Randomised trial of glutamine and selenium supplemented parenteral nutrition for critically ill patients. Protocol Version 9, 19 February 2007 known as SIGNET (Scottish Intensive care Glutamine or seleNium Evaluative Trial)

2 × 2 factorial, pragmatic, multicentre, double-blind, randomised controlled trial. The trial has an enrolment target of 500 patients. Inclusion criteria include: expected to be in critical care for at least 48 hours, aged 16 years or over, patients who require parenteral nutrition and are expected to have at least half their daily nutritional requirements given by that route.Allocation is to one of four iso-caloric, iso-nitrogenous groups: glutamine, selenium, both glutamine & selenium or no additional glutamine or selenium. Trial supplementation is given for up to seven days on the Intensive Care Unit and subsequent wards if practicable. The primary outcomes are episodes of infection in the 14 days after starting trial nutrition and mortality. Secondary outcomes include antibiotic usage, length of hospital stay, quality of life and cost-effectiveness.To date more than 285 patients have been recruited to the trial from 10 sites in Scotland. Recruitment is due to finish in August 2008 with a further six months follow up. We expect to report the results of the trial in summer 2009.This trial is registered with the International Standard Randomised Controlled Trial Number system. ISRCTN87144826Intensive care unit (ICU) and subsequent hospital mortality in the UK remains high, with figures of 15–20% and 30% respectively [1]. The cost per ICU bed-day exceeds ￡1,100 based on a mean from all trusts in England and Wales [2]. In many countries, including the UK, provision of intensive care is inadequate to meet demand. Infections acquired on the ICU have been associated with a two to three fold increased risk of death [3], this is associated with both illness and drug related impairment of the patient's immune system. Multiple portals for infection include: tracheal tubes, nasogastric tubes, chest and abdominal drains, central venous, pulmonary arterial and urinary catheters, wounds, and infective loci present before admission to ICU. These infections increase mortality, mo