Crystalloids: Mechanism and Indications

• Crystalloids supply water and sodium via intravenous injection to maintain osmotic gradient, classified by sodium concentration.
• Normal saline (0.9% NaCl) and Lactated Ringer's are commonly used crystalloids.

Mechanism of Action and Drug Effects

• Crystalloid solutions contain fluids and electrolytes, not proteins.
• Large quantities of crystalloids can decrease colloid oncotic pressure because of dilution.
• Crystalloids distribute faster into interstitial and intracellular compartments than colloids, so are better for treating dehydration, not just expanding plasma volume.

Indications

• Crystalloids are used as maintenance fluids
• Crystalloids compensate for insensible fluid losses and manage fluid/electrolyte imbalances, promoting urinary flow.
• Crystalloids are less expensive than colloids/blood, with no risk of viral transmission, anaphylaxis, or altered coagulation profiles.
• Use crystalloids or colloids for acute liver failure, burns, cardiopulmonary bypass, hypoproteinemia, renal dialysis, and shock depending on condition severity.
• Crystalloid contraindications include drug allergy, hypervolemia, or severe electrolyte disturbance (depending on type).

Adverse Effects

• Crystalloids can cause edema by leaking into tissues/cells, diluting plasma proteins and reducing colloid oncotic pressure.
• Large volumes of crystalloids are needed, and prolonged infusions may cause fluid overload, effects are short-lived.

Interactions

• Interactions with crystalloid solutions are rare.

Dosage

• Crystalloid dosage depends on the specific condition being treated.

Sodium Chloride

• Sodium chloride concentrations include isotonic (0.9%), hypotonic (0.45%, 0.25%), and hypertonic (3%, 5%).
• Normal saline (0.9% NaCl) is isotonic and contains 154 mEq of sodium per liter.
• Hypertonic saline (3%, 5%) is a high-alert solution and is contraindicated in increased, normal, or slightly decreased sodium concentrations
• Administer sodium chloride safely during pregnancy, but avoid in hypernatremia/hyperchloremia.
• Rapid sodium correction with hypertonic saline can cause fatal osmotic demyelination syndrome.
• Very low hypotonic saline (0.25% NaCl) use is not recommended as it causes hemolysis of RBCs.
• 5000-6000 mL of 0.9% NaCl increases intravascular volume by 1000 mL.
• Sodium chloride is considered a high-risk drug due to deaths occurring when infused inappropriately.

Colloids

• Colloids increase colloid oncotic pressure, moving fluid from interstitial to plasma compartment.
• Albumin, globulin, and fibrinogen should be within 7.4 g/dL but if below 5.3 g/dL colloids reverse by increasing oncotic pressure.
• Albumin, dextran, and hetastarch are commonly used colloids, and colloid oncotic pressure decreases with age/malnutrition.

Mechanism of Action and Drug Effects

• Colloids cannot pass into extravascular space, resulting in increased concentration of solid particles inside blood vessels compared to outside
• Because of this, fluid moves from extravascular space into blood vessels to make blood isotonic which increases blood volume, and they are termed "plasma expanders."
• They maintain colloid oncotic pressure for hours, and consist of proteins, carbs, fats, and animal collagen, with small particles to promote diuresis and large for plasma volume.
• Albumin is the exception, containing same-sized particles.

Indications

• Colloids treat shock, burns, and plasma volume expansion.
• Colloids maintain plasma volume longer than crystalloids but are more expensive and promote bleeding - Crystalloids are better for emergency short-term plasma volume expansion.
• Colloids are less likely than crystalloids to cause edema.

Adverse Effects

• Colloids lack oxygen-carrying ability/clotting factors, leading to impaired coagulation and bleeding if used.

Albumin

• Albumin is a natural protein produced by liver, responsible for 70% of colloid oncotic pressure.
• Human albumin from pooled blood is pasteurized but limited/expensive, derived from human donors.
• Albumin is contraindicated in hypersensitivity, heart failure, severe anemia, or renal insufficiency, available in 5% and 25% concentrations (pregnancy category C).

Blood Products

• Blood products are biologic drugs that increase plasma volume.
• RBC-containing products enhance tissue oxygenation, however, they are more expensive, and less available because they require human donors.
• Blood products are indicated when 25%+ blood volume is lost.

