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pulse oximetry

Indications: - evalation a monitoring of hemoglobin O2 saturation - at rest or with exercise Contraindications: - routine monitoring of hospitalizaed pediatric patients [3] - evaluation of hypoxia Reference interval: - normal values of SaO2 are 94-100% Principle: 1) continuous measurement of O2 saturation via optical properties of a pulsatile peripheral artery generally on the finger or ear 2) uses 2 wavelengths of light 3) measures oxyhemoglobin & total hemoglobin 4) new pulse oximeter measures carboxyhemoglobin & methemoglobin [2] Clinical significance: 1) values of SaO2 < 88% are consistent with hypoxia 2) oxygen desaturation with exercise is a sensitive, but not specific indicator of gas exchange abnormalities * pulse oximetry may more reliably identify hypoxia in whites than blacks [4,6,7] - 6.3-11.7% of blacks with pulse oximetry SaO2 of 92-96% found to have arterial blood gas oxygen saturation of < 88% vs 3.6% of whites [4,6] - hypoxemia more likely to occur in Black than in white patients (19.6% vs 15.6%) [7] - Asians & Native Americans also with less reliable SaO2 by pulse oximetry [6] - Asian, Black, & Hispanic patients may receive less supplemental oxygen than White patients,as a result of differences in pulse oximeter performance [8] Decreases: - hypoxia :threshold 87% Interferences: 1) carboxyhemoglobin (carbon monxide poisoning) 2) methemoglobin - cyanide poisoning 3) hyperbilirubinemia 4) anemia 5) dark skin pigmentation 6) fingernail polish 7) poor perfusion (shock) * in cases where finger pulse oximetry gives abnormal reading, check earlobe pulse oximetry prior to obtaining blood gases [1]

Related

hemoglobin oxygen saturation

Specific

overnight pulse oximetry

General

transcutaneous laboratory monitoring

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 19 American College of Physicians, Philadelphia 1998, 2006, 2022 - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  2. Barker SJ et al, Measurement of carboxyhemoglobin and methemoglobin by pulse oximetry. A human volunteer study. Anesthesiology 2006, 105:892 PMID: 17065881
  3. American Academy of Nursing Twenty-Five Things Nurses and Patients Should Question Choosing Wisely. An initiative of the ABIM Foundation Released April 19, 2018 (21-25) http://www.choosingwisely.org/societies/american-academy-of-nursing/
  4. Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Racial Bias in Pulse Oximetry Measurement. N Engl J Med 2020; 383:2477-2478. Dec 17. PMID: 33326721 https://www.nejm.org/doi/full/10.1056/NEJMc2029240
  5. FDA Sarety Communications. Feb 19, 2021 Pulse Oximeter Accuracy and Limitations: FDA Safety Communication. https://www.fda.gov/medical-devices/safety-communications/pulse-oximeter-accuracy-and-limitations-fda-safety-communication
  6. Henry NR et al. Disparities in hypoxemia detection by pulse oximetry across self-identified racial groups and associations with clinical outcomes. Crit Care Med 2022 Feb; 50:204. PMID: 35100193 https://journals.lww.com/ccmjournal/Abstract/2022/02000/Disparities_in_Hypoxemia_Detection_by_Pulse.5.aspx - Holder A, Wong AI. The big consequences of small discrepancies: Why racial differences in pulse oximetry errors matter. Crit Care Med 2022 Feb; 50:335 PMID: 35100196 https://journals.lww.com/ccmjournal/Citation/2022/02000/The_Big_Consequences_of_Small_Discrepancies__Why.18.aspx
  7. Valbuena VSM et al. Racial bias and reproducibility in pulse oximetry among medical and surgical inpatients in general care in the Veterans Health Administration 2013-19: Multicenter, retrospective cohort study. BMJ 2022 Jul 6; 378:e069775 PMID: 35793817 Free article https://www.bmj.com/content/378/bmj-2021-069775
  8. Gottlieb ER et al. Assessment of racial and ethnic differences in oxygen supplementation among patients in the intensive care unit. JAMA Intern Med 2022 Aug 1; 182:849. PMID: 35816344 PMCID: PMC9274443 (available on 2023-07-11) https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2794196