Transient increase of bispectral index in a patient with bronchoconstriction after endotracheal intubation

: A 62-year-old woman (148 cm, 48.5 kg) with a history of bronchial asthma underwent an emergency appendectomy. Ten days before the operation she developed symptoms of wheezing while under asthma medication. An endotracheal tube (7 mm) was inserted after the induction of general anesthesia with intravenous injection of fentanyl 100 micrograms, propofol 100 mg and vecuronium 10 mg under Sellick's maneuver. Anesthesia was maintained with 1% sevoflurane with oxygen 6l-min-1 just after intubation, but bilateral lung sound soon became weaker and ventilation difficult. Based on a diagnosis of bronchoconstriction, we started hyperventilation with 3% sevoflurane. Ventilation returned to normal after about 5 minutes. Percutaneous O2 saturation was maintained at 100% during this episode, but the BIS transiently rose to 82. Anesthesia was maintained with 2% sevoflurane and 50% nitrous oxide balanced with oxygen, and 250 mg aminophylline was administered. Upon completion of the operation, the endotracheal tube was removed without any events. The patient gave no sign of awareness during the operation. When severe bronchoconstriction prevents the absorption of anesthetics from the lung alveoli, additional intravenous anesthetics should be administered to maintain stable amnesia.