Nutritional Assessment of the Critically Ill Patient Terry L. Forrette, M.H.S., RRT

Transcription

1 Nutritional Assessment of the Critically Ill Patient Tools to understand metabolic monitoring GE Healthcare - R&S Global Training August 3,

2 Metabolic Rate Fuel Sources Substrate Utilization Metabolic rate Energy Balance Relationship Energy Balance Relationship Dietary Intake Stored Calories Intake Anabolism Expenditure Activity Energy Expenditure Catabolism Dietary Intake Stored Calories Intake > Expenditure Activity Energy Expenditure Expenditure = Metabolic Rate Increased Anabolism Expenditure = Metabolic Rate Catabolism Energy Balance Relationship Dietary Intake Stored Calories Stress Factors Activity Energy Expenditure Intake < Expenditure Anabolism Expenditure = Metabolic Rate Increased Catabolism How much fuel does the patient require? 2

3 Resting Energy Expenditure Basal Energy Expenditure REE or EE BEE Greenfield 1997 Expressions of Metabolic Rate How much fuel do we need? BEE - Basal Energy Expenditure Rarely seen in a hospital setting REE Resting Energy Expenditure Normal Kcal/kg/24hrs, 70 kg patient 2400 kcal EE Energy Expenditure. * In critically ill patient this value if often greater than 10% above BEE that is seen in normal patients at rest. (see Terry s Tip) TEE Total Energy Expenditure??? Pt Impact of Stress on Calculated REE Diagnosis Obstructive Jaundice Liver Transplant Liver Transplantcryptogenic cirrhosis Pneumonectomy pneumonia, bronch fistula Crohn s diseasesubtotal colectomy H-B Kcal/day Indirect Calorimetry Kcal/day Variance Kcal/day % error 50% 2% 23% 53% 33% 3

4 Fuel Sources Fat Lipids 120 g/d Out 120 g 70 kg normal individual Fat - 15kg In 120 g Carbohydrates CHO 300 g/d 300 g 72 g CHO g Protein - 13 kg 300 g 72 g Proteins Pro 72 g/d (in the form of nitrogen) Total Body Water 34 kg Minerals 70 kg normal individual What s in your tank? Out 1100 Kcal Lipids 140,000 Kcal In 1100 Kcal 1200 Kcal 300 Kcal CHO 1200 Kcal Protein 52,000 Kcal 1 Kcal = 1000 calories (c) 1200 Kcal 300 Kcal 4

5 Substrate Utilization The Respiratory Quotient (RQ) Spectrum RQ = VCO 2 /VO 2 Every fuel has it s cost At what cost? How much oxygen is consumed. Energy versus Metabolic Cost 1 gram kcal/min VO 2 VCO 2 RQ carbon dioxide produced Lipids CHO to generate our energy needs Pro The Clinical Situation Dictates the Blend of Substrates 5

6 The Cost of Metabolism A delicate balance between energy needs and costs The Wisdom of Yoda Metabolic rate How Much Fuel Sources What Type 6

7 Rule 4? Substrate Utilization The Cost Don t Make it too Complicated We are all one, but some of us have forgotten that. Every year 15 million children die from malnutrition. that we know of. Marasmus total calorie depletion Kwashiorkor The sickness the older child gets when the new baby comes 7

8 Triad of Nutritional Assessment Anthropometrics Biochemical Indices 1919 Harris-Bennedict Ideal Body Weight Triceps Skin Fold Arm Circumference Anthropometrics Calorimetry Anthropometrics Calorimetry Biochemical Indices Harris-Benedict Equation Estimates Basal Metabolic Rate - BMR (also referred to as BEE): Male BMR kcal/day = (kg) + 5 (cm) (yrs) Female BMR kcal/day = (kg) (cm) (yrs) Limitations Stress factor must be applied to BMR Predicts BMR with systematic errors of 15% Why Measure Metabolism? Subjects of Same Height and Weight Foster et al., Metabolism 37(5) , A B C D E Predicted ACTUAL

9 Terry Tip: EE for ICU patients is usually higher than the 10% increase above BEE that is seen at rest for normal patients. As long as steady-state conditions can be verified, the EE, whatever its level, is an accurate reflection of metabolic rate. Greenfield 1997 If you think you re stressed out Calorimetry Methods Direct & Indirect Systems What about this guy s day? Where the #!*@ is that PO? Anthropometrics Calorimetry Biochemical Indices A Direct Calorimeter for Human Use Metabolic Chamber Metabolic chamber at Pennington Biomedical Research Center 27,000L indirect pull calorimeter 24 - h EE Sleeping EE 9

10 The History of Indirect Calorimetry Indirect Calorimetry Closed circuit spirometry involves rebreathing same air. Open circuit spirometry involves breathing atmospheric air. Measurements with Mask and Mouthpiece Canopy Measurements Measurements during Mechanical Ventilation Continuous Measuring Systems Engstrom Erica Ventilator System GE Carestation 10

11 REEVUE by KORR Look How Far We Have Come! The ReeVue is the technological advancement that makes assessment of resting energy expenditure (REE): Look Where We Are Going Time for a break Photo courtesy of Cosmed Engineering Popular ICU Calorimetry Systems We will start back in 5 minutes 11

12 The Basics of IC Measurements CO 2 inspired CO 2 expired Golden Rule of Calculations: Let the computer do them Patient CO 2 elimination/min = VCO 2 = FICO 2 (VE) FICO 2 (VI) O 2 inspired O 2 expired Patient O 2 uptake/min = VO 2 = FIO 2 (VI) FEO 2 (VE) Weir Equation Weir Equation 12

