Predictors of oxygen saturation ≤95% in a cross-sectional population based survey.
BACKGROUND
Pulse oximetry has become an important tool in evaluating, and monitoring pulmonary diseases, but the knowledge about arterial oxygen saturation (SpO(2)) values in a general population is limited. The aim of this study was to describe the distribution of low pulse oximetry values in a general adult population and their association with certain predictors.


METHODS
A cross-sectional population based survey was performed in Tromsø, Norway, in 2007-2008. Valid SpO(2) and pre-bronchodilator spirometry was recorded in 6317 participants aged 38-87 years (57% women). Resting SpO(2) ≤95% was defined as an abnormal value. Predictors of SpO(2) ≤95% with p < 0.05 were entered into a binary multivariable logistic regression.


RESULTS
The prevalence of SpO(2) ≤95% was 6.3%. The strongest predictors in the logistic regression were increased body mass index (BMI) (OR of BMI ≥35 = 6.2, CI(4.2, 9.2)), and reduced forced expiratory volume in 1 s (FEV(1)) % predicted (OR of FEV1% predicted <50 = 4.1, CI(2.5, 6.7)), followed by increased age, male gender, and smoking (p < 0.001). Other significant predictors were elevated C-reactive protein (CRP) (p < 0.005), former smoking, breathlessness and elevated hemoglobin (p < 0.01).


CONCLUSIONS
Airflow limitation and other known signs of pulmonary diseases were, as expected, strongly associated with decreased oxygen saturation. Obesity was also a strong predictor of low SpO(2), and should be included among possible explanations when low SpO(2) values are encountered.
Department of Respiratory Medicine (Lungemedisinsk avdeling), University Hospital of North Norway, 9038 Tromsø, Norway. monica.linea.vold@unn.no
Monica Linea
ML
Vold
Ulf
U
Aasebø
Audhild
A
Hjalmarsen
Hasse
H
Melbye
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D012016:Reference Values; D012727:Sex Characteristics; D012907:Smoking / Q000097:blood; D014797:Vital Capacity / Q000502:physiology
D006454:Hemoglobins; D002097:C-Reactive Protein; D010100:Oxygen