Fluids and Electrolytes

What percentage of the human body is water?

60%

What is Intracellular fluid (ICF)?

fluid inside the cells

What is Extracellular fluid (ECF)?

Fluid outside the cells

What is Interstitial fluid (ISF)?

fluid between the cells

What is Intravascular fluid?

fluid inside the blood vessels

What is Transcellular fluid (TSF)?

body spaces (~1%)

What serves as a barrier in fluid distribution?

Cell membrane

What are the four methods of Fluid Movement?

Filtration, Diffusion, Active Transport, Osmosis

How does water move across a membrane?

Water moves from low solute concentration to high solute concentration

What determines Osmotic pressure?

the volume of fluid in a compartment

What is Edema?

Excess fluid in the interstitial space

What is Hypervolemia or fluid volume excess?

Excess fluid in the intravascular space

What is Water intoxication?

Excess fluid in the intracellular space

What causes Fluid Excess?

Caused by excessive sodium/water intake or inadequate sodium/water elimination (heart failure, lung failure, liver, renal failure)

What are the manifestations of Fluid Excess?

• JUGS: jugular vein distension

• PEE: polyuria

• FAT: Rapid weight Gain

• EDEMA (everywhere): peripheral, periorbital, cerebral)

• CRACK: crackles (fluid in lungs)

• BULGE: bulging fontanelles

• HYPERTENSION

What is Dehydration?

Hypovolemia / fluid volume deficit

What is Hypovolemia or fluid volume deficit?

Decreased fluid in the intravascular space

What does a decrease in fluid level lead to?

leads to increase in level of blood solutes, cell shrinkage, and hypotension

What causes Fluid Deficits?

Caused by inadequate fluid intake OR excessive fluid/sodium losses

What are examples of causes for Fluid Deficits?

• Diarrhea

• hemorrhage (decreased blood loss due to damaged blood vessels)

• prolonged hyperventilation

• burns/open wounds

What are the manifestations of Fluid Deficits?

• thirst

• altered level of consciousness

• hypotension

• flat jugular veins

• dry mucous membranes

• decreased skin turgor

• oliguria

• weight loss

• sunken fontanelles

What are Cations?

Positively charged electrolytes

What are Anions?

Negatively charged electrolytes

What do electrolytes play a role in?

Muscle and neural activity, Acid-base and fluid balance

What are the three main electrolytes listed?

• Sodium - Na+

• Potassium - K+

• Calcium - Ca²+

What is the most significant cation?

Sodium

What does Sodium control?

Controls serum osmolality/water balance

What is Depolarization?

sodium moves into cells

What is Repolarization?

sodium moves out of the cell

What is the normal range for Potassium?

3.5–5 mEq/L

What is the primary intracellular cation?

Potassium

What does Potassium play a role in?

• electrical conduction

• acid–base balance

• metabolism

What is the relationship between Potassium and Sodium?

Inverse relationship with sodium (one goes up, the other goes down)

What is the normal range for Calcium?

4–5 mEq/L

Where is Calcium mostly found?

Mostly found in the bone and teeth

What does Calcium play a role in?

• blood clotting

• hormone secretion

• receptor functions

• nerve transmission

• muscular contraction

What regulates Calcium?

vitamin K, parathyroid hormone, and calcitonin

What is Hypernatremia?

high levels of sodium (Sodium >145 mEq/L)

What happens to serum osmolality in Hypernatremia?

Serum osmolarity increases, resulting in fluid shifts into the vascular compartments

What are the manifestations of Hypernatremia?

• increased thirst

• dry and sticky mucous membranes

• dysphagia

• headache

• seizures

• lethargy

• coma

• blood pressure changes

• tachycardia

• decreased urine output

What is Hyponatremia?

low levels of sodium (Sodium <135 mEq/L)

What happens to serum osmolality in Hyponatremia?

Serum osmolarity decreases

What happens to water and cells in Hyponatremia?

Water shifts into cells, Cellular swelling

What are the manifestations of Hyponatremia?

• gastrointestinal upset

• poor skin turgor

• dry mucous membranes

• blood pressure changes

• pulse changes

• edema

• headache

• diminished deep tendon reflexes

• muscle weakness

• seizures

• coma

What is Hyperkalemia?

high levels of potassium (potassium >5 mEq/L)

What is Hypokalemia?

low levels of potassium (Potassium <3.5 mEq/L)

What are the manifestations of Potassium Dysregulation?

• paresthesia (feeling tingling)

• muscle weakness

• flaccid paralysis

• dysrhythmias (weird HR)

• cardiac arrest

• respiratory depression (hypoventilation; REALLY low breathing rates —> 8 and below)

• abdominal cramping

• nausea

• constipation/diarrhea

What is Hypercalcemia?

high levels of Calcium (Calcium >5 mEq/L)

What are the manifestations of Hypercalcemia?

