Flashcards in Fluids and Electrolytes Deck (169):
What are the two major body fluid compartments?
What are the two sub compartments of extracellular fluid?
What percentage of body weight is in fluid?
What percentage of body fluid is intracellular?
What percentage of body fluid is extracellular?
On average, what percentage of body weight does blood account for in adults?
How many liters of blood are in a 70-kg man?
What is the daily water requirement?
What is the daily potassium requirement?
What is the daily chloride requirement?
What is the daily sodium requirement?
What are the levels and sources of normal daily water loss?
Urine: 1200-1500 mL (25-30 mL/kg)
Sweat: 200-400 mL
Respiratory losses: 500-700 mL
Feces: 100-200 mL
What are the levels and sources of normal daily electrolyte loss?
Sodium and potassium: 100 mEq
Chloride: 150 mEq
What are the levels of sodium and chloride in sweat?
What is the major electrolyte in colonic feculent fluid?
Potassium: 65 mEq/L
What is the physiologic response to hypovolemia?
Sodium/water retention via renin/aldosterone; water retention via ADH; vasoconstriction via angiotensin II and sympathetics; low urine output and tachycardia (early), hypotension (late)
What is third spacing?
Fluid accumulation in the interstitial of tissues, as in edema (e.g. loss of fluid into the interstitium and lumen of a paralytic bowel following surgery)
When does third-spacing occur postoperatively?
Third-spaced fluid tends to mobilize back into the intravascular space around POD #3 (switch to hypotonic fluid and decrease IV rate)
What are the classic signs of third spacing?
Tachycardia, decreased urine output
What is the treatment for third spacing?
IV hydration with isotonic fluids
What are the surgical causes of metabolic acidosis?
Loss of bicarbonate (e.g. diarrhea, ileus, fistula, high-output ileostomy, carbonic anhydrase inhibitors).
Increase in acids (e.g. lactic acidosis from ischemia, ketoacidosis, renal failure, necrotic tissue).
What are the surgical causes of hypochloremic alkalosis?
NGT suction, loss of gastric HCl through vomiting/NGT
What are the surgical causes of metabolic alkalosis?
Vomiting, NG suction, diuretics, alkali ingestion, mineralocorticoid excess
What are the surgical causes of respiratory acidosis?
Hypoventilation (e.g. CNS depression, drugs, PTX, pleural effusion, parenchymal lung disease, acute airway obstruction)
What are the surgical causes of respiratory alkalosis?
Hyperventilation (e.g. anxiety, pain, fever, wrong ventilator settings)
What is the classic acid-base finding with significant vomiting or NGT suctioning?
Hypokalemic hypochloremic metabolic alkalosis
Why hypokalemia with NGT suctioning?
Loss of HCl causes alkalosis, driving K into cells
What is the treatment for hypokalemic hypochloremic metabolic alkalosis?
IVF, Cl/K replacement
What is paradoxic alkalotic aciduria?
Seen in severe hypokalemic, hypovolemic, hypochloremic metabolic alkalosis with paradoxic metabolic alkalosis of serum and acidic urine
How does paradoxic alkalotic aciduria occur?
H is lost in the urine in exchange for Na in an attempt to restore volume
With paradoxic alkalotic aciduria, why is H preferentially lost?
H is exchanged preferentially into the urine instead of K because of the low concentration of K
What can be followed to assess fluid status?
Urine output, base deficit, lactic acid, vital signs, weight changes, skin turgor, JVD, mucosal membranes, rales, central venous pressure, PCWP, CXR
With hypovolemia, what changes occur in vital signs?
Tachycardia, tachypnea, initial rise in diastolic BP because of peripheral vasoconstriction with subsequent decrease in both systolic and diastolic BP
What are the insensible fluid losses?
Loss of fluid not measured: feces, breathing (increased with fever, tachypnea), sweat (increased with fever)
What quantity of bile is secreted daily?
What quantity of gastric secretions are secreted daily?
What quantity of pancreatic secretions are secreted daily?
What quantity of small intestinal secretions are secreted daily?
What quantity of saliva is secreted daily?
What comprises NS?
154 mEq of Cl
154 mEq of Na
What comprises 1/2 NS?
77 mEq of Cl
77 mEq of Na
What comprises 1/4 NS?
39 mEq of Cl
39 mEq of Na
What comprises lactated Ringer's?
130 mEq of Na
109 mEq of Cl
28 mEq lactate
4 mEq K
3 mEq Ca
What comprises D5W?
5% dextrose (50 g) in water
What accounts for tonicity?
