Flashcards in SR 18 - Fluids and Electrolytes Deck (159):
Two major body fluid compartments?
Intracellular and extracellular
Two subcompartments of ECF?
Interstitial fluid (inbetween cells)
Intravascular fluid (plasma)
What percentage of body weight is in fluid?
What percentage of body fluid is intracellular?
What percentage of body fluid is extracellular?
What is the composition of body fluid?
Fluids - 60% of TBW
ICF - 40% TBW
ECF - 20% TBW
(60, 40, 20)
Mnemonic TIE (Total body fluid, Intracellular, Extracellular)
On average, what percentage of body weight does blood account for in adults?
How many liters of blood in a 70kg man?
0.07 x TBW
0.07 x 70kg = 5 liters
Fluid requirments every 24hrs for Water?
Fluid requirments every 24hrs for Potassium?
Fluid requirments every 24hrs for Chloride?
Fluid requirments every 24hrs for Sodium?
What are the levels and sources of normal daily water loss?
Urine - 1200-1500mL (25-30 mL/kg)
Sweat - 200-400mL
Respiratory losses - 500-700mL
Feces - 100-200mL
What are the levels of normal daily electrolyte loss?
Sodium and potassium - 100mEq
Chloride - 150mEq
What are the levels of sodium and chloride in sweat?
What is the major electrolyte in colonic feculent fluid?
Potassium - 65mEq/L
What is the physiologic response to hypoveolemia?
Sodium/H2O retention via renin
--> aldosterone, water retention via ADH, vasoconstriction via ATII and sympathetics
--> low urine output and tacycardia (early) and hypotensions (late)
What is third spacing?
Fluid accumulation in the interstitium of tissues
Loss of fluid into the interstitium and lumen of a paralytic bowel following surgery
Intravascular and intracellular spaces are the first two spaces
When does third-spacing resolve postoperatively?
Third-spaced fluid tends to mobilize back into the intravascular space around POD #3
You need to be mindful of fluid overload when the fluid returns intravascularly - Switch to hypotonic fluid and decrease IV rate
Classic signs of third spacing?
Decreased urine output
Treatment of third spacing?
IV hydration with isotonic fluids
Surgical causes of Metabolic acidosis?
Loss of bicarbonate - diarrhea, ileus, fistula, high-output ileostomy, carbonic anhydrase inhibitors
Increase in acids - lactic acidosis (ischemia), ketoacidosis, renal failure, necrotic tissue
Surgical causes of hypochloremic alkalosis?
NGT suction, loss of gastric HCL through vomiting/NGT
Surgical causes of metabolic alkalosis?
Vomiting, NG suction, diuretics, alkali ingestions, mineralocorticoid excess
Surgical causes of respiratory acidosis?
Hypoventilation (i.e. CNS depression), drugs (i.e. morphine), PTX, pleural effusion, parenchymal lung disease, acute airway obstruction
Surigcal causes of respiratory alkalosis?
Hyperventilation (i.e. anxiety, pain, fever, wrong vent setting)
Classic acid-base finding with sinigicant vomiting or NGT suctioning?
Hypokalemic hypochloremic metabolic alkalosis
Why do you get hypokalemia with NGT suctioning?
Loss of gastric fluid:
- Loss of HCL causes alkalosis
- Alkalosis drives K+ into cells
Treatment for hypokalemic hypochloremic metabolic alkalosis?
What is paradoxic alkalotic aciduria? Why does it happen?
Seen in severe hypokalemic, hypovolemic, hypochloremic metabolic alkalosis with paradoxic metabolic alkalosis of serum and acidic urine
Due to H+ loss in the urine in exchange for Na+ in an attempt to restore volume. H+ is preferentially lost over K+ due to the hypokalemia
What can be followed to assess fluid status?
Central venous pressure
With hypovolemia, what changes occur in vital signs?
Initial rise in diastolic pressure due to clamping down (peripheral vasoconstriction) with subsequent decrease in both systolic and diastolic blood pressure
What are the insensible fluid losses?
Loss of fluid that cannot be measured
Feces - 100-200mL/24hrs
Breathing - 500-700mL/24hrs (increases with fever and tachypnea)
Skin - 300mL/24hrs (increases with fever)
What is the quantity of daily secretions of bile?
What is the quantity of daily gastric secretions?
What is the quantity of daily pancreatic secretions?
What is the quantity of daily small intestine secretions?
What is the quantity of daily saliva secretions?
What happens to bile, gastric, pancreatic, small intestines and salivary secretions?
Most of them are reabsorbed
Mnemonic for remembering daily secretions from bile, gastric and small-bowel sources?
Bile = 1L
Gastric = 2L
Small-bowel = 3L
Per liter, components of NS?
154 mEq of Cl and Na
Per liter, components of 1/2 NS?
77 mEq of Cl and Na
Per liter, components of 1/4 NS?
