Background It has been stated that preoperative pulmonary function tests are essential to assess the surgical risk in patients with scoliosis.Arterial blood gas tests have also been used to evaluate pulmonary function before scoliotic surgery.However,few studies have been reported.The aim of this study was to investigate the roles of preoperative arterial blood gas tests in the surgical treatment of scoliosis with moderate or severe pulmonary dysfunction.Methods This study involved scoliotic patients with moderate or severe pulmonary dysfunction (forced vital capacity ＜60％) who underwent surgical treatment between January 2002 and April 2010.A total of 73 scoliotic patients (23 males and 50 females) with moderate or severe pulmonary dysfunction were included.The average age of the patients was 16.53 years (ranged 10-44).The demographic distribution,medical records,and radiographs of all patients were collected.All patients received arterial blood gas tests and pulmonary function tests before surgery.The arterial blood gas tests included five parameters:partial pressure of arterial oxygen,partial pressure of arterial carbon dioxide,alveolar-arterial oxygen tension gradient,pH,and standard bases excess.The pulmonary function tests included three parameters:forced expiratory volume in 1 second ratio,forced vital capacity ratio,and peak expiratory flow ratio.All five parameters of the arterial blood gas tests were compared between the two groups with or without postoperative pulmonary complications by variance analysis.Similarly,all three parameters of the pulmonary function tests were compared.Results The average coronal Cobb angle before surgery was 97.42° (range,50°-180°).A total of 15 (20.5％) patients had postoperative pulmonary complications,including hypoxemia in 5 cases (33.3％),increased requirement for postoperative ventilatory support in 4 (26.7％),pneumonia in 2 (13.3％),atelectasis in 2 (13.3％),pneumothorax in 1 (6.7％),and hydrothorax in 1 (6.7％).No significant differences in demographic characteristics or perioperative factors (P ＞0.05) existed between the two groups with or without postoperative pulmonary complications.According to the variance analysis,there were no statistically significant differences in any parameter of the arterial blood gas tests between the two groups.Conclusions No significant correlation between the results of the preoperative arterial blood gas tests and postoperative pulmonary complications existed in scoliotic patients with moderate or severe pulmonary dysfunction.However,the postoperative complications tended to increase with the decrease of partial pressure of arterial oxygen in the arterial blood gas tests.