Comparative Study Between Different Additives to Lidocaine 2٪ for Peribulbar Block in Vitreoretinal Surgery

Comparative Study Between Different Additives to Lidocaine 2٪ for Peribulbar Block in Vitreoretinal Surgery (Prospective Comparative Randomized Controlled Trial

Peribulbar block, is the favored anesthetic technique for numerous ophthalmic procedures due to its lower rate of associated complications .

Retinal surgeries have many problems to the anesthesiologists as these operations are often lengthy , involve a significant risk of postoperative pain ,and typically involve an elderly patient population with multiple comorbidities .

Many anesthesiologists consider the peribulbar block as a safe technique; however, it has the disadvantage of a slow onset of orbital akinesia and to produce it a more substantial volume or repeated injections of local anesthetic solution is required due to limited diffusion of local anesthetics . This also increases the frequency of complications, such as globe perforation and peribulbar hemorrhage .

To prevent this and to increase tissue perfusion, hyaluronidase and other adjuvants such as clonidine, epinephrine and alkalinization of local anesthetics were used to improve peribulbar block.

Hyaluronidase may reduce tissue viscosity , which facilitate the complete diffusion of anesthetic solution along tissue planes .

in regional anesthesia is the addition of hyaluronidase is associated with benefits such as faster onest of action and impoved block quality ,however ,evidence regarding its efficacy in peribulbar techniques remains inconsistent.

To improve the quality and duration of the block, various adjuvants have been investigated. Two promising agents are Midazolam, a benzodiazepine with hypothesized peripheral GABA-ergic action, and Cisatracurium, a non-depolarizing neuromuscular blocking agent. Midazolam may enhance sensory block and provide amnesia, while cisatracurium directly induces chemical paralysis of the extraocular muscles. However, a direct comparative study of their efficacy and safety profiles in this context is lacking. This study aims to fill that gap .

90 eligible patients were randomly allocated into three groups using computer-generated random numbers placed in sealed, opaque envelopes.

• Group L (Control): lidocaine 2٪ (4 ml) + Normal Saline (1 ml).
• Group M (Midazolam): lidocaine 2٪ % (4 ml) + Midazolam (1 mg in 1 ml).
• Group C (Cisatracurium): lidocaine 2٪ (4 ml) + Cisatracurium (0.5 mg in 0.5 ml) + Normal Saline (0.5 ml).

The total volume of the injectate was standardized to 5 ml for all groups.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status I-III patients -enrolled for elective vitreoretinal procedures under peribulbar block.

Exclusion Criteria:

• Patient refusal
• allergy to study drugs
• coagulopathy
• infection at the injection site
• significant axial myopia (axial length >26mm)
• neurological or neuromuscular disorders
• pregnancy
• inability to communicate.