L5 VT - FEAB

Water content varies with body mass, gender, and age. Lean body mass has a _______ percentage of water, while fat tissue has a _______ percentage of water.

higher; lower

1L of water = ___ lbs (or kg)

1L water = 1kg (2.2lbs)

(T/F) Body weight change is an excellent indicator of overall fluid volume loss or gain

True

Body water over the lifespan __________.

decreases; older adults have lower lean mass -> less body water (45-50%) -> higher risk of fluid imbalances

Intracellular fluid (ICF) makes up _/_ of all body water, while extracellular fluid (ECF) makes up _/_ of all body water

2/3; 1/3

What are the compartments of ECF?

intestitial, intravascular (plasma), transcellular

_/_ of the ECF is in the intravascular space as plasma and _/_ of the ECF is in the interstitial space. The transcellular is only a small fraction of the ECF, containing about ___.

1/4; 3/4; 1L

What are electrolytes?

substances whose molecules dissociate into ions when placed in water

What are cations and examples of it?

Positively charged ions: sodium, potassium, calcium, magnesium

What are anions and examples of it?

Negatively charged ions: bicarbonate, chloride, phosphate

What are concentrations of electrolytes expressed in?

milliequivalent per liter (mEq/L)

What is the most prevalent cation in the ICF?

Potassium (K+); with small amounts of magnesium and sodium

What is the most prevalent anion in the ICF?

Phosphate (PO₄³⁻); with small amounts of protein and bicarbonate

What is the most prevalent cation in the ECF?

Sodium (Na+); with small amounts of potassium, calcium, and magnesium

What is the most prevalent anion in the ECF?

Chloride (Cl-); with small amounts of bicarbonate, sulfate, and phosphate

What are processes that control movement of water and electrolytes in the body?

-Diffusion (simple and facilitated)

-Facilitated diffusion

-Active transport

-Osmosis

-Osmotic pressure

What is simple diffusion?

Movement of solutes from high -> lower concentration

What is facilitated diffusion?

Like diffusion but with a carrier protein (e.g. glucose moving into cells via insulin-dependent transport)

What is active transport?

Uses ATP to move solutes against their concentration gradient (e.g. sodium-potassium pump)

What is osmosis?

Movement of water across a semipermeable membrane from low solute concentration -> high solute concentration to dilute it (e.g. water moving into cells when ECF is hypertonic)

What is osmotic pressure?

The pressure (or "pulling force") created by solutes that draws water across a semipermeable membrane

What is osmolarity?

Number of milliosmoles per liter of solution

What is osmolality?

Number of milliosmoles per kilogram of solvent

*Preferred measurement to evaluate the concentration of plasma, urine, and other bodily fluids

What is hydrostatic pressure?

The force exerted by fluid in a compartment against the walls of the vessel (e.g. blood pressure is generated by heart's contraction). It pushes water out of the vascular space (capillaries) into the interstitial space

What is oncotic pressure (colloid osmotic pressure)?

Osmotic pressure caused by plasma proteins (mainly albumin). It pulls water into the vascular space from the interstitial space

What is edema caused by?

Shifts of plasma to interstitial, elevation of venous hydrostatic pressure, decrease in plasma oncotic pressure, elevation in interstitial oncotic pressure, destruction of lymphatic outflow (decreased removal of interstitial fluid)

How can you increase plasma oncotic pressure?

Administration of colloids, dextran, mannitol, or hypertonic solution to draw fluid from the interstitial space into the plasma

How can you increase tissue hydrostatic pressure?

Elastic compression gradient stockings to shift fluid from tissue back into plasma

What is first spacing?

Normal distribution of body water between compartments (ICF and ECF)

What is second spacing?

Abnormal accumulation of interstitial fluid (e.g. edema)

What is third spacing?

Fluid collects in nonfunctional areas and trapped, becoming difficult-impossible for it to move back into cells or blood vessels (e.g. ascites)

What are different mechanisms that regulates water balance?

-Hypothalamic-pituitary regulation: ADH release

-Kidneys: adjusting urine volume affected by ADH and aldosterone regulating sodium and water

-Adrenals: glucocorticoids and mineralocorticoids

-Stress: increases ADH and aldosterone secretions

-Cardiac: natriuretic peptides suppresses aldosterone and ADH secretion

-GI: oral intake of water, diarrhea and vomiting

What are gerontologic changes in fluid balance?

