Nutrition in Critical Care

Part I: Enteral Nutrition

Chris Miller, MEd, RD, CNSD

The Stress Response: Nutrition Implications

Fasting/Non-Stressed Decreased BMR Energy= Fat/Ketones Conserves

Glucose Protein:

• Net loss= 5-7 g N+ • Equivalent to 1-1.5 oz

protein/day

Metabolic Stress Very High BMR Energy Sources:

Glucose, Fatty Acids Protein (No Reservoir)

Poor Utilization of Nutrients

Hyperglycemia Hypertriglyceridemia

Net Protein Losses: >15 g.N= >3 oz protein Depletes heart, resp.

muscles, gut barrier Increases GI permeability

Nutrition Support Goals

Minimize nitrogen/ protein lossesMaintain weight/ minimize lossesMinimize infection riskMaintain gut function

Mucosal barrier function (need > 50% TF) Digestive enzymes Gallbladder contraction

Facilitate weaning from vent? Immune modulation

Enteral Feeding: Contraindications

Shock:High Risk for GI Ischemia/ Perforation Controversial- No clear guidelines Hold TF for distention, high residuals, unexplained acidosis

Ileus- Small Intestine Small Intestine-motility returns within hours of insult Stomach- may take 1-4 days for return of motility

Intestinal Obstruction/ Perforation Severe Acute Pancreatitis Without Jejunal Access Intractable N/V/D GIB with hemodynamic compromise High Output Fistula (> 500 cc/day)

Enteral Feeding: Formulary Selection

See Formulary Card Standard “Polymeric” : require digestion

Isotonic Fiber vs. No Fiber Vary in Protein Content/ Caloric Density

Specialty Disease Specific

Pulmonary & Diabetic: • Low CHO/ High Fat• Differ in Kcals/ ml

Concern re: potential immune effects of N-6 (Corn/Soy oil) fat load Elemental:

Low Fat Pre-digested

Immune Modulating Enteral Feedings

Immune Nutrients: Glutamine: Preserves Gut Integrity, Fuels Immune Cells Arginine: Stimulates Wound Healing, Activates Immune Cells N-3 Fatty Acids (Fish Oils): Immune enhancing/ anti-inflamatory

Reported Effects Infection rate, LOS, Vent Days

Formulas Oxepa: ARDS (Contains: Fish Oil/ Borrage Oils) Impact: GI Surgeries(Arginine, N-3 Fatty Acids, Nucleotides)

Administration Guidelines Notify RD ASAP- must be approved Start within 48 hrs. of dx/ OR Advance as rapidly as tolerated (25 cc q 8-12 hr) Continue for minimum of 5-7 days

Enteral Feeding:Aspiration Prevention

Residuals: Poor Correlation with other parameters!! Only found with gastric feeds (Not Small Intestinal) Do Not Hold unless > 125- 200 cc Reinfuse to maintain acid-base balance

GI Symptoms: More Reliable Nausea/ Vomiting Distention/ Constipation

Positioning HOB > 30 at all times Hold x 1 hour before lying flat for procedures

Blue Dye? NO Only detects < 25 % of aspirations Potential Harms: Infection/ Toxicity/ ? Deaths

Acute Care: Monitoring Nutrition Adequacy

Nitrogen Balance: Gold Standard Requires accurate intake/output data

Enteral/ Parenteral Intake Requires accurate 24hr Urine for Urea N+

Not accurate in Renal Failure/ Hepatic Encephalopathy

Calculation: Pro Intake (g)/ 6.25g - (UUN + 4*)

* Use factor of 6 for high output GI losses Goal: + 2-4 g/day Plateau Effect:

Metabolic response to stress may result in catabolism & impaired ability to use high N+ loads.