Mainly electrolytes (thus NS and LR are both isotonic)
What happens to the lactate in LR in the body?
Converted into bicarbonate, thus LR cannot be used as a maintenance fluid because patients would become alkalotic
What is the IVF replacement for gastric fluid loss (NGT)?
D5 1/2 NS + 20 KCl
What is the IVF replacement for biliary fluid loss?
LR +/- sodium bicarbonate
What is the IVF replacement for pancreatic fluid loss?
LR +/- sodium bicarbonate
What is the IVF replacement for small bowel fluid loss (ileostomy)?
What is the IVF replacement for colonic fluid loss (diarrhea)?
LR +/- sodium bicarbonate
What is the 100/50/20 rule?
Maintenance IV fluids for a 24-hour period:
100 mL/kg for the first 10 kg
50 mL/kg for the next 10 kg
20 mL/kg for every kg over 20
What is the 4/2/1 rule?
Maintenance IV fluids for hourly rate:
4 mL/kg for the first 10 kg
2 mL/kg for the next 10 kg
1 mL/kg for every kg over 20
What is the maintenance for a 70-kg man?
What is the common adult maintenance fluid?
D5 1/2 NS with 20 mEq KCl/L
What is the common pediatric maintenance fluid?
D5 1/4 NS with 20 mEq KCl/L (children have decreased ability to concentrate urine)
Why should sugar be added to maintenance fluid?
To inhibit muscle breakdown
What is the best way to assess fluid status?
Urine output (unless the patient has cardiac or renal dysfunction, in which case central venous pressure or wedge pressure is often used)
What is the minimal urine output for an adult on maintenance IV fluids?
30 mL/hr (0.5 mL/kg/hr)
What is the minimal urine output for an adult trauma patient?
How many mL are in 12 oz?
How many mL are in 1 oz?
How many mL are in 1 tsp?
What are common isotonic fluids?
What is a bolus?
Volume of fluid given IV rapidly.
Used for increasing intravascular volume, and isotonic fluids should be used.
Why not combine bolus fluids with dextrose?
Hyperglycemia may result
What is the possible consequence of hyperglycemia in the patient with hypovolemia?
Why not combine bolus fluids with a significant amount of potassium?
Hyperkalemia may result
Why should isotonic fluids be given for resuscitation?
If hypotonic fluid is given, the tonicity of the intravascular space will be decreased and water will freely diffuse into the interstitial and intracellular spaces (thus, use isotonic fluids to expand the intravascular space)
What portion of 1 L NS will stay in the intravascular space after a laparotomy?
In 5 hours, only 200 mL will remain in the intravascular space
What is the most common trauma resuscitation fluid?
What is the most common postoperative IV fluid after laparotomy?
LR or D5LR for 24-36 hours, followed by maintenance fluid
After a laparotomy, when should a patient's fluid be mobilized?
Classically, POD #3 (the patient begins to mobilize the third-space fluid back into the intravascular space)
What IVF is used to replace duodenal or pancreatic fluid loss?
LR (bicarbonate loss)
What is a common cause of electrolyte abnormalities?
What is a major extracellular cation?
What is a major intracellular cation?
What is the normal range for potassium level?
What are the surgical causes of hyperkalemia?
Iatrogenic overdose, blood transfusion, renal failure, diuretics, acidosis, tissue destruction, hemolysis
What are the signs and symptoms of hyperkalemia?
Decreased DTRs or areflexia, weakness, paresthesias, paralysis, respiratory failure
What are the ECG findings with hyperkalemia?
Peaked T waves, depressed ST segment, prolonged PR, wide QRS, bradycardia, ventricular fibrillation
What are the critical values for potassium?
K > 6.5
What is the urgent treatment for hyperkalemia?
IV calcium (cardioprotective); ECG monitoring; sodium bicarbonate IV (alkalosis drives K intracellularly); glucose and insulin; albuterol; sodium polystyrene sulfonate (Kayexalate) and furosemide (Lasix); dialysis
What is the non-acute treatment for hyperkalemia?
Furosemide (Lasix), sodium polystyrene sulfonate (Kayexalate)
What is the acronym for the treatment of acute symptomatic hyperkalemia?
CB DIAL K:
Calcium, Bicarbonate, Dialysis, Insulin/dextrose, Albuterol, Lasix, Kayexalate
What is pseudohyperkalemia?
Spurious hyperkalemia as a result of falsely elevated K in sample from sample hemolysis
What acid-base change lowers the serum potassium?
What nebulizer treatment can help lower K level?