Structural changes in kidneys decrease ability to conserve water, hormonal changes include a decrease in renin and aldosterone and increase in ADH and ANP, subcutaneous tissue loss leads to increased moisture lost

What is hypovolemia?

ECF volume deficit due to abnormal loss of body fluids, inadequate fluid intake, or fluid shift from plasma to interstitial

What is dehydration

loss of pure water without corresponding loss of sodium

What is hypervolemia?

Excess ECF volume due to excess intake of fluids, abnormal retention of fluids, or fluid shift from interstitial to plasma

What are normal sodium levels?

135-145 mEq/L

What are major roles of sodium?

Maintains ECF volume and concentration, generate and transmit nerve impulses, muscle contractility, acid-base balance

What are manifestations of hypernatremia?

Thrist, changes in mental status ranging from drowsiness, restlessness, confusion, lethargy to seizures and coma; symptoms of fluid volume deficit (tachycardia)

What are treatments for hypernatremia?

Treat underlying cause

-If water deficit: replace fluid orally or IV with isotonic or hypotonic fluids

-If excess in sodium: dilute with sodium-free IV fluids and promote sodium excretion with diuretics

What are manifestations of hyponatremia?

-Mild: headache, irritability, difficulty concentrating

-More severe: confusion, vomiting, seizures, coma

What are treatments for hyponatremia?

-If water excess: fluid restriction, loop diuretics, IV hypertonic saline solution (3% NaCL) FOR severe symptoms

-If abnormal fluid loss: fluid replacement with isotonic sodium-containing solution, encouraging oral intake, withholding diuretics, drugs that block vasopressin/ADH (so less sodium is excreted)

What is the significant caution of administering IV hypertonic saline solutions?

Hypertonic draws fluid from intracellular space into the vascular system and can rapidly increase blood volume; and if it is administered too quickly, it can cause intravascular volume overload and pulmonary edema

What are normal potassium levels?

3.5-4.5-5.0 (mEq/L)

What are major roles of potassium?

Nerve impulses, muscle contraction, cellular growth, cardiac rhythm maintenance, acid-base balance

What are causes of hyperkalemia?

Impaired renal function or renal failure, potassium shift from ICM to ECF, excessive intake of potassium adrenal deficiency and aldosterone deficient, acidosis, massive cell destructions, excessive exercise, beta-blockers, digoxin

What are manifestations of hyperkalemia?

Life-threatening arrhythmias, fatigue, confusion, tetany, muscle cramps, weak or paralyzed skeletal muscles, abdominal cramping or diarrhea

What are ECG effects with hyperkalemia?

Initial, tall, peaked T-waves and as potassium increases, cardiac depolarization decreases leading to flattened P waves, prolonged PR interval, depressed ST segment, and widening QRS.

What are treatments for hyperkalemia?

Stop oral and IV K+ intake, increase K+ excretion (thiazide diuretics, dialysis), patiromer (Veltessa), sodium zirconium cyclosilicate (ZS-9, Lokelma), and/or sodium polystyrene sulfonate (Kayexalate), force K+ from ECF to ICF by IV regular insulin with dextrose and sodium bicarbonate, continuous ECG monitoring, stabilize cardiac cell membrane by administering calcium

What are causes of hypokalemia?

Increased loss of K+ via kidneys or GI tract, K+ shift from ECF to ICF. dietary deficiency (rare)

What are manifestations of hypokalemia?

Cardiac complications, skeletal muscle weakness (legs), weakness of respiratory muscles, decreased GI motility, hyperglycemia (from impaired insulin secretion)

What are ECG effects with hypokalemia?

Impaired repolarization resulting in flattening of T wave and emergence of U wave, slighly peaked P wave, prolonged PR interval, and widened QRS

What is the treatment for hypokalemia?

KCI supplements orally or IV; always dilute IV KCI, NEVER give KCL via IVP or bolus, should not exceed 10mEq/hr, use an infusion pump

What are normal calcium levels?

8.5-10.5 mg/dL

What are causes of hypocalcemia?

