Unit 3 - Fluids and Electrolytes & Acid-Base Imbalances

100 vocabulary flashcards covering fluid and electrolyte balance, imbalances, and acid-base chemistry based on lecture notes.

Extracellular fluids (ECF)

Fluids located outside of the cells.

Interstitial fluids

Fluids in the space between cells and in tissues.

Plasma

The liquid portion of blood located in the intravascular space.

Intracellular fluids (ICF)

Fluids located inside the cells.

Normal ECF distribution

Approximately $1/3$ of total body water.

Normal ICF distribution

Approximately $2/3$ of total body water.

Filtration

The movement of fluid through a cell or blood vessel membrane because of differences in water volume pressing against confining walls.

Hydrostatic Pressure

The "water pushing pressure" that forces water outward from a confined space through a membrane.

Diffusion

The free movement of solute particles across a permeable membrane from an area of higher to lower concentration.

Facilitated diffusion

Movement of a solute, such as glucose, down a concentration gradient using a membrane protein like insulin to increase permeability.

Osmosis

The movement of water through selectively permeable membranes to achieve equilibrium of particle concentration.

Edema

Tissue swelling caused by excess filtration of fluid from capillaries and into the interstitial spaces.

Right-sided heart failure edema

Swelling caused by weakened heart pumping that leads to increased venous and capillary hydrostatic pressure.

Thirst mechanism

A homeostatic process where shrinking cells in the brain's thirst center trigger the urge to drink when ECF volume decreases.

Insensible fluid loss

Water loss through the skin, lungs, and stool which the body has no mechanism to control.

Normal insensible fluid loss

Approximately $500-1000\,mL/day$.

Obligatory urine output

The minimum amount of urine needed to excrete toxic waste products, usually $400-600\,mL/day$.

Antidiuretic hormone (ADH)

Also known as vasopressin, produced in the hypothalamus and stored in the posterior pituitary to increase water reabsorption in the kidneys.

Aldosterone

The "water and sodium saving hormone" secreted by the adrenal cortex that increases blood volume and osmolarity.

Natriuretic peptides (NPs)

Hormones secreted by heart cells in response to increased blood volume that increase urination to lower blood pressure.

Renin-Angiotensin-Aldosterone System (RAAS)

A pathway triggered by low blood pressure, sodium, or oxygen that results in vasoconstriction and increased blood volume.

Renin

A substance secreted by the kidneys that is required to start the RAAS pathway.

ACE inhibitors

Pharmacological agents ending in "-pril" that disrupt the RAAS pathway by reducing the production of angiotensin II.

Angiotensin receptor blockers (ARBs)

Pharmacological agents ending in "-sartan" that block receptors to reduce blood pressure.

Dehydration

A fluid volume deficit where fluid intake or retention does not meet the body's needs.

Skin turgor assessment (older adults)

Checking for dehydration by pinching skin on the chest (sternum) or forehead rather than the hand.

Hemoglobin and Hematocrit (in dehydration)

Lab values that typically increase due to hemoconcentration when a patient is dehydrated.

BUN (in dehydration)

A laboratory value that increases when a patient has a fluid volume deficit.

Fluid weight conversion ($1\,L$)

$1\,L$ of water is equal to $2.2\,lbs$ ($1\,kg$).

Fluid weight conversion ($1\,lb$)

A weight change of $1\,lb$ is equal to approximately $500\,mL$ of fluid.

Hypervolemia

An excess of body fluid in the intravascular space, also called fluid overload.

Dependent edema

Pitting edema that occurs in the areas of the body influenced by gravity, often a sign of fluid overload.

Loop diuretics

Drugs like furosemide used to increase water and sodium excretion in patients with fluid overload.

Normal Sodium range

$135-145\,mmol/L$.

Hyponatremia

A sodium deficiency often caused by prolonged diuretic use, resulting in confusion and muscle weakness.

Hypernatremia

Elevated sodium levels showing cellular dehydration symptoms like agitation, manic behavior, and seizures.

Normal Potassium range

$3.5-5.0\,mEq/L$.

Hypokalemia

Low blood potassium levels that can cause life-threatening dysrhythmias and respiratory muscle weakness.

ST depression

An ECG change commonly associated with hypokalemia.

Spiked T waves

An ECG finding frequently seen in patients with hyperkalemia.

Potassium IV administration rule

Never give IV push, IM, or SQ; never exceed an infusion rate of $20\,mEq/hr$.

Glucose/Insulin infusion

A treatment for hyperkalemia where insulin moves potassium from ECF to ICF and glucose prevents hypoglycemia.

Normal Calcium range

$9.0-10.5\,mg/dL$.

Thyrocalcitonin (TCT)

A hormone secreted by the thyroid gland when excess calcium is present.

Parathyroid hormone

A hormone released when more calcium is needed in the blood.

Hypocalcemia

A condition causing paresthesias, painful muscle spasms, and positive Chvostek/Trousseau signs.

Hypercalcemia

A condition causing increased blood clotting, decreased peristalsis, and severe muscle weakness.

Normal Magnesium range

$1.3-2.1\,mg/dL$.

Hypomagnesemia

A condition often occurring with hypocalcemia, frequently caused by malnutrition or alcohol use disorder.

Hypermagnesemia

A high magnesium level that puts the patient at risk for cardiac arrest; can be reversed with calcium.

