Drug Monitoring of Therapy with Midazolam in Patients with ARDS: A Single-Center Prospective Study

Background and Objectives: One of the two primary classes of drugs administered in ICUs for pharmacological sedation is benzodiazepines. Among these, anesthesiologists consider midazolam the most commonly used and clinically significant agent. Materials and Methods: A prospective, single-center investigation involving 25 patients was carried out in the ICU. The study population consisted of patients undergoing mechanical ventilation with an FiO₂ exceeding 60%, as well as ventilated individuals requiring additional support such as ECMO, NO, or ECCOR over 24 h before the study. Participants under 18 years of age or those not receiving continuous midazolam infusion were excluded. Measurements obtained from RASS and BIS were then compared with serum midazolam concentrations. On each day, when blood samples for midazolam measurements were taken, additional laboratory tests assessing renal and hepatic function were also carried out. Results: A negative correlation was shown between RASS and midazolam dosage (r = -0.44, p < 0.001), midazolam concentration (r = -0.33, p < 0.001), and α-OH-midazolam concentration (r = -0.24, p = 0.008). Similarly, a negative correlation was shown between BIS and midazolam concentration (r = -0.3, p = 0.016), as well as α-OH-midazolam (r = -0.3, p = 0.016). We observed that deceased patients received higher doses of midazolam to maintain the minimum level of required sedation compared to the others (135.5 ± 75.1 mg vs. 39.6 ± 59.2 mg; p = 0.002), indicating that these patients had higher concentrations of both midazolam and α-OH-midazolam (148.6 ± 83.5 µg/L vs. 27.2 ± 36.1 µg/L; p < 0.001, and 18 ± 15.9 vs. 5.3 ± 6.1 µg/L; p < 0.001). Conclusions: The results show that routine monitoring of midazolam does not provide additional clinical value. However, further studies are needed in high-risk groups. Despite the high mortality rate in the ICU for patients with severe respiratory failure, the six-month survival rate for discharged patients was high, exceeding 80%.