Acute renal disease, acute pancreatitis, loop diuretics, low mg+ levels, primary hypothyroidism (low PTH -> low calcium)

What are manifestations of hypocalcemia?

Positive Trousseau's or Chvostek's sign, laryngeal stridor, dysphagia, numbness and tingling around the mouth or in the extremities, dysrhythmias, weakness, fatigue, hyperreflexia, tetany

What is Chvostek's signs?

contraction of facial muscle

What is Trousseau's sign?

Carpal spasm triggered by the inflation of blood pressure cuff on arm

What are treatments of hypocalcemia?

Calcium and vitamin D supplements, IV calcium gluconate, rebreathe into paper bag (to prevent respiratory alkalosis common in hypocalcemics), treat pain and anxiety to prevent hyperventilation-induced respiratory alkalosis

What are causes of hypercalcemia?

Hyperparathyroidism, types of cancers (blood), thyrotoxicosis, hyperthyroidism, thiazide diuretics, excess dairy intake

What are manifestations of hypercalcemia?

Fatigue, lethargy, weakness, confusion, hallucinations, seizures, coma, dysrhythmias, bone pain, fractures, nephrolithiasis, polyuria, dehydration, high

What are treatments of hypercalcemia?

Bisphosphonates (gold standard), low calcium diet, stop medications related to hypercalcemia, increase weight-bearing activity, increase fluid intake, calcitonin

What are normal phosphate levels?

2.5-4.5 mg/dL

What are causes of hypophosphatemia?

Chronic diarrhea, alcohol abuse, hyperparathyroidism, diabetic ketoacidosis (DKA)

What are manifestations of hypophosphatemia?

CNS depression, muscle weakness and pain, dysrhythmias, heart failure, coma, rickets and osteomalacia

What are treatments of hypophosphatemia?

Increasing oral intake with dairy products, oral supplements or IV administration of sodium/ potassium phosphate (monitor levels every 6-12 hours)

What are causes of hyperphosphatemia?

Renal failure, phosphate enemas, thyrotoxicosis, hyperthermia

What are manifestations of hyperphosphatemia?

Tetany, muscle cramps, paresthesias (fingers/lips), hypotension, dysrhythmias, seizures (hypocalcemia), calcified deposits in soft tissue

What are treatments for hyperphosphatemia?

Identify and treat underlying cause, restrict intake of foods and fluids containing phosphorus, oral phosphate-binding agents, hemodialysis, volume expansion and forced diuresis, correct any hypocalcemia

What are major roles of magnesium?

DNA and protein synthesis, blood-glucose control, bp regulation, production of ATP

What are normal levels of magnesium?

1.7-2.2 mg/dL

What causes hypomagnesemia?

GI fluid loss, alcohol abuse, acute pancreatitis, diuresis, hyperglycemia

What are manifestations of hypomagnesemia?

Muscle cramps, tremors, hyperactive deep tendon reflexes, Chvostek's and Trousseau's signs, confusion, vertigo, seizures, dysrhythmias

What are treatments for hypomagnesemia?

Treat underlying cause, oral supplements, increase dietary intake, if severe IV magnesium

What are causes of hypermagnesemia?

Renal failure, use of IV magnesium, hypothyroidism, adrenal insufficiency

What are manifestations of hypermagnesemia?

Hypotension, facial flushing, lethargy, nausea and vomiting, impaired deep tendon reflexes, muscle paralysis, respiratory and cardiac arrest

What are treatments of hypermagnesemia?

Prevention first by stopping magnesium-containing drugs and limit dietary intake of magnesium-containing foods, fluids and diuretics to promote urinary excretion, dialysis

What are diseases that frequently develop acid-base imbalances?

Diabetes, COPD, kidney disease

What are the three mechanisms that regulate and maintain acid-base balance and pH?

-Buffer system: Immediately acts within seconds by binding or releasing hydrogen ions (bicarb, phosphate, protein buffers)

-Respiratory system: responds within minutes to hours through manipulation of CO2 exhalation (hyper/hypoventilating)

-Renal system: responds after hours-days but is the most powerful for long-term control by reabsorbing bicarb, excreting H+, or generating new bicarb