Fluid and Electrolyte Imbalances Flashcards
Tell me about normal fluid distribution
Total Body Water (TBW)
Total body water constitutes about 60% of body weight in a healthy adult, but this percentage can vary based on age, sex, and body composition. TBW is divided into two main compartments:
Intracellular Fluid (ICF): Approximately 2/3 of TBW, this is the fluid within cells. The ICF is the largest fluid compartment in the body.
Extracellular Fluid (ECF): Makes up about 1/3 of TBW and is subdivided into:
Interstitial Fluid: Fluid that bathes the cells and lies between cells and tissues.
Plasma: The liquid component of blood.
Transcellular Fluids: Include specialized fluids such as cerebrospinal fluid, synovial fluid in joints, aqueous humor in the eyes, and pleural, peritoneal, and pericardial fluids.
Tell me about normal electrolyte distribution
Electrolyte Distribution
Electrolytes are minerals that carry an electric charge when dissolved in body fluids. Important electrolytes include sodium, potassium, chloride, calcium, magnesium, phosphate, and bicarbonate. Their distribution and roles include:
Sodium (Na+)
Predominantly found in the ECF and is the principal cation (positively charged ion) in this compartment.
Critical for maintaining osmotic balance and fluid distribution between compartments.
Influences blood pressure and is integral to nerve and muscle function.
Potassium (K+)
- The main cation in the ICF.
- Essential for normal cell function, including nerve impulse transmission and muscle contraction.
- Plays a significant role in heart function.
Chloride (Cl-)
- The most abundant anion (negatively charged ion) in the ECF.
- Often follows sodium to maintain electrical neutrality and participates in maintaining osmotic pressure.
Calcium (Ca2+)
- Found in both the ECF and ICF, but most of the body’s calcium is stored in bones and teeth.
- Important for muscle contraction, nerve function, blood clotting, and bone strength.
Magnesium (Mg2+)
- Primarily an intracellular cation.
- Important for many biochemical processes, including energy production, DNA synthesis, and muscle relaxation.
Phosphate (HPO4^2-)
- Predominantly an intracellular anion, a small amount is present in the ECF.
- Important for energy storage and release as part of ATP, bone mineralization, and buffering systems.
Bicarbonate (HCO3-)
- Primarily found in the ECF.
- Crucial for maintaining the body’s pH balance through its role in the buffer systems.
Tell me about what Oedema is, the causes of oedema and the clinical manifestations of oedema.
Oedema is the accumulation of excess fluid in the interstitial spaces, which are the areas surrounding the cells of tissues. It can occur locally, affecting specific parts of the body, or it can be more generalized.
Causes of Oedema:
Increased Hydrostatic Pressure: Elevated blood pressure or volume can push fluid out of the capillaries and into the interstitial spaces. This often happens in conditions like heart failure, deep vein thrombosis, or prolonged standing.
Reduced Oncotic Pressure: Lower levels of plasma proteins, particularly albumin, reduce the ability of the bloodstream to pull water back from the tissue spaces. This can result from malnutrition, liver disease, or kidney disease.
Capillary Permeability: Inflammation or injury can make the capillary walls more permeable, allowing fluid and proteins to leak into the tissues. This is typical in burns, infections, or allergic reactions.
Lymphatic Obstruction:When lymph channels are blocked due to infection, tumors, or surgical removal of lymph nodes, fluid cannot drain properly, leading to edema.
Clinical Manifestations: Swelling, puffiness, stretched or shiny skin, and when pressed, the skin may hold the indent for a few seconds (pitting edema).
Tell me about fluid spacing
Fluid spacing refers to the distribution of body water in the different fluid compartments. There are three terms used to describe fluid spacing:
First Spacing: This is the normal distribution of fluid in both the intracellular and extracellular compartments. It represents normal body fluid distribution.
Second Spacing: Refers to an abnormal accumulation of interstitial fluid (edema). As discussed, it can result from various pathophysiological processes.
Third Spacing: Occurs when fluid accumulates in parts of the body where it does not easily exchange with the rest of the ECF. This typically happens in body spaces such as the peritoneal cavity (ascites), pleural cavity (pleural effusion), or in severe cases, pericardial sac (pericardial effusion) and bowel lumen. Third spacing can be particularly problematic because this fluid is effectively “lost” to circulation, meaning it doesn’t contribute to blood volume and can lead to hypovolemia and shock.
Implications of oedema and abnormal fluid spacing
Both edema and abnormal fluid spacing can have significant clinical implications:
Edema can impair tissue oxygenation and nutrient delivery, potentially leading to delayed wound healing, increased risk of infection, and pressure injuries.
Abnormal fluid spacing (especially third spacing) can lead to complications like hypovolemia, decreased cardiac output, and organ dysfunction.
Management of these conditions often involves treating the underlying cause, such as improving cardiac function, replacing albumin, managing inflammation, or relieving lymphatic obstruction. Additionally, diuretics may be used to increase fluid excretion and salt restriction may be recommended to decrease fluid retention.
