The investigators hypothesized that an ultrasound-guided lung recruitment maneuvers would be more effective in preventing postoperative atelectasis than conventional alveolar recruitment after surgical correction of idiopathic adolescent scoliosis.

In anesthetized children, the incidence of lung collapse with episodes of hypoxemia is high. Diaphragm dysfunction induced by general anesthesia is one of the most important factors in the genesis of regional losses of lung aeration; the mass of the abdominal organs pushes the diaphragm cranially compressing the lungs in the most dependent areas. Such regional lung collapse may range from slight loss of aeration to complete atelectasis.

Scoliosis correction surgery for adolescent idiopathic scoliosis (AIS) is effective in preventing deterioration of lung function caused by disease progression, and improving lung volume over the long term. However, complications of the respiratory system and pulmonary dysfunction may occur in the immediate postoperative period. General anesthesia (GA) and positive pressure ventilation can cause decreased lung volumes, expiratory flow rates, and oxygenation after surgery as a result of positive pressure ventilation, partial recovery of respiratory muscle, pain, and immobilization.

Lung ultrasound has been gaining consensus as a noninvasive, radiation-free tool for diagnosing various pulmonary diseases in adult and pediatric patients. Evidence supporting lung ultrasound use is expanding beyond emergency and critical care settings to perioperative care.

It has been reported that lung ultrasound (LUS) at a patient's bedside immediately following surgery can be useful for diagnosing respiratory complications. LUS has proven to be a valuable bedside diagnostic tool for pneumothorax, with high sensitivity and specificity (78.6% and 98.4%, respectively), and a higher rate of detecting abnormalities such as lung alveolar consolidation and pleural effusion than bedside chest X-ray or physical examination. LUS has also been used to diagnose anesthesia-induced atelectasis in pediatric patients.

Inclusion Criteria:

• Patients scheduled for elective correction of AIS
• aged between 10 and 25 years old
• American society of anesthesiologists (ASA) class I & II
• both genders

Exclusion Criteria:

• Morbidly obese patients
• patients with previous thoracic surgery
• upper or lower airway infection within 2 weeks before the surgery
• abnormal preoperative chest x-ray findings including atelectasis, pneumothorax, pleural effusion or pneumonia