metabolic status PPT (2/39)

REE definition. Increased REE?

resting energy expenditure (70% of total energy expenditure)

increased REE = more outside energy + healing energy usage (e.g. burns, trauma, surgery, sepsis). Helps calculate to prevent over/underfeeding.

direct calorimetry, how it work?

TOO DIFFICULT to do

shove someone in room, have some measurement system to measure heat (calories) off of body

indirect calorimetry: how it works? what 2 pieces of info do you gain?

measure heat produced by O2 consumed + CO2 removed (essentially RQ! VO2 vs ETCO2, 250/200 = 1.25/0.8).

gain 2 pieces of info through this way: REE and RQ.

what does the met cart measure (4)

1. pulmonary ventilation of every breath

2. O2 concentration

3. CO2 concentration

4. temperature, pressure, humidity (due to it being a dry, cool system)

what do you learn from the met cart? (2)

1. how much energy is expended

2. if they need fats, carbs or proteins

does CO2 have a backup like O2?

doesn’t have a backup like how O2 has ATP! when a pt is producing more CO2, their met system is running race and they have to be able to get it out of their system or it will build up in blood + cause problems.

understand failure to wean

if pt been on vent → weaker → muscle break down

met car indications

1. guide appropriate nutritional support

2. determine O2 cost of WoB to help select mode + settings

3. determine cause of increased vent requirements (high glucose → increase CO2 production → no weaning)

4. exercise physiology

pt population for metabolic measurements (7)

1. head trauma or paralysis

2. COPD

3. acute pancreatitis

4. long term vent

5. parenteral support (nutrients via IV)

6. morbid obesity

7. burn patients

where do measurements happen with met cart in the airway?

put measuring device inline w/ airway (past the Y but before the ETT to capture in + out) and it fxn’s side stream by taking measurements through air, so anything past the wye = mech. DS, affecting VT:DS, thus increasing WoB

how long does PEEP take to leave?

12-15min

metabolic measurement main contraindications

Pt. who cannot handle disconnection to input measuring device in

1. LEAKS!!!! (e.g cuff less, around ETT/trach, chest tube to sxn)

2. subcutaneous emphysema + communicating tracheal esophageal fistula

3. vent modes that use bias flow or leak compensation

metabolic measurement second contraindication

1. on such a high FiO2/PEEP that readings will be inaccurate

2. hemodialysis or peritoneal dialysis (cannot be w/I 4h as they subtract bicarb in the equation)

what state should pt be in pre procedure?

RESITNG STATE! no vent changes, sxn’ing, no nurse care, no diet change, NPO (unless continuous tube feedings 2h before), no nothing 30min-1h before

complications of met cart

1. reduction in alveolar ventilation

2. increased WoB

3. hypoxemia, bradycardia secondary to disconnection

how long does calibration take?

takes 30min to warm up gas analyzers and pneumotach 

how much VO2 per energy cost?

1L VO2 = 5kcal energy. means that even when you’re sleeping you’re burning calories.

what measurements does the met cart get (5)

1. Kcal/L (energy released from metabolism for each L of VO2)

2. VO2

3. VCO2

4. RER

5. REE

metabolic measurements + DS measurement

when ABG becomes available, DS can be determined to determine weaning failure

VD/VT = (PACO2 - PECO2)/PACO2
normal = 30%
normal vent = 40%
unsustainable = >60%

why use met cart?

FAILURE TO WEAN based off of how much we are feeding them and what we are feeding them, determining undernourishment.

older people and calorie consumption

consume fewer calories but have more muscle waste = different calorie need. bc of this, recommended for them to focus on building muscle by using building blocks of a muscle (amino acids in proteins).

physical inactivity and calorie consumption

lying in bed not using muscles leads to alterations of protein synthesis, causing rapid muscle breakdown, requiring more proteins than before.

COPD correlation w/ CO2 and carbs!

they retain CO2 in blood. you can increase CO2 by what you eat through CARBs. carbs, just like calories, are measurements of heat and sugars, and if intake increases, it increases their CO2 production. because of this, a natural retainer of CO2 w/ increased CO2 production and energy usage is a problem.

REE definition

resting energy expenditure, being 75-95% of total energy expenditure, w/ metabolism in brain, liver, heart and kidney being constant.v

variability in REE includes (4)

1. b/w people

2. during day (12%)

3. increases w/ illness

4. day to day (23%)

what can variability in REE be due to? (4)

1. demographics (size, gender, age)

2. activity, sleep

3. diet, starvation

4. illness, fever (13% per degree), cold, drugs

what increases REE (7)

1. burns

2. hypers (ventilation, thermia, thyroidism)

3. inflammation

4. metabolic acidosis

5. obesity, overfeeding

6. sepsis

7. stress, physical agitation

what decreases REE (4)

1. coma, anesthesia, sedation, paralysis

2. hypos (thermia, thyroidism, ventilation)

3. metabolic alkalosis

4. starvation/underfeeding

how much does long-term starvation reduce energy expenditure by?

30-40%

how does hypothermia increase REE?

exposure to hypothermia increases by shivering and non shivering thermogenesis, using more energy

medications increasing REE (4)

1. caffeine

2. aspirin

3. catecholamines

4. pressers 

medications decreasing REE (3)

general anesthesia including:

1. sedatives

2. analgesics

3. beta blockers

what value helps predict REE?

through RQ! it is derived from VCO2 and VO2, being the ratio b/w the two, reflecting which fuel body is using to create energy/heat. because of this, REE is amount of energy burned and RQ is the type of fuel used for that energy.

RQ for carbs, fats and proteins

carbs RQ = 1
fats RQ = 0.70
protein RQ = 0.81

balance b/w carb + lipid = 0.8-0.9

overfeeding = >1.0

factors increasing RQ (4)

1. hyperventilation

2. metabolic acidosis

3. overfeeding → lipogenesis

4. exercise

factors decreasing RQ (5)

1. hypoventilation

2. mild starvation w/ ketosis

3. diabetes w/ ketoacidosis or high rates of urinary glucose loss

4. gluconeogenesis → hypothermia

5. ETOH metabolism

how nutrition calculates Kcal use needed for pt

take fuel used + figure out what they need to change in terms of what they are providing for pt. based off of the RQ they can figure out what type of fuel is burning (ex., RQ 0.9 = carbs)

what counts as failed testing in regards to gas consumption (V) and RQs?

1. question validity of test

2. steady state not achieved (average VO2 + VCO2 changes <10% + average RQ changes <5%)

3. RQ falls outside of physiologic range of 0.67-1.3

   1. VO2 range = 1.7-3.4mL/min/kg

   2. VCO2 range - 1.4-3.1mL/min/kg

metabolic cart sources of error (3)

1. FiO2 >60%

2. air leaks

3. hemodialysis