39 mEq of Cl and Na
Per liter, components of LR?
130 mEq of Na
109 mEq of Cl
28 mEq of lactate
4 mEq K
3 mEq Ca
Per liter, components of D5W
5% dectrose (50g) in water
What accounts for tonicity?
NS/LR are both isotonic
1/2 NS is hypotonic
What happens to the lactate in LR in the body?
Converted to bicarbonate
Cannot use LR as maintanance fluid because the patient will become alkalotic
IV replacement based on anatomic site of losses - Gastric (NGT)?
D5 1/2 NS + 20 KCl
IV replacement based on anatomic site of losses - Biliary?
LR +/- sodium bicarbonate
IV replacement based on anatomic site of losses - pancreatic?
LR +/- sodium bicarbonate
IV replacement based on anatomic site of losses - Small bowel (ileostomy)?
IV replacement based on anatomic site of losses - colonic (diarrhea)?
LR +/- sodium bicarbonate
What is the 100/50/20 rule associated with calculation of maintenance fluids?
Maintenance fluids for 24hrs:
- 100mL/kg for first 10kg
- 50mL/kg for next 10kg
- 20mL/kg for ever kg over 20
Divide by 24 for hourly rate
What is the 4/2/1 rule associated with calculation of maintenance fluids?
Maintenance fluids for hourly rate:
- 4mL/kg for first 10kg
- 2mL/kg for next 10kg
- 1mL/kg for every kg over 20kg
What is the common adult maintenance fluid?
D5 1/2 NS with 20mEq KCl/L
What is the common pediatric maintenance fluid?
D5 1/4 NS with 20mEq KCl/L
(Due to children's decreased ability of children to concentrate urine)
Why should sugar (dextrose) be added to maintenance fluid?
To inhibit muscle breakdown
What is the best way to assess fluid status?
Unless patietn has cardiac or renal dysfunction - then use CVP or PCWP
What is the minimal urine output for an adult on maintenence IV?
What is the minimal urine ouptut for an adult trauma patient?
How many mL are in 12 oz?
How many mL are in 1oz?
How many mL are in 1tsp
What are common isotonic fluids?
What is a fluid bolus?
Volume of fluid given IV rapidly (i.e. 1L over 1 hour)
Used for increasing intravascular volume
Use isotonic fluid (NS, LR)
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?
Remember, LR only has 4mEq/L
Why should isotonic fluids be given for recuscitation?
If hypotonic fluid is given, the tonicity of the intravascular space will decrease and H2O will freely diffuse into the interstitial and intracellular space
Use isotonic fluid allow expanding of the intravascular space
What is the most common trauma resuscitation fluid?
What is the most common postoperative IVF after a laparotomy?
LR or D5LR for 24-36 hours, followed by maintenance fluid
After a laparotomy, when should a patient's fluid be mobilized?
POD 3 - third-space fluid starts moving back into the intravascular space
What IVF is used to replace duodenal or pancreatic fluid loss?
LR - for the bicarbonate loss
What is a common cause of electrolyte abnormalities?
What is a a major extracellular cation?
What is a major intracellular cation?
What are the surgical causes of hyperkalemia?
Tissue destruction (injury/hemolysis)
What are the signs and symptoms of hyperkalemia?
Decreased deep tendon reflexes or areflexia
What are the EKG findings of hyperkalemia?
Peaked T waves
Depressed ST segment
What are critical values for potassium?
What is the urgent treatment for hyperkalemia?
IV calcium (cardioprotective), ECG monitoring
Sodium bicarbonate IV (alkalosis will drive K+ intracellularly)
Glucose and insulin (will also drive K+ intracellularly)
Sodium polystyrene sulfonate (Kayexalate) and furosemide (Lasix)
Acronymn: CB DIAL K
What is the nonacute treatment for hyperkalemia?
Furosemide (Lasix), sodium polystyrene sulfonate (Kayexalate)
What acid-base change lowers the serum potassium?
What nebulizer treatment can help lower K+ levels?
What are surgical causes of hypokalemia?
Signs and symptoms of hypokalemia?
What are the ECG findings in hypokalemia?
Flattening of T-waves
U-waves (second wave after a t-wave)
ST segment depression
What is the rapid treatment of hypokalemia?
What is the maximum amount of KCl that can be given through peripheral IV?
What is the maximum amount of KCl that can be given through a central line?
What is the treatment of chronic hypokalemia?
What is the most common electrolyte-mediated ileus in the surgical patient?
What electrolyte conditions exacerbates digitalis toxicity?
What electrolyte deficiency can cause hypokalemia?
What electrolyte must you replace before replacing K?
Why does hypomagnesemia make replacement of K with hypokalemia nearly impossible?
Hypomagnesemia inhibits K+ reabsoprtion from the renal tubules
What are the surgical causes of hypernatremia?
Iatrogenic (i.e. TPN)
What are the signs/symptoms of hypernatremia?
