Comparison of Different Epidural Lidocaine-Bupivacaine Mixtures for Lower Limb Surgeries

Lower limb surgeries are commonly associated with significant perioperative and postoperative pain, requiring effective anesthetic techniques to provide adequate analgesia and improve patient outcomes. Epidural anesthesia is widely used because it offers effective intraoperative anesthesia, prolonged postoperative pain relief, improved physiological responses to surgical stress, and enhanced patient satisfaction. Local anesthetic agents such as lidocaine and bupivacaine are commonly administered for epidural blockade due to their different pharmacological characteristics.

Lidocaine has a rapid onset of action but a relatively shorter duration, whereas bupivacaine provides prolonged analgesia but has a slower onset of action. Combining these agents may provide the advantages of both drugs by achieving rapid onset with longer duration of action while maintaining hemodynamic stability.

This randomized controlled trial will be conducted at the Department of Anaesthesiology and Surgical ICU, Shaheed Mohtarma Benazir Bhutto Institute of Trauma, Karachi. Ninety-six patients aged 20-60 years, ASA class I and II, undergoing lower limb surgeries under epidural anesthesia will be enrolled and randomized equally into three groups.

Group A: 10 ml of 0.5% isobaric bupivacaine + 5 ml of 2% lidocaine Group B: 10 ml of 0.5% isobaric bupivacaine + 2.5 ml of 2% lidocaine + 2.5 ml normal saline Group C: 10 ml of 0.5% isobaric bupivacaine + 5 ml normal saline

The primary outcomes assessed will include time to onset of sensory blockade at T10 level, time to onset of motor blockade to Bromage Grade II, and duration of motor blockade until recovery to Bromage Grade I. Hemodynamic variables including mean arterial pressure and heart rate will also be recorded and compared among groups.

The study aims to determine the optimal epidural lidocaine-bupivacaine mixture that provides faster onset of anesthesia, adequate duration of block, and stable hemodynamic effects in patients undergoing lower limb surgeries.

Inclusion criteria

Patients undergoing lower limb surgeries under epidural block Age between 20-60 years Either gender American Society of Anesthesiologists (ASA) physical status I and II Patients willing to provide informed consent

Exclusion criteria

Contraindications to regional anesthesia including patient refusal and bleeding diathesis History of allergy to local anesthetics Patients undergoing emergency surgeries Deformities of the spine History of hypothyroidism or hyperthyroidism Pregnant patients