Fluid and Electrolyte Pathophysiology

Where do cells of the body contain fluid?

inside of them and are surrounded by fluid (outside)

Fluid in the body provides

the medium in which all of the biochemical reactions, necessary for life, can occur

The concentration of solutes, solvents, as well as the pH of body fluids are maintained within a __________ range in order to support life

narrow

Derangements in the body fluid composition can have

life threatening effects

The body fluid is distributed amongst

various compartments

The water within the body fluid can move ________ from compartment to compartment

freely

The solutes within the body fluid can only move based on

concentration gradients and the permeability of various compartments to those solutes

The two main compartments for body fluid are the

intracellular space

extracellular space

intracellular space, which contains

intracellular fluid

extracellular space, which contains

extracellular fluid

The extracellular space is further divided into the

interstitial and intravascular spaces

Intracellular fluid = _____ of body fluid

2/3

Extracellular fluid = _____ of body fluid

1/3

Intravascular ____% of body weight

5

Intravascular ____L

3

Should you add more of the blue chart??

Total Body Water (TBW) is maintained within a

narrow range despite any significant variations of water intake and/or elimination

What are the (3) primary sources of water intake

1. Drinking water

2. Ingestion of water contained within food

3. Byproduct of ATP production

What are (3) primary sources of water elimination

1. Renal excretion (greatest source of loss)

2. Stool

3. Evaporation from lungs, skin, sweat, etc. (insensible loss)

•Water moves freely between compartments based on:

• Concentration gradients

• Hydrostatic pressure gradients

What happens when you give a hypotonic fluids

cell swelling

Hydrostatic pressure gradients

Capillary hydrostatic pressure (blood pressure)

pushes water from blood stream (capillaries) to the interstitial space

Hydrostatic pressure gradients

Capillary oncotic pressure

sucks water into blood stream (capillaries)

Hydrostatic pressure gradients

Interstitial hydrostatic pressure

pushes water from interstitial space to blood stream (capillaries)

Hydrostatic pressure gradients

Interstitial oncotic pressure

sucks water from blood stream (capillaries) into the interstitial space

What is Hydrostatic pressure gradients

Basically 2 forces pushing water out of the blood stream and 2 forces pushes water into the blood stream

•Imbalance between any of the 4 forces (Hydrostatic pressure gradients) leads to altered water balance causing

1. Edema

2. Dehydration

Water movement picture?

What is edema

Excessive accumulation of fluid within the interstitial space

Edema is most often a problem of

How the fluid is distributed, not a water excess

Can edema cause dehydration and edematous at the same time?

What causes edema?

Capillary hydrostatic pressure (↑ or ↓)

(↑)

What causes edema?

Capillary oncotic pressure (↑ or ↓)

(↓)

What causes edema?

Interstitial hydrostatic pressure (↑ or ↓)

(↓)

What causes edema?

Interstitial oncotic pressure (↑ or ↓)

(↑)

What causes edema?

Capillary membrane permeability (↑ or ↓)

(↑)

What causes edema?

______ obstruction

Lymphatic

What are thing that are caused by edema via

Increased capillary hydrostatic pressure

• Venous obstruction

• Sodium/water retention

• Venous blood cots

• Tight clothing around extremities

• HTN

• Volume overload

What are thing that caused edema via

Increased capillary permeability

•Inflammation or immune response mediators released which increase capillary permeability

What are thing that cause edema via

Lymphatic obstruction

• Lymphatic vessels are blocked due to infection or tumor

• Lymphatic vessels damaged or removed intentionally during surgery

• Leads to lymphedema

Edema- Can be _____ or ______

localized or generalized

Edema can be ______

(fluid follows path based on gravitational pull)

dependent

Edema can be ______ if severe

pitting

Increased edema creates

________ against which __________ must try to overcome; in order to _______

resistance

arterial blood flow

perfuse tissues

Increased edema creates

can lead to _______ if severe

tissue ischemia

Kidneys and hormones are responsible for maintaining ___________ balance

sodium and water

______ follows _____, so changing _______ concentrations changes ______ concentrations

Water follows salt

sodium

water

•Sodium is regulated primarily by

aldosterone

Water is primarily regulated by

anti-diuretic hormone

Sodium accounts for _______ % of extracellular fluid cations

90

Since sodium is always associated with _______, it to is in very high concentrations in the ________ fluid

chloride

extracellular

Remember when ______ dissolves in fluid it floats around as ______ in water

salt (NaCl)

Na+ and Cl-

What are sodiums three main "roles" in the body?

