The development of chronic postoperative pain (CPP) following surgery is influenced by several factors, among which the intensity of acute postoperative pain in the immediate perioperative period and mechanisms related to nerve fiber injury play a crucial role. Previous studies have demonstrated that factors such as the severity of early postoperative pain, patient age, and the extent of surgical intervention may increase the risk of transition from acute to chronic pain. In recent years, growing attention has been directed toward anesthetic techniques and adjuvant analgesics (co-analgesics) administered during surgery, which may potentially reduce the incidence of CPP.

The aim of this study is to evaluate the effects of intraoperative intravenous infusions of dexmedetomidine or lidocaine during urethral reconstructive surgery on postoperative pain intensity, patient-reported quality of recovery, and the incidence and characteristics of chronic postoperative pain, including its neuropathic component. In particular, the study will investigate whether administration of these agents reduces pain intensity during the first 48 hours after surgery-which, according to existing evidence, may correlate with the risk of CPP development-and whether intraoperative infusion of lidocaine or dexmedetomidine translates into reduced pain severity and a lower risk of neuropathic pain at long-term follow-up (3, 6, and 12 months after surgery).

An important aspect of this project is that both investigational drugs-lidocaine and dexmedetomidine-have an established role in routine anesthesiology practice, and their safety profiles are well characterized and extensively documented in the medical literature. Intravenous lidocaine infusion has been used for many years as part of multimodal perioperative analgesia; numerous randomized controlled trials and meta-analyses have confirmed its efficacy in reducing postoperative pain intensity and opioid requirements, with a low risk of adverse effects when administered at therapeutic doses. Dexmedetomidine has been routinely used for years both in intensive care units and as a component of general anesthesia across a wide range of surgical procedures. Its analgesic, anxiolytic, and opioid-sparing effects have been supported by a substantial body of clinical evidence, and the doses used in the present protocol are consistent with established clinical practice.

Lidocaine and dexmedetomidine are drugs with a long history of clinical use in anesthesiology and intensive care medicine, and their safety has been extensively documented. Intravenous lidocaine infusion at therapeutic doses constitutes an established component of multimodal perioperative analgesia. Its efficacy in reducing postoperative pain intensity, decreasing opioid requirements, and attenuating the inflammatory response to surgical injury has been demonstrated in numerous prospective randomized trials and meta-analyses. Dexmedetomidine, a selective α₂-adrenergic receptor agonist, is routinely used both for sedation and analgesia in intensive care units and as a component of balanced anesthesia in a wide range of surgical procedures. Its analgesic, sympatholytic, and opioid-sparing properties, together with its favorable effects on hemodynamic stability, have been supported by a substantial body of clinical evidence. The dose ranges employed in the present protocol fall within the limits recommended by current guidelines and are consistent with established clinical practice.

The objective of this study is to determine whether the pharmacological properties of these two agents may be beneficial in preventing chronic postsurgical pain in patients undergoing urethral reconstructive surgery, an area in which high-quality methodological evidence remains scarce.

b) Detailed Methodology Study population The study will enroll patients aged 18-75 years with physical status classification of American Society of Anesthesiology status (ASA) I-III who are scheduled to undergo urethral surgery (e.g., urethral reconstruction, urethroplasty, or treatment of urethral strictures).

Study Design

1. Recruitment

   Participants will be recruited from among patients of the Department of Urology, Centre of Postgraduate Medical Education, Orlowski Hospital, Warsaw, who are scheduled for urethral reconstructive surgery. During the pre-anesthetic clinic visit or following hospital admission on the day preceding surgery, patients will receive detailed information about the study and an informed consent form for participation in the clinical trial. They will have the opportunity to ask questions and receive comprehensive answers. Signed consent forms will be collected on the morning of surgery.

2. Randomization and Blinding

Patients will be randomly assigned to one of three groups:

Dexmedetomidine group: intravenous dexmedetomidine bolus of 0.6 μg/kg administered over 10 minutes before induction of anesthesia, followed by continuous infusion at 0.6 μg/kg/h until the end of surgery; Lidocaine group: intravenous lidocaine bolus of 1.5 mg/kg administered over 10 minutes before induction of anesthesia, followed by continuous infusion at 1.5 mg/kg/h until the end of surgery; Control group: placebo consisting of 0.9% sodium chloride administered according to an identical volume-based regimen.

Randomization will be performed using the website www.randomizer.org with equal allocation among the three study groups.

Blinding will be ensured using opaque, sealed envelopes containing the randomization number. The envelope will be opened immediately before preparation of the study infusion on the day of surgery, following acquisition of informed consent, by a physician who is a member of the research team but will not be involved in the patient's subsequent intraoperative or postoperative care. This physician will prepare the study medication in a 50-mL syringe according to the coded allocation:

1. - dexmedetomidine 4 μg/mL
2. - lidocaine 10 mg/mL
3. - 0.9% sodium chloride (NaCl)

Neither the patient nor the clinical staff involved in perioperative care will be aware of treatment allocation (double-blind design).

Patient data will be collected in a secure database inaccessible to unauthorized individuals and will include demographic data (age, height, body weight, ASA status, comorbidities, substance use, location of urethral stricture), surgical data (fluid administration, duration of surgery, blood loss), and intervention-related data (total amount of study drug administered and anesthesia-related complications such as hypotension or bradycardia requiring vasoactive treatment).

3. Perioperative Management

Upon arrival in the operating room, standard monitoring of vital signs will be initiated and prophylactic antibiotics administered according to institutional protocols.

The study drug infusion will then be started at a rate of 0.9 mL/kg/h and continued for 10 minutes, corresponding to a dose of 0.6 μg/kg dexmedetomidine or 1.5 mg/kg lidocaine.

Subsequently, the infusion will be continued until placement of the final skin suture at a rate of 0.15 mL/kg/h, corresponding to 0.6 μg/kg/h dexmedetomidine or 1.5 mg/kg/h lidocaine.

General anesthesia will be induced and maintained using standard doses of opioids and anesthetic agents, with maintenance by inhalational anesthesia using sevoflurane.

Postoperatively, all patients will receive standardized multimodal analgesia consisting of paracetamol 1 g every 6 hours, metamizole 1 g every 6 hours, and intravenous dexketoprofen 50 mg three times daily. In cases of insufficient analgesia (pain intensity >3 on the Numeric Rating Scale [NRS]), buprenorphine 0.3 mg intravenously or intramuscularly will be administered at intervals no shorter than 2 hours, with an additional intravenous bolus of 0.3 mg permitted for breakthrough pain if required.

4. Assessment of Acute Pain and Quality of Recovery

During the first 48 postoperative hours, pain intensity will be assessed using the Numeric Rating Scale (NRS 0-10) both at rest and during coughing at predefined time points: 2, 4, 8, 24, and 48 hours after surgery.

Total opioid consumption (buprenorphine) during the first 24 hours and time to first opioid administration will be recorded.

Before discharge, patients will complete the Polish version of the Quality of Recovery questionnaire (QoR-15).

Inclusion Criteria:

• ASA status less or equal 3
• Scheduled for reconstructive surgery of urethra
• Able to understand information provided and to sign informed consent for participation in the study

Exclusion Criteria:

• known allergy to one of the investigated medications
• current chronic pain
• known chronic use of opioids, gabapentinoids and antidepressants

Perioperative infusion content known only to investigator that is responsible for infusion preparation and is not involved in patient's care.