Mechanism of Action and Drug Effects

• Blood products increase colloid oncotic pressure to the same manner as colloids, and hypertonic crystalloids by pulling fluid from the extravascular space to the intravascular space, and considered "plasma expanders".
• RBC products carry oxygen and maintain colloid oncotic pressure for hours/days, and have all benefits/hazards of human blood.

Blood Product Indications

• Cryoprecipitate and PPF manages acute bleeding (50%+ slow loss or 20% rapid).
• FFP increases clotting factor levels.
• PRBCs increase oxygen-carrying capacity in anemia, hemoglobin deficits, and losses of up to 25% total blood.
• Whole blood is similar to PRBCs but more beneficial in extreme loss of blood volume because it has plasma/proteins.
• Blood must not be administered with any solution other than normal saline.

Interactions

• As with crystalloids and colloids, blood products are very similar if not identical to normal physiologic substances; therefore they are involved in very few interactions.
• Calcium and aspirin, may interact with the blood components.
• Blood products can be administered with normal saline ONLY.

Packed Red Blood Cells

• PRBCs are from centrifuged whole blood with RBCs separated.
• PRBCs have better oxygen-carrying capacity than other products but are high cost, limited shelf life, transmit viruses, trigger allergies/bleeding.

Fresh Frozen Plasma

• FFP is from centrifuged whole blood with cellular elements removed for coagulation disorders.
• FFP has similar plasma-expanding capability to dextran, and less than hetastarch, but transmits pathogens.

Potassium

• Potassium is abundant electrolyte (150 mEq/L) inside cells, with most (95%) intracellular.
• Plasma potassium ranges from 3.5-5 mEq/L, and changes can harm neuromuscular/cardiovascular systems.
• Potassium comes from fruits, juices, vegetables, fish, meats, averaging 35-100 mEq daily and is removed by kidneys.

Hypokalemia

• Hypokalemia is potassium deficiency (below 3.5 mEq/L) from decreased intake, shifting of potassium into cells, increased renal excretion, diarrhea, vomiting, or tube drainage.
• Diuretics, steroids, beta blockers, and aminoglycosides can cause hypokalemia.
• Early hypokalemia includes hypotension, lethargy, confusion, muscle weakness, nausea, while late symptoms include cardiac irregularities, neuropathies, paralytic ileus.
• Low serum potassium increases digoxin toxicity, potentially causing ventricular dysrhythmias.
• Treatment involves identifying/addressing cause and restoring potassium levels (>3.5 mEq/L).
• Mild hypokalemia can be addressed with potassium-rich foods, while significant cases require oral/parenteral supplements.

Hyperkalemia

• Hyperkalemia is high potassium levels (above 5.5 mEq/L) from increased intake, reduced renal excretion, or redistribution after burns/rhabdomyolysis.
• Symptoms include fatigue, weakness, paresthesia, palpitations, paralysis, along with heart-related clinical signs.
• Severe hyperkalemia (>7 mEq/L) can precipitate ventricular fibrillation and cardiac arrest.

Mechanism of Action and Drug Effects

• Potassium is involved in muscle contraction, nerve impulses, heartbeats, acid-base balance, isotonicity, cell characteristics, enzymatic reactions, gastric secretion, renal function, tissue synthesis, and carbohydrate metabolism.

Contraindications

• Contraindications include allergy, hyperkalemia, renal disease, dehydration, untreated Addison disease, hemolytic disease, and tissue breakdown.
• Intravenous potassium can be given no faster than 10 mEq/hr in unmonitored patients.

Interactions

• Potassium-sparing diuretics and ACE inhibitors can produce a hyperkalemic state if used concurrently.
• Sodium Zirconium Cyclosilicate (Lokelma) treats hyperkalemia orally but has delayed onset and is unsuitable for emergencies.

