Fluid Imbalances

FLUID IMBALANCES:STUDY QUESTIONS

1. Explain the risks of the groups listed below, in terms of body water content and renal function and any other related factors, for dehydration if their fluid intake were significantly reduced.

a. lean young adults

women 50% body water content

men 60% body water content

Renal Function- about 300-500 ml. day

Related factors for dehydration-Also through

skin and lungs

b. Infants

About 70-75% body water content

Renal function decreases at birth because kidneys immature

Related factors for dehydration: this skin allows water to easily evaporate (insensible fluid loss); large body surface area related to weight

c. Elderly

Women-40% body water content

Men-50% body water content

Renal function: kidneys less efficient as you age

Related factors for dehydration: more risk bc lose skeletal muscle mass and replaced by fatty tissue and layers skin become thinner and more h20 evaporates

d. Obese

Body water content: about 30-50%

Renal function:

Related factors: adipose tissue does not hold h20

2. If person has an acute weight gain or weight loss of 1 kg, how much fluid have they likely gained or lost?

Gained or lossed of 1 liter per kg

(clothing, scale, dressing important to remain constant)

How can fluid balance be monitored in patients?

Input and output records

Daily weight

Calibrated scale

Gains Losses

Oral intake Urine 1500ml

Water 1000 ml Insenible Losses

Food 1300 ml Lungs 300ml

H20 of oxidation 200 ml Skin 500ml

Total 2500 ml Feces 200ml

Total 2500ml

3. Explain how the serum sodium, serum osmolality, urine volume, urine specific gravity, and hematocrit are used to determine whether a person has a fluid deficit or fluid excess.

Serum sodium:

Serum osmolality:

Urine volume: urine osmolality reflects kidneys ability to produce concentrated or diluted urine based on serum osmolality and need for water conservation or excretion. Ratio of urine osmolality to serum osmolality= 1:1

Dehydrated person may have urine concentration= 3:1 or 4:1

Ex. When person sleep over night urine more concentrated

Urine osmolality may exceed 1000 mosm/kg H20

Those with difficulty concentrating urine may have urine serum ratio that is less than or equal to 1:1

Ex. Diabetes insipidus or chronic renal failure

Urine Specific Gravity- compares weight of urine with that of water, providing Indux of solute concentration.

Water considered to be 1.000

Change in specific gravity from 1.010 to 1.020 is an increase in 400 mosm/kg H20

In Na depleted state kidneys try to conserve Na, urine specific gravity is normal and urine Na and Cl concentrations are low

Hematocrit-males 45-52%

Females 37-48%

When red cells pulled to bottom

If fluid volume decreases then plasma volume decreases making red cells more concentrated and hematocrit number increases.

In fluid excess-hematocrit decreases

4. Explain the effects of infusion of an isotonic, hypotonic, and hypertonic intravenous solution on cell volume. Give an example of a clinical situation for which each of these 3 types of solution would be used.

Isotonic-same osmolality as ICF (280 mosm/L)

-fluid

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