F.E.N Flashcards
Fluids for revascularization
NS
LR
Fluid mostly stays in intravascular space, hence ideal for revascularization
Fluids for maintenance
Ideal: D5W 1/2NS +/- 20 or 40 mEq K
D5W = free water, will distribute into all areas so not ideal for revascularization
20-40 mL/kg/day
Signs/Symptoms of intravascular volume depletion
Tachycardia
Hypotension
Orthostatic changes
BUN/SCr > 20:1
Dry mucous membranes
Decreased skin turgor
Reduced UOP
Dizziness
Improved BP/HR after 500-1000mL bolus
**If pt has these factors, first replete with fluids then address other causes for symptoms
IV fluid dose in sepsis
30mL/kg
Colloids
5%,25% albumin, hetastarch, packed red blood cells, dextran
Too large to cross capillary membrane, so practically all remains in intravascular space
Why avoid hetastarch and dextran?
Coagulopathy and kidney impairment
Albumin 25%
hyperoncotic - would cause dehydration if given during revascularization
Beneficial in redistribution of fluid (ascities, pleural effusion)
Possible uses for colloids
-failure of crystalloids (after ~4-6L)
-large volume parecentesis in cirrhotic patient
-low albumin concentration who have required large volume resuscitation fluids
-25% albumin + diuretics if significant edema and low albumin (if regular diuretic ineffective)
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Plasma osmolality range
275-290 mOsm/kg
Osmolality
measure of osmoles of solute per kg of solvent
Osmolarity
measure of osmoles of solute per L of solution
Plasma osmolality estimation
(2 * Na) + (glucose/18) + (BUN/2.8)
Change in plasma osmolality
Increase: osmotic shift of fluid into plasma (cell dehydration, shrinkage)
Ex: NaCl 3% (hypertonic)
Decrease: osmotic shift of fluid into cell (cell overhydration, swelling)
Ex: NaCl 0.225% (hypotonic)
Uses of hypertonic saline
TBI to reduce ICP
Symptomatic hyponatremia
Chronic asymptomatic hyponatremia Tx
Ex: SIADH
Fluid restriction (<1000mL/day)
Do NOT use hypertonic saline
Pseudohyponatremia Tx
Ex: DKA
Insulin - to correct blood sugar. This will then normalize sodium
NOT hypertonic saline
Corrected sodium equation
Serum Na + [(1.6 * (glucose - 100))/100]
Hyponatremia with hypervolemia tx
Ex: heart failure
Fluid restriction OR diuresis
NOT hypertonic saline
Hypertonic saline dose for TBI
3%: 250mL over 1-15 minutes thru central line (or 2-4 mL/kg)
23.4%: 30mL over 20-30 min thru central line
Na increase goal in symptomatic hyponatremia
0.5-1 mEq/L/hr (to max of Na 120 mEq/L)
NO MORE THAN 10-12 MEQ IN 24 HRS!!!!
Hypertonic saline rate in symptomatic hyponatremia
IBW * desired rise of sodium/hr (ex:1)
Generally, 1-2 mL/kg/hr
Can do 250mL over 30 min
OR
50 mL bolus every 30 min for 2 doses
Osmotic demyelination syndrome
Permanent neurologic damage that can occur due to rapid correction of sodium
More likely in cases of chronic hyponatremia than acute
Prevent by increasing Na no more than 10-12 mEq/L in 24 hrs or 18 mEq/L in 48 hrs.
Hypotonic solutions
Avoid using IV fluid with <150 mOsm/L (can cause hemolysis, patient death)
NEVER USE STERILE WATER ALONE IV
If 0.225% sodium chloride ordered, try to recommend D5W instead, in combo with D5W or at least thru central line
Hypovolemic hyponatremia
from fluid loss, renal loss, third spacing, cerebral salt wasting
If Urine Na <20 = nonrenal loss (diarrhea, emesis)
If Urine Na >20 = renal loss
Give fluids or NaCl tabs or fludrocortisone
Euvolemic hyponatremia
Dilutional sodium (SIADH, meds)
Urine Na >20, Urine Osmolality >100
fluid restriction, demeclocycline, conivaptan/tolvaptan
Hypervolemic hyponatremia
HF, cirrhosis, nephrotic syndrome
Urine Na <20 (HF, cirrhosis)
Urine Na >20 (acute/chronic renal failure)
Na, water restriction, treat underlying cause, conivaptan/tolvaptan, diuretic
Meds associated with hyponatremia
Thiazide diuretics
Antiepileptics (carbamazepine, oxcarbazepine)
SSRI, TCAs
Symptoms of hyponatremia with levels of Na
120-125: nausea, malaise
115-120: HA, lethargy, obtundation, unsteadiness, confusion
<115: delirium, seizure, coma, respiratory arrest, death
Vasopressin antagonists
Conivaptan (IV) tonivaptan (PO)
-use in SIADH or HF, cirrhosis
-Increases sodium but not shown to improve clinical outcomes
-Substrate & inhibitor of CYP3A4. Interactions may increase sodium too rapidly!
-Do not use along with fluid restriction - may increase too rapidly!
