Inorganic fluoride in prolonged isoflurane sedation

An 18-year-old girl received isoflurane sedation for 48 h to facilitate mechanical ventilation. This resulted in a serum inorganic fluoride level of 37.3 mumol.l-1 when the isoflurane was stopped. As the serum fluoride level may continue to rise after isoflurane and as this level is approaching toxicity, the role of isoflurane sedation in the critically ill should be approached cautiously.