Partial Neuromuscular Blockade in Acute Hypoxemic Respiratory Failure

Controlling respiratory effort in patients with AHRF can be challenging, as they often exhibit a very high respiratory drive despite receiving high doses of sedatives. Consequently, these patients usually receive full neuromuscular blockade, with the goal to avoid such injurious respiratory efforts. Unfortunately, full neuromuscular blockade is not without complications. To address this issue, the use of partial neuromuscular blockade has been proposed as a strategy to maintain respiratory muscle activity while providing lung protective ventilation.

The objective of this study is to demonstrate the safety and feasibility of safe spontaneous breathing using partial NMB in moderato to severe AHRF patients supported with invasive mechanical ventilation.

Once adequate sedation has been ensured, an infusion of cisatracurium will be started to maintain spontaneous breathing with moderate levels of inspiratory effort, defined by expiratory occlusion pressure (Pocc) between -5 and -15 cmH2O. After establishing a sedation and NMB dosing regimen at which safe spontaneous breathing is achieved, we will document whether these targets can be maintained over a 48-hour period.

On December 11 2025, this study has been amended to broaden eligibility criteria from patients with acute respiratory distress syndrome supported on extracorporeal membrane oxygenation (ECMO) to patients with AHRF supported with invasive mechanical ventilation or with venovenous-ECMO. Additionally, the study intervention duration was extended from 24 hours to 48 hours or until hypoxemia is resolved (FiO2 ≤ 40% on PEEP ≤ 8 cmH2O), whichever occurs first. Finally, the study intervention was modified to remove the use of esophageal balloon, and to include sedation and neuromuscular blockade titration targeting Pocc between -5 to -15 cmH2O and according to predefined safety criteria assessed using train of four, respiratory drive and comfort assessments. A total of 15 patients will be enrolled after the amendment, in addition to the 8 patients already enrolled, for a total of 23 patients. Going forward, only patients in whom the intervention is initiated will count toward the study sample size.

Inclusion criteria

Patients supported on invasive mechanical ventilation for moderate to severe AHRF (PaO2/FiO2 < 150 mm Hg or FiO2 ≥ 60% with an SpO2 ≤ 97% or receiving venovenous extracorporeal membrane oxygenation)

Exclusion criteria

• Contraindication to neuromuscular blockade (allergy, history of malignant hyperthermia)
• Contraindication to ulnar nerve stimulation (bilateral peripheral neuropathy, skin burns on both wrists)
• Previous history of a formally diagnosed neuromuscular disorder