Conditions of Fluid Imbalance

Question 1

Total body water (TBW) represents ____ total body wt

Answer 1

45-60%

Question 2

what is the fraction of distribution of the 2 fluid compartments?

Answer 2

2/3 intracellular fluid: mostly in muscle cells

• osmolality must be maintained for cells to fxn
• H2O freely crosses cell membranes, not Na+
• intra osmoles mostly large proteins that don’t move

1/3 ECF: (3/4 interstital water, 1/4 intravascular water)

• dominant ECF tonically active particle is Na+
• K+, glucose, urea, albumin also prevalent

Question 3

_______ maintains distribution of fluids in the compartments
– Concentration of dissolved ions (electrolytes), proteins, and other large
molecules
– Water moves freely across cell membranes to maintain osmotic equilibrium

Answer 3

osmotic pressure

Question 4

define hypotonic, isotonic, hypertonic sltn

Answer 4

hypotonic: water goes in, more solutes inside cell
isotonic: equal conc inside and outside
hypertonic: water leaves cell, more solutes outside cell

Question 5

Intracellular fluid (ICF) volume is crticial for ________

Answer 5

normal cell function

– e.g., alterations to ICF volume in the brain can result in significant dysfunction
(confusion ⟹ death)
- diminished cognition

Question 6

Extracellular fluid (ECF) volume is crticial for ________

Answer 6

essential for tissue perfusion (delivery of

oxygen & nutrients; removal of metabolic waste products)

Question 7

When assessing a patient’s clinical fluid status, we are mostly concerned with?

Answer 7

ECF (can’t measure what’s happening in indiviaul cells)

(interstitial water and intravascular water [serum/plasma/blood volume])

• Blood volume and serum osmolality are tightly regulated (homeostasis)
• Homeostasis can be disrupted by a variety of acute and chronic diseases as well as the intended and unintended effects of drug therapy (eg. diuretics)

Question 8

name signs and symptoms of dehydraiton (8)

Answer 8

• Postural changes: (lying ⟹ standing) dizziness, HR↑ (to maintain perfusion), SBP↓
• Dry mucous membranes
• Skin tenting (poor skin turgor)
• Cool extremities
• ↓Capillary refill
• ↓Cognitive function (decreased eprfusion)
• Sunken eyes (orbital depression)
• ↓Urine output (concentrated urine, kidneys try to conserve water after sensing low blood volume)

Question 9

Signs & Symptoms of Dehydration in an Infant or
Young Child (6)

Answer 9

• 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
• Listlessness or irritability (change from normal behaviour)
Send for medical attention immediately

Question 10

Dehydration Management

mild dehydration

Answer 10

• Typical maintenance is 2000-3000 mL/day
– 6-8 x 250 mL glasses of water per day
• If the patient is mildly dehydrated, encourage them to drink (water, WHO-ORS, water+salt, sports drink)

Question 11

Dehydration Management

what types of IV fluid replacement?

Answer 11

D5W (5% Dextrose†) Hypotonic (Ineffective osmoles=diffuse easily across the semi-permeable water,)
0.45% NaCl (half normal saline) Hypotonic, solution enters cells
Lactated Ringer’s Isotonic
0.9% NaCl (normal saline) Isotonic - of you want to retain volume in vascular space
3% NaCl (hypertonic saline)

Hypertonic saline rarely used: Brain trauma, trying to reduce the fluid volume within the brain or pateint is extremely dehydrated - use small volumes of 3% NaC; (hypertonic)
Hypertonic sucks water out of cells, rapidly diminish states of consciousness, increase risk of mortality

Question 12

Edema

• what is the usual cause?
• first sign?

Answer 12

• Excess fluid volume in the extracellular compartment
– Usually caused by heart, kidney, or liver failure
– Also occurs in pregnancy and malnutrition

First sign is often swelling in the feet, ankles, and lower legs
⟹ described as pitting edema (Assess how far up the ankle and lower leg and how deep the divot is)

Question 13

Signs & Symptoms of Edema

• pulmonary (3)
• other (3)

Answer 13

• Pulmonary edema
– Increase in respiratory rate
– Shortness of breath sensation
– Crackles (rales) present on auscultation
• Weight gain
• Increased jugular venous pressure
• Positive hepatojugular reflux: firm pressure over the liver temporarily increases venous return to the heart

Question 14

management of edema

• which classes of medications (3)

Answer 14

• Correct the underlying cause
– Heart failure (ACEi, beta blockers)
– Sodium restriction (1,000 to 2,000 mg/day)

• Medications: diuretics (↑ renal sodium excretion)
– Loop diuretics (furosemide, ethacrynic acid)
– Thiazide diuretics (hydrochlorothiazide, chlorthalidone, metolazone)
– Potassium sparing diuretics (triamterene, amiloride, spironolactone)