Table 1 Inclusion and exclusion criteria

Inclusion

- Patients aged over 18 years

- Patients who had undergone elective surgical procedures

- Patients who received general anaesthesia only

- American Society of Anaesthesiologists (ASA) from 1 to 3

Exclusion

- Patients who were undergoing cardiac, thoracic or neurological surgeries, as well as patients who were undergoing abdominal emergency surgery

- Patients who are having a history of pulmonary disease or cardiovascular comorbidities

- Patients undergoing elective surgery that lasted more than 4 h (240 min)

- American Society of Anaesthesiologists (ASA) from 4 to 5