Background: Hypoxemia is a serious situation; physical examination alone is insufficient to detectoxygenation failure. As oxygenation requirements are largely determined by pulse oximetry, vs. arterial blood gas, which is invasive and not a real-time technique. Various parameters are known to have effects on pulse oximetry values other than various disease processes. Before interpreting an abnormal pulse oximetry value, it will be prudent to know the effects of those personal parameters.

Methods: We sought to determine the distribution of oximetry (SpO₂) values in awake, asymptomatic adults, and the effect of personal characteristics like smoking, gender, respiratory rate, blood pressure, and body mass index (BMI) on these values.

It is a prospective cross-sectional study, sampling oximetry readings in adults without acute cardiac or pulmonary disease, who had no history of chronic lung disease. Participants were invited to participate if they were in normal health, as we excluded anyone with respiratory or cardiac symptoms.

Results: Data from 338 people in the southern region of Saudi Arabia were collected; seventy-five of them (22.2%) were female and 263 (77.8%) were male, mean age was 29.6 years. Smoking status: never smoked, 277 (82%); previous smoker, 7 (2%); current smoker, 54 (16%). Room-air SpO₂ values of less than 92% were noted in 6% of asymptomatic volunteers.

Statistical analysis showed no effects due to age (p = 0.27), smoking history (p = 0.69), gender (p = 0.33), blood pressure (p = 0.3), respiratory rate (p = 0.819), body mass index (p = 0.45) on SpO₂ levels as assessed by room air pulse oximetry.

Conclusion: Personal characteristics, such as age, gender, smoking history, blood pressure, respiratory rate, and BMI had no effect on room-air SpO₂ values.

Keywords: pulse oximetry; BMI; saturation; oxygen.

1. Grace, RF. Pulse oximetry: Gold standard or a false sense of security? Med J Aust 1994;160:638.
2. Hanning, CD, Alexander-Williams, JM. Pulse oximetry: A practical review. Brit Med J1995; 311:367.
3. Pierson, DJ. Pulse oximetry versus arterial blood gas specimens in long-term oxygentherapy. Lung 1990; 168 Suppl:782.
4. Mower WR, Myers G, Nicklin EL, et al. Pulse oximetry as a fifth vital sign inemergency geriatric assessment. Acad Emerg Med 1998; 5:858-65.
5. Mower WR, Sachs C, Nicklin EL, et al. Pulse oximetry as a fifth pediatric vital sign.Pediatrics 1997; 99:681-6.
6. Tierney Jr LM, Whooley MA, Saint S. Oxygen saturation: a fifth vital sign. West J Med1997; 166:285-6.
7. Kline JA, Nelson RD, Jackson RE, et al. Criteria for the safe use of D-dimer testing inemergency department patients with suspected pulmonary embolism: a multicenterUS study. Ann Emerg Med 2002; 39:144-52.
8. Kaye KS, Stalam M, Shershen WE, et al. Utility of pulse oximetry in diagnosingpneumonia in nursing home residents. Am J Med Sci 2002; 324:237-42.
9. Vold ML, Aasebo U, Hjalmarson A, Melbye H. Predictors of oxygen saturation less than 95%in a cross-sectional population-based survey. Resp Med 2012; 106(11):1551-8.
10. Forey BA, Thornton AJ, Lee PN. Systematic review with meta-analysis of the epidemiological evidence relating smoking to COPD, chronic bronchitis, and emphysema. BMC Pulmonary Med 2011; 11:36.
11. Witting MD, Scharf, SM. Diagnostic room-air pulse oximetry: effects of smoking, race, and sex. Am J Emerg Med 2008; 26:131–136.
12. Vishesh K Kapur , Anthony G Wilsdon , David Au , Mark Avdalovic et al. Obesity Is Associated With a Lower Resting Oxygen Saturation in the Ambulatory Elderly: Results From the Cardiovascular Health Study. Respir Care 2013;58(5):831–837.
13. Monica Linea Vold, Ulf Aasebo, Hasse Melbye. Low FEV1, smoking history, and obesity are factors associated with oxygen saturation decrease in an adult population cohort. International Journal of COPD 2014:9 1225–1233.
14. Mustafa Ozdal, Zarife Pancar, Vedat Çinar, Murat Bilgiç. Effect of Smoking on Oxygen Saturation in Healthy Sedentary Men and Women.EC Pulmonology and Respiratory Medicine 4.6 (2017): 178-182.
15. Bhogal AS Mani AR. Pattern Analysis of Oxygen Saturation Variability in Healthy Individuals: Entropy of Pulse Oximetry Signals Carries Information about Mean Oxygen Saturation. Front. Physiol. 8:555.doi: 10.3389/fphys.2017.00555.

Dr Kamalasanan. C.G

Additional Professor, Dept of Internal Medicine, Government Medical College, Calicut, 673008, Kerala, India