasive measurements obtained from blood gas samples.

When comparing invasive and noninvasive measurements and interpreting values, cau-

tion should be used, as the calculated values obtained from the blood gas sample may

differ from the SpO

, SpCO and SpMet 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 (PO2) and saturation,

such as: pH, temperature, the partial pressure of carbon dioxide (PCO2), 2,3-DPG,

and fetal hemoglobin. In the case of SpCO and SpMet, 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 are abnormal (less than 90%

for arterial oxygen saturation, and greater than 1% for methemoglobin concentration).

As blood gas samples are usually taken over a period of 20 seconds (the time it takes to

draw the blood) a meaningful comparison can only be achieved if the core oxygen satu-

ration and carboxyhemoglobin concentration of the patient are stable and not changing

over the period of time that the blood gas sample is taken.

MASIMO SET SIGNAL EXTRACTION TECHNOLOGY FOR SpO

MEASUREMENTS

Masimo Signal Extraction Technology’s signal processing differs from conventional

pulse oximeters. Conventional pulse oximeters assume that arterial blood is the only

blood moving (pulsating) in the measurement site. During patient motion, however, the

non-arterial blood also moves, causing conventional pulse oximeters to read low values,

because they cannot distinguish between the arterial and venous blood movement

(sometimes referred to as noise). Masimo SET pulse oximetry utilizes parallel engines

and adaptive digital ﬁ ltering. Adaptive ﬁ lters are powerful because they are able to

adapt to the varying physiologic signals and/or noise and separate them by looking at

the whole signal and breaking it down to its fundamental components. The Masimo SET

signal processing algorithm, Discrete Saturation Transform

(DST)

, reliably identiﬁ es

the noise, isolates it and, using adaptive ﬁ lters, cancels it. It then reports the true arterial

oxygen saturation for display on the monitor.

SpCO AND SpMet MEASUREMENTS DURING PATIENT MOTION

The Radical-7 displays measurements of SpCO and SpMet during patient motion.

However, because of the changes in the physiological parameters such as blood volume,

arterial-venous coupling, etc. that occur during patient motion, the accuracy of such mea-

surements are not reliable.

MASIMO SET PARALLEL ENGINES

MASIMO SET DST

Digitized,

Filtered &

Normalized

R/IR

(Conventional

Pulse Oximetry)

Adaptive

Filter with

DST

SST

Proprietary

Algorithm 5

Saturation

Post

Processor

Confidence

Based

Arbitrator

MEAS

CONF

MEAS

CONF

MEAS

CONF

MEAS

CONF

MEAS

CONF

Proprietary

Algorithm 4

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 54 55

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