Radiometer Medical ApS, Åkandevej 21, DK-2700 Brønshøj, Tel: +45 38 27 38 27, radiometer

1. Transcutaneous measuring principles – tc and saturation RTC, June 2006 Radiometer Medical ApS, Åkandevej 21, DK-2700 Brønshøj, Tel: +45 38 27 38 27, www.radiometer.com

2. Agenda • Saturation • sO2, pO2(a), ODC • SpO2 • Light emission • Light detection • Animations • Calibration curves • Cautions/limitations • tc • New illustrations • New animations • Summing up - table

3. Methods of measuring blood gas

4. sO2 and pO2 http://www.nellcor.com/_Catalog/PDF/Edu/MON_F.a.00838v1 ClinicalMonoPul.pdf

5. sO2 and the ODC • sO2 vs. pO2(a) • Standard ODC: • sO2= 90 % corresponds topO2(a)= 60 mmHg • Abnormal/critical ODC: • Shifts due to temperature, pH, 2,3-DPG, pCO2(a) At a constant pO2 of 45 mmHg/6 kPa, sO2 may be either 80 % or 88 % depending on whether arterial pH is 7.25 or 7.40 • Conclusions: • sO2 is not suited for detection of hyperoxemia (high pO2(a)) • sO2 cannot be used to predict pO2(a)

6. Definition of saturation, sO2 • Arterial oxygen saturation • Utilization of oxygen transport capacity • Normal range 95-99 % • When sO2 is below normal range, the patient can benefit from supplemental oxygen • NO information about tHb, ventilation or O2 release to tissue • Available from BG CO-ox analyzers, BG analyzers, pulse oximeters

7. What does pulse oximetry measure? • Arterial oxygen saturation • SpO2 • Measuring range 70-100 % • SpO2 based on empirically determined sO2(a) calibration curves • I.e. SpO2 is NOT identical to sO2(a), which is measured by CO-ox analyzers • From measured O2Hb and HHb • And SpO2 is NOT identical to sO2(e), which is estimated by BG analyzers • From pO2(a) and pH-corrected standard ODC • E.g. ABL5

8. Light emission -hemoglobin absorption • Dual light source • Red light 660 nm • Infrared light 900 nm • Alternating diode cycles • O2Hb absorbs more IR light • I.e. it looks more red • HHb absorbs more red light • I.e. it looks less red http://www.nellcor.com/_Catalog/PDF/Product/OxiMaxTechNote.pdf

9. Light detection – pulse amplitude • Photodetector • One detector for both wavelengths • Isolate absorption from pulsating arterial blood • I.e. discard the ”base line” absorption http://www.nellcor.com/_Catalog/PDF/Product/OxiMaxTechNote.pdf

10. Baseline animation

11. sO2 animation

12. From light absorption to SpO2 • Red-to-infrared pulse Modulation Ratio (R) • Ratio translated to SpO2 from calibration curve http://www.nellcor.com/_Catalog/PDF/Product/OxiMaxTechNote.pdf

13. Choosing the right calibration curve • Curve defined for each sensor • Each LED has its own characteristics • Grouped and paired with a corresponding resistor • Resistor housed in sensor plug • Monitor recognizes resistor value and chooses the appropriate calibration curve

14. SpO2– when to be cautious? • Extreme hypoxemia (< 70 %) and hyperoxemia (> 95 %) • Sensor matching to site • DysHb – SpO2 may be normal despite low tHb • Anemia – SpO2 may be normal despite low tHb • Dye used for medical purposes • E.g. Methylene blue (likewise for CO-oximetry) • Low perfusion (likewise for tc) • Hypothermia (likewise for tc) • Peripheral constriction • Shivering (motion artifacts) • Medication (likewise for tc) • Peripheral constriction • Light interference • Nail polish

15. E5280 • Combi tcpO2/tcpCO2 • E5260 • Single tcpCO2 tc – new sensor illustrations • E5250 • Single tcpO2

16. tc – new E5250 animation

17. tc – new E5260 animation

18. tc – new E5280 animation

19. tc– new physiological measuring princ. animation

20. Table to summarize

21. Radiometer Training Center, June 2006 Radiometer Medical ApS, Åkandevej 21, DK-2700 Brønshøj, Tel: +45 38 27 38 27, www.radiometer.com