Comparison of recorded values from six pulse oximeters.
Recorded values (SpO2) of oxygen saturation from six noninvasive pulse oximeters were compared to each other and to the value from a cooximeter. Simultaneous measurements were obtained from each instrument in eight healthy nonsmoking volunteers rendered hypoxic greater than 70% SpO2. Functional arterial oxygen saturation (SaO2), fractional SaO2 (%HbO2), and percent fraction of carboxyhemoglobin (HbCO) and methemoglobin (MetHb) were determined by a cooximeter. The difference between SaO2 and %HbO2 was 2.3 +/- 0.3 (SD) % (p less than .001) with 1.4 +/- 0.1% HbCO and 0.9 +/- 0.1% MetHb. The SpO2 values in two instruments were close to %HbO2, while the other instruments correlated approximately with SaO2. The greatest SpO2 difference among the instruments was 2.7 +/- 1.9% (p less than .001). These results may indicate that, under normal dyshemoglobin levels, some pulse oximeters are calibrated to estimate SaO2 and others to estimate %HbO2. Since the pulse oximeter using two wavelengths cannot measure accurately %HbO2 or SaO2 in the presence of dyshemoglobin, SpO2 values would be independent from %HbO2 and SaO2. A standard calibration method for pulse oximeters should be established by the manufacturers.
Choe
H
H
Department of Anesthesiology, Chonbuk University Medical School, Korea.
Tashiro
C
C
Fukumitsu
K
K
Yagi
M
M
Yoshiya
I
I
D000328:Adult; D002138:Calibration; D002263:Carboxyhemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008706:Methemoglobin / Q000032:analysis; D010092:Oximetry / Q000295:instrumentation*; D010100:Oxygen / Q000097:blood
D008706:Methemoglobin; D002263:Carboxyhemoglobin; D010100:Oxygen