Reference values for arterial blood gases in the elderly

Objectives: We present reference values for arterial blood gas measurements for persons > 70 years old. At the same time, we wish to examine how different criteria for exclusion from the reference sample with regard to previous smoking and various comorbidities might influence reference values. Methods: After first screening a random sample of the general elderly population by postal questionnaire, we selected 146 men and women without respiratory disease, significant dyspnea, symptomatic heart disease or hypertension, or current smoker status. Arterial blood samples were drawn from subjects while in the supine position. Results: The mean (SD; lower limit of normal) Pao(2) and arterial oxygen saturation (Sao(2)) for men was 77.0 mm Hg (9.1; 62.0) and 95.3% (1.4; 93.0), respectively, and for women was 73.5 mm Hg (8.4; 59.6) and 94.8% (1.7; 92.0). Mean (SD; upper limit of normal) Paco(2) was 39.4 mm Hg (3.3; 44.8) for both sexes. None of the blood gas variables were associated with age, smoking history, or presence of various comorbidities. Conclusions: The reference values for Pao(2) and Sao(2) in elderly persons are sex specific but age independent. Ex-smokers and persons with nonpulmonary comorbidities who do not have significant respiratory symptoms need not be excluded from the reference sample for arterial blood gases.