Foundations: fluid imbalances

Module 3

Intracellular fluid (ICF) fluid inside the cells takes up __ of body fluids

2/3

Extracellular fluids (ECF) outside the cell includes

Interstitial + Intravascular + Transcellular fluid

Interstitial fluid

between the cells 3rd space

intravascular fluid

inside the blood vessels

Transcellular fluid

water between epithelial-lined spaces

fluid balance is maintained by osmosis where water moves

from areas of low solute concentration to high solute concentration

fluid movement is regulated by

hydrostatic pressure

osmotic pressure

oncotic pressure

hydrostatic pressure is pressure exerted by blood against capillaries

pushing force moves fluid from intravascular space into interstitial/intracellular space

osmotic pressure is exerted by solutes (particles) like sodium

pulling force moves fluid into intravascular space from interstitial/intercellular space

oncotic pressure is exerted by albumin

pulling force helps keep fluid in intravascular space

hydrostatic pressure

high: fluid out

low: fluid in

osmotic and oncotic pressure

high: fluid in

low: fluid out

solute concentration is measured using

osmolality

osmolarity

osmolality is the number of particles in a solution measured in

weight (kg)

osmolarity is the number of particles in a solution measured in

volume (L)

how is thirst triggered in response to fluid loss

Fluid loss increases Na⁺ concentration → increases osmolarity → water moves out of cells → cells shrink → stimulates hypothalamic osmoreceptors (thirst center) → causes conscious sensation of thirst and desire to drink fluids.

what is the role of ADH in fluid balance

Increased osmolarity stimulates osmoreceptors → ADH is released from the posterior pituitary → kidneys reabsorb more water → blood water content increases → urine output decreases.

what triggers renin release in the RAAS system

Decreased renal perfusion (low blood flow/low blood pressure) triggers release from the kidneys

what is the first step after renin is released

renin converts angiotensin into angiotensin 1

what is the role of aldosterone in RAAS

increase Na reabsorption and H2O retention in the kidneys

why is RAAS the body’s 911 system

Because it rapidly activates to restore low blood pressure by conserving fluid and constricting blood vessels.

3 causes of edema

increased hydrostatic pressure

decreased oncotic pressure

increased capillary permeability

↑ Intravascular volume = ↑Hydrostatic pressure

pushes water out of intravascular into interstitial and intracellular spaces

↓ Albumin = ↓ Oncotic Pressure

Fluid leaks out intravascular into interstitial spaces

↑ Capillary pores

Easier for fluid to pass through membrane

fluid sources

oral intake (fluids and solid food)

IV infusion

tube feeding

obligatory fluid loss

waste products (urine)

insensible fluid loss

sweating

exhalation

other fluid losses

stool

vomiting

fluid overload

excess fluid resulting in hemodilution

hypervolemia

excess water and electrolytes (still proportioned)

extra volume in the circulatory system

excessive intake etiology

water consumption

IVs

blood transfusion

inadequate output fluid volume excess etiology

Organ/system failure resulting in chronic stimulation of the RAAS

Heart & Liver failure

altered kidney function fluid volume excess etiology

Acute & Chronic Kidney Disease

excessive sodium intake fluid volume excess and the conversion of water etiology

IVFs

diet

endocrine disorders fluid volume excess etiology

Cushing’s disease

SIADH

Signs and symptoms of fluid volume excess

edema

JVD

dyspnea

crackles

orthopnea

weight gain

hypertension

tachycardia

HTN

bounding peripheral pulses

laboratory results of fluid volume excess

decreased Hct, BUN, Serum Na, specific gravity

lack of fluid in the body like dehydration

loss/deficit of total body water

actual/relative

Hypovolemia

lack of water and electrolytes

decrease in circulating blood volume

insufficient water intake etiology

impaired thirst mechanism

dysphasia

NPO

anorexia/nausea

confusion

enteral feedings w/o proper H2O admin

inadequate fluid replacement etiology

Infusion rate is insufficient

Hypertonic IV fluids ( pulls fluid out of cell into vascular →cellular dehydration)

excessive output with a fluid volume deficit etiology

Excessive diaphoresis
Prolonged fever
GI – prolonged vomiting and/or diarrhea and nasogastric suctioning
Renal – diuretic use
Endocrine disorders - adrenal insufficiency and diabetes Insipidus
Third spacing – burns
Hemorrhage

signs/symptoms of a fluid volume deficit

Increased thirst
Dry mucous membranes
Fatigue
Confusion
Hypotension - d/t low volume
Tachycardia – in attempt to compensate for low BP
Weak peripheral pulses
Oliguria
Delayed capillary refill
Decreased skin turgor

laboratory values for fluid volume deficit

increased Hct, BUN, Serum Na, Specific gravity

oral rehydration

Client can safely consume adequate amounts of fluid orally

intravenous rehydration

Clients who are unsafe to consume liquids orally or cannot consume enough fluid necessary to restore balance.
Fluid administered directly into bloodstream

tonicity

The ability of solution to affect fluid volume within a cell

Isotonic

Equal Solute Concentration → No Fluid Shift

Hypertonic

Higher Solute Concertation → Fluid moves out of cell

Hypotonic

Lower Solute Concentration → Fluid moves into cells

Flow rate

rate in which solution is infused (mL/hr)

Nurses’ role with flow rates

calculate infusion rates

monitor infusion rates

assess patient

IV infection

Redness, Swelling,Warmth, Purulent Drainage at insertion site

IV phlebitis

Painful,Warm, Red along the vein

IV Infiltration

Edema, Pallor, Cool to Touch

IV extravasation

Pain, Burning/Stinging, Swelling, Redness at/around insertion side

Nursing intervention for local infection at IV site

Stop the infusion
Remove IV catheter
Administer ABX as prescribed

Nursing intervention for phlebitis

Stop the infusion
Remove IV catheter
Elevate the extremity and apply a warm compress

Nursing intervention for infiltration

Stop the infusion
Remove IV catheter
Elevate the extremity
Apply warm or cool compress (based on the IVF and policy

Nursing intervention for extravasation

Stop the infusion
Remove IV catheter
Elevate the extremity
Apply warm or cool compress (based on the IVF and facility policy)
Administer treatment/antidote as indicated
Monitor carefully for s/sx infection or tissue damage