Sevoflurane- Safety in Long-term Sedation Procedures

Patients needing intensive care often require sedative drugs to reduce anxiety and agitation during ventilator care and invasive therapeutic and diagnostic procedures. At present there is no optimal sedative agent for these patients. The most commonly used sedative agents in intensive care units are midazolam and propofol. Both drugs have side effects of clinical importance. At present, a viable alternative to intravenous sedation is inhalatory sedation. Sevoflurane, as other inhaled anesthetic agents, is sedative in low doses. A new simplified method of administration of isoflurane or sevoflurane has been developed. The Anesthetic Conserving Device is a modified heat-moisture exchanger (HME) that permits direct infusion of sevoflurane to the airway, where it is vaporized in an evaporator rod in the device. However, the use of sevoflurane is limited to anesthesia and sedation lasting no more than 12 hours, since the possible renal problems posed by inorganic fluoride in prolonged operations remain the subject of controversy. The primary aim (and primary hypothesis) of the current trial is to determine whether sevoflurane can be administered as a sedative drug for more than 48 hours without clinically relevant physiopathological effects on kidney and liver function. Other end-points of the trial are to evaluate the quality of sedation of sevoflurane, in terms of sedation control, the rapidity and predictability of awakening, and the incidence of delirium in critical care patients.