Innokas Yhtyma Oy VC150 用户手册
8-16
VC150 Vital Signs Monitor
KO00065K
Masimo SpO
2
: Masimo rainbow
®
SET
®
SpO
2
and special features
In the case of SpO
2
, 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
effects of variables that shift the relationship between the partial pressure of
oxygen (PO
2
) and saturation, such as: pH,temperature, the partial pressure of
carbon dioxide (PCO
2
), 2,3-DPG, and fetal hemoglobin. In the case of SpCO,
different results are also expected if concentration of methemoglobin in the
blood gas sample is abnormal (greater than 2% for methemoglobin
concentration).
blood gas sample is abnormal (greater than 2% for methemoglobin
concentration).
High levels of bilirubin may cause erroneous SpO
2
, SpMet, SpCO, and SpHb
readings. As blood 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 oxygen saturation, carboxyhemoglobin, and methemoglobin concentration
of the patient are stable and not changing over the period of time that the blood
gas sample is taken. Subsequently, blood gas and laboratory CO-Oximetry
measurements of SpO
time it takes to draw the blood) a meaningful comparison can only be achieved if
the oxygen saturation, carboxyhemoglobin, and methemoglobin concentration
of the patient are stable and not changing over the period of time that the blood
gas sample is taken. Subsequently, blood gas and laboratory CO-Oximetry
measurements of SpO
2
, SpCO, SpMet, SpHb, and SpOC may vary with the rapid
administration of fluids and in procedures such as dialysis. Additionally, drawn
whole blood testing can be affected by sample handling methods and time
elapsed between blood draw and sample testing.
whole blood testing can be affected by sample handling methods and time
elapsed between blood draw and sample testing.
Measurements with Low Signal IQ should not be compared to laboratory
measurements.
measurements.
General Description for Total Arterial Oxygen Content (CaO
2
)
Oxygen (O
2
) is carried in the blood in two forms, either dissolved in plasma or
combined with hemoglobin. The amount of oxygen in the arterial blood is
termed the oxygen content (CaO
termed the oxygen content (CaO
2
) and is measured in units of ml O
2
/dL blood.
One gram of hemoglobin (Hb) can carry 1.34 ml of oxygen, whereas 100 ml of
blood plasma may carry approximately 0.3 ml of oxygen*. The oxygen content is
determined mathematically as:
blood plasma may carry approximately 0.3 ml of oxygen*. The oxygen content is
determined mathematically as:
CaO
2
= 1.34 (ml O
2
/g Hb) x Hb (g/dL) x HbO
2
+ PaO
2
(mm Hg) x (0.3 ml O
2
/100
mm Hg/dL)
Where HbO
2
is the fractional arterial oxygen saturation and PaO2 is the partial
pressure of arterial oxygen.
For typical PaO
2
values, the second part of the above equation (PaO
2
[mm Hg] x
[0.3 ml O2/ 100 mm Hg/dL]) is approximately 0.3 ml/dL. Furthermore, for typical
carboxyhemoglobin and methemoglobin levels, the functional saturation (SpO
carboxyhemoglobin and methemoglobin levels, the functional saturation (SpO
2
)
as measured by a pulse oximeter is given by:
SpO
2
= 1.02 x HbO
2
*Martin, Laurence. All You Really Need to Know to Interpret Arterial Blood Gases,
Second Edition. New York: Lippincott Williams & Wilkins, 1999.
Second Edition. New York: Lippincott Williams & Wilkins, 1999.