A 46-year-old female patient with class 3 (BMI > 40 kg/m2) obesity has been admitted to your ICU with community-acquired pneumonia. She is sedated and ventilated with no other organ dysfunction. You are considering starting nutritional therapy.

a)    Outline the metabolic derangements likely to be present in this patient. (20% marks)

b)    How would you make an assessment of this patient’s current nutritional status?
(40% marks)

c)    Outline your nutritional regimen in particular your optimal target protein and energy delivery.
(40% marks)
 

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College answer

  1. A number of metabolic derangements affect fuel utilization:

    • Insulin resistance

    • Impaired glucose tolerance,

    • Increased fatty acid mobilization

    • Hyperlipidemia

    • Obese patients, compared to lean counterparts, may have accelerated protein degradation and depletion of lean body mass.

    • “Metabolic X syndrome” may exist: insulin resistance, hyperinsulinemia, hyperglycaemia, coronary artery disease, hypertension, and hyperlipidemia.

    • Obese patients are more likely to have a pre-existing pro inflammatory state.

    • Obese patients have increased resting energy expenditure secondary to increased BMI, with central adipose tissue being more metabolically active than peripheral adipose tissue.

  1. Assessment

    • Assess patterns of weight change and nutrition intake prior to the admission

    • Anthropometrics –actual body weight, ideal body weight, usual body weight, height, BMI, and waist circumference should be determined

    • (Biomarkers of the metabolic syndrome; triglycerides, cholesterol, glucose serum albumin and pre-albumin)

  1. Nutritional Regimen

  • High protein (anabolic) hypocaloric feeding (reduced complications from overfeeding) should be provided to the obese critically ill patient regardless of whether the route of nutrition therapy is enteral or parenteral

  • Most studies using this method give11-14kcal/kg/actualBWperday or 22-25kcal/kgIBW per day- equates to about 60-70% of calorie requirement determined by indirect calorimetry or predictive equation.

  • Protein requirements should be met to maximise protein synthesis and preserve lean body mass (> 2.0g/kg IBW/d for class 1 and 2 obesity and > 2.5g/kg IBW/d for class 3). Note: TARGET trial suggested hypocaloric and eucaloric feeding have same effects on mortality when protein level constant

Discussion

This SAQ is identical to Question 24 from the first paper of 2012. The only difference is that the college added "Note: TARGET trial..." at the end. The spectrum of metabolic derangements present in the obese ICU patient is detailed elsewhere.  In short, these are the major metabolic abnormalities one can expect from an obese patient in the ICU:

  • Insulin resistance and impaired glucose tolerance
  • Increased fatty acid mobilization and hyperlipidemia
  • Accelerated protein degradation
  • The proinflammatory state of obesity
  • The endocrine derangements due to an excess of fatty tissue
  • The increased resting metabolic rate of obesity

Assessment of nutritional status is also detailed elsewhere; in brief the assessment takes the shaped of a structured approach, from history to investigatons:

History:

  • Premorbid weight and the pattern of its change
  • Premorbid nutritional routine
  • Diseases affecting gastrointestinal function (eg. coeliac disease)
  • Disease affecting satiety control (eg. Prader-Willi syndrome)
  • Factors influencing metabolic substrate utilisation (eg. thyroid dysfunction, hypoadrenalism, Cushings disease or corticosteroid therapy)

Examination:

  • Observed quality of nails and hair
  • Subcutaneous fat measurements (triceps)
  • Muscle bulk and muscle tone of quadriceps and deltoids
  • Presence of oedema and ascites

Anthropometry

  • BMI
  • Ideal body weight
  • Lean body mass

Biochemistry:

  • Cholesterol and triglycerides
  • Random BSL
  • HbA1C
  • Serum cortisol
  • TFTs
  • Albumin and prealbumin

Nutrition for the obese ICU patient is presently a topic of hot debate. The most recent suggestions are summarised elsewhere. In short, the published consensus statements suggest we follow a certain pattern:

References

References

Marik, Paul, and Joseph Varon. "The obese patient in the ICU." CHEST Journal113.2 (1998): 492-498.

El-Solh, Ali, et al. "Morbid obesity in the medical ICU." CHEST Journal 120.6 (2001): 1989-1997.

Jeevanandam, Malayappa, David H. Young, and William R. Schiller. "Obesity and the metabolic response to severe multiple trauma in man." Journal of Clinical Investigation 87.1 (1991): 262.

YALE, JEAN-FRANÇOIS, LAWRENCE A. LEITER, and ERROL B. MARLISS. "Metabolic Responses to Intense Exercise in Lean and Obese Subjects*." The Journal of Clinical Endocrinology & Metabolism 68.2 (1989): 438-445.

Port, Ava M., and Caroline Apovian. "Metabolic support of the obese intensive care unit patient: a current perspective." Current opinion in clinical nutrition and metabolic care 13.2 (2010): 184.

McClave, Stephen A., et al. "Nutrition Therapy of the Severely Obese, Critically Ill Patient Summation of Conclusions and Recommendations." Journal of Parenteral and Enteral Nutrition 35.5 suppl (2011): 88S-96S.

Wichansawakun, Sanit, et al. "Metabolic Support of the Obese Intensive Care Unit Patient." Integrative Weight Management. Springer New York, 2014. 215-224.

Mogensen, Kris M., et al. "Validation of the Society of Critical Care Medicine and American Society for Parenteral and Enteral Nutrition Recommendations for Caloric Provision to Critically Ill Obese Patients A Pilot Study." Journal of Parenteral and Enteral Nutrition (2015): 0148607115584001.

Frankenfield, David C., Christine M. Ashcraft, and Dan A. Galvan. "Prediction of resting metabolic rate in critically ill patients at the extremes of body mass index." Journal of Parenteral and Enteral Nutrition 37.3 (2013): 361-367.

Ireton-Jones, Carol S., and Coni Francis. "Obesity: nutrition support practice and application to critical care." Nutrition in clinical Practice 10.4 (1995): 144-149.

Ireton-Jones, C. S., and W. W. Turner Jr. "Actual or ideal body weight: which should be used to predict energy expenditure?." Journal of the American Dietetic Association 91.2 (1991): 193-195.

Ravussin, Eric, et al. "Twenty-four-hour energy expenditure and resting metabolic rate in obese, moderately obese, and control subjects." The American Journal of Clinical Nutrition 35.3 (1982): 566-573.

Choban, Patricia S., et al. "Hypoenergetic nutrition support in hospitalized obese patients: a simplified method for clinical application." The American journal of clinical nutrition 66.3 (1997): 546-550.

Dickerson, Roland N. "Management of the Obese Patient." Nutrition Support for the Critically Ill. Springer International Publishing, 2016. 173-193.

Jeevanandam, Malayappa, David H. Young, and William R. Schiller. "Obesity and the metabolic response to severe multiple trauma in man." The Journal of clinical investigation87.1 (1991): 262-269.

Coeffier, Moise, and Fabienne Tamion. "The Stress Response of Critical Illness: Metabolic and Hormonal Aspects, Hormonal Regulation, Particular Clinical Situations “Morbid Obesity”." The Stress Response of Critical Illness: Metabolic and Hormonal Aspects. Springer, Cham, 2016. 217-225.