Edinburgh Clinical Trials


Alpha 2 agonists for sedation to produce better outcomes from critical illness: A randomised, parallel-group, allocation concealed, controlled, open, phase 3 pragmatic clinical and cost- effectiveness trial with internal pilot

Many patients in intensive care (ICU) need help to breathe on a breathing machine and need pain killers and sedatives to keep them comfortable and pain free. However, keeping patients too deeply sedated can make their ICU stay longer, can cause ICU confusion (delirium) and afterwards may cause distressing memories. Ideally we want to keep patients less sedated, but it is difficult to get the balance of sedation and comfort right. The purpose of this study is to compare if patients on dexmedetomidine or clonidine come off the ventilator quicker than those just on propofol. We will also see if there was a difference between the groups in the number of people who experienced delirium in ICU, compare how comfortable people were and measure if participants memories of being in ICU differed.


A2B trial logo

Chief Investigator: Professor Timothy Walsh

Number and location of participating sites / geographical scope (by region/ country): UK – 40-50 sites

EudraCT number:  2018-001650-98


Funder: NIHR Health Technology Assessment (HTA) Programme. Ref : HTA 16/93/01

Start and End date

Of grant award: April 2018 - July 2024

Of recruitment: Grant start date: July 2018 - October 2023

Current Status: Database Locked on 30 April 2024, pending closure


Study Protocol:


Patient Information Sheets:



England/Rest of UK:


All UK:


Frequently Asked Questions: 


Co-enrolment Agreements:

Co-enrolment between A2B and the following non-CTIMP studies has been agreed:  ADAPT-Sepsis; A-STOP; BLING III, The Norepinephrine Response Test (NRT) study; REST; FLO-ELA; EFFORT; RADAR-2; GAinS; Cryostat-2, SARIPOC, HOT-ICU, INHALE, ABC Post-ICU, RECOVERY-RS, UK-ROX, MERIT, SCUFFD, T4P, iRehab, PRONTO

Co-enrolment between A2B and the following observational/sampling studies has been agreed:  Appetite; Genomic; Iona; EPICS; ILTIS, Sepsis Immunomics, PARIS, Aspi-Flu, Phind, MOSES, ARDS-Neut, PQIP, CIRCA, KRAKIL, VAMp-Sepsis, Gut-Liver Axis (GLA), ISARIC, PREFIBRILLATE, PIMMS, CandiRes, ENLIST, NOVEL, IMPACCT, SQUEEZE, BioAID, METABOLIC, UNIVERSAL, Barriers and Facilitators, D-RISC-2, LicuID


Trial team contact: A2B@ed.ac.uk

Sponsor: The University of Edinburgh and Lothian Health Board, ACCORD (ref: AC18022),The Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ.  http://accord.scot/

Chief Investigator: Professor Timothy Walsh Timothy.Walsh@ed.ac.uk

Trial Manager: Sîan Irvine, Edinburgh Clinical Trials Unit, Usher Building, The University of Edinburgh, 5‒7 Little France Road, Edinburgh BioQuarter ‒ Gate 3, EDINBURGH EH16 4UX sian.irvine@ed.ac.uk

ECTU Involvement: Trial management /Statistics/ Database and randomisation service.