Hypernatremia symptoms
Lethargy, weakness, irritability
>158: severe (twitching, seizures, coma, death)
Hypernatremia treatment
-reduce by 0.5mEq/L/hr or 12mEq/L/day
-Need to replace free water - do orally or by D5W
-Can use D5W + 0.225% NaCl
Estimated water deficit
(0.4 * IBW) * ((Serum sodium/140) -1)
Hypokalemia causes
-Increased intracellular shift of K (alkalosis, insulin/carb load, B-agonism, hypothermia)
-increased GI losses
-Increased urinary losses
-Hypomag
Symptoms of hypokalemia
Usually occur when K <3.0
-muscle weakness
-ECG changes (flattened T wave, elevated U wave)
-Cardiac arrhythmia
-Digoxin toxicity
-Rhabdomyolysis
K 3.0-3.5 Tx
PO
40-80 mEq/day
Divide doses > 60 mEq to avoid GI side effect
K 2.5-3.0 tx
PO : 120 mEq/day in divided doses
Or
IV: 60-80 mEq at 10-20 mEq/hr if s/s
Check K 2 hr post infusion
K 2.0-2.5 tx
IV KCl 10-20mEq/hr until normalized
Consider continuous ECG
K <2.0 tx
IV KCl 20-40 mEq/hr until normalized
MUST have continuous ECG monitoring
Hyperkalemia causes
-Increased intake of K
-Increased exctracellular shift (acidosis, insulin deficiency, B blockade, Digoxin overdose, rewarming after hypothermia, succinylcholine)
-Reduced urinary excretion (K sparing diuretic, ACE/ARB, TMP)
Symptoms of hyperkalemia
-Muscle weakness or paralysis (If K >8)
-Abnormal ECG (peaked T waves, QRS widening)
-Arrhythmia (initial manifestation can be ventricular fibrillation)
Urgent/immediate Treatment of hyperkalemia when
K >6.5
Severe muscle weakness
ECG changes
Hyperkalemia Treatment
1) Normalize ECG
–Calcium gluconate 10mL slowly over 2-10 min, may repeat in 5 min
–Caution w/ digoxin due to risk of hypercalcemia causing sudden death
2) Shift K intracellulary
–Insulin and glucose
–Sodium bicarb 50mEq slowly over 5 min
–Albuterol 10-20 mg neb over 10 min
3) Increase K excretion
–Diuretic
–Patiromer or sodium zirconium cyclosilicate > sodium polysterene sufonate
–Dialysis as last line
Magnesium concentration
1.7-2.3
Rate of magnesium IV
1g/hr to avoid hypotension & increased renal excretion due to rapid administration
Phosphorus concentration
2.5-4.5
Hypomagnesemia causes
-impaired intestinal absorption (UC, diarrhea, pancreatitis, laxative abuse)
-inadequate intake
-hypokalemia
-increased renal excretion
-alcoholism, delirium tremens
Hypophosphatemia causes
-Increased renal excretion (diuretic, glucocorticoid, sodium bicarb)
-refeeding syndrome
-respiratory alkalosis
-DKA treatment
Max rate of phosphate infusion
7.5mmol/hr (usually given over 3-6 hours)
Calcium concentration
8.5-10.5
Corrected Ca equation =
serum Ca + 0.8 (4-albumin)
Administration of calcium IV concerns
Calcium chloride: must be central line due to risk of limb ischemia
Calcium gluconate: may be given peripherally
Rate: no faster than 60mg/min due to risk of hypotension, bradycardia, asystole
Usually give over 1-2 hours
Water needs while on EN
30 mL/kg/day of water
Macro kcal/g
Dextrose: 3.4 kcal/g
Lipid: 10 kcal/g
AA: 4 kcal/g
PN Caloric requirements
BMI <30: 25-35 kcal/kg/day based on ABW
BMI > 30: 11-14 kcal/kg based on ABW or 22-25kcal/kg based on IBW
PN fluid requirements
30-35 mL/kg/day
OR
2500-3500 mL/day
Maintain UOP 0.5-2 mL/kg/hr
PN AA requirements
0.8-2 g/kg/day on ABW
Maintenance: 0.8-1 g/kg/day
Moderate stress: 1.3-1.5 g/kg/day
Severe stress: 1.5-2 g/kg/day
Higher requirements ok for BMI >30
CKD: may need protein restriction
PN lipid reqiurements
After figuring out protein needs, subtract protein kcal from total kcal. 20-30% of that is kcal of lipid needed
PN dextrose requirements
kcal will be the remainder after figuring out protein & lipid
Usually around 150-200 g/day
PN Maintenance electrolyte needs
Na: 1-2 mEq/kg/day
K: 1 mEq/kg/day
Phos: 10-40 mmol/day
Ca: 10-15 mEq/day
Mg: 8-20 mEq/day
Concentration of Ca, phos to prevent precipitation
Ca: 6mEq/L or less
Phos: 30 mmol/L or less
Refeeding syndrome
Risk: anorexia, alcohol use disorder, cancer, chronically ill, poor nutritional intake for 1-2 weeks, malabsorption, unintentional weight loss)
Hypophosphatemia, hypokalemia, hypomagnesemia
Prevent by providing 1/2 strength, monitoring, increasing prn
Replace prior to initiating PN
Prealbumin
use to monitor nutritional status, preferred over albumin.
normal 16-40
PN acid-base imbalances
Metabolic alkalosis: change Na / K to chloride
Metabolic acidosis: change Na / K to acetate
Respiratory: address underlying cause (hypercapnia = overfeeding)
When to withhold lipids in PN
Trig > 400
