Inhaled Sedation in the ICU

Sedation is often required to facilitate comfort and provide necessary care for patients who are critically ill and require mechanical ventilation. Intravenous sedatives are the current standard of care in this patient population. Inhaled volatile agents that are routinely used for general anesthesia, like isoflurane and sevoflurane, are also being explored for their potential role in the ICU setting. Already, inhaled volatile agents are prescribed for routine ICU sedation in several countries, though their use for ICU sedation is not approved by United States regulatory authorities as of the time of this writing. The efficacy and safety profiles of inhaled sedatives for short-term use are well understood through decades of experience in the operating room. Their rapid onset and elimination via the lungs, potential opioid-sparing effects, and preservation of spontaneous breathing make them intriguing potential alternatives or adjuncts to standard-of-care sedation during critical illness. Technological advancements, consisting of compact vaporizers, volatile agent reflectors, and scavenger systems, allow the delivery of inhaled sedatives via modern ICU ventilators. However, these systems require specialized clinical training and considerations. Rigorous clinical trials evaluating the use of inhaled volatile agents for prolonged sedation of patients receiving mechanical ventilation remain limited, and whether these theoretical advantages translate to patient-centered benefit, relative to intravenous agents, remains unknown. Recent findings suggest prolonged deep sedation with inhaled sevoflurane predisposes to nephrogenic diabetes insipidus and acute kidney injury during critical illness, and that it is potentially harmful in patients with ARDS. Isoflurane may have a more favorable safety profile, but rigorous data are sparse on isoflurane use for more than a few days. This narrative review evaluates the evidence regarding the use of inhaled sedatives in patients in ICU who require mechanical ventilation. It also provides an overview of the clinical and technical aspects of this therapy to inform health care providers of a novel option, in many countries, for the sedation of patients undergoing mechanical ventilation.