Alterations in arterial oxygen tension associated with age, weight, and smoking

The present study was undertaken to determine relationships between pre- and postoperative arterial oxygen tension levels in selected patients undergoing openheart surgery with cardiopulmonary bypass. A second purpose was to determine how the variables age, weight, and smoking were related to both pre- and postoperative arterial oxygen levels. Fourteen subjects admitted to the McKay-Dee Hospital in Ogden, Utah for openheart surgery from November 1973 to April 197U comprised the study sample. Subjects were weighed on admission to the hospital and categorized as normal or overweight. Subjects were also categorized as either smokers or nonsmokers. Arterial blood samples were drawn preoperatively and on the third postoperative day. A third sample was drawn on available subjects the ninth postoperative day. Data were analyzed using multiple correlation techniques. Pre- and postoperative arterial oxygen tensions for each subject in the sample were variable. Preoperatively, all but two subjects had arterial oxygen levels in the mild hypoxemic range. All subjects were hypoxemic postoperatively with the lowest values occurring on the third postoperative day. Analysis of data by the categories age and weight showed no statistically significant correlation between these variables and the pre- and postoperative arterial oxygen levels. An analysis of variance was conducted on all combinations of subject variables for both pre- and postoperative arterial oxygen values. No statistically significant results were found. Smoking was a statistically significant variable related to the arterial oxygen tensions of subjects in this investigation. There were no statistically significant differences shown between the smokers! and nonsmokers! preoperative arterial oxygen tensions. On the third postoperative day, however, the arterial oxygen tensions of the smokers were significantly lower than the arterial oxygen tensions of nonsmokers. Another statistically significant finding was that subjects with the highest preoperative arterial oxygen values had the lowest arterial oxygen values on the third postoperative day.