Acid-Base Balance

The regulation of free hydrogen ion production and elimination to maintain arterial pH between $7.35$ and $7.45$.

pH

A measure of the body fluids' free hydrogen ion level.

Acidic pH

A value below $7.0$ indicating a high concentration of hydrogen ions.

Alkaline (Basic) pH

A value above $7.0$ indicating a low concentration of hydrogen ions.

Acids

Substances that release hydrogen ions when dissolved in water.

Bases

Substances that bind with hydrogen ions in solutions, such as bicarbonate ($HCO_3$).

Buffers

The first line of defense against pH changes that can act as either an acid or a base.

Most common base in the body

Bicarbonate ($HCO_3$).

Most common acid in the body

Carbonic acid ($H_2CO_3$).

Lactic acid

An acid produced by the incomplete breakdown of glucose under anaerobic conditions (hypoxia, sepsis, shock).

Ketoacids

Acids formed from the incomplete breakdown of fatty acids.

Chemical Acid-Base Control

The use of protein buffers (albumin, globulins, hemoglobin) and chemical buffers (bicarbonate, phosphate) for rapid response.

Respiratory Acid-Base Control

The second line of defense that regulates pH by hyperventilating (losing $CO_2$) or hypoventilating (retaining $CO_2$).

Kidney Acid-Base Control

The most powerful regulator of pH that responds to large fluctuations via bicarbonate reabsorption and ammonia secretion.

Full compensation

A state where the pH is normal because the body's compensation mechanisms are completely effective.

Partial compensation

A state where the pH is still abnormal despite the activation of compensation mechanisms.

$PaO_2$ (Normal Range)

$80-100\,mm\,Hg$.

Bicarbonate ($HCO_3$) (Normal Range)

$21-28\,mEq/L$.

Lactate (Arterial Normal Range)

$3-7\,mg/dL$ ($0.3-0.8\,mmol/L$).

Metabolic Acidosis

A condition characterized by an overproduction of hydrogen ions or a loss of bicarbonate, resulting in pH < $7.35$.

Kussmaul respirations

Deep, rapid breathing seen in metabolic acidosis as the lungs attempt to blow off $CO_2$ and decrease $H^+$.

Respiratory Acidosis

A condition caused by impaired gas exchange or respiratory depression, resulting in $CO_2$ retention and pH < $7.35$.

Combined Metabolic and Respiratory Acidosis

A severe state occurring when conditions like DKA and COPD exist simultaneously.

Acidosis and Potassium relationship

Acidosis causes hyperkalemia as $H^+$ moves into cells and $K^+$ moves out into the ECF.

Acidosis cardiovascular symptom

Initially increased heart rate/output, progressing to bradycardia and hypotension as it worsens.

Cerebral aneurysm/trauma effect

Can compromise brainstem neurons and lead to respiratory acidosis via respiratory depression.

Mucolytics

Drugs used in respiratory acidosis to help clear airway obstructions.

Albuterol

A bronchodilator used to improve ventilation in patients with respiratory acidosis.

Corticosteroids

Anti-inflammatory drugs used to treat underlying causes of respiratory acidosis.

Alkalosis

A condition where arterial blood pH is above $7.45$ due to excess base or acid deficit.

Metabolic Alkalosis

Caused by excessive intake of antacids, prolonged vomiting, or thiazide/loop diuretics.

Respiratory Alkalosis

Caused by excessive loss of $CO_2$ through hyperventilation (anxiety, fear, or improper mechanical ventilation).

Chvostek sign

A positive neurological sign in alkalosis indicating neuroexcitability/tetany.

Trousseau sign

A clinical indicator of hypocalcemia and alkalosis involving carpal spasms when a BP cuff is inflated.

Alkalosis effect on Potassium/Calcium

Alkalosis often occurs alongside hypokalemia and hypocalcemia.

Anesthesia and Opioids

Common pharmacological causes of respiratory depression leading to respiratory acidosis.

Sodium Chloride

Where sodium goes, water follows; a key concept in fluid balance.

Arginine vasopressin deficiency (AVP-D)

A potential cause of dehydration involving hormone deficiency.

Furosemide

A loop diuretic that can cause metabolic alkalosis by increasing hydrogen ion excretion.

Salicylate toxicity

A condition that can cause either respiratory alkalosis (stimulation of respiratory center) or metabolic acidosis.

V-fib and Heart block

Serious cardiac complications associated with hyperkalemia.

Paresthesia

Tingling or numbness often assessed in both electrolyte imbalances and alkalosis.

Peripheral resistance

Reduced in patients taking ACE inhibitors to lower blood pressure.

Hypoxia/Ischemia

Clinical conditions that lead to the overproduction of hydrogen ions and metabolic acidosis.

Ammonia

Secreted by kidneys to combine with $H+$ and form ammonium for excretion in urine.

Weight Gain

The best clinical indicator for fluid retention or overload.

Orthostatic hypotension

A symptom of dehydration characterized by a drop in blood pressure when standing.

Cyanosis

A clinical sign of ineffective breathing seen in respiratory acidosis but not typically in metabolic acidosis.

ABG interpreted as Respiratory

When the pH and $PaCO_2$ arrows go in opposite directions.

ABG interpreted as Metabolic

When the pH and $HCO_3$ arrows go in the same direction.