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

Transcription

1 Nutritional Assessment of the Critically Ill Patient Sponsored by GE Healthcare Metabolic Rate

2 How Much Fuel Does the Patient Need? Resting Energy Expenditure Basal Energy Expenditure REE or EE BEE

3 Metabolic Rate Resting Basal Greenfield 1997 Energy Sources Fat Lipids 120 g/d Carbohydrates CHO 300 g/d Out kg normal individual Lipids 140,000 In 1100 Proteins Pro 72 g/d CHO 1200 Protein 52,000 1 = 1000 calories (c)

4 What s in your tank? Substrate Utilization The Respiratory Quotient (RQ) Spectrum 0.81 What s the cost? How much oxygen is consumed carbon dioxide produced to maintain metabolism? RQ = VCO 2 /VO 2 The Cost of Metabolism 0.70 CO 2 VO 2 CO 2 VO 2 1.0

5 Mind what you have learned. Save you it can. Metabolic rate How Much Energy Sources What Type Substrate Utilization The Cost Triad of Nutritional Assessment Don t Make it Too Complicated Predictive Equations Biochemical Indices Calorimetry

6 Measured versus Predicted EE Subjects of Same Height and Weight Foster et al., Metabolism 37(5) , A B C D E Predicted Metabolic Rate Basal Resting Actual Greenfield 1997 The History of Indirect Calorimetry??? Popular ICU Systems The Basics of IC Measurements CO 2 inspired CO 2 expired Patient CO 2 elimination/min = VCO 2 = FICO 2 (VE) FICO 2 (VI) O 2 inspired O 2 expired Patient Engstrom Erica Ventilator System O 2 uptake/min = VO 2 = FIO 2 (VI) FEO 2 (VE)

7 Weir Equation Steady-State Conditions Cellular = Exhaled CO 2 RQ cellular Case Study A 53 post-op 5 days following a AAA. The patient was conscious and responding to commands while breathing spontaneously between ventilator breaths. RER exhaled Things that effect CO 2 Elimination Circulation Diffusion Ventilation 5 min min 20 min 30 min Data Collected min Ventilation (L/min) RQ REE (kcal/24 hr) and some problems have no remedy

8 Case Study 1 Insufficient calories Case Study Case Study 2 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??? The patient was started on feedings via NGT at TCI Pred EE RQ IC EE TCI = Total Caloric Intake Excessive CHO calories Case Study Case Study 3 Ms RP, hx COPD, admitted to MICU with AVF requiring ventilatory support. IC on day 3. TCI CHO/Fat EE RQ : Unable to wean due to high V E requirements to maintain PaCO 2. IC study 18 hours after diet change. TCI CHO/Fat EE RQ : Ventilator Management

9 Case Study Naysayers - Objections - Prejudices 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 Comments: IC studies were useful to R/O excessive CHO feedings and measure V D which was increased secondary to excessive PEEP levels. Thank You