Lecture 1 - Fluid Imbalances

where is intracellular fluid predominantly found

mostly in muscle cells

H20 and Na+ movement across membranes

H20 moves freely, Na+ doesn’t

what are intracellular osmoles

mostly large proteins that don’t move

what is the dominant extracellular tonically active particle

Na+

(other prevalent ones: K+, glucose, urea, albumin)

ratio of intracellular fluid : extracellular fluid

2/3 : 1/3

ratio of interstitial water : intravascular water of extracellular fluid (1/3 of total fluid)

3/4 : 1/4

hypotonic environment

higher concentration of solute in the cell compared to extracellular environment

water moves INTO cells causing them to swell

isotonic environment

equal concentration of solute inside and outside the cell, resulting in no net movement of water.

hypertonic environment

higher concentration of solute in the extracellular environment compared to the cell, causing water to move OUT of the cells and shrink them.

what is the function of osmotic pressure

maintain distribution of fluids between compartments of fluid (i.e. intracellular, extracellular)

what is osmotic pressure influenced by

concentration of dissolved electrolytes, proteins, other large molecules (cannot move across membranes so water moves freely to maintain equilibrium)

what is intracellular fluid (ICF) needed for

volume is critical for normal cell function

what is extracellular fluid (ECF) needed for

volume is essential for tissue perfusion

what is interstitial fluid

fluid between or around tissues

What is intravascular water

fluid found inside blood vessels e.g. plasma

s/s of dehydration (adult)

dry mucous membranes

skin tenting (pinch skin and takes long to go back to normal)

decreased urine output

postural changes (lying → standing = decreased SBP, dizziness, increased HR)

decreased capillary refill

cool extremities

decreased cognitive function

s/s of dehydration - infant/young child

dry mouth and tongue

lack of tears when crying

no wet diaper for 3 hours

sunken eyes/cheeks

sunken soft spot on top of skull

irritability

***requires immediate medical attention***

typical fluid maintenance per day

2000-3000mL

6-8 × 250 mL glasses of water

management of mild dehydration

drink - water, WHO-ORS (world health organization oral rehydration solution), water + salt, sports drink and increased fluid intake.

management of severe dehydration

depends on severity, medical attention/IV fluid replacement

IV replacements for severe dehydration

what is edema

excess fluid volume in extracellular compartment

usually caused by heart/kidney/liver failure

may occur during pregnancy or due to malnutrition

s/s of edema

swelling in feet/ankles/lower legs (gravity), pitting (push on swelled area and it leaves a pit, measure severity of edema by depth and duration of pit)

weight gain

increased jugular venous pressure

Positive hepatojugular reflux (firm pressure over the liver temporarily increases venous return of the heart) (see lecture slides for video)

s/s of pulmonary edema

increased respiratory rate

SOB sensation

crackles present using stethoscope

medications to manage edema

diuretics = increase sodium excretion and water follows

• loop diuretics (furosemide, ethacrynic acid) = strong

• thiazide diuretics (HCTZ, chlorthalidone, metolazone)

• K sparing diuretics (spironolactone, triamterene, amiloride) (depending on K levels)

loop diuretics

• furosemide, ethacrynic acid= strong

thiazide diuretics

• HCTZ, chlorthalidone, metolazone

K sparing diuretics

• spironolactone, triamterene, amiloride (depending on K levels)