Untitled Quiz

Fluids and Electrolytes (Chapter 45)

• Objectives:
  • Review fluid dynamics
  • Identify different forms of fluid replacement
  • Identify conditions requiring fluid therapies
  • Discuss potassium and sodium imbalances and their treatment
  • Identify implications for client care receiving fluid and electrolyte therapies

Fluid Balance

• Total Body Water (TBW):
  • 60% of adult human body is water
• Compartments of TBW:
  • Intracellular fluid (ICF): 67%
  • Interstitial fluid (IF): 25%
  • Plasma volume (PV): 8%
  • Extracellular fluid (ECF): 33%
• Components of ECF:
  • Interstitial fluid
  • Blood (plasma + cells)
  • Blood constituents (plasma proteins, RBCs, platelets, WBCs)
• Distribution in ECF:
  • Determined by bulk flow and Starling forces

Capillary Microcirculation

• Balance of pressures:
  • Hydrostatic pressure (blood pressure)
  • Colloid osmotic pressure (due to plasma proteins)

Fluid Balance

• Water balance:
  • Water intake = water loss
• Imbalances:
  • Edema
  • Dehydration and fluid loss

IV Fluid Administration

• Reasons for IV fluids:
  • Dehydration
  • Electrolyte imbalances
  • Blood component deficiencies
  • Nutrition

IV Fluids: Types

• Crystalloids:

  • Solutions of electrolytes and small molecules
  • Do not contain proteins/large molecules (colloids)

• Examples:

  • Normal saline (0.9% NaCl)
  • Half normal saline (0.45% NaCl)
  • Hypertonic saline (3% sodium chloride)
  • Lactated Ringer's
  • D5W
  • Normosol/Plasmalyte

• Uses of Crystalloids:

  • Treat dehydration (volume loss/maintenance)
  • Fluid replacement (compensate for insensible losses)
  • Manage electrolyte imbalances (e.g., Ringer's lactate)
  • Promote urinary flow
  • Expand plasma volume (e.g., 3% NaCl)

• Indications (Crystalloids):

  • Acute liver failure
  • Acute nephrosis
  • Burns
  • Hypovolemic shock
  • Renal dialysis

• Crystalloids: Adverse Effects

  • Edema (peripheral or pulmonary)
  • Fluid overload
  • May dilute plasma proteins
  • Effects may be short-lived

• Colloids:

  • Increase colloid osmotic pressure
  • Move fluid from interstitial to plasma compartment
  • "Plasma volume expanders"
  • Restore blood pressure and initiate diuresis
  • Examples:
    • Dextran 40 or 70
    • Hetastarch / hydroxyethyl starch (HES)
    • Modified gelatin
    • Albumin

• Indications (Colloids):

• Trauma, Burns, Sepsis, Hypovolemic shock

• Colloids: Adverse Effects

  • Usually safe
  • Concerns in renal failure
  • May cause altered coagulation (bleeding)
  • No oxygen-carrying capacity

Blood & Blood Products

• Characteristics:
  • Most expensive and least available
  • Require human donors
• Examples:
  • Whole blood
  • RBC products (carry oxygen)
  • Clotting factors (from plasma)
  • Platelets
• Indications (Blood Products):
  • Increase oxygen-carrying capacity (e.g., anemia, substantial hemoglobin deficits)
  • Blood loss >25%
  • Increase clotting factor levels (e.g., coagulation disorders and disseminated intravascular coagulation (DIC).
• Adverse Effects (Blood Products):
  • Transfusion reactions (blood type and cross-match)
  • Transmission of pathogens (hepatitis B, C, HIV)

Client Care

• Crystalloids: Administer slowly, monitor for fluid overload and possible heart failure, monitor for transfusion reactions.
• Colloids: Administer slowly, monitor for fluid overload and possible heart failure, monitor for transfusion reactions.
  • Blood products monitor for transfusion reactions.

Advantages/Disadvantages of Crystalloids and Colloids

• Crystalloids: Few side effects, low cost, widely available, short duration of action, may cause edema
• Colloids: Longer duration of action, less fluid required to correct hypovolemia, higher cost, may cause volume overload, may interfere with clotting, risk of anaphylactic reactions.

Plasma Electrolytes

• Principal ECF electrolytes: Sodium (Na+), Chloride (Cl-)
• Principal ICF electrolyte: Potassium (K+)
• Others: Calcium, magnesium, phosphorus

Plasma Potassium

• Functions: Skeletal muscle contraction, nerve impulse transmission, regulates heartbeat, acid-base balance, etc.
• Abundance: 95% of body's potassium is intracellular
• Normal ECF: 3.5 to 5 mmol/L
• Sources: Foods (fruit, fish, vegetables, etc)
• Excretion: Kidney function
• Hypokalemia: Deficiency (<3.5 mmol/L) Causes: diuretics, vomiting, diarrhea, malabsorption, etc. Symptoms: muscle weakness, lethargy, cardiac dysrhythmias, irregular pulse, paralytic ileus.
• Hyperkalemia: Excess (>5 mmol/L) Causes: K+ supplements, ACE inhibitors, renal failure, excessive K+ loss from cells, or K+-sparing diuretics. Symptoms: irregular heartbeat, cardiac arrest, muscle weakness, paralysis, paresthesia.
• Treatment: Oral or IV administration (IV given slowly, never in a bolus or as an undiluted solution)

Plasma Sodium

• Functions: Controls water distribution, fluid and electrolyte balance, osmotic pressure of body fluids, acid-base balance
• Normal concentration: 135 to 145 mmol/L
• Sources: Dietary intake of sodium chloride (salt, fish, meats, etc)
• Hyponatremia: Deficiency (<135 mmol/L) Causes include hypokalemia causes, prolonged diarrhea, vomiting, renal issues. Symptoms: lethargy, stomach cramps, hypotension, vomiting, diarrhea, seizures
• Hypernatremia: Excess (>145 mmol/L) Causes: kidney malfunction, inadequate water consumption, and dehydration. Symptoms: edema, hypertension, flushing, dry/sticky mucous membranes, elevated temp, decreased urine output.
• Treatment: Mild cases are treated with oral sodium chloride and/or fluid restriction. Severe cases need IV normal saline or lactated Ringer's.

Client Care (General)

• Monitoring:
  • Serum electrolyte levels during therapy
  • Infusion rate and appearance of fluid/solution
  • Infusion site
  • Infiltration and other IV complications
• Therapeutic response:
  • Monitoring normal lab values (RBC, WBC, Hgb, Hct, electrolytes)
  • Improved fluid volume status
  • Increased tolerance of activities.