What is hypovolemic shock?
Hypovolemic shock is a serious condition that occurs when the body loses more than 20% of its blood or fluid supply. This severe fluid loss makes it impossible for the heart to pump a sufficient amount of blood to the body, leading to multiple organ failure if not promptly treated. This condition can stem from various causes, including external bleeding from trauma, internal bleeding (such as from ruptured aneurysms or gastrointestinal bleeding), or severe fluid loss from other causes like severe dehydration or burns.
What is the Pathophysiology of hypovolemic shock?
The primary issue in hypovolemic shock is the reduction in intravascular volume, which decreases the venous return to the heart, thereby diminishing the stroke volume and cardiac output. With less blood circulating back to the heart, the heart pumps less blood out, which reduces blood pressure and limits the blood flow to peripheral tissues. To compensate, the body initiates various mechanisms:
Vasoconstriction: The blood vessels constrict to raise blood pressure and maintain blood flow to vital organs.
Increased Heart Rate: The heart beats faster to increase cardiac output.
Redistribution of Blood Flow: Blood flow is redirected away from the skin, muscles, and gastrointestinal tract to prioritize vital organs like the brain and heart.
What are the clinical manifestations of hypovolemic shock?
Symptoms and signs of hypovolemic shock vary based on the severity of the fluid loss but generally include:
Low Blood Pressure: One of the earliest signs of shock.
Rapid, Weak Pulse: Due to decreased blood flow combined with tachycardia.
Cold, Clammy Skin: As blood flow is redirected away from the skin towards vital organs.
Rapid Breathing: The body’s attempt to increase oxygen levels.
Decreased Urine Output: Due to reduced blood flow to the kidneys.
Altered Mental State: Such as anxiety, confusion, or lethargy, due to decreased blood flow to the brain.
Weakness or Dizziness: Especially on standing, due to low blood pressure.
How is hypovolemic shock treated?
The treatment of hypovolemic shock is aimed at rapidly restoring the volume of fluid in the body to prevent organ damage:
Fluid Replacement: This can be with crystalloids (e.g., saline solution), colloids (e.g., albumin), and blood products, depending on the cause and severity of the fluid loss.
Control of Bleeding: Immediate measures to stop any ongoing bleeding.
Oxygen and Airway Support:To ensure adequate oxygenation.
Medications: Such as vasopressors, may be used to increase vascular tone and improve cardiac output if fluids alone do not stabilize the patient.
Monitoring and Support: Continuous monitoring in an intensive care setting is critical for assessing the response to treatment and recovery.
Prompt and effective treatment is crucial to manage hypovolemic shock, as delays can lead to severe complications and increase the risk of death.
What are electrolytes
Electrolytes are minerals in your body that have an electric charge. They are found in your blood, urine, tissues, and other body fluids. Electrolytes are important because they help balance the amount of water in your body, balance your body’s acid/base (pH) level, move nutrients into your cells, move wastes out of your cells, ensure that your nerves, muscles, the heart, and the brain work the way they should.
Tell me about Isotonic alterations
When the concentration of solutes (mainly electrolytes) outside the cell is equal to that inside the cell, leading to no net movement of water into or out of the cells. Isotonic fluid loss or gain does not cause cells to shrink or swell but decreases or increases overall fluid volume. Common in situations of blood loss or normal saline infusion.
Isotonic dehydration doesn’t disrupt the balance of electrolytes but reduces overall fluid volume, impacting blood pressure and circulation.
Tell me about hypotonic alterations
Occur when the concentration of solutes in the extracellular fluid (ECF) is lower than that inside the cells (intracellular fluid, ICF). This causes water to move into the cells, causing them to swell. A common cause is overly rapid rehydration with pure water after dehydration, diluting extracellular sodium.
Hypotonic hydration (water intoxication) can lead to cellular swelling, potentially causing neurological symptoms due to brain cells swelling.
Tell me about hypertonic alterations
Arise when the concentration of solutes in the ECF is higher than inside the cells. Water moves out of the cells into the ECF, causing the cells to shrink. This can be caused by excessive sodium intake or dehydration where water loss exceeds solute loss.
Hypertonic dehydration can lead to neurological impairments and intense thirst due to cellular shrinkage.
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What is hyponatremia and what are its symptoms?
Definition: Hyponatremia occurs when there is a low sodium level in the blood (<135 mEq/L).
Symptoms: Confusion, headaches, seizures, fatigue, and muscle spasms or cramps.
Management: Treat underlying cause, restrict fluid intake if dilutional, administer sodium if severe.
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What is hypernatremia and what are its symptoms?
Definition: Hypernatremia is a high sodium level in the blood (>145 mEq/L).
Symptoms: Thirst, agitation, restlessness, irritability, muscle twitching.
Management: Gradual lowering of sodium with IV hypotonic fluids or oral water intake.
