الفهرس 
IntroductionOnly 14 pages are availabe for public view
Abstract
For many ophthalmic surgeons, local anesthesia has become the preferred option over general anesthesia because of the quicker rehabilitation and the avoidance of possible complications of general anesthesia. Vitreoretinal surgery is commonly done under peribulbar anesthesia supplemented with intravenous sedation.
Sedation is regarded as an important adjunct to ophthalmic anesthesia. Pharmacological sedation results in depression of the level of consciousness that is sufficient to achieve anxiolysis, amnesia and somnolence without loss of verbal communication. The clinical practice of sedation during ophthalmic local anesthesia varies among procedures and clinicians and is not without complications.
The ideal sedative for ophthalmic procedures performed under local anesthesia should have a rapid onset but a short duration of action to ensure rapid awakening and early return-to-home readiness, especially in the setting of day surgery. The agent should be non-toxic, non-accumulating and have predictable activity with minimal side effects. In a cost-conscious environment, cost-effectiveness is another important attribute.
The available drugs are benzodiazepines, intravenous anesthetic induction agents (e.g. propofol), opiates and α2 agonists such as dexmedetomidine or clonidine.
Common adverse effects of midazolam include prolonged recovery after long term or high dose use, hypoxemia, hypotension and respiratory depression when paired with an opioid. The adverse respiratory profile, unpredictable attenuation of stress response to surgery (tachycardia and hypertension) and associated post-operative nausea and vomiting of benzodiazepines and opioids create the need for a sedative drug that can be used safely during monitored anesthesia care.
Propofol is commonly used for conscious sedation, mainly because its half-life is brief, and because it allows accurate control of the depth of sedation. Propofol has a low incidence of side effects, particularly excitatory phenomena, involuntary movements and post-operative nausea and vomiting (PONV) but has no analgesic properties. Since propofol has no analgesic component, an opioid is often given to prevent the unintentional reflex to painful stimuli, and thus may result in a higher incidence of confusion, excessive sedation, disorientation or respiratory depression.
The α2 agonist dexmedetomidine provides “conscious sedation” with adequate analgesia and minimal respiratory depression. It is a sedative – hypnotic, anxiolytic and sympatholytic that can attenuate the stress response to surgery (mitigating tachycardia, hypertension) and also decrease intraocular pressure during ophthalmic surgery under local anesthesia. It is the primary sedative drug for orthopedic, ophthalmic (posterior segment surgery), dental, plastic surgeries, for sedation in intensive care and for various diagnostic procedures. Dexmedatomidine is labelled for intensive care and procedural sedation in the USA and India.
In our study, 45 patients were allocated into three groups of 15 patients each. group A sedated with Midazolam infusion (1 mg/hr.) while group B sedated with propofol (1-2 mg/kg/hr) and finally group C sedated with dexmedatomedine (0.5 μg/kg/h for 10 min followed by 0.2 μg/kg/h).
The sedation level of the patients was monitored using Ramsey sedation score, also patient and surgeons’ satisfaction was polled. Vital data (blood pressure, Heart rate and oxygen saturation) were also monitored over the procedure.
Our study showed that dexmedatomedine was superior in reaching the targeted sedation level although it took it longer to reach the desired level of sedation. Also, it provided better surgeon and patient satisfaction with less adverse effects. There was no difference between the three drugs regarding hemodynamic effects.