What are the surgical causes of hypokalemia?
Diuretics, certain antibiotics, steroids, alkalosis, diarrhea, intestinal fistulae, NG aspiration, vomiting, insulin, insufficient supplementation, amphotericin
What are the signs and symptoms of hypokalemia?
Weakness, tetany, N/V, ileus, paresthesia
What are the ECG findings with hypokalemia?
Flattening of T waves, U waves, ST segment depression, PAC, PVC, atrial fibrillation
What is the rapid treatment for hypokalemia?
What is the maximum amount of KCl that can be given through a peripheral IV?
What is the maximum amount of KCl that can be given through a central line?
What is the chronic treatment for hypokalemia?
What is the most common electrolyte-mediated ileus in the surgical patient?
What electrolyte condition exacerbates digitalis toxicity?
What electrolyte deficiency can actually cause hypokalemia?
What electrolyte must you replace first before replacing potassium?
Why does hypomagnesemia make replacement of potassium with hypokalemia nearly impossible?
Hypomagnesemia inhibits K reabsorption from the renal tubules
What is the normal range for sodium level?
What are the surgical causes of hypernatremia?
Inadequate hydration, diabetes insipidus, diuresis, vomiting, diarrhea, diaphoresis, tachypnea, iatrogenic (e.g. TPN)
What are the signs and symptoms of hypernatremia?
Seizures, confusion, stupor, pulmonary or peripheral edema, tremors, respiratory paralysis
What is the usual treatment supplementation given slowly over days for hypernatremia?
D5W, 1/4 NS or 1/2 NS
How fast should you lower the sodium level in hypernatremia?
Guideline is < 12 mEq/L per day
What is the major complication of lowering the sodium level too fast with hypernatremia?
Seizures (not central pontine myelinolysis)
What are the surgical causes of hypovolemic hyponatremia?
Diuretic excess, hypoaldosteronism, vomiting, NG suction, burns, pancreatitis, diaphoresis
What are the surgical causes of euvolemic hyponatremia?
SIADH, CNS abnormalities, drugs
What are the surgical causes of hypervolemic hyponatremia?
Renal failure, CHF, liver failure, iatrogenic fluid overload
What are the signs and symptoms of hyponatremia?
Seizures, coma, N/V, ileus, lethargy, confusion, weakness
What is the treatment for hypovolemic hyponatremia?
NS IV, correct underlying cause
What is the treatment for euvolemic hyponatremia?
If SIADH: furosemide and NS acutely, fluid restriction
What is the treatment for hypervolemic hyponatremia?
Dilutional fluid restriction and diuresis
How fast should you increase the sodium level in hyponatremia?
Guideline < 12 mEq/L per day
What may occur if you correct hyponatremia too quickly?
Central pontine myelinolysis
What are the signs and symptoms of central pontine myelinolysis?
2. Spastic quadriplegia
3. Horizontal gaze paralysis
What is the most common cause of mild postoperative hyponatremia?
What is pseudohyponatremia?
Spurious lab value of hyponatremia as a result of hyperglycemia, hyperlipidemia, or hyperproteinemia
What are the causes of hypercalcemia?
Calcium supplementation IV; Hyperparathyroidism, Hyperthyroidism; Immobility, Iatrogenic (thiazide diuretics); Mets, Milk alkali syndrome; Paget's disease (bone); Addison's disease, Acromegaly; Neoplasm (colon, lung, breast, prostate, multiple myeloma); Zollinger-Ellison syndrome (MEN-I); Excessive vitamin A; Excessive vitamin D; Sarcoid
What are the signs and symptoms of hypercalcemia?
"Stones, bones, abdominal groans, and psychiatric overtones"
Polydipsia, polyuria, constipation
What are the ECG findings with hypercalcemia?
Short QT interval, prolonged PR interval
What is the acute treatment of hypercalcemic crisis?
Volume expansion with NS, diuresis with furosemide (not thiazides)
What are options (other than volume expansion and furosemide) for lowering the calcium level?
Steroids, calcitonin, bisphosphonates (pamidronate), mithramycin, dialysis (last resort)
How can the calcium level be determined with hypoalbuminemia?
(4 - measured albumin level) X 0.8, then add this value to the measured calcium level
What are the surgical causes of hypocalcemia?
Short bowel syndrome, intestinal bypass, vitamin D deficiency, sepsis, acute pancreatitis, osteoblastic metastasis, aminoglycosides, diuretics, renal failure, hypomagnesemia, rhabdomyolysis
What is Chvostek's sign?
