Table 2 Definition of postoperative pulmonary complications (PPCs)

Respiratory insufficiency

At least one of the following criteria:

• SpO₂ < 90%

• PaO₂/FiO₂ < 300

• PaCO₂ > 45 mmHg

• Dyspnea with respiratory distress or use of accessory muscles

Respiratory infection

Evidence of new pulmonary infiltrates on chest radiograph plus at least two of the following Johanson criteria:

• Body temperature >38 °C or <35.5 °C

• White blood cell count >12,000 mm³ or <4000 mm³

• Purulent sputum

• Presence of a new or evolving infiltrate on chest radiograph within 7 days after surgery

Pleural effusion

Evidence of new hazy opacity of one

hemithorax with preserved vascular shadows on the supine radiograph, or posterior costophrenic angle blunting on a lateral chest radiograph, or evidence of a new hypo-anechoic area between visceral and parietal pleura on chest ultrasonography

Atelectasis

Evidence on chest radiography of new parenchymal thickening surrounded by hyperinflated lung

Aspiration pneumonitis

Inhalation of gastric content in the perioperative period with subsequent acute lung injury

Bronchospasm

New expiratory wheezing responsive to treatment with bronchodilators

Pneumothorax

Presence of air within the pleural space detected with chest radiograph or loss of lung sliding of gliding sign on ultrasonographic lung examination