Predictive risk factors for pulmonary oxygen transfer in patients undergoing coronary artery bypass grafting

The ratio of arterial oxygen tension to inspired oxygen fraction (PaO2 / Fi O(2)) is a useful indicator for weaning patients From mechanical ventilatio n and a reliable predictor of pulmonary dysfunction after cardiac surgery. The aim of this study was to elucidate the patient characteristics and vari ables that affect the PaO2 / FiO(2) ratio. Between 1994-1998, 167 patients who underwent coronary artery bypass grafti ng (CABG) were examined retrospectively. Spearman's correlation coefficient s were calculated between the PaO2 / FiO(2) ratio and intubation period, an d length of ICU stay, Patients were then divided into two groups with a PaO 2 / FiO(2) ratio < 350 and PaO2 / FiO(2) ratio <greater than or equal to> 3 50. Univariate analysis of the putative risk factors was performed. A logis tic regression model was developed to evaluate factors that would influence the PaO2 / FiO(2) ratio. A significant correlation was observed between the PaO2 / FiO(2) ratio and intubation period, and length of ICU stay. Univariate predictors of a PaO2 / FiO(2) ratio < 350 were low body weight, low preoperative PaO2, long oper ation time, high FiO(2), low postoperative PaO2, history of smoking, hypert ension and opening of pleura (p < 0.05). Excellent prediction was found wit h a model consisting of preoperative PaO2 and hypertension. Conclusion: The results of this study suggest that patients with a low preo perative PaO2 or hypertension may need more careful peri- and postoperative management since these factors are closely associated with the PaO2 / FiO( 2) ratio.