MonitoringNutrition Adequacy: Acute Care

Albumin: Poor Nutritional Indicator Good Prognostic Indicator Half Life: 20 days Not an acute phase protein

Low in: liver dz, infection, post-op, overhydration, inflammation

MonitoringNutrition Adequacy: Acute Care

Pre-albumin: Good indicator in absence of acute stress Half life: 2-3 days Not an acute phase protein

Low in: liver dz, infection, post-op, inflammation, hemodialysis

High in: renal failure

Monitoring:Nutrition Labs

Date Wt.#

Kcals Prot,.g/day

N+g. day

Alb(nl> 3.5)

Prealb.(nl >17)

UUNg/day

N-Bal(goal= +2)

Comment

6/13 134# 2.7 Adm/OR6/17 <7.06/26 132# 2160 99 15.84 1.3 <7.0 6.9* + 4.94 Re-op 6/257/3 130# “ “ 8.27/4 “ “ 10.57/8 “ “ 13.7

7/11 133# 2160 99 15.84 8.1 +3.74 Cor 7/97/18 “ “ 9.67/21 161# “ “ 1.8 10.3 n/v/LFT7/26 160# “ “ 1.6 11.07/28 2160 99 8.4 +1.4 - +3.4 Dep. on CT

output8/7 157# 2298 110 2.1 16.9

* Sample N-Balance Calculation:N Intake - N output = N Balance99g. prot./6.25 - (6.9g. UUN +4 for insensible losses) = + 4.94

Case Study: Diarrhea

Potential Cause Infection/ C-dif

Promotility Agents/ Laxatives

Hypertonic Meds(K,PO4) Sorbitol

Gut Fluora Changes Gut Edema/3rd Spacing Tube Feeding Rate

Treatment Clean TF Technique Antibiotics D/C Reglan & Dulcolax

Change Lytes to IV ? D/C Guaifenesin,

Change tylenol to crushed tabs

Start Lactinex granules Diuresis as tolerated Decrease to 30 cc/hr

Nutrition in Acute Care

Part II: Parenteral Nutrition

Parenteral Nutrition:Route/ Timing

See Decision Tree on Back of TPN form Indications for Parenteral Nutrition:

Nonfunctioning GI TractSevere PCM: NPO/Clears x 3-5 daysAll others: 7-9 days> 14 days before TPN- Increased complication rate

Pre-op Feeding for Severely Malnourished OnlyRequires > 7 days

Severe Acute Pancreatitis without jejunal access Prolonged Hemodynamic Instability

TPN Ordering:General Guidelines

Patient ID must be on order Deadline for TPN Orders: 12: 00 Noon Reordering TPN:

Changes Which Require New Order Form Any change in composition of formula

• Dextrose, AA• Lytes• Additives/ Insulin

Increase in rate Changes Allowed in MD Order Section

Renewal ( Must be done daily) Decrease in Rate Changes in IV lipids

Parenteral Nutrition: How to Start

MD Ordering: See Guidelines on back of TPN Order Forms Review baseline labs before admin.

RN Order Sets/ Responsibilities Labs Wts I/O’s Check infusion rates, components daily

CPN vs. PPN(Per Liter/ Without Lipids)

Component CPN PPN

Kcal (Standard)

Volume 1-3 L 1.5 L

Duration of Tx. 7 d <7 d

Route of Admin. CVL Periph.

CHO % Limit < 30% < 7%

Lipids Optional Essential

mOsm 2000 6-900

PN: Initiation and Progression Peripheral PN:

Initiation: 2 L/ day Discontinuation:

No Taper Necessary

Central PN Initiation:

Start 1 L/ day or 40 ml/hr Advance by 500-100 ml/day if

• Glu 150• TG’s < 400• Electrolytes & Volume Tolerated Well

Discontinuation: High Risk for Rebound Hypoglycemia Taper to 30 cc/hr Infusion Rate x 1 hour prior to D/C.

