The present study will be conducted involving 40 patients aged 18-65 years with ASA physical status I and II, scheduled for acute or elective hand or forearm surgery under the lateral infraclavicular block. Patients will be divided into two groups based on smoking status: Group I (non-smokers) and Group II (smokers who smoke ≥20 cigarettes/day for over 1 year).

Using a high-frequency linear ultrasound transducer, the axillary artery, vein, and the three nerve cords will be identified in the lateral infraclavicular region. After disinfection with ethanol-chlorhexidine, a sterile drape will be placed, and the attending anesthesiologist will perform the ultrasound-guided infraclavicular brachial plexus block with a triple injection technique. A total of 10 mL of bupivacaine 0.25% and prilocaine 0.05% will be injected at all three nerve cords.

The primary outcome will be the sensory blockade onset time, while secondary outcomes will include the duration of sensory and motor blockade, motor blockade onset time, time to first postoperative rescue analgesia, and total consumption of rescue analgesia. Postoperative pain will be assessed using the Visual Analogue Scale (VAS) within the first 24 hours at intervals of 2, 4, 8, 12, 16, and 24 hours. If VAS exceeds 30 cm, rescue analgesia with 0.05 mg/kg intravenous morphine sulfate will be administered.

Inclusion Criteria:

• ASA physical status I and II
• Scheduled for acute or elective hand or forearm surgery under the lateral infraclavicular block

Exclusion Criteria:

• morbid obesity (body mass index > 40)
• bleeding disorder
• coagulopathy
• medication with vitamin K antagonists
• high-dose or fractionated heparin treatment
• allergy to local anaesthetics
• infection at the site of needle insertion
• peripheral neurological disease
• pregnancy

Patients aged 18 to 65 years, classified as ASA physical status I and II, scheduled for acute or elective hand or forearm surgery with a lateral infraclavicular block.