Fluid and Electrolyte Management Quiz

Fluid and Electrolyte Imbalance

• Fluid and electrolyte balance is a complex process.
• Electrolyte is a substance containing free ions, acting as an electrically conductive medium.
• Osmosis is the net movement of the solvent across a semi-permeable membrane from a high solute potential to a low solute potential.
• Body fluids are distributed in two compartments: intra- and extra-cellular.

Movement of Body Fluids

• Diffusion
• Osmosis
• Active transport

Fluid and Electrolyte Disturbance

• Approximately 60% of an adult's weight is fluid (water and electrolytes).
• Intracellular fluids (ICF) make up 2/3 of body fluid.
• Extracellular fluids (ECF) make up 1/3 of body fluid.
  • Intravascular fluids= plasma
  • Interstitial fluids surround cells
  • Trancellular fluids (e.g., cerebrospinal, pericardial, synovial)
• Total body water (TBW): 42 L. 60% of body weight
• Extracellular fluid (ECF): 14 L, 1/3 TBW.
• Intracellular fluid (ICF): 28 L, 2/3 TBW.
• Interstitial fluid: 80% of ECF = 11 L
• Plasma: 20% of ECF = 3 L

Average Daily Intake and Output in an Adult

• Intake:
  • Oral liquids: 1300 mL
  • Water in foods: 1000 mL
  • Water by metabolism: 300 mL
  • Total Intake: 2600mL
• Output:
  • Urine: 1500 mL
  • Stool: 200 mL
  • Insensible loss through lungs: 300 mL
  • Insensible loss through skin: 600 mL
  • Total Output: 2600 mL

Normal Lab Results

• Na+: 135-145 mEq/L
• K+: 3.5-5.5 mEq/L
• Ca²⁺: 8.5-10.5 mEq/L
• Cl⁻: 96-106 mEq/L
• Mg²⁺: 1.5-2.5 mEq/L

Importance of Fluid Balance

• Fluid management is crucial in hospitalized patients.
• Fluid imbalances (loss or gain of body water) can cause serious problems, ranging from lightheadedness to convulsions, coma, and death.
• Fluid therapy can be life-saving but is not without risk.

Types of IV Fluids

• Hypotonic (1/2 NS)
• Isotonic (NS, LR, Albumen)
• Hypertonic (Hypertonic saline)
• Crystalloids
• Colloids

Crystalloid vs Colloid

• Crystalloids have small particles (e.g., NaCl).
• Colloids have large particles (e.g., albumin).
• Colloids stay longer in circulation.
• Smaller amount of colloids is needed compared to crystalloids to achieve the same volume expansion. (250 ml albumin = 4 L NS)

IV Modes of Administration

• Peripheral IV
• PICC
• Central line
• Intraosseous

IV Problem: Extravasation/Infiltration

• Visual inspection with a penlight is the most sensitive indicator of extravasation.
• Assessing the infusion flow rate doesn't indicate fluid distribution.

Components of Fluid Therapy

• Maintenance therapy replaces ongoing losses.
• Replacement therapy corrects existing deficits in water and electrolytes.

Maintenance Therapy

• Usually used when a patient is not expected to eat or drink normally for an extended period (e.g., surgery, ventilator).
• Many patients are NPO (nothing by mouth) for 12 hours.
• Patients who are not eating for one to two weeks benefit from parenteral or enteral nutrition.
• Maintenance requirements are broken down into water and electrolyte requirements.

Water Requirements

• Two liters of water per day are generally sufficient for adults
• Most water intake comes from food and oxidation reactions (not external liquid consumption).
• In healthy patients, minimal water needs only 500 mL daily with regular diet.
• Water needs in patients not eating must be supplemented through maintenance fluids.
• Water requirement increases due to elevated body temperature and ongoing fluid losses (e.g., fever, sweating, burns, surgical drains).

4/2/1 Rule (Weight + 40)

• This formula is used to calculate maintenance fluid rates.
• 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for any kg above 20
• This rule is comparable to the pediatric formula.
• This method equates to 60 mL/hr for the first 20 kg, then plus an additional 1 mL/kg/hr for any subsequent weight.
• (Weight in kg + 40) = Maintenance IV rate/hour

What to Put in Fluids

• D5 1/2NS + 20 mEq K @ WT+40/hr: A practical starting point for maintaining fluid balance
• Dextrose (D5) added for calories when patients aren't eating.

Start D5 1/2NS + 20 mEq K, Then Adjust:

• Adjust solution concentration according to sodium levels, either increasing or decreasing proportionally.
• Increase potassium if plasma potassium levels are falling. Keep the current rate if everything is proceeding as expected.

###Assessment and Diagnostic Evaluation

• Health history and physical exam
• Serum BUN and creatinine
• Hematocrit (should be high)
• Urine specific gravity
• Serum electrolytes level (assessing hypo/hyperkalemia, natremia, etc)

Fluid Volume Disturbance: Hypovolemia

• Contributing factors: loss of water and electrolytes (vomiting, diarrhea, burns), decreased intake (anorexia, nausea, inability to access fluids), some disease (DM, Diabetes Insipidus)
• Symptoms: weight loss, general weakness, dizziness, increased pulse.

###Kidney Function Control

• Adrenocorticotropic hormone (ADH) regulates urine concentration and volume.
• ADH release is stimulated by decreasing water concentration or decreased blood volume.
• ADH promotes water reabsorption in the kidneys, concentrating urine and decreasing urine volume.