Case Study: Refeeding Syndrome

Date NutrientIntake

Glu K Mg(1.7- 2.4)

PO4(2.8- 4.6)

Comment

8/4 Baseline 73 3.1/ 2/4 2.1 2.1

8/5 D-5 200 4.2/ 3.2 2.0 0.1 Life-threatening PO4

8/6 NS/ ½ NS 104/ 73 4.2/ 3.3 - 1.2

8/7 “ 46 5.7/ 2.6 3.7 10.6/ 1.5 D5 rx/ TPN @ 6 pm

8/8 TPN/TF/D-5 273 5.5/ 3.2 2.2 2.9/ 1.1

8/9 TPN/ TF/D5 127- 209 2.7/ 3.8 1.7 1.7/ 2.0 TF held due to BP

8/10 TPN/ D-5 122-168 3.0/ 3.9 - 3.6/ 2.1

8/11 “ 123-141 3.8/ 3.3 1.8 3.9

8/12 TPN/TF/D-5 122-198 4.0/ 3.6 1.7 4.3 TF restarted

Refeeding Syndrome At Risk: Chronically Malnourished

Wasting of lean tissue/ muscle Cardiac/ pulmonary atrophy

Depletion of intracellular nutrients Magnesium Potassium Phosphorus Vitamins(esp. thiamin) and minerals

Metabolic Complications of Refeeding Severe, life-threatening electrolyte shifts Hyperglycemia Refeeding edema Cardiopulmonary Failure

Guidelines for Refeeding

Electrolytes: Check Baseline Labs (K, Mg, PO4) Do not start feeding until lytes WNL

Carbohydrate: < 150-200 g/day Fluid: may need to restrict to < 1000ml/day Vitamins:100 mg Thiamine, MVI, others prn Monitoring

DAILY CMP, PO4- AGGRESSIVE REPLETION!!! Glu: may need insulin rx. Close I/O, wts daily to assess fluid status (watch for CHF)

PN Complications:Acute

Source: Green, K and Cress M. Metabolic Complications of Parenteral Nutrition. Supp. Line. 15(1): 5, 1993.

Metabolic Hyperglycemia Elevated Triglycerides Immune suppression Fluid & Electrolyte Imbalances Rebound Hypoglycemia Hypercapnia

Infectious Line Impaired Gut Barrier Function

Mechanical

Glycemic Control: Outcomes

Critical Care/ Vent Patients (NEJM, 2001)

Intensive (80-110) vs Standard (Rx if > 215)Decreased:

• Mortality ( 42%): due to sepsis/ MOSF• Bacteremia: 46%• ARF --- HD: 41%• CC Polyneuropathy: 44%

Glycemic Control: Outcomes

Post MI (Lancet, 2000): Meta-analysis Non- Diabetics

Fasting Glu > 109 mg/dl• 3.9 fold increase in Mortality

Fasting Glu >144• 3.1 fold increase in CHF/ Cardiogenic Shock

Diabetics• Fasting Glu > 144mg/dl: 1.7 fold increase in

Mortality

Glycemic Control: Basic Guidelines

Do not start TPN if Glu > 200 Glycemic Goals

Ideal: 80-110 (achieved via gtt) Minimum Goal: < 140 mid-TPN

Order SSI for all PPN/TPN patients Ask MD to adjust SSI if glucoses > goal

Avoid Other CHO sources TF, IV Dextrose

If hyperglycemia exists/ anticipated: Add Insulin to TPN Starting Guideline: 0.1 u/ g. Dextrose If insulin is added

Minimum: 10 u/L Sticks to tubing

Glycemic Control: Treatment Options

Insulin gtt- most flexible Allows tightest control without risk of hypoglycemia

TPN insulin: Benefit: CHO & Insulin in same source

• If TPN discontinued abruptly/ insulin also d/c’d RISK: Hypoglycemia with changing status

• Consider reason (meds, stress, pancreatitis) Do not cover other sources of CHO with TPN insulin!!

Sub Q: Caution If TPN is D/C’d

Decrease Dextrose in TPN Increase infusion time (cyclic)

Acute Complications: Lipids

Pancreatitis IV Lipids OK in the absence of TG > 400

Hypertriglyceridemia Goal mid- lipid infusion: < 4-500

DO NOT HOLD LIPIDS FOR TRIGLYCERIDE LAB! TG > 800-1000:

High risk for pancreatitis Tx:

Hold lipids Glycemic Control +/- Decreased Dextrose Recheck as status changes

Acute Complications: Lipids

Sepsis/ ARDS: Omega 6 FA’s:

Necessary for EFA’s long term Exaggerated inflammatory responseImpaired immune response

RX: limit (1.0 g/kg) or hold lipids