Nursing Fundamentals: Fluids & Electrolytes, Tissue Integrity, and Acid-Base Balance

Flashcards testing core terminology and concepts for Fluid & Electrolytes, Pressure Injury Staging, Wound Healing, and Acid-Base Balance.

First Spacing

The normal distribution of fluids between the intracellular and extracellular compartments.

Second Spacing

An abnormal accumulation of fluid in the interstitial compartment, clinically recognized as edema.

Third Spacing

The movement of fluid into a non-contributory space (such as in ascites or severe burns) where it is unavailable to both extracellular and intracellular compartments.

Osmolarity

The concentration of solute particles expressed as the number of solutes per liter of fluid.

Osmolality

The concentration of solute particles expressed as the number of solutes per kilogram of fluid, commonly used to describe solute concentration within the body.

Diffusion

A form of passive transport in which molecules or particles spontaneously spread from an area of higher concentration to an area of lower concentration.

Osmosis

A passive movement of a solvent across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Active Transport

The movement of molecules across a semipermeable membrane against a concentration gradient (from lower to higher concentration) using energy released from an ATP molecule.

Sodium ($Na^+$)

The major extracellular fluid cation with a normal range of $135\text{--}145\,mEq/L$, regulated primarily by the kidneys and aldosterone to control fluid volume and osmolality.

Hyponatremia

A serum sodium level below $135\,mEq/L$ that causes water to be drawn into cells from the ECF, resulting in cellular swelling and potential cerebral edema if severe.

Hypernatremia

A serum sodium level exceeding $145\,mEq/L$ that pulls water out of cells into the ECF, resulting in cellular dehydration and potential neurological impairment.

Potassium ($K^+$)

The primary intracellular cation with a normal range of $3.5\text{--}5.0\,mEq/L$, essential for cellular metabolism, acid-base balance, and cardiac electrical conduction.

Hypokalemia ECG Changes

Electrocardiogram alterations caused by low potassium levels, characterized by flattened T-waves, ST-segment depression, and the appearance of U-waves.

Hyperkalemia ECG Changes

Electrocardiogram alterations caused by elevated potassium levels, characterized by tall tented T-waves, wide QRS complexes, prolonged PR intervals, and ST-segment depression.

Chloride ($Cl^-$)

An extracellular anion with a normal serum range of $95\text{--}105\,mEq/L$ that plays a major role in fluid balance, osmolality, and acid-base status.

Calcium ($Ca^{2+}$)

An essential cation ($8.5\text{--}10\,mg/dL$) whose ionized form regulates neuromuscular activity, cell membrane stability, and blood coagulation.

Trousseau's Sign

A sign of latent tetany and hypocalcemia characterized by carpal spasm induced by inflating a blood pressure cuff above systolic pressure on the arm.

Chvostek's Sign

A clinical indicator of hypocalcemia demonstrated by twitching of the facial muscles in response to tapping over the facial nerve anterior to the ear.

Magnesium ($Mg^{2+}$)

An intracellular electrolyte ($1.6\text{--}2.6\,mg/dL$) vital for carbohydrate and protein metabolism, enzyme activation, and neuromuscular transmission.

Phosphate ($PO_4^{3-}$)

An electrolyte ($2.5\text{--}4.5\,mg/dL$) that supports ATP production, RBC function, tissue oxygen delivery, nerve impulse conduction, and muscle contraction.

Isotonic IV Solution

An intravenous solution (such as $0.9\%$ Normal Saline or Lactated Ringer's) that matches body fluid osmolality, expanding intravascular volume without fluid movement between compartments.

Hypotonic IV Solution

An intravenous solution (such as $0.45\%$ Normal Saline) with lower osmolality than plasma, causing fluid to shift out of vessels into body cells.

Hypertonic IV Solution

An intravenous solution (such as $3\%$ Normal Saline or $D_5NS$) with higher osmolality than plasma, drawing fluid out of cells and into the vascular space.

Hetastarch

An isotonic colloid solution administered to increase oncotic pressure and expand fluid volume in conditions like hypovolemic shock, trauma, or burns.

Pressure Injury

Localized damage to the skin and/or underlying tissue, typically over a bony prominence, resulting from pressure or pressure combined with shear.

Stage 1 Pressure Injury

Intact skin presenting with localized non-blanchable erythema, typically over a bony prominence, which may be accompanied by pain, temperature changes, or alteration in firmness.

