Nutrition in the critically ill

Amie KershawCritical Care Dietitian

Manchester Royal Infirmary

OverviewMalnutrition

Aims of nutrition support

Nutritional requirements

Nutrition support

Potential complications

Developing areas

Malnutrition in hospital

What is malnutrition?

“Malnutrition is a state of nutrition in which a deficiency or excess (or imbalance) of energy, protein and other nutrients cause measurable adverse effects on tissue/body form (body shape, size and composition) function and clinical outcome.”

Elia, (2000)

Definition of malnutrition

A body mass index (BMI) <18.5kg/m

Unintentional weight loss >10% in 3 – 6 months

A BMI <20kg/m and unintentional weight loss >5% in 3 – 6 months

Why does malnutrition develop?

Impaired intake

Impaired digestion and absorption

Altered nutritional requirements

Excess nutrient losses

Malnutrition Many people are malnourished prior to

admission to hospital

People in hospital are at risk of becoming malnourished or further malnourished

Prevalence of malnutrition in hospital has been quoted as 40% (McWhirter & Pennington, 1994)

Up to 43% of patients in ICU are malnourished (Giner et al, 1996)

Consequences of malnutrition

Weight loss

Weakness and fatigue

Impaired ventilatory drive DEATH

Depression / apathy Poor wound healing

Impaired immune functionWebb (1999), Garrad (1996)

Nutritional Screening – why?

Government initiatives + recommendations

2003 Food, Fluid and Nutritional Care (NHS Quality Improvement, Scotland)

2002 Nutrition and Catering Framework (Welsh Assembly Government)

2001 NSF for Older People (DH) 2001 Essence of Care (DH)+ 2006 Nice Guidelines

Malnutrition Universal Screening Tool (MUST)

Anticipate/prevent malnutrition

Confirm malnutrition

To facilitate planning of appropriate nutritional

support

To act as a method of monitoring progress

Takes into account the past, present and future

Can be used across a variety of settings

MUST

To be completed for each patient on admission and rescreen weekly (or more often if indicated)

ACTION to be taken according to the high, medium or low risk score

Completed assessment forms to be kept with patient documentation

Nutrition Support

Why feed the critically ill?

Provide nutritional substrates to meet protein and energy requirements

Help protect vital organs and reduce break down of skeletal muscle

To provide nutrients needed for repair and healing of wounds and injuries

To maintain gut barrier function To modulate stress response and improve

outcome

Nutritional RequirementsEnergy

Calculation of basal metabolic rate with additional factors for:

Stress Activity Energy required to metabolise food (diet induced

thermogenesis)

Protein

Typically 0.8 – 1g protein/kg, increased during stress

Fluid

30ml/kg for >60yrs and 35ml/kg for < 60yrs

Metabolic consequences of overfeeding

Hyperlipidemia (increased fat levels in the blood)

Azotemia (increased urea)

Hyperglycaemia (high blood sugar levels)

Fluid overload

Hepatic dysfunction (abnormal liver function tests, fatty deposits in the liver)

Excess CO2 production

Respiratory compromise

Klein (1998)

Enteral feeding“If the gut works – use it”

Nasogastric (NG)

Nasojejunal (NJ)

Percutaneous Endoscopic Gastrostomy (PEG)

Percutaneous Endoscopic Jejunostomy (PEJ)

Radiologically Inserted Gastrostomy (RIG)

Surgical Gastrostomy

Surgical Jejunostomy (JEJ)

Common feeds used on ICUType of feed Features Uses

Standard / multifibre

1kcal/ml Most patients

Energy / energy multifibre

1.5kcal/ml Increased requirements

Fluid restriction

Concentrated 2kcal/ml

Low electrolytes (i.e. Potassium, phosphate)

Fluid restrictionRenal with high

blood electrolytes

Oxepa 1.5kcal/ml

High fat – omega-3 fats

High antioxidants (vitamins)

ARDS – 1 study

Low sodium 1kcal/ml

Low in salt

intracranial hypertension

Peptisorb Predigested malabsorption

Indications for Parenteral Nutrition

Long term:

Inflammatory bowel disease Radiation enteritis Motility disorders Extreme short bowel syndrome Chronic malabsorption

Short term:

