The accuracy of pulse oximetry in the emergency department.
ABSTRACT The objective of this retrospective study was to identify factors affecting the accuracy of pulse oximetry in the ED. Over a 3-year period, 664 consecutive emergency department (ED) patients had simultaneous arterial blood gas (ABG) and pulse oximeter readings taken. Pulse oximeter saturations (SpO2) were compared with ABG CO-oximeter saturations (SaO2) for accuracy. Multiple variables including age, sex, hemoglobin, bicarbonate, pH, and carboxyhemoglobin (COHb) were analyzed to see if they affected SpO2 accuracy. ROC curves were used to determine the best pulse oximeter threshold for detecting hypoxia. Using multivariate analysis, COHb was the only statistically significant factor affecting the accuracy of pulse oximetry. In patients with COHb <2%, SpO2 overestimated SaO2 by more than 4% in 8.4% of cases. In patients with COHb > or = 2%, SpO2 overestimated SaO2 by more than 4% in 35% of cases. The best pulse oximetry threshold for detecting hypoxia is 92%. At this threshold, if COHb is <2%, pulse oximetry has a sensitivity of 0.92 and specificity of 0.90. If COHb is > or =2%, sensitivity is 0.74 and specificity is 0.84. For patients likely to have a COHb < 2, pulse oximetry is an effective screening tool for detecting hypoxia. However, more caution must be exercised when using pulse oximetry in patients likely to have a COHb > or = 2%.
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ABSTRACT: Pulse oximetry is a widely used technique in biomedical optics, but currently available pulse oximeters rely on empirical calibration approaches, which perform poorly at low saturations. We present an exact solution for pulse oximetry and show how this can be used as the basis for the development of a semi-empirical calibration approach that may be useful, especially at low saturations and variable probe geometries. This new approach was experimentally tested against traditional empirical calibration techniques on transmission pulse oximetry for monitoring of fetal sheep using a minimally invasive spiral probe. The results open the way for the development of more accurate pulse oximetry.IEEE Transactions on Biomedical Engineering 06/2004; · 2.28 Impact Factor
Article: Effect of nail polish on oxygen saturation determined by pulse oximetry in critically ill patients.[show abstract] [hide abstract]
ABSTRACT: Nail polish of different colours may alter accuracy and precision of pulse oximetry as previous data in healthy volunteers suggest. This trial evaluates the oxygen saturation determined by pulse oximetry and haematoximetry with nail polish of nine different colours applied. Fifty critically ill and mechanically ventilated patients in an ICU were investigated in a prospective clinical-experimental trial. On nine finger nails polish of different colours was applied in a predetermined consecutive order. Functional oxygen saturation was determined by pulse oximetry (SpO2) on each finger for each colour with the finger sensor probe both in the normal position and at a 90 degrees rotation. Simultaneously oxygen saturation was determined by haematoximetry (SaO2). Accuracy (bias, DeltaS = SaO2-SpO2) and precision (standard deviation, S.D.) of pulse oximetry were analyzed with the t-test. A value of P < 0.05 was considered significant. While black (DeltaS = +1.6+/-3.0%), purple (DeltaS = +1.2+/-2.6%) and dark blue nail polish (DeltaS = +1.1+/-3.5%, each N = 50) had the greatest effect (P < 0.05), all other colours, including colourless nail polish, had a smaller effect (mean bias +0.2 to +0.9%). A rotation of 90 degrees reduced the bias from +2.8 to +1.3% (N = 10, n.s.). Nail polish does not alter pulse oximetry readings in mechanically ventilated patients to a clinically relevant extent. The mean error of measurement for all colours was within the manufacturers' specified range of +/-2%. A 90 degrees rotation of the sensor probe does not eliminate errors in measurement. To remove nail polish might be helpful to decrease the error of measurement in some cases.Resuscitation 02/2007; 72(1):82-91. · 3.60 Impact Factor
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ABSTRACT: Pulse oximetry is used regularly to assess oxygen saturation levels. The objective of this commentary is to discuss a rationale for using pulse oximetry in chiropractic practice. Pulse oximetry may offer doctors of chiropractic a way to monitor patients' oxygen saturation levels. Quantification of saturation values with heart rate may give clinical aid to the management of chiropractic patients. Markedly reduced saturation levels may necessitate medical referral, whereas mildly reduced levels could lead to changes in chiropractic management. Pulse oximetry has the potential to be an integral part of chiropractic practice.Journal of chiropractic medicine 06/2012; 11(2):127-33.