Authors' objectives: Choice of sedation of critically ill patients is a core element of intensive care practice. The alpha 2 agonists for sedation to produce better outcomes from critical illness (A2B) trial tested the effectiveness of two alpha agonist sedatives versus propofol in reducing time on mechanical ventilation in 38 intensive care units in the United Kingdom. To evaluate both how this complex trial was implemented and how this may have influenced trial outcomes, an understanding of the contextual and practice variation across multiple sites was required.

Authors' results and conclusions: Site intervention adherence ratings for fidelity, dose and reach were low (4), moderate (20) and high (14). Participants from 12 intensive care units in each of phase 1 (33 staff) and phase 2 (36 staff) provided qualitative data; participating intensive care units differed between phases. Factors identified in phase 1 focused on intervention delivery and trial conduct and incorporated both organisational and participant-related factors. In phase 2, participant-related factors included clinician preference, individual equipoise, clinician resistance and staff capability and capacity, while A2B trial-related factors included concerns relating to safety and side effects, overnight deep sedation practice, patient comfort and trial documentation. Many of these factors were impacted by the COVID-19 pandemic, particularly in regard to staffing numbers and experience. Optimal sedation practice is influenced by multiple factors related to clinician perceptions, capacity and capability. Priorities in care focus on short-term safety and comfort. Limitations in staffing mean that longer-term consequences related to recovery and rehabilitation are second tier considerations.

Authors' methods: A mixed-methods, multiphase design was used following extensive pre-trial exploration of current practice. Quantitative data were drawn from the main trial database covering 38 sites to assess the intervention’s fidelity, dose and reach in each site. Data were analysed descriptively and provided a low-moderate-high rating. Qualitative data were collected by interviews mid trial (phase 1) and end of trial (phase 2). Participants were recruited from a random sample of 30 intensive care units active at the time of sampling and included the principal investigator, research nurses and clinical staff. Semistructured interviews, informed by the trial’s logic model, lasted 45–60 minutes. Data collection focused on whether the intervention could be delivered as intended, factors that impacted upon successful delivery and understanding intervention adherence. Analysis used a framework approach based on the logic model. Data collection and qualitative analyses were completed prior to knowing the primary results of the trial. Due to the impact of the COVID-19 pandemic, most data collection occurred remotely through video-conferencing rather than planned at site observation and interviews.

Project Status: Completed

URL for project: https://www.journalslibrary.nihr.ac.uk/programmes/hta/NIHR136090

Year Published: 2025

URL for published report: https://www.journalslibrary.nihr.ac.uk/hta/published-articles/GJTW0620

URL for additional information: English

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: England, United Kingdom

DOI: 10.3310/GJTW0620

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk