During tracheal intubation，choose the regular Left Double-lumen endobronchial tube according to the traditional method. The selection of double-lumen tube sizes using traditional methods relies on two factors: height and gender. In this study, all patients planned to be enrolled are female, so the traditional corresponding relationship is roughly as follows:

For patients with a height of less than 152 cm, a 32Fr (French) tube is often selected.

For patients with a height between 152 - 165 cm, a 35Fr tube is often selected. For patients with a height between 165 - 177 cm, a 37Fr tube is often selected. For patients with a height of more than 177 cm, a 39Fr tube is often selected.

Following intubation, the attending anesthesiologist inserted the fiberoptic bronchoscope (FOB) to reposition the left-sided double-lumen tube (LDLT) for optimal placement.（Confirmed by FOB: The left upper lobe and lower lobe bronchi were clearly visualized through the bronchial lumen, the left mainstem bronchus was seen via the tracheal lumen, and the bronchial cuff was positioned just below the carina).

Fiberoptic bronchoscopic adjustment immediately following intubation，if the DLT moves less than 1.0cm after the first intubation, it is regarded as successful

Intubation difficulty（when an anesthetist with over 3 years of DLT intubation experience needs ≥3 attempts or intubation time ≥10 min during DLT intubation）

After inflating the endotracheal tube cuff with 2-6 ml of air and the bronchial cuff with 1-3 ml of air respectively, cuff pressures are measured and should be < 25 cm H₂O and < 20 cm H₂O respectively. Absence of an air leak from the endotracheal tube when peak airway pressure reaches 30 cm H₂O during positive-pressure ventilation is considered an indicator of adequate seal.

The VIDIAC score is comprised of: E, the interaction between the blade tip and epiglottis; V, the best view of the vocal cords from the blade camera; and A, enlargement of the arytenoids. The score range of the VIDIAC score is from -1 to 5 points. The VIDIAC score classification is as follows: Easy, with a score of -1 or 0; Moderate, with a score of 1; Difficult, with a score of 2; Severe, with a score of ≥3.

Intubation Resistance

1. No resistance
2. Mild resistance
3. Moderate resistance (Significant resistance encountered at the subglottis, although the tracheal tube segment can be advanced past the subglottis)
4. Severe resistance(The tracheal tube segment cannot pass the subglottis and must be replaced with the next smaller size)

LDLT depth (cm) = 12 + [patient height (cm) × 10-¹](streamdown:incomplete-link)

if the DLT moves more than 1.0cm after the first intubation, it is regarded as Misplacement

Campos Classification of Lung Collapse:

Excellent: The operated lung is completely collapsed, the surgical field is satisfactorily exposed, and no intervention by the surgeon is required.

Good: The operated lung is mostly collapsed with some residual gas in the lung, but there is no ventilation in the lung, and the surgical field is relatively satisfactorily exposed.

Poor: The operated lung is not collapsed or only partially collapsed, which interferes with the surgical operation and requires intervention by the surgeon.

SaO₂≤90% and ≥1min, airway pressure>35cm H₂O, poor lung atelectasis, or according to experience, all need to use fiberoptic bronchoscope to confirm the position

if the DLT moves more than 1.0cm after the first intubation, it is regarded as Misplacement

hypoxemia means arterial oxygen saturation≤90%, and ≥60s

after repositioning to supine position, the double-lumen tube is withdrawn to the main trachea, and the mucosa within a 1cm radius of the carina is assessed using a fiberoptic bronchoscope

Left main bronchus transverse diameter (TD-LMB) (cm) Left main bronchus anteroposterior diameter (APD-LMB) (mm) Left main bronchus equivalent diameter (ED-LMB) (cm) DLT model selected based on MPR

Bronchial window measurement data Left main bronchus anteroposterior diameter (APD-LMB) (mm) DLT model selected based on bronchial window

The Numeric Rating Scale (NRS) is a widely used tool for assessing pain intensity, recognized for its simplicity, ease of administration, and high reliability across various patient populations.

The scale ranges from 0 to 10, where:

0 indicates "no pain at all." 10 represents "the worst imaginable pain."

Postoperative 30-day complications by using Clavien-Dindo score

postoperative pulmonary complications include: Pneumonia,Atelectasis,Respiratory failure,Pleural effusion,Bronchospasm,Pulmonary embolism If any of the above conditions is present, it is considered that there is a postoperative pulmonary complication.

The postoperative recovery is assessed using the quality of recovery-15 questionnaire (QoR-15) .The QoR-15 has 15 questions. Each question is rated on a 10-point scale, ranging from 0 (none of the time or poor) to 10 (all of the time or excellent). The maximum score (best recovery) is 150

arterial blood can be drawn from the specimen for examination.

arterial blood can be drawn from the specimen for examination.