Comparative Study between the Efficacy of Fentanyl, Antihistamines, and Dexmedetomidine in Suppressing Photic Sneeze Reflex during Peribulbar Block

BACKGROUND: The photic sneeze reflex (autosomal dominant) is a condition that causes sneezing in response to numerous stimuli, such as looking at bright lights or periocular (surrounding the eyeball) injection. Unexpected or sudden sneezing during injection can be a dangerous side effect in periocular injection, in which abrupt head movement may cause globe injury. AIMS: We intended to evaluate the efficacy of adding fentanyl, dexmedetomidine, and antihistamines on the incidence of the sneeze reflex associated with propofol sedation during periocular local anesthesia injections. SETTINGS AND DESIGN: Our study was a randomized, prospective, double-blinded and controlled clinical study. PATIENTS AND METHODS: This study was conducted in Ain Shams and Fayoum university hospitals at the ophthalmic surgery department. After obtaining approval from our universities ethical committee and written informed valid consents from the patients, 90 patients were included in this study. The study population included patients of both sex, ASA grade 1 and 2, in the age ranging from 18-65 years. Patients were scheduled for cataract extraction surgeries and received peribulbar block. Then patients were randomly divided into three groups (30 patients each) using a computer- generated table of random numbers. Patients were preoxygenated with supplemental oxygen by nasal cannula, all 90 patients received intravenous propofol 1mg.kg- 1 bolus for sedation and were randomized to receive adjunctive drug 2 to 4 minutes prior to propofol injection: 30 patients received intravenous fentanyl 1 μmg.kg(-1) (Group F), 30 patients received dexmedetomidine 1μmg.kg(-1) (Group D), and 30 patients received antihistamine (pheniramine 22.75 mg) (Group H). The same local anesthetic admixture, consisting of 5 mL 2% lidocaine with 90 IU hyaluronidase, combined with 5 mL 0.5% plain bupivacaine in a 10-mL syringe at room temperature was administered to all patients using peribulbar block technique. A masked observer (surgeon or anesthesia assistant) recorded whether the patient had a sneezing event. Continuous cardiorespiratory monitoring was performed intraoperatively. Intraoperative and postoperative medication side effects were recorded including bradycardia (HR <55 beats/min), hypotension (MAP <50 mmHg sustained for >10 min), oxygen desaturation (SpO2<90%), nausea, vomiting and prolonged sedation using Ramsay Sedation Score (RSS). STATISTICAL ANALYSIS USED: Student's t-test and Chi-square test were used for analysis. RESULTS: The demographic data of the three study groups revealed non-significant differences between the three study groups as regards age, sex distribution, and the duration of surgery. No patient was excluded after inclusion to the study. All patients were able to complete the entire study and their data were included in the final analysis. Five events of sneezing had occurred in 90 patients. Two in (D) group and three in (H) group with is no statistically significant difference between the three groups as regard sneezing. Bradycardia, hypotension and sedation had occurred significantly in group (D) compared to group (F) and group (D). No patient suffered from nausea, vomiting or oxygen desaturation in all studied groups. No statistically significant difference as regards patient satisfaction between the three studied groups. CONCLUSION: Fentanyl, dexmedetomidine and antihistamines with propofol sedation suppress photic sneeze reflex during peribulbar block.