Definitions
Duration of organ support in the critical care unit was defined as the number of days alive and free from support of each of the following organ systems, as defined by the UK Department of Health CCMDS during the first 30 days following randomisation.36 Patients who died within the first 30 days were assigned zero days alive and free from organ support. Organ support definitions were as follows:
Advanced respiratory – indicated by one or more of invasive mechanical ventilatory support through a translaryngeal tube or tracheostomy; bilevel positive airway pressure through a translaryngeal tube or tracheostomy; continuous positive airway pressure through a translaryngeal tube; or extracorporeal respiratory support.
Advanced cardiovascular – indicated by one or more of receipt of multiple intravenous and/or rhythm controlling drugs (of which at least one must be vasoactive) when used simultaneously to support or control arterial pressure, cardiac output or organ/tissue perfusion; continuous observation of cardiac output and derived indices; an intra-aortic balloon pump or other assist device; or temporary cardiac pacemaker.
Renal – indicated by receipt of acute renal replacement therapy (e.g. haemodialysis, hemofiltration, etc.); or receipt of renal replacement therapy for chronic renal failure when other acute organ support is received.
Neurological – indicated by one or more of central nervous system depression that was sufficient to prejudice the airway and protective reflexes (except when caused by sedation prescribed to facilitate mechanical ventilation or by poisoning, e.g. deliberate or accidental self-administered overdose, alcohol, drugs, etc.); receipt of invasive neurological monitoring or treatment (e.g. intracranial pressure monitoring, jugular bulb sampling, external ventricular drain, etc.); receipt of continuous intravenous medication to control seizures and/or for continuous cerebral monitoring; or receipt of therapeutic hypothermia using cooling protocols or devices.
Gastrointestinal – indicated by receipt of PN or EN (i.e. any method of feeding other than normal oral intake).
