Nutritional Care of the Bariatric
Patient in Critical Care
Christine Ward
Bariatric Dietitian
September 2011
Aim
 To identify factors that may impact on the
nutritional care of the bariatric patient group
 Why this group may require a Critical Care
admission?
 What are the potential issues regarding
feeding?
 Which BMR estimation equation is most
appropriate for the bariatric patient?
Factors that may impact on nutritional
care of bariatric patients






Obese patients generally viewed as over nourished
Potentially deficient in a number of nutrients
Respond to injury differently; can not
utilise/mobilise fat stores for energy as well as lean
counterparts
Will draw on lean mass for energy
Considered that they may already metabolically
stressed due to obesity
2 weeks Pre-operative dietary restriction
~1000kcal/day
The bariatric candidate over nourished or not?
Vitamin/mineral
Folate
Folate & B12
Iron
Zinc
25 OH Vit D
Vit D & Secondary
hyperparathyroidism
ERI
Ernst et al 2009
%
%
40
15
40
50
40
50
3.4
18.1
n/a
24.6
25.4
36.6
4/9/2015
4
Type of Surgery
Laparoscopic Procedures

Restrictive
• Adjustable Gastric Band
• Sleeve Gastrectomy

Restrictive and Malabsorptive
• Roux-en-Y-Gastric Bypass
• Duodenal Switch /BPD
Critical care admission?
• Planned Critical Care
•Clotting issues thrombolysis
•CPAP: patient not independent
Unplanned Bariatric patients in
Critical Care
•Undiagnosed sleep apnoea
•Prolonged ventilation
•Large bleeds - liver
•Conversion to open procedure
•Rhabdomyolysis, renal failure, sepsis,
respiratory failure
•Anastomotic leak or stricture
ERI: 5% patients (6-20% cited in many papers)
Feeding Route?
 Usual Protocol post surgery
 Oral Route
Immediately post bariatric surgery if gut intact
• day 1; sips,
• day 2; clear fluid,
• day 3; free fluid
 Use of nutritional supplements, high protein
where appropriate
Enteral or Parenteral Nutrition
? NG, NJ , gastrostomy / jejunostomy
• Altered gastrointestinal anatomy/function
• Which feed?
TPN
 How soon?
• ?Within 48 hours or ? NICE 2006
• Re-feeding issues K, Mg, PO, thiamin
• Biochemistry monitoring (daily or as local protocol)
• Is it possible to meet nutritional requirements?

Overfeeding vs. under feeding
Risks from nutritional support for the
obese patient
 Overfeeding



Increase C02 , breathing and prolonged
mechanical ventilation
Promotes fat infiltration of liver (esp. CHO)
Cautious administration of CHO (dextrose) fat and
fluid for obese with T2DM, Congestive heart
failure, metabolic syndrome (exacerbation of
conditions)
Hypo energetic feeding and protein
sparing
 Improved glucose control
 Improved serum iron binding and albumin
 Appropriate energy deficit without increasing
lean tissue catabolism can be achieved

Dickerson et al 2004, Choban et al 2005, 1997
50% of energy requirements and 2.1g protein /kg
IBW resulted in N balance
Aim of nutritional support in critically
ill patients?
 Meeting
measured energy requirements
vs. preservation of lean body mass vs.
risks of under or overfeeding
BMR Prediction Equations (Schofield)
 Criticism




of current PENG guidance
Estimations equations based on healthy
population
Inappropriate use of stress factors; overestimates
Use of static variable such as weight, the body’s
physiology ?temperature and respiration rate
Based on a linear relationship between weight
and BMR
 However


Findings from Horgan and Stubs 2003 reexamination of Schofield equation:
Small numbers of obese patients
• BMI>30 =4.5%
• The linear relationship between BMR, weight, height
and age only evident to a weight of ~ 70-75kg
BMR Prediction Equations
Over estimates requirements for high BMI
 Adipose tissue to lean tissue relationship 75:25
 Main determinant of BMR is lean tissue
 Obese have a higher absolute BMR due to a
greater total mass of metabolically active tissue
 BMR /Kg is lower due to the higher proportion of
adipose tissue
 BMR/Kg of fat free mass for most subjects is the
same

Henry/Oxford Equations 2005
 Based on studies from 1914-2005
 10,552 BMR values
 Rigorous evaluation of methodology
 Advantages
 Contains a more representative sample of the
world population
SACN recommendations (draft)
(www.sacn.gov.uk)
 Use of Henry BMR equations



Weight only
Height and weight
Henry found no significant advantage in ht & wt
equation
 For predicting BMR using weight only

(height difficult to obtain in clinical setting)
 Launch later this year
Assessment prior to feeding
As you would for other obese or lean individual
• Up to date weight crucial

• Scales suitable for purpose, bed, hoist, stand on,
• Immediately pre-surgical for bariatric patients available
• Reported weight or estimated
• Knowledge of patient background,
• type of surgery,
• nutritional intake prior to surgery,
• amount of weight loss/time
• Potential for nutritional deficiencies
Calculating nutritional requirements?
Energy requirements
Non stressed

Feed to BMR using actual body weight
with -400-1000kcal for decrease in energy stores
Mild to moderate stress:


Calculate as normal
Omit stress and activity avoiding adverse effects of
overfeeding
Severe stress

Might be necessary to add a stress factor to BMR
Obesity Double Check
In order of decreasing accuracy / evidence
1. Ireton Jones energy equations
(critically ill but not ventilated)
2.
Adjusted average weight
(PENG pocket guide4)
3.
19-21 kcal/kg actual body weight
(critically ill only) Glynn 1999, Alberda 2002
Protein Requirements4

0.2g N/kg Actual body weight x 6.25

And where


BMI >30 use 75% of the value estimated from actual
weight
BMI> 50 use 65% of the value estimated from actual
weight
Fluid Requirements4

Very individual; ventilation,

The guidelines err on side of caution
 Fluid requirements not a linear relationship with
weight,
 Avoid fluid overload
Consider, is volume sensible? 2000-3000mls
 Have losses been taken into account

Final thoughts
Estimated Energy requirements only starting
point
 Review and monitor patient regularly
 Consider duration of nutritional support?
 Are nutritional goals being met?
 Requirements change: patients clinical condition,
nutritional status, stress level, prognosis
 Never blindly follow guidelines: clinical
judgement required

References
1.
2.
3.
4.
5.
American Society for Metabolic and Bariatric Surgery
Guidelines 2008
Ernst B, Thurnheer M, Schmid S M, Schultes B. Evidence for
the necessity to systematically assess micronutrient status
prior to bariatric surgery. Obesity Surgery. 2009; 19:66-73
Flancbaum L, Belsley S, Drake V, et al. Preoperative
nutritional status of patients undergoing Roux-en-Y gastric
bypass for morbid obesity. J Gastrointest Surg.
2006;10(7):1033-7
A Pocket Guide to Clinical Nutrition. 3rd Edition. The
Parenteral and Enteral Nutrition Group of the British
Dietetic Association. 2007
Cheatham ML, Safcsak K, Brezinski SJ, et al Nitrogen
balance, protein loss and open abdomen. Crit Care Med.
2007;35:127-131