Arterial oxygen partial pressure and cardiovascular surgery in elderly patients

Arterial blood gas assessment is still routinely performed in candidates for a cardiovascular surgery. Whether sampling arterial blood is useful in an elderly patient with a near normal lung function and who meets all other criteria for operability, is unknown. Therefore, it was our purpose to provide reference values for arterial blood gases in these patients and to examine how the level of arterial oxygen partial pressure (PaO(2)) might influence postoperative outcome. We retrospectively studied arterial blood gases in 201 patients, aged 70-92 years with normal or near normal ventilatory function awaiting a planned cardiovascular surgery. PaO(2) averaged 81.6+/-7.6 mmHg and PaCO(2) averaged 37.7+/-3.2 mmHg. Both were independent of age. Factors associated with mortality according to bivariate analysis were: gender (female), type of surgery (valve replacement), and a low PaO(2) with strictly no ventilatory abnormality. In conclusion, PaO(2) values in elderly patients with cardiac disease and normal ventilatory function are greater than those obtained by extrapolation from healthy younger subjects. PaO(2) measurement should be recommended prior to cardiovascular surgery in elderly patients since a low PaO(2) with strictly normal ventilatory function is significantly associated with an increased risk for postoperative mortality.