Severe pancreatitis Mucositis post-chemo with

intolerance of enteral nutrition Gut failure Prolonged nil by mouth (NBM)

post major excisional surgery High output or enterocutaneous

fistula Intractable vomiting Malnourished patient unable to

establish enteral nutrition

Complications of Nutrition Support

Prokinetics - Gut motility medication

Indication for use Possible causes

- High gastric aspirates - Medications

- Gut failure

- Diabetic stasis

Prokinetics of choice

- Metoclopramide

- Erythromycin

- Major cause of underfeeding

Diarrhoea

Nosocomial (hospital acquired)

Non-infectious causes: medications

sorbitol, magnesium salt containing antibiotics – 5 – 30% incidence (McFarland)

feed malabsorption, faecal impaction, low albumin - not major risk factors

Fibre in EN - a combination of soluble & insoluble fibre

colonic blood flow, promote sodium & water retention and therefore may help control diarrhoea

“Severe fluid and electrolyte shifts and related metabolic complications in

malnourished patients undergoing refeeding.”

Solomon &Kirby (1990)

Refeeding Syndrome

Refeeding Syndrome

During starvation

Insulin concentrations decrease and glucagon levels rise

Glycogen stores rapidly converted to glucose Gluconeogenesis activated – glucose

synthesis from protein and lipid breakdownCatabolism of fat and muscle loss of lean

body mass, water and minerals

Refeeding Syndrome

During refeeding Switch from fat to carbohydrate metabolism Insulin release stimulated by glucose load cellular glucose, phosphorus, potassium

and water uptakeExtracellular depletion of phosphate,

potassium, magnesiumClinical symptoms

Clinical SymptomsElectrolytes Cardiac Respiratory Hepatic Renal

Low phosphorus

Altered myocardial function

Arrhythmia

CHF

Acute ventilatory drive

Liver dysfunction

Low potassium

Arrhythmia

Cardiac arrest

Respiratory depression

Exacerbation of hepatic encephalopathy

Polyuria

Polydipsia

Decreased GFR

Low magnesium

Arrhythmia

Tachycardia

Respiratory depression

Clinical SymptomsElectrolytes GI Neuromuscular Haematologic

Low phosphorus

Lethargy, weakness, seizures, coma, confusion, paralysis, rhabdomyolysis

Haemolytic anaemia, WBC dysfunction, thrombocytopenia

Low potassium Constipation

Ileus

Paralysis,

rhabdomyolysis

Low magnesium

Abdo pain

Anorexia

Diarrhoea

Constipation

Ataxia

Confusion

Muscle tremors

Weakness

Tetany

Who is at risk?

NICE guidelines (2006)

Some risk:People who have eaten little or nothing for

more than 5 days

Who is at risk?

High risk: One or more of the following:

- BMI < 16kg/m- unintentional weight loss > 15% in last 3

– 6 months- Little or no nutritional intake for >10days- Low levels of potassium, phosphate or magnesium prior to feeding

Who is at risk?

High risk: Two or more of the following:

- BMI < 18.5kg/m

- Unintentional weight loss > 10% in last 3 – 6 months

- Little or no nutritional intake for more than 5 days

- History of alcohol abuse or drugs: insulin, chemotherapy, antacids or diuretics

Managing refeeding syndrome

Consider Pabrinex (high dose thiamine) and balanced multivitamin/mineral supplement

Feed cautiously – 10kcal/kg for first 2 days, 5kcal/kg in extreme cases (dietitian will advise). Increase slowly (over 4 -7 days)

Monitor biochemistry regularly including phosphate, magnesium and potassium correcting low levels as necessary

Developments in

Nutrition Support

Immunonutrition

Potential to modulate the activity of the immune system by interventions with

specific nutrients

ImmunonutritionNutrients most often studied: Arginine - can enhance wound healing and

improve immune function. Conditionally essential amino acid.

Glutamine – Precursor for rapidly dividing immune cells, thus aiding in immune function. Conditionally essential.

Branched chain amino acid’s – support immune cell functions.

Omega 3 fatty acids – lowers magnitude of inflammatory response, modulate immune response.

Immunonutrition

Espen guidelines (2006): Immune modulating formula beneficial in the

following patient groups:- upper GI surgery- mild sepsis- trauma

If unable to tolerate <700ml/d immune modulating formula should be stopped.

Not recommended for routine use in ICU patients

Immunonutrition

Espen Guidelines (2006) Glutamine should be added to a standard

enteral formula in burned and trauma patients

Insufficient data to support enteral glutamine supplementation in surgical or heterogeneous critically ill patients