12 | Inhalational sedation with sevoflurane via the mirus system in SARS-COV-2–related acute respiratory distress syndrome: clinical experience, depth monitoring, and perspectives for a pilot study

Background. Sedation in patients with moderate-to-severe ARDS due to SARS-CoV-2 pneumonia requires precise titration to ensure adequate control of respiratory drive and comfort while maintaining hemodynamic stability and optimizing gas exchange. Volatile agents such as Sevoflurane are gaining interest in intensive care as alternatives to intravenous sedatives, due to their bronchodilatory, anti- inflammatory, and lung-protective properties, as well as their favorable pharmacokinetic profile. Advanced monitoring systems now allow continuous assessment of hypnotic depth and nociceptive balance during inhalational sedation—an approach still not widely applied in this setting.

Case Presentation. In the ICU of the University Hospital of Sassari, we report the case of a 75-year-old male (BMI 29.3) with major depressive disorder admitted for acute respiratory failure due to SARS-CoV-2 pneumonia (PaO₂/FiO₂ =131 mmHg). The patient initially received propofol and morphine; however, due to worsening oxygenation and bronchoconstriction, neuromuscular blockade with cisatracurium was initiated. Propofol was then replaced with Sevoflurane administered via the MIRUS system for 72 h. Continuous Depth-of-Anesthesia (qCON) and Nociception (qNOX) monitoring were implemented. With a MAC of 0.7, achieved through concomitant opioid use, qCON values(51.5 [50-55]) and qNOX(35 [33-36]), remained within the target range for adequate sedation and analgesic levels.

During sevoflurane administration, a marked improvement in gas exchange was observed (PaO₂/FiO₂ from 131 to 201 mmHg), along with enhanced ventilatory mechanics and stable hemodynamics (MAP 70 [70–75] mmHg) despite pulmonary sepsis. No relevant cardiovascular or neurological adverse effects occurred.

Results. This case demonstrates the feasibility and clinical benefit of sevoflurane sedation in ARDS, with improved oxygenation, pulmonary mechanics, and preserved hemodynamic stability. The association of the volatile agent with an opioid allowed the maintenance of lower MAC values while ensuring adequate hypnotic depth and nociceptive control, optimizing both sedation quality and physiological tolerance.

Conclusions. Based on this experience, we aim to develop a pilot study evaluating the physiological effects of sevoflurane focusing on respiratory drive modulation, bronchodilation, gas exchange efficiency, and hemodynamic stability ARDS. Given that volatile anesthetics also exert cardiocerebral protection and anti-inflammatory actions beyond sedation, this research could validate their role as multimodal, targeted therapies in critical care.