acid–base disturbances

Nursing Care
of Clients with
Altered Fluid,
Electrolyte, and
Acid–Base Balance
Fluid and Electrolyte Balance
• Necessary for life, homeostasis
• Nursing role: help prevent, treat fluid,
electrolyte disturbances
• Approximately 60% of typical adult is fluid
– Varies with age, body size, gender
• Intracellular fluid
• Extracellular fluid
– Intravascular
– Interstitial
– Transcellular
• “Third spacing”: loss of ECF into space that does
not contribute to equilibrium
• Active chemicals that carry positive (cations),
negative (anions) electrical charges
– Major cations: sodium, potassium, calcium,
magnesium, hydrogen ions
– Major anions: chloride, bicarbonate, phosphate,
sulfate, and proteinate ions
• Electrolyte concentrations differ in fluid
Regulation of Fluid
• Movement of fluid through capillary walls
depends on
– Hydrostatic pressure: exerted on walls of blood
– Osmotic pressure: exerted by protein in plasma
• Direction of fluid movement depends on
differences of hydrostatic, osmotic pressure
Regulation of Fluid
• Osmosis: area of low solute concentration to area
of high solute concentration
• Diffusion: solutes move from area of higher
concentration to one of lower concentration
• Filtration: movement of water, solutes occurs
from area of high hydrostatic pressure to area of
low hydrostatic pressure
• Active transport: physiologic pump that moves
fluid from area of lower concentration of one of
higher concentration
Active Transport
• Physiologic pump that moves fluid from area
of lower concentration to one of higher
• Movement against concentration gradient
• Sodium-potassium pump: maintains higher
concentration of extracellular sodium,
intracellular potassium
• Requires adenosine (ATP) for energy
Fluids Animation
Fluid Volume or
Electrolyte Imbalance
• Causes of fluid loss
– Vomiting, diarrhea
– Gastrointestinal suctioning, intestinal fistulas, and
intestinal drainage
– Diuretic therapy, renal disorders, endocrine
– Sweating from excessive exercise, increased
environmental temperature
– Hemorrhage
– Chronic abuse of laxatives
Fluid Volume or
Electrolyte Imbalance
• Cause of Fluid Loss in the Older Adult
– Self limiting fluids (fear of incontinence)
– Physical disabilities
– Cognitive impairments
– Older adults without air conditioning
Fluid Volume Imbalances
• Fluid volume deficit (FVD): hypovolemia
• Fluid volume excess (FVE): hypervolemia
Fluid Volume Deficit
• Loss of extracellular fluid exceeds intake ratio
of water
– Electrolytes lost in same proportion as they exist
in normal body fluids
• Dehydration: loss of water along with
increased serum sodium level
– May occur in combination with other imbalances
Fluid Volume Deficit (cont’d)
• Dehydration
– Causes: fluid loss from vomiting, diarrhea, GI
suctioning, sweating, decreased intake, inability to
gain access to fluid
– Risk factors: diabetes insipidus, adrenal
insufficiency, osmotic diuresis, hemorrhage, coma,
third space shifts
Fluid Volume Deficit (cont’d)
• Manifestations: rapid weight loss, decreased
skin turgor, oliguria, concentrated urine,
postural hypotension, rapid weak pulse,
increased temperature, cool clammy skin due
to vasoconstriction, lassitude, thirst, nausea,
muscle weakness, cramps
• Laboratory data: elevated BUN in relation to
serum creatinine, increased hematocrit
– Serum electrolyte changes may occur
Fluid Volume or
Electrolyte Imbalance
• Treatment for Fluid Volume Deficit (FVD)
– Oral, intravenous, or enteral routes
– Manage the effects and prevent further
complications by monitoring intake, assessing lab
values, and observing vital signs and skin integrity
Fluid Volume Deficit - Nursing
• I&O, VS
• Monitor for symptoms: skin and tongue
turgor, mucosa, UO, mental status
• Measures to minimize fluid loss
• Oral care
• Administration of oral fluids
• Administration of parenteral fluids
Fluid Volume Excess
• Due to fluid overload or diminished homeostatic
