Table 2 Definitions of PPCs

Respiratory infections

Receiving antibiotics for a suspected respiratory infection and met at least one of the following criteria: new or changed sputum, new or changed lung opacities, fever, leukocyte count >12 × 10⁹/L

Respiratory failure

PaO₂ < 60 mmHg on room air, a ratio of PaO₂ to inspired oxygen fraction < 300, or arterial oxyhemoglobin saturation measured with pulse oximetry < 90% and requiring oxygen therapy

Pleural effusion

Chest X-ray demonstrating blunting of the costophrenic angle, loss of the sharp silhouette of the ipsilateral hemidiaphragm in upright position, evidence of displacement of adjacent anatomical structures, or (in supine position) a hazy opacity in one hemithorax with preserved vascular shadows

Atelectasis

Lung opacification with a shift of the mediastinum, hilum, or hemidiaphragm toward the affected area, and compensatory overinflation in the adjacent nonatelectatic lung

Pneumothorax

Air in the pleural space with no vascular bed surrounding the visceral pleura

Bronchospasm

Newly detected expiratory wheezing treated with bronchodilators

Aspiration pneumonitis

Acute lung injury after inhalation of regurgitated intragastric contents