The Pilot Clinical Investigation planned is a prospective, unblinded randomized pilot trial comparing sedation management using a protocol based on responsiveness with standard sedation management. The hypothesis is that responsiveness will improve a range of patient-based and economic outcomes, including the duration of mechanical ventilation and duration of coma in the ICU. The purpose of the pilot study is to gather information for designing a full study that might show the validity of the outcome hypothesis.

Inclusion Criteria:

Patients mechanically ventilated via an endotracheal tube and receiving intravenous sedation with a hypnotic agent (midazolam or other benzodiazepine) or propofol by continuous infusion.

Exclusion Criteria:

• Primary intracerebral disorder (includes cardiac arrest with probable hypoxic brain injury; intrac-ranial haemorrhage; head injury causing reduced conscious level prior to intubation)
• Patient who is already awake at the time of enrolment defined as RASS ³ -1
• Age <16 years
• Patient not expected to survive the next 24 hours
• Patient receiving long term ventilation prior to ICU admission
• Patient with a long term tracheostomy prior to ICU admission
• Patient transferred sedated and mechanically ventilated from another ICU unless recruitment is possible within 24 hours of first ICU admission
• Patient receiving continuous neuromuscular blocking agent at the time of screening for enrolment
• Previously enrolled in the trial during a separate ICU admission during this hospital stay
• Status epilepticus
• Confirmed meningitis or encephalitis at the time of screening for enrolment
• Chronic neurological disease interfering with normal neuromuscular function, e.g. motor neurone disease, Guillain-Barre syndrome or inherited neuromyopathies