Table 1.
Standardized PPCs according to the european perioperative clinical outcome definitions.
| Pneumonia | Patient received antibiotics for a suspected respiratory infection and met one or more of the following criteria: new or changed sputum, new or changed lung opacities, fever, white blood cell count >12 × 109·L−1 |
|---|---|
| Respiratory failure | Postoperative arterial oxygen partial pressure <8 kPa (60 mm Hg) on room air, an arterial oxygen partial pressure to oxygen fraction ratio <40 kPa (300 mm Hg) or arterial oxyhaemoglobin saturation measured with pulse oximetry <90% and requiring oxygen therapy |
| Pulmonary embolism | Lung opacification with a shift of the mediastinum, hilum or hemidiaphragm toward the affected area and compensatory overinflation in the adjacent non-atelectoic lung |
| Pulmonary embolism | Diagnosed by CT angiography without severity grading |
| Bronchopleural fistula | Diagnosed by flexible bronchoscopy, persistently requiring reoperation |
| Pleural empyema | Fever, white blood cell count >12 × 109· L−1 and CT scan |
The results of this study were dichotomous variables, and we calculated the relative risk (RR) using 95% confidence intervals. Heterogeneity was quantified by the I2 statistic. If the I2 value was >50%, the heterogeneity was considered significant. A bias test was also performed. All statistical analyses were processed using Review Manager software (RevMan, version 5.3) and Stata software, version 14.