• maintenance of conduction of nerve impulses

• Regulation of acid-base balance (sodium bicarbonate)

• Transport of substances across the cellular membrane (Sodium-Potassium-ATP pump)

Alterations in sodium and water balance are _______ related

closely

When sodium concentration is altered, changes in

water volume occur

Alterations in the concentration of sodium in water are generally referred to in terms of

tonicity

(which is the change in electrolyte concentrations in relation to water)

Hypotonic Alterations (picture)

Isotonic Alterations (picture)

Hypertonic Alterations (picture)

What is the most common type of alteration between: Isotonic, Hypertonic, Hypotonic

Isotonic Alterations

Isotonic Alterations occur when there is a

proportional change in both the total body water (TBW) and the electrolytes

What are examples of Isotonic Alterations

• Hemorrhage (isotonic fluid loss)

• Sweating (isotonic fluid loss)

• Excessive IV fluid administration (isotonic fluid excess)

• Hypersecretion of aldosterone (isotonic fluid excess)

What are examples of Isotonic Alterations (isotonic fluid loss)

• Hemorrhage

• Sweating

What are examples of Isotonic Alterations (isotonic fluid excess)

• Excessive IV fluid administration

• Hypersecretion of aldosterone

Hypertonic Alterations - occur when

the electrolyte concentration is higher than normal in the extracellular fluid

(> 294 mOsm)

Hypernatremia

Amount of electrolytes increase in relation to water

Dehydration

Amount of water decreases in relation to electrolytes

Hypertonic Alterations

•Occurs when serum sodium levels

> 145 mEq/L

Hypernatremia can occur in

-

-

-

- hypovolemic

- euvolemic

- hypervolemic states

Risk factors for Hypertonic Alterations

1. Advanced age

2. Impaired mental state

3. Fever

4. Diarrhea

5. Vomiting

6. Use of diuretics

What is the MOST common and MOST severe sign of Hypertonic Alterations

•Central nervous system

What are Signs and symptoms of Hypertonic Alterations

1. Weakness

2. Lethargy

3. Muscle twitching

4. Hyperreflexia

5. Confusion

6. Coma

7. Seizures

Hypovolemic hypernatremia

• Loss of body sodium accompanied by a relative greater loss of body water

Hypovolemic hypernatremia

results from: (3 things)

loop diuretics

GI losses

failure of kidneys to concentrate urine

What is the MOST COMMON hypernatremia

Euvolemic

Euvolemic hypernatremia results from

loss of free water (water without sodium following it)

• Diabetes insipidus

• Water loss from burns

Hypervolemic Hypernatremia

• Rare

• Gain in in body water with a relatively larger increase in body sodium

• Infusion of hypertonic solutions

Hypotonic Alterations

• Occurs when the electrolyte concentration is lower than normal in the extracellular fluid

(< 280 mOsm)

Hypotonic Alterations

Leads to

intracellular overhydration (cell swelling)

Hypotonic Alterations

Is most pronounced in what two organs

the brain and lungs

What are the most common causes of

Hypotonic Alterations

• Sodium deficit (hyponatremia)

• Free water excess (water intoxication)

Hyponatremia

Develops when serum sodium concentration decreases to

< 135 mEq/L

What is the MOST COMMON electrolyte disorder

Hyponatremia

•Hyponatremia can have ..... varieties

-

-

-

- hypovolemic

- euvolemic

- hypervolemic varieties

Most individuals with Hyponatremia are

asymptomatic

Hyponatremia

can have issues with

edema and nervous cells depolarizing and repolarizing normally

Hyponatremia

Signs and symptoms

What is the sodium levels when symptoms are

Nausea and vomiting

125-130 mEq/L

Hyponatremia

Signs and symptoms

What is the sodium levels when symptoms are

lethargy, headache, confusion, apprehension, seizures, coma

Na+ < 125 mEq/L

hypovolemic hyponatremia

•Occurs with

loss of total body fluid and relatively larger loss of body sodium

hypovolemic hyponatremia

• Caused by

prolonged vomiting, severe diarrhea, inadequate aldosterone (adrenal insufficiency)

Euvolemic hyponatremia

Loss of

sodium without significant loss of body water

Euvolemic hyponatremia

Caused by

SIADH, inadequate dietary sodium intake, and glucocorticoid deficiency

Dilutional hyponatremia

Caused by

excessive intake of free water (drinking too much or D5W IV fluids)

Hypervolemia hyponatremia

Occurs when

there is an increase in sodium but a relatively larger increase in body water

Hypervolemia hyponatremia

Caused by

congestive heart failure or cirrhosis of the liver

Hypochloremia (lab value)

Serum chloride level < 97 mEq/L

Hypochloremia occurs with

hyponatremia

cystic fibrosis

elevated bicarbonate concentration

What is the major intracellular electrolyte

Potassium

Potassium intracellular concentration is

150 to 160 mEq/L,

Potassium extracellular concentration

3.5 to 5.0 mEq/L