effect of local anesthesia versus induced hypotensive anesthesia on quality of external dacryocystorhinostomy operation

Conditions: Patient With Nasolacrimal Duct Obstruction; External Dacryocystorhinostomy Operation

Summary: bleeding is one of the important complications during dacryocystorhinostomy, which dissatisfy ophthalmic surgeon, reduces surgical field visualization, and increases the duration of surgery thus, the management of this complication is a great consideration during this operation. the aim of this study is to compare the efficacy of combined local and general anesthesia in a group of patients undergoing external dacryocystorhinostomy (dcr) operation versus the efficacy of general anesthesia with induced hypotensive anesthesia

dacryocystorhinostomy or dcr is among the common oculoplastics surgeries performed for managing epiphora due to nasolacrimal duct obstruction. the main purpose of dcr surgery is to eliminate the obstruction and to accomplish normal tear. dcr is a procedure performed to drain the lacrimal sac in which lacrimal flow is diverted into the nasal cavity through an artificial opening made at the level of the lacrimal sac in cases of chronic dacryocystitis or symptomatic nasolacrimal duct obstruction not relieved by simple probing and stringing. dacryocystorhinostomy (dcr) operation can be performed externally or endoscopically. external dcr was first described by toti and this procedure was modified with the use of flaps by many authors. it is the gold standard of treatment with a reported success rate of more than 90%. bleeding during dacryocystorhinostomy (dcr) is trivial, but because of the anatomical vessel variation and presence of tiny vessels in the field of dcr, it can obscure the surgical field and complicate the operation. one of the effective approaches for controlling bleeding tendency during dcr is to reduce blood pressure in patients. ideal hypotensive medications administered to reduce blood pressure should have specific features such as easy to administration, being with rapid onset and offset without side effects, rapid elimination without any toxic metabolites, and having a predictable and dose-dependent action. nitroglycerine (tng) is a direct vasodilator agent, especially in veins, and produces hypotension, and is preferred by clinicians because of rapid onset and offset time and easy titration. another mechanism for controlling bleeding is infiltrating the incision site by local anesthetic with admixed epinephrine to promote local vasoconstriction to decrease blood loss and prolong the duration of local anesthesia providing more time for analgesia. in this study, the investigators will compare the efficacy of local versus induced hypotensive anesthesia in generally anesthetized patients undergoing external dcr operation on amount of blood loss, quality of the surgical field, intraoperative hemodynamics, and surgeon satisfaction

Eligibility criteria:
inclusion criteria: * american society of anesthesiologists physical status i and ii * patients who are scheduled for external dacryocystorhinostomy operation exclusion criteria: * patient refusal. * patients with history for cerebrovascular. * patients with history for coronary insufficiency. * local skin infection at site of injection. * known hypersensitivity to the study drugs. * extremes of age. * patients with any type of arrhythmias. * hematological diseases. * bleeding abnormality * coagulation abnormality