• Risk factors: heart failure, renal failure, cirrhosis of liver
• Contributing factors: excessive dietary sodium or sodiumcontaining IV solutions
• Manifestations: edema, distended neck veins, abnormal
lung sounds (crackles), tachycardia, increased BP, pulse
pressure and CVP, increased weight, increased UO,
shortness of breath and wheezing
• Medical management: directed at cause, restriction of
fluids and sodium, administration of diuretics
Fluid Volume Excess - Nursing
• I&O and daily weights; assess lung sounds, edema,
other symptoms; monitor responses to
medications- diuretics
• Promote adherence to fluid restrictions, patient
teaching related to sodium and fluid restrictions
• Monitor, avoid sources of excessive sodium,
including medications
• Promote rest
• Semi-Fowler’s position for orthopnea
• Skin care, positioning/turning
of Imbalances
• Hyponatremia
– Muscle cramps, weakness, fatigue
– Dulled sensorium, irritability, personality changes
• Hypernatremia
– Most serious effects are seen in the brain
– Lethargy, weakness, irritability can progress to
seizures, coma, and death
of Imbalances
• Hypokalemia
– EKG changes (flattened or inverted T waves)
– Skeletal muscle weakness
• Hyperkalemia
– Cardiac arrest
– Paresthesias
– Abdominal cramping
of Imbalances
• Hypocalcemia
– Tetany, paresthesias, muscle spasms
– Hypotension
– Anxiety, confusion, psychosis
• Hypercalcemia
– Muscle weakness, fatigue
– Personality changes
– Anorexia, nausea, vomiting
of Imbalances
• Hypomagnesemia
– Muscle weakness and tremors
– Dysphasia
– Tachycardia hypertension
– Mood and personality changes
• Hypermagnesemia
– Depressed deep tendon reflexes
– Hypotension
– Respiratory depression
of Imbalances
• Hypophosphatemia
– Muscle pain and tenderness
– Muscle weakness and paresthesias
– Confusion
– Manifestations of hypophosphatemia
– Muscle spasms, tetany
– Soft tissue calcifications
Maintaining Acid-Base Balance
• Normal plasma pH 7-35-7.45: hydrogen ion
• Major extracellular fluid buffer system;
bicarbonate-carbonic acid buffer system
• Kidneys regulate bicarbonate in ECF
• Lungs under control of medulla regulate CO2,
carbonic acid in ECF
• Plasma pH is an indicator of hydrogen ion (H+) concentration.
• Normal range pH (7.35–7.45).
• Buffer systems
– Kidneys
– Lungs
• The H+ concentration is extremely important:
– Increased concentration H+
• Increased acidity
• Lower the pH.
– Deceased H+ concentration
• Increased alkalinity
• Higher the pH.
• pH range compatible with life (6.8–7.8)
Acid-Base Disorders
• Acidosis: hydrogen ion concentration above
normal (pH below 7.35)
• Alkalosis: hydrogen ion concentration below
normal (pH above 7.45)
• Metabolic Acidosis: bicarbonate is decreased
in relation to the amount of acid
Acid-Base Disorders
• Metabolic Alkalosis: excess of bicarbonate in relation
to the amount of hydrogen ion
• Respiratory Acidosis: CO2 is retained, caused by
sudden failure of ventilation due to chest trauma,
aspiration of foreign body, acute pneumonia, and
overdose of narcotics or sedatives
• Respiratory Alkalosis: CO2 is blown off, caused by
mechanical ventilation and anxiety with
Arterial Blood Gases
• pH 7.35 - (7.4) - 7.45
• PaCO2 35 - (40) - 45 mm Hg
• HCO3ˉ 22 - (24) - 26 mEq/L
– Assumed average values for ABG interpretation
• PaO2 80 to 100 mm Hg
• Oxygen saturation >94%
• Base excess/deficit ±2 mEq/L
• Respiratory acidosis
↑ PaCO2, ↑ or normal
and HCO3 −, ↓ pH
Kidneys eliminate H+
retain HCO3−
• Respiratory alkalosis
↓ PaCO2, ↓ or normal
and HCO3−, ↑ pH
Kidneys conserve H+
excrete HCO3−
• Metabolic acidosis
↓ or normal PaCO2,
↓ HCO3−, ↓ pH
Lungs eliminate CO2,
conserve HCO3−
• Metabolic alkalosis
↑ or normal PaCO2,
↑ HCO3−, ↑ pH
Lungs ↓ ventilation to↑
PCO2, kidneys
conserve H+ to
excrete HCO3−
IV Site Selection
Complications of IV Therapy
Fluid overload
Air embolism
Septicemia, other infections
Infiltration, extravasation
Clotting, obstruction

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