13 A Few Basics on Steady-State Steady-State Conditions Cellular = Exhaled CO 2 RQ CO 2 production from metabolism PvCO 2 RER = RQ Things that effect CO 2 Elimination CO 2 elimination From the. lungs (VCO 2 ) RER Circulation Diffusion Ventilation Cellular > Exhaled CO 2 Data is??? Cellular < Exhaled CO 2 Data is??? PaCO 2 PaCO 2. VCO 2 & RQ Circulation. VCO 2 & RQ Circulation Ventilation Ventilation Case Study Steady vs. Non-Steady State A 53 post-op 5 days following a AAA and had failed several ventilator weaning trials. The patient was conscious and responding to commands while breathing spontaneously between the ventilator breaths. An IC study was ordered to determine if her nutritional status was interfering with weaning. A VO2 or VCO2 (mls/min) Energy Expendature (kcal/day) VO2 VCO2 EE Data Collected Ventilation (L/min) RQ REE (kcal/24 hr) 5 min 10 min min 20 min 30 min B VO2 or VCO2 (mls/min) Energy Expendature (kcal/day) VO2 VCO2 EE 13

14 Identifying Steady State Conditions Precision Identifying Steady-State Conditions Variable Minute Ventilation Cardiac Output F I O 2 setting Oxygen Consumption Carbon Dioxide Production Ideal Change Less than 5% Less than 5% Less than 0.6% Less than 2% Less than 2% Acceptable Change No greater than 10% No greater than 10% No greater than 2% +/- 10%* +/- 6%* If there is a leak, you can assume you will have problems * AARC Clinical Practice Guidelines Is it that big of a deal? Why is it so important? 14

15 Collecting Protocols There is nothing in the manual about this! Continuous Studies Smooth out periods of non-steady state More reflective of TEE Equipment issues and cost Intermittent Snap shot of REE More influence from activity Cost effective? If this is hard for you understand Time VO2(ml/min) VCO2(ml/min) EE(kcal/d) RQ 3/22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : Just imagine how they feel How Much? What Type? Just the facts, ma am... What is the Cost? Time VO2(ml/min) VCO2(ml/min) EE(kcal/d) RQ 3/22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ : /22/ :

16 Clinical Subsets Maintaining a positive N 2 balance Measured vs. Actual calories: REE vs. caloric load Maintain caloric load within +/- 10 of REE **Caloric restriction in ALI/ARDS population Providing correct type of calories Use RQ to determine cardiopulmonary load > 1.0 increased ventilator load - WOB < 0.7 increase oxygen delivery demands Non-nutritional applications R/O dead space Titrating PSV Determining C.O. Assessing flow dependent oxygen consumption ** ARDSNet Case Study 1 Case Study 75 yo Dx with H1N1 flu. BMI was 30% of predicted with evidence of muscle catabolism. Temp 38.2, HR 115, BP 147/98 TCI Pred EE RQ IC EE??? Insufficient calories The patient was started on feedings via NGT at 2200Kcal. TCI Pred EE RQ IC EE TCI = Total Caloric Intake Case Study 2 Case Study Excessive CHO calories Ms RP, hx COPD, admitted to MICU with AVF requiring ventilatory support. IC on day 3. TCI CHO/Fat EE RQ : Unable to wean ventilator due to high VE requirements to maintain PaCO 2. IC study 18 hours after diet change. TCI CHO/Fat EE RQ : Comments: This patient s CHO load was excessive leading to lipogensis and CO 2 retention. 16

17 Non-Nutritional Applications Cardiovascular Measuring C.O. by indirect Fick C.O. = (a-vo 2 ) x VO 2 Measuring flow dependent VO 2 in septic ARDS to avoid mathematical coupling Pulmonary mechanics and WOB VO 2 of respiratory muscles Measuring influence of PEEP on V D Titrating ventilator settings Case Study 3 Ventilator Management Case Study Mr. KS requiring high V E to maintain PaCO 2. Gas exchange studies were performed to determine increased V D or VCO 2. (TCI 2110 kcal) PEEP EE RQ V E V D /V T CI Terry s Tip: Look at the patient s minute volume. If it is greater than 150mL/min/kg there is either a problem with dead space, increased VCO2, or both. (applies to ventilated patients) IC becomes a valuable tool to differentiate between these two conditions. Comments: IC studies were useful to R/O excessive CHO feedings and measure V D which was increased secondary to excessive PEEP levels which depressed his cardiac output. Case Study A 23 MVA was 4 days post-admit to the surgical intensive care unit. On SIMV at 10 bpm with 10 PS. Look beyond the acceptable to find the extraordinary PS Level VO 2 (ml/min/kg) SaO 2 (%) RSBI Steve Jobs 17

18 Old ways of thinking Consider other possibilities Get old results Financial Impact: Cost Impact of Malnutrition: Robinson, G., M. Goldstein, G. Levine. Impact of Nutritional Status on DRG Length of Stay. JPEN 11:49-51, Condition Average Hospital (100 patients) Charges(Per Patient) Malnourished $16,691 Borderline Malnourished $14,118 Normally Nourished $ 7,692 Hospitals were reimbursed from $4,352 to $5,124 for each patient Financial Impact: Cost Impact of Overfeeding: Foster, Gary, L. Knox, D. Dempsey, J. Mullen. Caloric Requirements in Total Parental Nutrition. J Am Coll Nutr, Vol 6, No. 3, , Resting energy expenditure (REE) was measured in 100 patients receiving TPN. Only 48% were within % of the predicted Harris-Benedict values. By using indirect calorimetry, the hospital was able to reduce the TPN usage by 22%, saving 6,947 liters per year. What is the risk? 22% Reduction in TPN Usage 18

19 Naysayers - Objections - Prejudices Thank You 19