Nursing Process

• Verify medication order for accuracy/safety, assess patient needs, and do not substitute.
• Assess for infusion of fluids and/or electrolytes on the solution to be infused, infusion equipment, infusion rate of the solution, concentration of the parenteral solution, and compatibilities as well as the mathematical calculations and laboratory values (e.g., serum sodium, chloride, and potassium levels).
• Note isotonic solutions augment extracellular volume in blood loss/vomiting, and isotonic NaCl dilutes blood transfusions.
• Hydrating/hypotonic solutions given parenterally prevent/treat dehydration, moving fluid from vein to tissues/cells.
• Hypertonic solutions move fluids from ISF to veins, only inside hospital due to risks.
• Review medications/solutions prescribed, focusing on GI, renal, cardiac, and hepatic diseases, medication history, dietary habits, and fluid/electrolyte status.
• Assess skin turgor, mucous membranes, urinary specific gravity, vital signs, intake, and output, documenting skin rebound elasticity.
• Symptoms of hypokalemia include hypotension, lethargy, confusion, nausea, and muscle weakness. Late symptoms include cardiac irregularities, neuropathies, and paralytic ileus.
• Avoid potassium w/ ACE inhibitors/potassium-sparing diuretics. Potassium-related contraindications include renal disease, untreated Addison disease, severe tissue trauma, and dehydration.
• Assess GI tract before oral potassium, because oral potassium supplements may be ulcerogenic.
• Hypertonic solutions are rarely used because of the risk for cellular dehydration and vascular volume overload and are associated with phlebitis.

Implementation

• Intravenous potassium diluted because undiluted potassium can cause cardiac arrest.
• Double-check the order, amount of diluent, and concentration of potassium to diluent.
• Give diluted potassium when there is adequate urine output of at least 0.5 mL/kg/min
• Never intravenous push or bolus potassium replacement!
• Severe hyperkalemia treatment has intravenous sodium bicarbonate, calcium gluconate/chloride, or dextrose with insulin, shifting intracellular potassium.
• Note rapid correction of acute, severe hyponatremia causes water movement into the brain and cerebral edema.
• Adaptations make brain vulnerable if chronic hyponatremia is corrected too rapidly, osmotic demyelination syndrome may occur.
• Hypernatremia is treated with fluid intake/diet, intravenous dextrose in water dilutes sodium and enhances urine output, and rapid correction may cause brain edema.
• The correction of hyponatremia and hypernatremia must be carefully treated by a physician experienced in diagnosis and treatment of electrolyte imbalances.

Evaluation

• Monitor improvement of lab values and fluid volume in response to correct therapy
• Therapeutic effects include improved energy levels and tolerance of activities of daily living as well as evaluation of the patient’s cardiac, respiratory, musculoskeletal, and gastrointestinal functioning.
• Assess therapeutic/adverse effects, including volume overload (distended neck veins, shortness of breath) related to albumin therapy

Patient-Centered Care: Patient Teaching

• Teach about hyponatremia (lethargy, hypotension, stomach cramps, vomiting, diarrhea, seizures) and hypernatremia (edema, hypertension, flushed skin, dry mucous membranes, thirst, temperature, urination changes); both are related to fluid volume status.
• Teach early hypokalemia (hypotension, lethargy, confusion, nausea, muscle weakness) and hyperkalemia (muscle weakness, paresthesia, paralysis, cardiac rhythm abnormalities).
• Advise to mix potassium chloride per instructions, take with food, and report GI upset, and potential drug interactions.
• Educate on sustained-release potassium, difficulties swallowing, or adverse effects like vomiting, abdominal pain, or black stools. Also, educate on foods high in potassium.
• Teach to take extended-release potassium in full, with meals/water, and follow instructions to manage difficulty swallowing or using effervescent tablets.
• Emphasize salt substitutes contain potassium and highlight irritation at IV site if applicable, as well as safe salt tablet use.

Key Points

• TBW divides into intracellular/extracellular (plasma or between tissues/organs).
• Colloids are protein particles that cannot leak out with high risk for hypervolemia/heart failure.
• Blood products carry oxygen because they contain hemoglobin, indicated in 25% of blood loss.
• Monitor intake/output, weights, heart/breath sounds, lab values, pulse oximeter readings should improve.
• Dehydration is hypotonic (salt loss), hypertonic (fever/perspiration), or isotonic (diarrhea/vomiting) and requires assessing intake/output, skin turgor, urine specific gravity, and blood levels of potassium, sodium, and chloride.
• Administer intravenously hypertonic solutions very cautiously because of overzealous replacement. This leads to hypervolemia.
• Hyponatremia leads to lethargy, hypotension, stomach cramps, vomiting, diarrhea, and seizures, while hypernatremia leads to symptoms of water retention.
• Monitor vital signs when administering blood products and because solution of D5W results in hemolysis of red blood cells and blood products must be given only with NS (0.9% NaCl).