[Prediction of respiratory complications after surgery of the abdominal aorta]

The most frequent type of complication in patients undergoing aortic surgery is respiratory. Preoperative lung function (PFT) and arterial blood gas measurement (ABG) are often carried out to assess the risk more precisely. The aim of the present retrospective study was to determine which value of lung function test could identify patients who developed such complications. "Receiver Operating Characteristic" (ROC) curves and the area beneath the curve for the diagnosis of respiratory complications were calculated for each variable of PFT and ABG. The greatest Youden index for each variable was chosen as indicative pulmonary function criterion of increased risk of pulmonary complications. One hundred and ninety-five patients (age: 65 +/- 10 years) were included. Respiratory complications occurred in 15% of patients. Respiratory complications increased from 12% if the vital capacity (VC) was > or = 77% of the predicted value to 35% if the VC was < 77% (P = 0.002), and from 10% if the FEV1 was > 76% to 34% if the FEV1 was > or = 76% (P = 0.0005). A decreased PaO2 or increased PaCO2 was not correlated with an increased incidence of respiratory complications. Length of stay in ICU or in hospital were increased when VC or FEV1 were low. Frequency of pulmonary complications was 9% in patients without PFT abnormalities, 16% in patients with either diminished VC or FEV1 and 35% in patients with both lowered VC and FEV1. However, all the areas under the ROC curves were < 0.7 and the sensitivity of the different variables was low. It is concluded that routine preoperative PFT and ABG cannot predict respiratory complications after abdominal aortic surgery.