Facial muscle spasm with tapping of facial nerve
What is Trousseau's sign?
Carpal spasm after occluding blood flow in forearm with blood pressure cuff
What are the signs and symptoms of hypocalcemia?
Chvostek's sign, Trousseau's sign, perioral paresthesia (early), increased DTRs (late), confusion, abdominal cramps, laryngospasm, stridor, seizures, tetany, psychiatric abnormalities (e.g. paranoia, depression, hallucinations)
What are the ECG findings with hypocalcemia?
Prolonged QT and ST interval (peaked T waves are also possible, as in hyperkalemia)
What is the acute treatment of hypocalcemia?
IV calcium gluconate
What is the chronic treatment of hypocalcemia?
PO calcium, vitamin D
What is the possible complication of infused calcium if the IV infiltrates?
Tissue necrosis (never administer peripherally unless absolutely necessary)
What is the best way to check the calcium level in the ICU?
Check ionized calcium
What is the normal range for magnesium level?
What is the surgical cause of hypermagnesemia?
TPN, renal failure, IV over supplementation
What are the signs and symptoms of hypermagnesemia?
Respiratory failure, CNS depression, decreased DTRs
What is the treatment for hypermagnesemia?
IV calcium gluconate, insulin and glucose, dialysis (similar for hyperkalemia), furosemide (Lasix)
What are the surgical causes of hypomagnesemia?
TPN, hypocalcemia, NG suction, aminoglycosides, renal failure, diarrhea, vomiting
What are the signs and symptoms of hypomagnesemia?
Increased DTRs, tetany, asterixis, tremor, Chvostek's sign, ventricular ectopy, vertigo, tachycardia, dysrhythmias
What is the acute treatment for hypomagnesemia?
What is the chronic treatment for hypomagnesemia?
PO Magnesium oxide
Hypomagnesemia may make it impossible to correct what other electrolyte abnormality?
What are the surgical causes of hyperglycemia?
Diabetes (poor control), infection, stress, TPN, drugs, lab error, drawing over IV site, somatostatinoma, glucagonoma
What are the signs and symptoms of hyperglycemia?
Polyuria, hypovolemia, confusion, coma, polydipsia, ileus, DKA (Kussmaul breathing), abdominal pain, hyporeflexia
What is the treatment for hyperglycemia?
What is the Weiss protocol?
Sliding scale insulin
What is the goal glucose level in the ICU?
What are the surgical causes of hypoglycemia?
Excess insulin, decreased caloric intake, insulinoma, drugs, liver failure, adrenal insufficiency, gastrojejunostomy
What are the signs and symptoms of hypoglycemia?
Sympathetic response (diaphoresis, tachycardia, palpitations), confusion, coma, headache, diplopia, neurologic deficits, seizures
What is the treatment for hypoglycemia?
Glucose (IV or PO)
What is the normal range for phosphorus level?
What are the signs and symptoms of hypophosphatemia?
Weakness, cardiomyopathy, neurologic dysfunction (ataxia), rhabdomyolysis, hemolysis, poor pressor response
What is a complication of severe hypophosphatemia?
What are the causes of hypophosphatemia?
GI losses, inadequate supplementation, medications, sepsis, alcohol abuse, renal loss
What is the critical value for phosphorus level?
< 1.0 mg/dL
What is the treatment for hypophosphatemia?
Supplement with sodium phosphate or potassium phosphate IV
What are the signs and symptoms of hyperphosphatemia?
Calcifications (ectopic), heart block
What are the causes of hyperphosphatemia?
Renal failure, sepsis, chemotherapy, hyperthyroidism
What is the treatment for hyperphosphatemia?
Aluminum hydroxide (binds phosphate)
If hyperkalemia is left untreated, what can occur?
Ventricular tachycardia or fibrillation
Which electrolyte is an inotrope?
What are the major cardiac electrolytes?
Potassium (dysrhythmias), magnesium (dysrhythmias), calcium (dysrhythmias, inotrope)
Which electrolyte must be monitored closely in patients on digitalis?
What is the most common cause of electrolyte-mediated ileus?
What is a colloid fluid?
Protein-containing fluid (albumin)
What is the rationale for using an albumin-furosemide "sandwich"?
Albumin will pull interstitial fluid into the intravascular space and the furosemide will then help excrete the fluid as urine
An elderly patient goes into CHF on POD #3 after a laparotomy. What is going on?
Mobilization of the third-space fluid into the intravascular space, resulting in fluid overload and resultant CHF
What fluid is used to replace NGT aspirate?
D5 1/2 NS with 20 KCl