Fluid Balance and Dehydration Overview

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Questions and Answers

What percentage of total body weight does total body water (TBW) typically represent?

20-30%

70-85%

30-40%

45-60% (correct)

Which compartment's volume is critical for normal cell function?

Intracellular fluid (ICF) (correct)

Interstitial fluid

Blood plasma

Extracellular fluid (ECF)

What condition can significantly alter intracellular fluid volume in the brain?

Dehydration

Electrolyte imbalance (correct)

Hypotonic solution

Hypertension

What is the primary concern when assessing a patient's clinical fluid status?

Extracellular fluid volume Signup and view all the answers

What sign might indicate dehydration based on changes in cognitive function?

Confusion Signup and view all the answers

What symptom is common in infants experiencing dehydration?

Lack of tears when crying Signup and view all the answers

When blood volume and serum osmolality are disturbed, what physiological response is typically affected?

Homeostasis Signup and view all the answers

What is a characteristic sign of dehydration noted in older children and adults?

Cool extremities Signup and view all the answers

What impact does osmotic pressure have on fluid distribution?

Maintains fluid distribution across compartments Signup and view all the answers

What physical sign is indicative of dehydration caused by poor skin turgor?

Skin tenting Signup and view all the answers

What is the typical daily maintenance fluid requirement for hydration?

2000-3000 mL/day Signup and view all the answers

What is the expected outcome of encouraging fluid intake in a mildly dehydrated patient?

Improvement in hydration status Signup and view all the answers

What is the first sign of edema often observed in patients?

Swelling in the feet and ankles Signup and view all the answers

Which of the following fluids is classified as isotonic?

Lactated Ringer’s Signup and view all the answers

What causes pitting edema primarily?

Fluid retention due to organ failure Signup and view all the answers

What medication class is typically used to increase renal sodium excretion?

Diuretics Signup and view all the answers

In patients with pulmonary edema, which of the following symptoms is least likely to present?

Swelling in lower extremities Signup and view all the answers

What dietary recommendation is typically made to manage edema related to heart failure?

Limit sodium intake Signup and view all the answers

What fluid replacement option is classified as hypertonic?

3% NaCl Signup and view all the answers

Which of the following diuretics is considered a loop diuretic?

Furosemide Signup and view all the answers

Study Notes

Total Body Water

Represents 45-60% of total body weight
Distributed into two main compartments:
- Intracellular fluid (ICF): Inside cells
- Extracellular fluid (ECF): Outside cells, divided into interstitial fluid and intravascular fluid

Fluid Balance

Osmotic pressure maintains distribution of fluids between compartments
Water moves freely across cell membranes to maintain osmotic equilibrium
ICF volume is critical for normal cell function
ECF volume is essential for tissue perfusion

Clinical assessment mainly focuses on ECF volume (interstitial water and intravascular water)
Blood volume and serum osmolality are tightly regulated
Homeostasis can be disrupted by various diseases and drug therapy

Dehydration

Signs and symptoms include:
- Dry mucous membranes
- Skin tenting (poor skin turgor)
- Decreased urine output
- Postural changes: dizziness, increased heart rate, decreased blood pressure
- Cool extremities
- Decreased capillary refill
- Decreased cognitive function
- Sunken eyes (orbital depression)

Dehydration in Infants and Young Children

Signs and symptoms include:
- 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
Seek medical attention immediately if these signs are present

Dehydration Management

Typical maintenance fluid intake is 2000-3000 mL/day (6-8 glasses of water)
Encourage drinking water, oral rehydration solutions (ORS), or sports drinks for mild dehydration
Medical referral and intravenous fluid replacement may be necessary for severe dehydration

Fluid Tonicity and Distribution

D5W (5% Dextrose): Hypotonic, 666 mL ICF, 333 mL ECF
0.45% NaCl (Half normal saline): Hypotonic, 333 mL ICF, 666 mL ECF
Lactated Ringer's: Isotonic, 30 mL ICF, 970 mL ECF
0.9% NaCl (Normal saline): Isotonic, 0 mL ICF, 1000 mL ECF
3% NaCl (Hypertonic saline): Hypertonic, -2000 mL ICF, 3000 mL ECF
Dextrose is an ineffective osmole

Edema

Excess fluid volume in the ECF
Often caused by heart, kidney, or liver failure, also occurs in pregnancy and malnutrition
First sign is often swelling in feet, ankles, and lower legs (pitting edema)
Pulmonary edema is a serious complication, characterized by increased respiratory rate, shortness of breath, and crackles on auscultation
Other signs include weight gain, increased jugular venous pressure, and positive hepatojugular reflux

Edema Management

Correct the underlying cause
Sodium restriction (1000-2000 mg/day)
Medications: diuretics
- Loop diuretics: furosemide, ethacrynic acid
- Thiazide diuretics: hydrochlorothiazide, chlorthalidone, metolazone
- Potassium sparing diuretics: triamterene, amiloride, spironolactone

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Description

This quiz covers vital concepts related to total body water, fluid balance, and the conditions associated with fluid status. It highlights the importance of intracellular and extracellular fluid and the physiological implications of dehydration. Test your knowledge on how fluid volume affects normal cell function and overall health.