Effect of Ultra-Low-Dose Naloxone Added to Fentanyl and Lidocaine for Peribulbar Anesthesia in Cataract Surgery: A randomized prospective clinical trial.

Interventions: The patients were randomized into 2 groups (30 patients each) to undergo peribulbar anesthesia. Group I: patients received 50 micrograms fentanyl and lidocaine 2% with hyaluronidase 15 IU/ml. Group II: patients received 100 nanograms naloxone, 50 micrograms fentanyl and lidocaine 2% with hyaluronidase 15 IU/ml. Preoperatively , no premedication was given and, intravenous cannula was inserted. The patients were monitored continuously for ECG, heart rate, pulse oximetery. Arterial blood pressure (ABP) was measured non-invasively every 5 minutes. Topical local anesthetic (benoxinate hydrochloride) was applied to the eye then, with the eye in the primary gaze position, a 25-gauge short bevel needle was inserted trans-conjunctivally at the junction between the medial two thirds and lateral third of the inferior orbital rim in a strictly posterior direction. Depth of needle insertion was limited to 25mm. The anesthetic mixture was injected after aspiration test and, the injection was continued until subconjunctival edema and lid fullness appeared. Intermittent digital compression was applied to lower the intraocular pressure until sufficient motor block occurred. Pain was assessed during and after surgery at 30, 60, 90 minutes 2, 3, 4, 6 and 8 hours post-operatively, using Visual Analogue Score (VAS). 0 = no pain, to 10 = maximum pain, 1-3 = mild pain, 4 - 6 = moderate pain, > 6 = severe pain. Patients with moderate or severe pain received diclofenac sodium 75 mg intramuscular injection.