Continuous vs Bolus Neuromuscular Blockade Regimens in Moderate to Severe Hypoxemic Respiratory Failure and ARDS (COBRA) (COBRA)

The Effect of Continuous vs Bolus Neuromuscular Blockade Regimens for Patients With Moderate to Severe Hypoxemic Respiratory Failure and ARDS (COBRA): A Pilot Randomized Controlled Trial

Current clinical guidelines, such as those from the Surviving Sepsis Campaign and ARDSNet, recommend short-term NMBA use for patients with moderate to severe ARDS who exhibit persistent ventilator dyssynchrony or high plateau pressures despite deep sedation . However, they do not provide clear recommendations regarding the mode of administration. As a result, clinicians are left to extrapolate from limited or indirect evidence, which may lead to practice variation, uncertainty, and suboptimal care.

This pilot randomized controlled trial is designed to directly address this critical gap by comparing intermittent bolus administration versus continuous infusion of NMBAs in a pragmatic, real-world ICU setting. The study will assess feasibility metrics necessary to plan a definitive trial and generate preliminary clinical data on safety and effectiveness. By clarifying the comparative benefits and risks of each approach, the results may influence practice guidelines, reduce variation in care, and improve patient outcomes and reduce practice variation.patient outcomes, optimize resource use, and inform future guidelines on the management of moderate to severe ARDS.

Study Overview

• Status: Not yet recruiting
• Conditions: ARDS (Acute Respiratory Distress Syndrome)
• Intervention / Treatment: Drug: Neuromuscular Blocking Agent - Bolus Dosing; Drug: Neuromuscular Blocking Agent - Continuous Infusion

Detailed Description

Study Title: The Effect of Continuous vs Bolus Neuromuscular Blockade for Patients with Moderate to Severe HRF and ARDS: A Pilot Randomized Controlled Trial

Background:

Acute Respiratory Distress Syndrome (ARDS) affects ~10% of ICU patients and carries high morbidity and mortality. Neuromuscular blockade agents (NMBAs), especially cisatracurium, have historically been administered via continuous infusion to improve oxygenation and reduce ventilator-induced lung injury. However, recent evidence (e.g., ROSE trial) questions this approach, and emerging guidelines suggest intermittent bolus dosing may offer similar benefits with fewer adverse effects. There is a lack of direct comparative data, creating uncertainty in clinical practice.

Hypothesis & Objectives:

The study hypothesizes that a multicenter RCT comparing intermittent bolus vs continuous NMBA infusion in ARDS is feasible and that bolus dosing may show trends toward improved outcomes (e.g., ventilator-free days, fewer adverse events).

Primary objective: Assess feasibility of a definitive trial. Feasibility aims: 1. Recruitment rate (target ≥75%) 2. Protocol adherence (≥85%) 3. Data completeness (≥95%) 4. Safety monitoring of adverse events.

Secondary (exploratory) objectives: Compare 28-day ventilator-free days (VFDs), mortality, ICU/hospital length of stay, and ICU-acquired weakness.

Methods: This is a multicenter, prospective, pilot RCT in Alberta ICUs. 100 adult patients with moderate to severe ARDS will be randomized within 24 hours of diagnosis to either: 1. Intermittent bolus NMBA dosing OR 2. Continuous NMBA infusion (up to 48 hours). Both arms will receive lung-protective ventilation and guideline-based sedation.

Analysis: Feasibility outcomes will be described with 95% confidence intervals. Exploratory clinical outcomes will follow intention-to-treat principles using regression models. Results will inform design and sample size for a full-scale trial.

Risks & Mitigation: Risks such as protocol non-adherence, ICU-acquired weakness, and data loss will be managed via clinician education, adherence monitoring, and real-time data checks. Safety protocols, including allowance for rescue boluses and adherence to sedation best practices, will be enforced.

Team: Led by Drs. Parhar and Doig with a multidisciplinary team of critical care and clinical trial experts, the group has a strong track record in ICU research and implementation.

Significance & Knowledge Translation: This study addresses a critical evidence gap in ARDS care. Findings will inform future guidelines and practice by establishing whether bolus NMBA administration is a feasible, effective, and safer alternative to continuous infusion. Results will be disseminated through academic and clinical networks and will lay the groundwork for a large-scale, definitive RCT.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Ken Parhar, MD MSc MPH; Phone Number: 000-000-0000; Email: ken.parhar@albertahealthservices.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Age ≥18 years

• Mechanically ventilated and on a controlled ventilation mode
• Diagnosis of moderate to severe ARDS (PaO₂/FiO₂ ≤150 mmHg on PEEP ≥5 cm H₂O)
• Bilateral pulmonary infiltrates consistent with ARDS
• Randomized within 24 hours of meeting ARDS criteria

Exclusion Criteria:

• Pregnancy
• Known allergy or contraindication to rocuronium
• Neuromuscular disorders (e.g., myasthenia gravis, Guillain-Barré syndrome)
• Brain death or decision for withdrawal of life-sustaining therapy
• Enrollment in a conflicting interventional trial

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Bolus Dosing; Bolus dosing	Drug: Neuromuscular Blocking Agent - Bolus Dosing; Intermittent administration of NMBA; Other Names: Bolus dosing
Active Comparator: Continuous Infusion; Continuous infusion	Drug: Neuromuscular Blocking Agent - Continuous Infusion; Continuous infusion of NMBA; Other Names: Continuous infusion

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recruitment rate among eligible patients	Recruitment rate among eligible patients	Within 48 hours of meeting ARDS criteria
Protocol adherence rate	Protocol adherence rate	for the first 28 days of mechanical ventilation
Proportion of missing baseline characteristics and outcomes	Proportion of baseline characteristics and outcomes that are missing	First 28 days of invasive ventilation post ARDS diagnosis.
Compositive Safety	rates of ICU acquired weakness, unplanned extubation, and other SAE	First 28 days of invasive ventilation post ARDS diagnosis.

Collaborators and Investigators

• Sponsor: University of Calgary

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): January 1, 2028

Study Registration Dates

• First Submitted: June 13, 2025
• First Submitted That Met QC Criteria: April 30, 2026
• First Posted (Actual): May 5, 2026

Study Record Updates

• Last Update Posted (Actual): May 14, 2026
• Last Update Submitted That Met QC Criteria: May 11, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: mechanical ventilation; ARDS; Neuromuscular Blockade
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Lung Diseases; Lung Injury; Acute Lung Injury; Physiological Effects of Drugs; Peripheral Nervous System Agents; Neuromuscular Agents; Pharmacologic Actions; Chemical Actions and Uses; Neuromuscular Blocking Agents
• Other Study ID Numbers: REB25-1049

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No