Lung function test
A preoperative evaluation of lung
function was performed, and the results were classified according to
lung function test
guidelines
issued by the Chinese Society of Respiratory
Medicine.[16]Values were determined for the percentage of predicted value of the
forced expiratory volume in the first second (FEV1% pre), percentage of
predicted value of the ratio of forced expiratory volume in the first
second (FEV1) to forced vital capacity (FVC) (FEV1/FVC% pre),
percentage of predicted value of maximal mid-expiratory flow (MMEF%
pre), and the percentage of predicted value of maximal mid-expiratory
flow mid-expiratory flow (MEF% pre). The FVC% pre is the main
indicator of restrictive ventilatory dysfunction. The criterion for
obstructive ventilation disorder was a FEV1/FVC% pre value
≥ 92% or a FEV1% pre <
80%, and the criterion for small airway dysfunction was at least two
values of MMEF% pre, MEF50% pre, and MEF25% being lower than the
lower limit of normal (LLN, 65%). The severity of ventilatory
dysfunction was based on FEV1% pre: mild (70%-79%), moderate
(60-69%), moderate-severe (50%-59%), and severe (35%-49%), and very
severe (< 35%).[17]