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BCPS study guide
Fluid electrolytes and nutrition
Question | Answer |
---|---|
kcal in 1 gram of dextrose | 4.3 kcal/g (3.4 kcal/g if glycerol.) |
kcal in 1 gram of lipid | 10 kcal/g |
kcal in 1 gram of AA | 4 kcal/g |
maximum concentration of dextrose in PN | 10% |
max concentration of calcium in PN | 5 mEq/L |
max concentration of potassium in PN | 40 mEq/L |
max concentration of AA in PN | 4% |
max infusion rate of lipid in 2-in-1 PN | 0.1 g/kg/hr |
urine output target | 0.5-2 ml/kg/hr |
typical fluid requirement for pt who is not fluid restricted [for PN should only use maintenance NOT replacement] | 30-35 ml/kg/day (~2500-3500 ml/day) |
For patients with a BMI of <30 what is their daily caloric requirement | 25-35 kcal/kg/day using actual body weight |
how do you determine caloric requirements for pts with BMI greater than 30 | either use actual body weight and do 11-14 kcal/kg/day OR use IBW and do 22-25. some practitioners say use adjusted body weight or the Harris-Benedict equation. hopefully im not expected to have that memorized cuz it aint gonna happen. |
amino acid requirements for PN | if BMI less than 30 maintenance is 0.8-1 g/kg/day. and depending on stress may need up to 2 g/kg/day.protein requirements inc with increased BMI and renal pts on HD may require higher AA concentrations to maintain nitrogen balance without need less. |
how do you calculate the non-protein calories in PN | figure that lipid is 20-30% of total daily calories and the rest is dextrose (minus AAs) |
amino acid PN requirements for renal failure patients | if not on HD or CRRT then do 0.5-1 g/kg/day. if on IHD do 1.2-1.5 g/kg/day. if on CRRT then do 1.5-2 g/kg/day |
electrolyte imbalances that are hallmarks of refeeding syndrome | hypomag, hypokalemia, hypophos. |
prevention strategies for refeeding | cut initial caloric intake by 50% of total requirements then advance to goal. supplement prior to initiation of PN. identify risk factors such as anorexia, alcoholism, chronic illness, poor nutrition for 1-2 wks, malabsorption, cancer etc |
how does prealbumin levels help in PN | if low indicates malnutrition |
for every L of D5W given how much remains in the vascular space | 100 ml. this is b/c D5W metabolizes to H2O and CO2. therefore acts as free water and goes everywhere. |
for every L of NS or LR, how much remains in the vascular space | 25% |
for every L of albumin how much remains in the vascular space | 5% - all of it stays 25% - you get a 5 fold increase due to increased oncotic pressure |
how many L of fluid does a typical adult have and how much is in each of the body compartments | 42 L approximately. 60% of the total fluid is intracellular. the remaining 40% is extracellular and of that, 75% is interstitial fluid and 25% intravascular extracellular fluid which accounts for ~5L |