Before undergoing minimally invasive lung surgery, patients with small lung nodules often need a procedure called "CT-guided hook wire localization." This involves using a CT scanner to help doctors place a tiny wire in the lung to mark the exact location of the nodule for the surgeon. While very helpful for the surgery, this wire placement can be highly painful for patients.

The main purpose of this clinical trial is to find out if giving patients a pain-relieving medication called parecoxib sodium before the procedure can effectively reduce their pain. Parecoxib sodium is a standard, non-opioid painkiller given through an IV.

Additionally, researchers want to discover the best time to give this medication. Because operating room schedules can change, patients will receive the IV medication at different times before their localization procedure (ranging from less than an hour to more than 3 hours beforehand). By looking at these different wait times, researchers hope to identify the "golden window"-the exact timing that provides the most pain relief.

During the study, participants will be randomly assigned by a computer to one of two groups:

The Study Group: Will receive the active pain medication (parecoxib sodium).

The Control Group: Will receive a placebo (a saltwater solution with no active medicine).

To ensure the results are fair and unbiased, participants have a 2 in 3 chance of receiving the active medication, and neither the patients nor their doctors will know which assignment they received. Immediately after the wire is placed, participants will be asked to rate their pain on a scale of 0 to 10.

By comparing the pain scores between the two groups and looking at the different medication timings, researchers hope to create better, more comfortable care guidelines for future lung surgery patients.

Background and Scientific Rationale Preoperative CT-guided hook wire localization is a critical step in Video-Assisted Thoracoscopic Surgery (VATS) for the precise resection of small, indeterminate lung nodules. However, the puncture of the parietal pleura induces acute, severe pain. This pain not only impairs the patient's perioperative experience but also leads to poor compliance (such as the inability to hold breath), which significantly increases the risk of procedure-related complications including pneumothorax, intrapulmonary hemorrhage, and wire dislodgement.

Parecoxib sodium, a highly selective COX-2 inhibitor, is widely used for perioperative pain management due to its strong analgesic properties and lack of interference with platelet function. While its theoretical pharmacokinetic profile suggests a peak analgesic effect between 1.5 to 2 hours post-administration, the inherent unpredictability of sequential operating room schedules makes a rigid, fixed preoperative dosing time highly impractical in real-world clinical settings.

Study Design and Methodology This is a single-center, prospective, randomized, double-blind, placebo-controlled clinical trial. The study employs a 2:1 asymmetric randomization ratio (Parecoxib Sodium : Placebo) stratified by the expected number of localized nodules (single vs. multiple). This specific ratio is designed to maximize the collection of real-world timing data in the intervention group while maintaining adequate statistical power against the control group.

Allocation concealment is strictly enforced using sequentially numbered, opaque, sealed envelopes (or an equivalent centralized electronic system). The study drug and placebo (0.9% normal saline) are prepared by an independent, unblinded research nurse to ensure identical volume and appearance. The patients, localization physicians, surgeons, and follow-up assessors remain completely blinded to the treatment assignment.

The "Natural Time Gradient" and Optimization Strategy A core methodological innovation of this trial is the embrace of the unpredictable nature of surgical wait times. Rather than enforcing a strict dosing schedule, the protocol dictates that the study drug be administered on an event-driven basis (e.g., when the preceding surgery enters the closure phase or upon a transport call from the CT suite).

This approach naturally generates a time gradient of administration-to-puncture intervals (ranging from roughly 30 minutes to over 6 hours). Researchers will record precise timestamps for both the intravenous administration (T1) and the moment of CT-guided puncture (T2).

Data Analysis and Clinical Translation While the primary objective tests the overall efficacy of pre-emptive parecoxib sodium in reducing immediate post-puncture pain, the critical secondary objective is to define the "golden clinical window" for this intervention.

By utilizing Restricted Cubic Splines (RCS) modeling, the research team will analyze the exact time interval ($\Delta T = T2 - T1$) as a continuous variable against the reported pain scores. This non-linear analysis aims to plot a dose-time-effect curve, pinpointing the optimal timeframe for drug administration. The ultimate goal is to translate these findings into a standardized, evidence-based Standard Operating Procedure (SOP) for perioperative pain management in minimally invasive thoracic surgery.

Inclusion Criteria:

• Voluntarily agreed to participate in the study and signed the informed consent form approved by the Ethics Committee.
• Male or female adult patients aged 18 years or older.
• Histologically or cytologically confirmed non-small cell lung cancer (NSCLC) scheduled for Video-Assisted Thoracoscopic Surgery (VATS).
• Requires preoperative CT-guided hook wire localization of lung nodules.
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.
• American Society of Anesthesiologists (ASA) physical status classification of I or II.
• Fully conscious with no psychiatric or neurological disorders, and capable of fully understanding and correctly using the Visual Analog Scale (VAS) for pain assessment.

Exclusion Criteria:

• Known history of hypersensitivity to parecoxib sodium, other COX-2 inhibitors, sulfonamides, aspirin, or other non-steroidal anti-inflammatory drugs (NSAIDs).
• History or presence of active peptic ulcer disease, gastrointestinal bleeding, or gastrointestinal perforation.
• Severe cardiovascular diseases, including but not limited to unstable angina, history of myocardial infarction within the past 6 months, severe arrhythmias, or poorly controlled hypertension.
• Coagulation disorders with a bleeding tendency (e.g., hemophilia) or currently receiving full-dose anticoagulation therapy, which the investigator believes may significantly increase the bleeding risk of the hook wire localization.
• Severe, uncontrolled pulmonary diseases (e.g., severe chronic obstructive pulmonary disease [COPD], interstitial pneumonia) that the investigator believes pose an unacceptable risk for the procedure.
• Currently using other analgesic medications that cannot be discontinued during the study period.
• Any other conditions that, in the investigator's judgment, might interfere with the outcome assessment or increase the risk to the subject.

All collected de-identified individual participant data (IPD) that underlie the results reported in the primary publication will be shared. This specifically includes demographic data, group assignment, precise timestamps for drug administration and the localization procedure (T1 and T2), primary outcome data (VAS pain scores), and secondary outcome data (patient satisfaction scores, rescue analgesia requirements, and incidence of procedure-related complications).

Beginning 6 months and ending 36 months following article publication.

Who: Researchers who provide a methodologically sound research proposal that is approved by the Institutional Review Board (IRB) or an independent review committee.

What: De-identified individual participant data (IPD) underlying the published results, along with the Study Protocol and Statistical Analysis Plan.

How: Requests should be submitted via email to the corresponding author dylan919@me.com. Data sharing is subject to institutional approval, ethical clearance, and the execution of a strict data transfer agreement.