• dysrhythmias

• EKG changes

• personality changes

• confusion

• decreased memory

• headache

• lethargy

• stupor

• coma

• muscle weakness

• decreased deep tendon reflexes

• nausea

• vomiting

• constipation

• abdominal pain

• pancreatitis

• renal calculi

• polyuria

• dehydration

What is Hypocalcemia?

low levels of Calcium (Calcium <4 mEq/L)

What does Hypocalcemia increase?

Increases cellular excitability

What are the manifestations of Hypocalcemia?

• dysrhythmias

• increased bleeding

• anxiety

• confusion

• depression

• irritability

• fatigue, paresthesia, increased deep tendon reflexes, tremors, muscle spasms, seizures, laryngeal spasms, increased bowel sounds, abdominal cramping, and positive Trousseau's and Chvostek's signs

What is Trousseau sign?

occlusion of arterial blood flow elicits carpal spasm

What is Chvostek sign?

tapping patient's facial nerve prompts brief facial spasm

What is Acidosis?

Increased H, Decreased pH

What is Alkalosis?

Decreased H, Increased pH

What is the normal serum pH?

7.35- 7.45

What reflects hydrogen concentrations?

pH reflects hydrogen concentrations

What is the relationship between hydrogen and pH?

Hydrogen is an acid, The more hydrogen, the lower the pH

What are acids by-products of?

Acids are by- products of metabolism

What are the three systems that work to maintain acid- base balance?

the buffers, respiratory system, renal system

What are buffers?

Chemicals that combine with an acid or base to change pH

What are the four major buffer mechanisms?

• bicarbonate-carbonic acid system

• protein system

• phosphate system

• hemoglobin system

What does the bicarbonate-carbonic acid system buffer?

Buffers blood and interstitial fluids

What does the protein system buffer?

Intra and extracellular acids and bases – most abundant buffers

What does the phosphate system buffer?

Renal tubules

What does the hemoglobin system buffer?

Weak acid, capillary system

How does the Respiratory System manage pH?

Manages pH by altering carbon dioxide excretion

What happens to pH when respirations speed up?

More CO2 is exhaled → CO2 leaves the blood → acidity decreases → pH increases (higher pH)

What happens to pH when respirations slow down?

• Slow respirations = CO₂ stays (less C0₂ exhaled) = acid increases = pH decreases

How does the Renal System regulate pH?

Alters the excretion or retention of hydrogen or bicarbonate

Why is the Renal System more effective?

because it permanently removes hydrogen

What is the response time of the Renal System?

Responds the slowest, but lasts the longest

What is Respiratory Acidosis?

Results from carbon dioxide retention, increases carbonic acid

What causes Respiratory Acidosis?

Caused by conditions that result in hypoventilation or decreased gas exchange

What are examples of causes for Respiratory Acidosis?

• acute asthma exacerbations

• COPD

• airway obstructions

• pulmonary edema

• pneumonia

• drug overdose

• central nervous system depression

What are the manifestations of Respiratory Acidosis?

• headache

• blurred vision

• tremors

• muscle twitching

• vertigo

• irritability

• disorientation

• lethargy

• coma

• blood pressure fluctuations

• diaphoresis

What is Metabolic Acidosis?

Results from a deficiency of bicarbonate or an excess of hydrogen

What causes Metabolic Acidosis?

• Bicarbonate deficit: intestinal and renal losses

• Acid excess: tissue hypoxia resulting in lactic acid accumulation

• ketoacidosis

• drugs

• toxins

• renal retention

What is Respiratory Alkalosis?

Results from excess exhalation of CO2, leads to carbonic acid deficits

What causes Respiratory Alkalosis?

conditions that result in hyperventilation

What are examples of causes for Respiratory Alkalosis?

• acute anxiety

• pain

• fever

• hypoxia

• gram-negative septicemia

• aspirin overdose

• excessive mechanical ventilation

• hypermetabolic states

What are the manifestations of Respiratory Alkalosis?

• paresthesia

• dizziness

• vertigo

• syncope

• muscle twitching

• seizures

• tachycardia

• dysrhythmias

• dry mouth

• excessive diaphoresis

• anxiety and coma

What is Metabolic Alkalosis?

Results from excess bicarbonate, deficient acid, or both

What causes Metabolic Alkalosis?

• Excess bicarbonate: excessive antacid use, use of bicarbonate-containing fluids, hypochloremia

• Deficient acid: gastrointestinal loss, hypokalemia, renal loss, hypovolemia, hyperaldosteronism

What are the manifestations of Metabolic Alkalosis?

• mental confusion

• hyperactive reflexes

• paresthesia

• seizures

• respiratory depression

• dysrhythmias

• coma