Isoflurane produces profound muscle relaxation and enhances the action of tubocurarine, pancuronium and to a lesser extent vecuronium and atracrium. Halothane produces plasma bromides in proportion to dose and length of exposure. Bromides appear 2 to 3 days after the beginning of exposure, and their half-life is between 9 and 25 days. Symptoms of metabolic encephalopathy include headache, drowsiness, agitation, delirium, hallucination, lethargy, and coma. Enflurane can be responsible for fluoride-induced renal failure.
Halogenated agents cause progressive electroencephalographic changes.
At 1 MAC, EEG frequency decreases and voltage increases. At 1.5 MAC, burst suppression appears. At 2 MAC, the EEG becomes isoelectric. All these EEG changes are reversible.