[Neosynephrine mydriasis combined with general anesthesia with halothane in ocular surgery]

Ophthalmologic surgical interventions are performed in numerous cases under general anaesthesia with halothane, many of which requiring a preoperatory mydriasis. Neosinerfin is alpha-adrenoceptive sympathomimetic. Local use, in a 10% concentration produces a strong mydriasis, resistant to the opening of the aqueous chamber during the intervention. Its systemic effects are remarkable: it induces a peripheral blood vessel constriction which can unleash a reflex bradycardia followed by a shortcoming of the cardiac flow. The halothane has various effects upon the heart: reduces the cardiac frequency, reduces the conduction speed of the cardiac impulse stimulating rhythm disorders, sensitizes the myocardium to the action of adrenaline, diminishes the heart's contraction force and the cardiac flow. The cumulative effects of seosinefrin and halothane cause major cardio-vascular changes: sinus bradycardia, ventricular arrhythmia, arterial hypotension. These are reasons for which the pre- and intraoperatory use of neosinefrin is unadvisable. Under this circumstances the collaboration between the ophthalmologist and anesthesiologist is very important, each of them having specific tasks. The ophthalmologist: preoperatory, the optimal pupillary dilatation may be obtained with tropicamide and diclofenac 0.1%, preoperatory, if the general anesthesia must be combined with local anesthesia, anesthetics in association with adrenalin should not be used; immediately postoperatory local use of atropine should be applied with cautiousness. The anesthesiologist: preoperatory he will not interrupt anti-hypertensive, anti-arrhythmia, anti-angina medication, with the mention that adrenoceptive alpha blockers (Prazosin) are indicated in comparison to adrenoceptive beta blockers because they diminish the risk of rhythm disorders; the use of clonidine and avoiding of phenobarbital in the premedication of the patient. As far as it is possible, it is recommended that halothane is replaced with izofluran or enfluran or enfluran which have a great tolerance to exogenous adrenoceptives.