Pulmonary or peripheral edema
What is the usualy treatment of hyponatremia, slowly over days?
D5W, 1/4NS or 1/2NS
How fast should you lower the sodium levels in hypernatremia?
What is the major complication of lowering sodium too rapidly?
What are the surigcal causes of hypovolemic hyponatremia?
What are the surigcal causes of euvolemic hyponatremia?
What are the surigcal causes of hypervolemic hyponatremia?
Liver failure (cirrhosis)
Iatrogenic fluid overload (dilutional)
Signs and symptoms of hyponatremia?
What is the treatment of hypovolemic hyponatremia?
NS IV, correct underlying cause
What is the treatment of euvolemic hyponatremia?
SIADH - furosemide and NS acutely, fluid restriction
What is the treatment of hypervolemic hyponatremia?
Dilutional - fluid restriction and diuretics
How fast should you increase the sodium level in hyponatremia?
What can happen if you correct hyponatremia too quickly?
Central pontine myelinolysis
What are the signs of central pontine myelinolysis?
Horizontal gaze paralysis
What is the most common cause of mild postoperative hyponatremia?
What is pseudohyponatremia?
Spurious lab values of hyponatremia as a result of hyperglycemia, hyperlipidemia, or hyperproteinemia
Signs and symptoms of hypercalcemia?
Stones, bones, adbominal groans and psychiatric overtones
Polydipsia, polyuria, constipation
ECG findings of hypercalcemia?
Short QT interval
Prolonged PR interval
What is the acute treatment of hypercalcemic crisis?
Volume expansion with NS, diuresis with furosemide
What are less traditional options for the treatment of hypercalcemia?
Dialysis (last resort)
How do you adjust calcium levels in hypoalbuminemia?
(4 - measured albumin level) x 0.8 + measured calcium level
What are the surgical causes of hypocalcemia?
Short bowel syndrome
Vitamin D deficiency
Osteoblastic metastasis (prostate, medulloblastoma, bronchial carcinoid)
Signs and symptoms of hypocalcemia?
Chvostek's and Trousseau's signs
Perioral paraesthesia (early)
Increased deep tendon reflexes (late)
Psychiatric abnormalities (paranoia, depression, hallucinations)
ECG findings in hypocalcemia?
Prolonged QT and ST interval
(Possible peaked T-waves)
Acute treatment of hypocalcemia?
IV calcium gluconate
What is the chronic treatment of hypocalcemia?
What is the possible complications of infused calcium if the IV infilrates?
Only administer peripherally in an absolute emergency
Calcium gluconate is less toxic that calcium chloride during an infiltration
What is the best way to check calcium levels in the ICU?
Ceck ionized calcium
What is the normal range for magnesium level?
What are the surgical causes of hypermagnesemia?
IV over supplementation
What are the signs and symptoms of hypermagnesemia?
Decreased deep tendon reflexes
What is the treatment of hypermagnesemia?
Calcium gluconate IV
Insulin + glucose
What are the surgical causes of hypomagnesemia?
Signs and symptoms of hypomagnesemia?
Increased deep tendon reflexes
Acute treatment of hypomagnesemia?
What is the chronic treatment of hypomagenesemia?
Magnesium oxide PO
(AE - diarrhea)
What are the surgical causes of hyperglycemia?
Diabetes (poor control)
Decreased caloric intake
Signs and symptoms of hyperglycemia?
DKA (Kussmaul breathing)
Treatment of 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?
Decreased caloric intake
What are the signs and symptoms of hypoglycemia?
Sympathetic response (diaphroesis, tachycardia, palpitations)
What is the treatment for hypoglycemia?
IV or PO glucose
What is the normal range for phosphorus levels?
What are the signs and symptoms of hypophosphatemia?
Neurologic dysfunction (i.e. ataxia)
Poor pressor response
What is a complication of severe hypophophatemia?
What are causes of hypophosphatemia?
What is the critical value for phosphate?
What is the treatment for hypophosphatemia?
Supplement with sodium phosphate or potassium phosphate IV
What are the signs and symptoms of hyperphosphatemia?
What are the causes of hyperphosphatemia?
What is the treatment for hyperphosphatemia?
Aluminum hydroxide (binds phosphate)
If hyperkalemia is left untreated, what can occur?
Vtach/fib --> death
What electrolyte is an inotrope?
What are the major cardiac electrolytes?
Calcium (dysrhythmias, inotrope)
Which electrolyte must be monitored closely in patients on digitalis?
Most common cause of electrolyte-mediated ileus?
What is a colloid fluid?
Protein-containing fluid (albumin)
An elderly patient goiens into CHF on POD 3 after a laparotomy. What is going on?
Mobilization of third-space fluid --> fluid overload --> CHF
(also run cardiac enzymes and ECG to R/O an MI)
What fluid is used to repalce NGT aspirate?
D5 1/2 NS with 20 KCl