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/FiO2) is a useful indicator for weaning patients from mechanical ventilation and a reliable predictor of pulmonary dysfunction after cardiac surgery. The aim of this study was to elucidate the patient characteristics and variables that affect the PaO2/FiO2 ratio. Between 1994-1998, 167 patients who underwent coronary artery bypass grafting (CABG) were examined retrospectively. Spearman's correlation coefficients were calculated between the PaO2/FiO2 ratio and intubation period, and length of ICU stay. Patients were then divided into two groups with a PaO2/FiO2 ratio < 350 and PaO2/FiO2 ratio > or = 350. Univariate analysis of the putative risk factors was performed. A logistic regression model was developed to evaluate factors that would influence the PaO2/FiO2 ratio. A significant correlation was observed between the PaO2/FiO2 ratio and intubation period, and length of ICU stay. Univariate predictors of a PaO2/FiO2 ratio < 350 were low body weight, low preoperative PaO2 long operation time, high FiO2, low postoperative PaO2 history of smoking, hypertension and opening of pleura (p < 0.05). Excellent prediction was found with a model consisting of preoperative PaO2 and hypertension.


CONCLUSIONS
The results of this study suggest that patients with a low preoperative PaO2 or hypertension may need more careful peri- and postoperative management since these factors are closely associated with the PaO2/FiO2 ratio.
Suematsu
Y
Y
Department of Cardiothoracic Surgery, University of Tokyo, Japan.
Sato
H
H
Ohtsuka
T
T
Kotsuka
Y
Y
Araki
S
S
Takamoto
S
S
D000328:Adult; D000368:Aged; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D011659:Pulmonary Gas Exchange; D012044:Regression Analysis; D012121:Respiration, Artificial; D012189:Retrospective Studies; D012307:Risk Factors; D014692:Ventilation-Perfusion Ratio
D010100:Oxygen