Regulation of Sodium Ion Levels in the Extracellular Fluids

• Renin-angiotensin-aldosterone system (RAAS) controls sodium reabsorption and water reabsorption in response to low blood pressure.

Fluid Volume Disturbance: Hypervolemia

• Contributing factors: compromised regulatory mechanism (renal failure, congestive heart failure, cirrhosis), excess administration of fluids containing sodium, prolonged corticosteroid therapy, increased fluid intake.
• Symptoms: weight gain, increased blood pressure, edema, shortness of breath.

Assessment and Diagnostic Evaluation (Hypervolemia)

• Decreased BUN, creatinine, serum osmolality, and hematocrit (due to plasma dilution).
• Increased urine sodium if kidneys are excreting excess fluid.
• Chest X-Ray (CXR) may show pulmonary congestion.

Electrolyte Imbalance: Hyponatremia

• Contributing factors: use of diuretics, loss of GI fluids, gain of water.
• Symptoms: anorexia, nausea, vomiting, headache, lethargy, confusion, seizures.

Hyponatremia Continued

• Treatment: correct underlying disorder, fluid restriction, diuretics, hypertonic saline to increase sodium level.

Electrolyte Imbalance: Hypernatremia

• Contributing factors: water deprivation, hypertonic tube feeding, diabetes insipidus.
• Symptoms: thirst, hallucination, lethargy, restlessness, pulmonary edema.

Hypernatremia Continued

• Treatment: correct underlying disorder, free water replacement (0.6 * kg BW * [(Na/140)-1]), slow infusion of D5W, rest over 16-24 hrs to avoid cerebral edema

Electrolyte Imbalance: Hypokalemia

• Contributing factors: diarrhea, vomiting, gastric suction, corticosteroid administration, diuretics.
• Symptoms: fatigue, anorexia, nausea, vomiting, muscle weakness, ECG changes (flat T waves, ST depression, U waves)

Hypokalemia Continued

• Treatment: check renal function, treat alkalosis, decrease sodium intake, PO or IV potassium supplements.

Electrolyte Imbalance: Hyperkalemia

• Contributing factors: renal failure, crush injury, burns, blood transfusion, IV potassium administration.
• Symptoms: bradycardia, arrhythmias, anxiety, irritability, ECG changes (peaked T waves, widened QRS, progressing to sine waves or V-fib).

Hyperkalemia Continued

• Treatment: remove iatrogenic causes, Acute: Ca-gluconate (IV), Sodium bicarbonate (IV), D50W (IV) and (IV) regular insulin, emergent dialysis, hydration, diuresis, kayexalate.

Calcium Imbalances

• Hypocalcemia: Often seen in hypoalbuminemia. Ionized calcium is measured. Symptoms are often not evident until Ca levels are very low. Possible causes include low Mg levels, high pancreatitis activity, hyper-PO4 levels. Check for secondary causes. Symptoms include paresthesia, numbness, tingling, circumoral numbness, tetany, seizures, trousseau's sign, chvostek's sign, EKG change that shows a prolonged QT interval.
• Hypercalcemia: Usually caused by hyperparathyroidism or malignancy, thiazides, chronic kidney problems, milk alkali syndrome, acute adrenal insufficiency. Symptoms include nausea, vomiting, abdominal pain, confusion, lethargy, and mental status changes ("bones, stones, abdominal groans, and psychic overtones").

Calcium Continued

• Treatment (for hypocalcemia): Acute: IV Calcium chloride or gluconate, chronic: Oral Calcium carbonate, Vitamin D.
• Treatment (for hypercalcemia): hydration, loop diuretics, steroids, mitrocyamin, calcitonin, managing underlying cause and treating the immediate issues.

Magnesium Imbalances

• Hypomagnesemia: Contributing factors include malnutrition, burns, pancreatitis, SIADH, parathyroid surgery, and primary hyperaldosteronism. Symptoms include weakness, fatigue, MS changes, hyperreflexia, seizures, arrhythmias. Treatment: IV or oral magnesium replacement.
• Hypermagnesemia: Contributing factors include renal insufficiency, antacid abuse, adrenal insufficiency, hypothyroidism, and iatrogenic. Symptoms include nausea, vomiting, weakness, hyporeflexia, paralysis of voluntary muscles, EKG changes (AV block, prolonged QT). Treatment: discontinue magnesium source, IV Ca Gluconate for acute episodes, and hemodialysis.

Phosphate Imbalances

• Hyperphosphatemia: Contributing factors include renal insufficiency, hypoparathyroidism. Treatment includes restricting phosphate, and administering phosphate-binding antacids (e.g., amphogel).

Acid-Base Disturbances

• Normal values for pH, PCO2, PO2, and HCO3
• Various acid-base imbalances with corresponding interpretations.

Types of IV Solutions

• Isotonic (NS, LR, D5W): Does not change osmolarity, increases TBW, used to increase intravascular space. Complications are circulatory overload.
• Hypotonic (0.45% saline): Decreases intravascular osmolarity; results in intracellular expansion; used in cellular dehydration; complications include shock, increased ICP, contraindicated in cerebral edema and hypotension.
• Hypertonic (D5%.45%, D5%/NS, D5%/LR): Increases intravascular osmolarity; results in intracellular and interstitial dehydration; used for intracellular expansion; complications include circulatory overload; contraindicated for intracellular dehydration and hyperosmolar states.