The goal of this study is to evaluate whether topical flurbiprofen reduces the incidence and severity of postoperative sore throat (POST) and hoarseness in patients undergoing double-lumen tube (DLT) intubation for elective thoracic surgery.

The main question is: Does topical flurbiprofen reduce POST and hoarseness compared with placebo in patients undergoing DLT intubation? Researchers will compare topical flurbiprofen spray with placebo spray.

Participants will:

• Receive a DLT sprayed with either topical flurbiprofen or placebo before intubation.
• Be assessed for POST and hoarseness at 15 minutes, 2 hours, 12 hours, 24 hours, and 48 hours after surgery.

Postoperative sore throat (POST) is a common complication after general anesthesia involving airway manipulation, with reported incidence rates of up to 62%. It includes a spectrum of symptoms such as throat pain, pharyngitis, laryngitis, tracheitis, cough, hoarseness, and dysphagia, typically occurring in the early postoperative period. Although generally self-limiting, severe cases may cause dyspnea and dysphagia, reduce patient satisfaction, and in some cases prolong hospital stay.

POST results from laryngeal and tracheal mucosal injury during tracheal intubation. The pathophysiology is multifactorial, involving direct airway trauma, mucosal irritation and inflammation, ischemia from cuff compression, regurgitation of gastric contents, and gastric tube placement. Risk factors include female sex, younger age, smoking, lung disease, prolonged surgery, patient repositioning, difficult intubation, larger tube diameter, stylet use, high cuff pressure, and frequent suctioning.

The use of double-lumen tubes (DLTs), required for thoracic surgery with one-lung ventilation, has been associated with an even higher incidence of POST due to larger tube size, stylet-assisted insertion, and increased glottic trauma.

Several strategies have been investigated to prevent POST, including cuff pressure control, local anaesthetics, corticosteroids, and nonsteroidal anti-inflammatory drugs (NSAIDs). Dexamethasone and lidocaine have shown some benefit, but results are inconsistent, and POST remains prevalent in clinical practice.

Flurbiprofen, a nonsteroidal anti-inflammatory drug, is available as an oromucosal spray (8.75 mg/dose) and is widely used for sore throat relief in general practice. It reduces airway inflammation and provides analgesia when applied locally. Previous studies suggest that flurbiprofen spray applied to the cuff of laryngeal mask airways or single-lumen tubes reduces POST severity. However, limited evidence is available in the setting of DLT intubation, which carries a higher risk of POST.

This randomized, double-blind, placebo-controlled trial will investigate whether topical flurbiprofen spray applied to the cuff of a DLT before intubation reduces the incidence and severity of POST and hoarseness in patients undergoing elective thoracic surgery. Participants will be randomized to receive either topical flurbiprofen spray or placebo, with outcomes assessed at multiple time points up to 48 hours postoperatively. The study will be conducted at a single academic center, with standardized anesthesia management and blinding of patients, clinicians, and outcome assessors.

Inclusion Criteria:

• Patient aged 20-80 years
• Undergoing elective thoracic surgery
• Requiring DLT intubation for lung separation
• ASA physical status classification I-III
• Able to communicate and understand the study

Exclusion Criteria:

• Contraindications to use of flurbiprofen, including allergies to flurbiprofen or NSAIDs, active peptic ulcer/ hemorrhage, history of gastrointestinal bleeding or perforation, severe colitis, severe heart failure, chronic kidney disease (CKD) stage IV or end-stage kidney disease (ESRD), or liver failure
• Recent or recurrent upper respiratory tract infection
• History of sore throat or hoarseness within 1 month prior to surgery
• History of previous airway surgery
• Chronic pain conditions
• Pregnancy

Withdrawal criteria

• Fail DLT intubation
• Inability to extubation at the end of surgery

Individual participant data will not be shared because this is a single-centre investigator-initiated study with a limited sample size, and the data contain potentially sensitive patient information. De-identified summary data may be made available upon reasonable request to the principal investigator