Nutrition of the Critically Ill Obese Patient

OVERVIEW

High protein hypocaloric feeding is preferred for critically ill obese patients (supported by SCCM/ ASPEN joint Consensus statement)

ENERGY REQUIREMENTS

Determination

  • prediction equations for REE in the obese are highly unreliable
  • no consensus as to which prediction equation for REE is most accurate in obese patients
  • Indirect calorimetry is the preferred method for measuring REE but this is often unavailable or impractical
  • For calculation of REE the Penn State equation and adjusted HBE have the strongest evidence to support their use

BODY COMPOSITION AND METABOLIC RATE

  • obese patients have increased resting energy expenditure secondary to increased BMI
  • central adipose tissue is more metabolically active than peripheral adipose tissue
  • adipose tissue is less metabolically active than fat free mass (FFM)
  • obese patients have increased amount of lean body mass

METABOLIC DERANGEMENT IN OBESE PATIENTS

Causes — the usual response to critical illness modified by:

  • Insulin resistance
  • obesity is a pro-inflammatory state
  • altered body composition

Effects

  • Impaired glucose tolerance
    — exacerbates stress-induced hyperglycemia
  • Increased fatty acid mobilization
    — high FFA plasma levels and hyperlipidemia
  • accelerated protein degradation
    — depletion of lean body mass
    — high amino acid plasma levels
    — energy stores from lean mass is used preferentially in the obese (unlike lean people who use FFAs)

ASSESSMENT

History

  • dietary history
  • any significant gain or loss of weight and whether this change was intentional
  • risk factors for enteral failure
    — e.g. changes in gastrointestinal function, prior abdominal or bariatric surgeries, and/or mechanical limitations to eating

Examination (often limited by body habitus)

  • CVS, RESP, GI exam
  • volume status
  • muscle wasting (chronic protein-calorie malnutrition)
  • check entire skin surface for integrity and presence of wounds
    — check skin folds carefully
    — may need additional staff / lifting equipment
  • determine height and weight accurately -> calculate BMI
    — monitor weight daily, preferably with calibrated bed scale
  • 24 hour fluid balance

NUTRITION STRATEGY

High protein hypocaloric enteral nutrition

  • enteral feeds preferred
  • 60–70% of target energy requirements or 11–14 kcal/kg actual body weight per day
  • protein (often 50–60% total calories) at:
    — 2.0 g/kg IBW per day for class I and II obesity (BMI 30-35 and 35-40 respectively)
    — 2.5 g/kg IBW per day for class III obesity (BMI >40)

Rationale

  • prevents complications of overfeeding, such as:
    — hyperglycemia (also improves insulin sensitivity)
    — fluid retention
    — increased lipogenesis
    — hepatic steatosis
    — increased CO2 production, which increases the work of breathing
  • preserves fat free mass (FFM)
  • promotes steady weight loss

Contra-indications

  • if need to avoid high-protein nutrition
    — e.g. progressive renal failure or hepatic encephalopathy
  • if full caloric (dextrose) loads  preferred
    — e.g history of hypoglycemia, diabetic ketoacidosis, or severe immunocompromised state

CONTROVERSIES

  • High protein hypocaloric enteral feeding approach has not been validated by a high quality RCT
  • mild obesity may confer a survival advantage in critical illness, steady weight loss through hypocaloric feeding might negate this

References and Links

LITFL

Journal articles

  • Port AM, Apovian C. Metabolic support of the obese intensive care unit patient: a current perspective. Curr Opin Clin Nutr Metab Care. 2010 Mar;13(2):184-91. Review. PubMed PMID: 20040861; PubMed Central PMCID: PMC3278904.

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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