According to the 2016 Society of Critical Care Medicine (SCCM) clinical practice guideline on sustained neuromuscular blockade, a continuous intravenous infusion of a neuromuscular blocking agent (NMBA) may be considered early in the course of acute respiratory distress syndrome (ARDS) in adults with a PaO₂/FiO₂ ratio < 150 (weak recommendation, moderate-quality evidence). The recommendation is informed by randomized trials of cisatracurium infusions in ARDS patients but does not compare different agents or recommend one neuromuscular blocking agent (NMBA) over another. Specifically, three multicenter randomized trials (n= 431) evaluated early 48-hour cisatracurium infusions in mechanically ventilated ARDS patients, showing improved oxygenation, reduced 28-day and hospital mortality, and decreased risk of barotrauma without increasing intensive care unit (ICU)-acquired weakness. Mechanistically, NMBA therapy may provide benefit by preventing ventilator asynchrony and reducing lung stress from high airway pressures. While the guidance does not make comparative recommendations between different NMBAs, experts note that at the time of publication, no randomized trials of continuous infusions of agents other than cisatracurium in ARDS patients had been reported. Notably, a 2020 expert consensus on neuromuscular blockade in ARDS similarly highlights that cisatracurium is the only NMBA studied in large randomized trials and should generally be the preferred agent if an infusion is used. The impact of using other NMBA infusions in ARDS remains uncertain. In the largest trials, cisatracurium was given as a 15 mg bolus followed by a 37.5 mg/h infusion for 48 hours, but optimal dosing is unclear, and clinicians may titrate to clinical paralytic effect. Some evidence suggests that its benefits may relate not only to neuromuscular blockade but also to potential anti-inflammatory effects, so dosing decisions should weigh potential benefits and harms. [1], [2]
Review articles on the management of NMBAs in critically ill patients describe cisatracurium and rocuronium as commonly used agents with distinct pharmacologic profiles. Cisatracurium, a purified cis-cis isomer of atracurium, is an intermediate-acting NMBA with approximately three times the potency of atracurium, predictable recovery, and organ-independent Hofmann elimination, making it suitable for continuous infusion even in patients with liver or kidney dysfunction. Its favorable safety profile includes minimal histamine release, low vagolytic activity, and a low rate of hypersensitivity reactions, although rare postmarketing anaphylactic events have been reported. Cisatracurium has been studied in various ICU populations, with the strongest evidence for continuous infusion in ARDS, where trials have shown reduced inflammatory mediators and improved 90-day mortality. Rocuronium is an intermediate- to long-acting aminosteroid NMBA with faster onset but variable recovery, particularly in patients with hepatic dysfunction or multiorgan failure, and may require lower doses to achieve target paralysis in critically ill patients. Rocuronium has minimal histamine release and no direct sympathomimetic effects, though mild vagolytic activity may occur at higher doses, and rare cases of hyperthermia have been reported. Overall, while direct comparative data are not detailed within the reviews, the authors suggest that cisatracurium’s predictable pharmacokinetics, favorable safety profile, and clinical trial evidence make it the most frequently studied agent for continuous infusion in ICU patients, whereas rocuronium demonstrates more variable recovery times, particularly in those with hepatic or multiorgan dysfunction. [3], [4]