Fluids Flashcards
What is normal urine rate?
0.5 - 1.0ml/kg per hour
How much fluid do adults need per day?
35ml/kg per day or 1500ml/m2 per day
How much fluid do you lose due to fever every day?
250ml/day per degree centrigrade of fever
How do you estimate how much fluid you lose due to operative losses?
hours NPO x baseline maintenace IV fluid requirement + # hours of case x baseline IV fluid requirement + operative blood loss + insensible losses
Estimation of insensible losses:
1-3ml/kg per hour for minor procedure
4-7ml/kg per hour for intermediate procedure
8-12 ml/kg per hour for major procedure
What is pseudohyponatremia?
Low sodium due to:
1. hypertriglyceridemia (lots of fat)
2. hypoerproteinemia (lots of proteins)
What are the causes of isotonic hyponatremia? (4)
- Infusions of isotonic glucose
- Mannitol
- Glycine
- Post-TURP
What are the causes of hypertonic hyponatremia?(5)
- After hypertonic infusions of glucose
- Mannitol
- Glycine
- After TURP
- Hyperglycemia
What are the causes of hypovolemic hyponatremia?(3)
- GI losses (vomiting, diarrhea, fistula)
- Skin losses (thermal injury)
- Renal losses (diuretics, diabetes insipidus, salt wasting nephritis, peritoneal dialysis)
What are the causes of isovolemic hyponatremia? (6)
- Water intoxication
- Iatrogenic causes
- Secretion of ADH
- Hypokalemia
- Drugs (sulfonylureas, carbamazepine, phenothiazines, antidepressants)
- Reset thermostat
What are the causes of hypervolemic hyponatremia? (3)
- CHF
- Liver failure
- Drugs (indomethacin, carbamazepine, vincristine, vinblastine, cyclophosphamide, nicotine derivatives)
What is the formula to estimate sodium deficit?
Na+ deficit = (Desired Na+ level - actual Na +level) x TBW
What type of fluid do you use to correct hypovolemic hyponatremia?
REplace with 0.9% NaCl,
Monitor frequently to avoid too rapid of correction
How do you correct isovolemic hyponatremia?
Corrected by addressing the underlying disorder
What is a major complication of rapid infusion of hypertonic saline solutions?
Central pontine myelinosis
What are the 4 causes of hypervolemic hyponatremia?
- Iatrogenic (excessive administration of Na+) (5)
- Conn syndrome
- Cushing syndrome
- Steroid Use
- Congenital adrenal hyperplasia
What is Conn’s Syndrome?
Also known as primary aldosteronism…
What are the two effects of rapid reversal of hypernatremia?
- Cerebral edema
- Uncal herniation
How do you correct hypernatremia?
- Address the underlying disorder
- Calculate the free water deficit. H20 deficit = (0.6 x kg of body weight) x [(serum Na+/140)-1]
- Replace half the deficit in the first 24 hours and then the remainder in the following 2 days
- USE A HYPOTONIC FLUID such as D5W
At what level do you see the clinical signs of hypokalemia?
2.5 mEq/L
What are the clinical signs of hypokalemia?
- CV - sensitization to digitalis and epi, arrhythmias, electrocardiographic changes (low voltage, flattened T waves, ST segment depression, prolonged Qt interval and prominent U waves)
- CNS - parasthesias, paralysis
- GI - constipation, ileus
- M/S - weakness, cramps, myagias, rhabdomyolysis
What are the causative factors of hypokalemia in a surgical patient?
- GI (diarrhea, gastric drainage via vomiting or NG tube)
- Diuretics
- Insulin administration
How do you treat hypokalemia?
- Ensure adequate renal function before beginning replacements
- Treat the alkalosis
- Decrease Na+ intake
- Enteral replacement is preferred
- If not enteral, parenteral is preferred.
For every decrease of K+ on blood work, how much decrease is there in the total body stores?
For every 1 mEq decrease, there is a 100-200 mEq decrease in total body stores.
How much potassium is there in a banana?
10mEq K+
What is the maximum amount of KCl can you administer through a peripheral IV?
No more than 10mEq/h
What is the maximum amount of KCl can you administer through a central line?
No more than 20 mEq/h but can also be up to 40mEq/h if the patient has cardiac monitoring and is in the intensive care unit.
What are the signs and symptoms of hyperkalemia?
CV- peaked T waves, flattened P waves, QRS prolongation, cardiac arrest, ventricular fibrillation
M/S - weakness and parasthesias
GI - N/V, diarrhea, intestinal colic
What are the causative factors of hyperkalemia?
- Pseudohyperkalemia - can occur in hemolysis, thrombocytosis and leukocytosis
- Acidosis
- Insulin deficiency
- Reperfusion syndrome
- Tissue necrosis (crush injuries)
- Burns
- Electrocution
- Beta blocker therapy
- Digitalis
- Succinylcholine
- Renal insufficiency (most common cause in surgical patient)
- MRA
- Mineral corticoid deficiency
How do you treat mild hyperkalemic? (i.e. <6.0mEq/L)
- Remove the exogenous source
- Add lasix