Stage 2 Pressure Injury

Partial-thickness skin loss with exposed dermis featuring a viable, pink/red, moist wound bed or an intact/ruptured serum-filled blister without slough, eschar, or visible adipose tissue.

Stage 3 Pressure Injury

Full-thickness skin loss exposing subcutaneous fat tissue, where fascia, muscle, tendon, cartilage, and bone are not exposed or directly palpable.

Stage 4 Pressure Injury

Full-thickness skin and tissue loss with directly visible or palpable fascia, muscle, tendon, cartilage, or bone, often presenting with slough, eschar, undermining, or tunneling.

Unstageable Pressure Injury

Full-thickness tissue loss in which the actual depth and base of the wound are completely obscured by slough or eschar.

Deep Tissue Pressure Injury (DTPI)

Persistent, non-blanchable deep red, maroon, or purple discoloration (or blood-filled blister) stemming from pressure and shear damage originating at the bone-muscle interface.

Braden Scale

A standardized risk assessment tool that measures sensory perception, moisture, activity, mobility, nutrition, and friction/shear to predict pressure ulcer risk.

Hemostasis Phase

The initial wound healing phase occurring immediately post-injury, characterized by local vasoconstriction, platelet aggregation, and clot formation.

Inflammatory Phase

The second phase of wound healing in which neutrophils and macrophages clean debris and bacteria from the wound bed, often producing localized redness, heat, and swelling.

Proliferative Phase

The wound healing phase characterized by fibroblast activity, collagen production, angiogenesis, formation of granulation tissue, epithelialization, and wound contraction.

Maturation Phase

The final stage of wound healing starting at $2\text{--}3\text{ weeks}$ post-injury, where collagen reorganizes and scar tissue gains tensile strength over months to years.

Primary Intention Healing

Wound closure mechanism where clean surgical or traumatic edges are approximated with sutures, staples, or glue, leading to minimal tissue loss and rapid healing.

Secondary Intention Healing

Wound healing process where significant tissue loss forces the wound to remain open and heal from the bottom up via granulation tissue formation.

Tertiary Intention Healing

Delayed primary closure in which a contaminated or infected wound is left open initially to reduce infection risk before being surgically closed.

Acid

A chemical compound that releases hydrogen ions ($H^+$) when dissolved in a solution.

Base

A chemical compound that accepts hydrogen ions ($H^+$) when dissolved in a solution.

pH

The logarithmic measurement of hydrogen ion concentration in a solution, where an increase in $H^+$ decreases pH and a decrease in $H^+$ increases pH.

Acidemia

An arterial blood condition defined specifically by a serum pH value below $7.35$.

Alkalemia

An arterial blood condition defined specifically by a serum pH value above $7.45$.

Volatile Acid

An acid capable of being eliminated from the body as a gas, represented solely in the body by carbonic acid ($H_2CO_3$).

Bicarbonate-to-Carbonic Acid Ratio

The physiological proportion of bicarbonate ($HCO_3^-$) to carbonic acid ($H_2CO_3$), normally maintained at $20:1$ to keep blood pH within normal parameters.

Buffer Systems

Chemical mechanisms that prevent major changes in pH by rapidly binding to hydrogen ions in acidic conditions or releasing hydrogen ions in alkaline conditions.

ROME Mnemonic

An acronym for interpreting ABGs where Respiratory indicates Opposite movement ($pH \uparrow PaCO_2 \downarrow$ or $pH \downarrow PaCO_2 \uparrow$) and Metabolic indicates Equal movement ($pH \uparrow HCO_3^- \uparrow$ or $pH \downarrow HCO_3^- \downarrow$).

Respiratory Acidosis

An acid-base imbalance marked by $pH < 7.35$ and $PaCO_2 > 45\,mmHg$, resulting from hypoventilation and pulmonary retention of carbon dioxide.

Respiratory Alkalosis

An acid-base imbalance marked by $pH > 7.45$ and $PaCO_2 < 35\,mmHg$, caused by hyperventilation blowing off carbon dioxide faster than it is produced.

Metabolic Acidosis

An acid-base imbalance marked by $pH < 7.35$ and $HCO_3^- < 22\,mEq/L$, caused by increased acid production (e.g., DKA, lactic acidosis) or excessive bicarbonate loss.

Metabolic Alkalosis

An acid-base imbalance marked by $pH > 7.45$ and $HCO_3^- > 26\,mEq/L$, caused by significant hydrogen ion loss (e.g., severe vomiting, gastric suctioning) or bicarbonate gain.