Intensive Nutrition in Critically Ill Adults

Background:

Nutrition is a commonly provided therapy in critical illness, but data about effectiveness is sparse. Best practice guidelines recommend enteral nutrition (EN), a specialised solution delivered into the gastrointestinal tract, as the first line of nutrition therapy. The majority of best practice guidelines also recommend delivery of energy and protein amounts close to predicted requirements in critical illness over the course of Intensive Care Unit (ICU) admission, however the only evidence to support this is from observational data. Although recommended that energy and protein requirements be met, and observational data suggests this is of benefit, there are practical challenges with the provision of EN. International practice surveys report the average energy and protein provided is approximately 59% of the patients predicted requirements, for multifactorial reasons. The addition of parenteral (intravenous) nutrition has been proposed as a method to provide additional energy when EN is insufficient, termed supplemental parenteral nutrition (PN). The ability of this strategy to deliver additional energy and protein to patients during critical illness has been proven in several feasibility/pilot trials, but the benefit on clinical and functional outcomes is unknown.

Despite observational data suggesting benefit when energy and protein delivery is optimised close to requirements, no large scale randomised controlled trials (RCTs) have confirmed improved clinical outcomes in critical illness, with some showing no effect with delayed nutrition or even harm. There are several possible reasons for the lack of observed benefit from RCTs to date; the interventions may have been applied at a time when the patient's metabolism is not in a phase of recovery; interventions have been short in duration and; studies have not addressed what happens to nutrition intake in the post ICU period of hospitalisation in critically ill individuals.

Aims:

To determine whether the use of a pre-tested supplemental PN strategy in the ICU and an intensive nutrition intervention after discharge to the hospital ward is feasible and will deliver more total energy than standard nutrition care over the entire hospital stay, in critically ill patients with at least one organ system failure.

A further aim is to develop a research program that will determine whether optimisation of energy to critically ill patients over the entire period of hospitalisation improves clinically-meaningful outcomes.

Hypothesis:

In critically ill patients with at least one organ failure, the use of a supplemental PN strategy in ICU and an intensive nutrition intervention on the hospital ward will lead to an increase in daily energy delivery of at least 15% over the entire hospital stay when compared to standard care.

Fifteen percent has been estimated as the minimum acceptable clinical difference between the two groups.

Objectives:

The major objectives are:

• To determine whether the whole hospital nutrition intervention leads to increased amounts of total energy delivered over the period of hospital stay
• To determine if the whole hospital nutrition intervention is safe in regards to adverse effects
• To determine if the post-ICU nutrition intervention is practically feasible when applied in multiple hospitals, across multiple wards
• To measure the clinical outcomes in patients and provide information to assist design of a larger randomised controlled trial

Inclusion criteria

Patients in intensive care who meet all of the following will be eligible:

• Admitted to intensive care between 72 hours and 120 hours
• Receiving invasive ventilator support
• At least 18 years of age
• Have central venous access suitable for PN solution administration
• Have 1 or more organ system failure (respiratory, cardiovascular or renal) related to their acute illness defined as:

• PaO2/FiO2 ≤ 300 mmHg
• Currently on 1 or more continuous inotrope/vasopressor infusion which were started at least 4 hours ago at a minimum dose of:

• Noradrenaline ≥ 0.1mcg/kg/min
• Adrenaline ≥ 0.1 mcg/kg/min
• Any dose of vasopressin
• Milrinone > 0.1 mcg/kg/min
• Renal dysfunction defined as:

• Serum creatinine 2.0-2.9 times baseline OR
• Urine output 0.5ml/kg/hr for ≥ 12 hours OR
• Currently receiving renal replacement therapy
• Currently has an intracranial pressure monitor or ventricular drain in situ

Exclusion criteria

Patients will be excluded if:

• Both EN and PN cannot be delivered at enrolment (i.e. either an enteral tube or a central venous catheter cannot be placed or clinicians feel that EN or PN cannot be safely administered due to any other reason)
• Currently receiving PN
• Clinician believes a specific parenteral formula is indicated
• Death is imminent in the next 96 hours
• There is a current treatment limitation in place or the patient is unlikely to survive to 6 months due to underlying/chronic illness
• More than 80% of energy requirements have been satisfactorily delivered via the enteral route in the last 24 hours
• Dialysis dependent chronic renal failure
• Suspected or known pregnancy
• Product contraindication
• The treating clinician does not believe the study to be in the best interest of the patient