Fluid, Electrolyte, and AcidBase Imbalances
Chapter 17 Overview
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Water Content of Body
• Body Fluid Compartments
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Water Content of Body
Fig. 17-2. Relative volumes of three body fluids. Values represent fluid distribution in a young male adult.
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Electrolytes
Fig. 17-3. Electrolyte content of fluid compartments.
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Mechanisms Controlling Fluid and
Electrolyte Movement
• Diffusion
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Mechanisms Controlling Fluid and
Electrolyte Movement
Fig. 17-4. Diffusion is the movement of molecules from an area of high concentration to an area of low
concentration. Eventually the sugar molecules are evenly distributed.
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Mechanisms Controlling Fluid and
Electrolyte Movement
• Facilitated Diffusion
• Active Transport
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Mechanisms Controlling Fluid and
Electrolyte Movement
Fig. 17-5. Sodium-potassium pump. As sodium (Na+) diffuses into the cell and potassium (K+) diffuses out of the
cell, an active transport system supplied with energy delivers Na+ back to the extracellular compartment and K+ to
the intracellular compartment. ATP, Adenosine triphosphate.
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Mechanisms Controlling Fluid and
Electrolyte Movement
• Osmosis
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Mechanisms Controlling Fluid and
Electrolyte Movement
Fig. 17-6. Osmosis is the process of water movement through a semipermeable membrane from an area of low
solute concentration to an area of high solute concentration.
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Mechanisms Controlling Fluid and
Electrolyte Movement
• Osmosis, continued
 Measurement of osmolality
 Osmotic movement of fluids
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Mechanisms Controlling Fluid and
Electrolyte Movement
Fig. 17-7. Effects of water status on red blood cells. A, Hypotonic solution (H2O excess) results in cellular
swelling. B, Isotonic solution (normal H2O balance) results in no change. C, Hypertonic solution (H2O deficit)
results in cellular shrinking.
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Mechanisms Controlling Fluid and
Electrolyte Movement
• Hydrostatic Pressure
• Oncotic Pressure
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Fluid Movement in Capillaries
Fig. 17-8. Dynamics of fluid exchange between a capillary and tissue. An equilibrium exists between forces filtering
fluid out of the capillary and forces absorbing fluid back into the capillary. Note that the hydrostatic pressure is
greater at the arterial end of the capillary than at the venous end. The net effect of pressures at the arterial end of
the capillary causes a movement of fluid into the tissue. At the venous end of the capillary, there is net movement
of fluid back into the capillary.
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Fluid Movement in Capillaries
• Fluid Shifts
 Shifts of plasma to interstitial fluid
• Elevation of venous hydrostatic pressure
• Decrease in plasma oncotic pressure
• Elevation of interstitial oncotic pressure
 Shifts of interstitial fluid to plasma
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Regulation of Water Balance
• Hypothalamic Regulation
• Pituitary Regulation
• Adrenal Cortical Regulation
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Regulation of Water Balance
Fig. 17-9. Factors affecting aldosterone secretion. ACTH, Adrenocorticotropic hormone.
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Regulation of Water Balance
Fig. 17-10. Effects of stress on fluid and electrolyte balance. ACTH, Adrenocorticotropic hormone; ADH,
antidiuretic hormone; CRH, corticotropin-releasing hormone.
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Regulation of Water Balance
• Renal Regulation
• Cardiac Regulation
• Gastrointestinal Regulation
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Regulation of Water Balance
• Insensible Water Loss
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Gerontologic Considerations
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Fluid and Electrolyte Imbalances
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Calcium Imbalances
• Hypercalcemia
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Calcium Imbalances
• Hypocalcemia
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Magnesium Imbalances
Fig. 17-10. Effects of stress on fluid and electrolyte balance. ACTH, Adrenocorticotropic hormone; ADH,
antidiuretic hormone; CRH, corticotropin-releasing hormone.
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Acid-Base Imbalances
• pH and Hydrogen Ion Concentration
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Acid-Base Imbalances
Table 17-11. Terminology Related to Acid-Base Physiology.
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Acid-Base Imbalances
Fig. 17-6. Osmosis is the process of water movement through a semipermeable membrane from an area of low
solute concentration to an area of high solute concentration.
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Acid-Base Imbalances
• Acid-Base Regulation
 Buffer system
 Respiratory system
 Renal system
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Acid-Base Imbalances
• Alterations in Acid-Base Balance
 Respiratory acidosis
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Acid-Base Imbalances
Fig. 17-17. Kinds of acid-base imbalances. A, Respiratory imbalances caused by carbonic acid (CA) excess and
carbonic acid deficit. B, Metabolic imbalances caused by base bicarbonate (BB) deficit and base bicarbonate
excess.
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Acid-Base Imbalances
• Alterations in Acid-Base Balance,
continued
 Respiratory alkalosis
 Metabolic acidosis
 Metabolic alkalosis
 Mixed acid-base disorders
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Acid-Base Imbalances
• Clinical Manifestations
 Blood gas values
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Acid-Base Imbalances
Table 17-15. Normal Arterial Blood Gas Values *
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Acid-Base Imbalances
Table 17-16. Arterial Blood Gas (ABG) Analysis.
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Assessment of Fluid, Electrolyte,
and Acid-Base Imbalances
• Subjective Data
 Important health information
• Past health history
• Medications
• Surgery or other treatments
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Assessment of Fluid, Electrolyte,
and Acid-Base Imbalances
• Subjective Data, continued
 Functional health patterns
• Health perception–health management
pattern
• Nutritional-metabolic pattern
• Elimination pattern
• Activity-exercise pattern
• Cognitive-perceptual pattern
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Assessment of Fluid, Electrolyte,
and Acid-Base Imbalances
• Objective Data
 Physical examination
 Laboratory values
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Oral Fluid and Electrolyte
Replacement
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Intravenous Fluid and Electrolyte
Replacement
• Solutions
 Hypotonic
 Isotonic
 Hypertonic
 Intravenous additives
 Plasma expanders
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