Crystalloid Versus Hydroxyethyl Starch Trials

Inclusion Criteria: * Written informed consent has been obtained or if not possible, the procedure for obtaining informed consent has been approved by the ethics committee. * Fluid resuscitation is required to increase or maintain intravascular volume that is in addition to maintenance fluids, enteral and parenteral nutrition, blood products and specific replacement fluids to replace ongoing insensible or fluid losses from other sites (e.g., fistula losses from the gastrointestinal tract, urinary losses from diabetes insipidus or the polyuric phase of acute renal failure or to correct metabolic derangements). * The ICU clinician considers that both 6% hydroxyethyl starch (130/0.4) and saline are equally appropriate for the patient and that no specific indication or contraindication for either exists. * The requirement for fluid resuscitation must be supported by AT LEAST ONE of the following clinical signs: 1. Heart rate \> 90 beats per minute 2. Systolic blood pressure (SBP) \< 100mmHg or mean arterial pressure (MAP) \< 75mmHg or at least 40mmHg decrease in SBP or MAP from the baseline recording 3. Central venous pressure \< 10mmHg 4. Pulmonary artery wedge pressure \< 12 mmHg 5. Respiratory variation in systolic or mean arterial blood pressure of \>5 mmHg 6. Capillary refill time \> one second 7. Urine output \< 0.5 ml/kg for one hour Exclusion Criteria: * Previous allergic reaction to hydroxyethyl starch solution. * Primary non-traumatic intracranial haemorrhage or severe traumatic intracranial haemorrhage (mass lesion \> 25 ml). * Patients who are receiving renal replacement therapy or in whom the ICU physician considers renal replacement therapy is imminent (i.e. renal replacement therapy will start in 6 hours) * Patients with documented serum creatinine value ≥ 350µmol/L and urine output averaging ≤ 10ml / hr over 12 hours * Severe hypernatraemia (Serum sodium \> 160 mmol/l) or severe hyperchloraemia (Serum chloride \> 130 mmol/l). * Women of child bearing age (18-49 years old), unless evidence of documented menopause, hysterectomy or surgical sterilisation or negative pregnancy test before randomisation * Breastfeeding * Patients who have received \> 1000mL hydroxyethyl starch in the 24 hours before randomization. * Patients admitted to the ICU following cardiac surgery; patients admitted to ICU following cardiac surgery. * Patients admitted to the ICU for the treatment of burns or following liver transplantation surgery. * Death is deemed imminent and inevitable or the patient has an underlying disease process with a life expectancy of \< 90 days. * A limitation of therapy order has been documented restricting implementation of the study protocol or the treating clinician deems aggressive care unsuitable. * Patient has previously been enrolled in the CHEST study. * Patient has previously received fluid resuscitation that was prescribed within the study ICU during this current ICU admission. * Patient has been transferred to the study ICU from another ICU and received fluid resuscitation for the treatment of volume depletion in that other ICU.