Fluid & electrolytes

1. Fluid & Electrolytes
Acid –Base Balance
Chapter 4

2. Amount/Composition of Body Fluids
• 60% of body weight = fluid.
• Age, gender, body fat influence amount.
• Body fluid is divided into 2 compartments
• Intracellular space (2/3) – fluid in cells
• Extracellular space (1/3) – fluid outside of cells
• Intravascular space (fluid in blood vessels: plasma) 3.5L
• Interstitial space (lymph fluid) 10L
• Transcellular fluid spaces (cerebrospinal, pericardial, synovial, intraocular) 1L

3. Electrolytes: Active chemicals in body fluids
Cations: Positively Charged
• Sodium
• Potassium
• Calcium
• Magnesium
• Hydrogen
Anions: Negatively Charged
• Chloride
• Bicarbonate
• Phosphate
• Sulfate
• proteinate

4. Vocabulary
• Diffusion: The natural tendency of a substance to move from an area
of high concentration to one of lower concentration.
• Hydrostatic pressure: the pressure exerted by the fluid on the walls
of the blood pressure by the heart
• Oncotic pressure: Pressure exerted on the capillaries primarily by
albumin.
• Osmolality: The concentration of fluid that affects the movement of
water between fluid compartments by osmosis.
• Osmosis: The movement of water caused by a concentration
gradient.
• Tonicity: The ability of all solutes to cause an osmotic driving force
that promotes water movement from one compartment to another.

5. Average Daily I & O (Adult)
Average Intake = 2600 ml/day
• Oral Liquids = 1300 ml
• Solid Foods = 1000 ml
• Oxidation = 300 ml
Average Output = 2600 ml/day
• Kidneys (urine) = 1500
• Skin (perspiration) = 600
• Lungs (respiration) = 400
• GI Tract (feces) = 100

6. Sensible vs. Insensible Loss
Sensible Loss:
Fluid loss that can be measured
• Urination
• Defecation
• Bleeding
• Wound drainage
• Gastric drainage
• Vomiting
Insensible Loss:
Fluid loss that cannot be measured
• Perspiration
• Respiration
• Changes in humidity levels,
respiratory rate and depth, and
fever affect insensible loss

7. Homeostasis
• Organs involved in homeostasis include:
• Kidneys
• Lungs
• Heart
• Adrenal glands
• Parathyroid glands
• Pituitary glands

8. Hypovolemia
(fluid volume deficit)
• FVD occurs when loss of ECF exceeds intake of fluid.
• Hypovolemia or FVD ≠ dehydration - Dehydration is loss of H2O only!!
• Causes:
• Vomiting/Diarrhea
• GI suctioning
• Sweating
• Decreased intake
• Risk Factors:
• Diabetes insipidus
• Adrenal insufficiency
• Osmotic diuresis
• Hemorrhage
• 3rd spacing
• Coma

9. Hypovolemia
(fluid volume deficit)
• Signs (Manifestations):
• Acute weight loss
• Decreased skin turgor
• Oliguria
• Concentrated urine w/high specific gravity
• Weak rapid pulse
• Flattened neck veins
• Decreased central venous pressure
• Elevated BUN out of proportion to creatinine (>20:1)

10. Hypervolemia
(fluid volume excess)
• Isotonic expansion of the ECF caused by:
• Abnormal retention of water AND sodium. (proportionately)
• Occurs secondary to retention of Na+
• Causes:
• Fluid overload
• Diminished function of homeostatic mechanisms
• Cirrhosis, heart/renal failure
• Excessive table salt

11. Hypervolemia
(fluid volume excess)
• Manifestations:
• Weight gain
• Edema
• Polyuria
• Distended neck veins
• Crackles in lung fields SOB/wheezing
• Tachycardia
• Increased blood/pulse pressure
• Increased central venous pressure

12. Sodium (135-145 mEq/L)
Hyponatremia
• Causes:
• ↑ Vasopressin/ADH
• SIADH
• Adrenal Insufficiency
• Diuretics
• Hypervolemia
• Liver Failure
• Heart Failure
• Psychogenic polydipsia
Hypernatremia
• Causes:
• Dehydration/Hypovolemia
• Diabetes Insipidus
• Ingestion/Infusion of Hypertonic
Solutions
• Cushing’s Syndrome
• Hyperaldosteronism
• Loss of pure water (excessive
sweating or respiratory infections)

13. Sodium (135-145 mEq/L)
Hyponatremia
• Signs & Symptoms:
• Nausea/Vomiting
• Headache
• Malaise
• Confusion
• Diminished Reflexes
• Confusion
• Convulsions
• Stupor or Coma
Hypernatremia
• Signs & Symptoms:
• Thirst
• Lethargy
• Edema
• Decreased vascular volume
• Neurologic Dysfunction
(d/t dehydration of brain cells)
• Irritability
• Weakness
• Seizures
• Coma

14. Sodium (135-145 mEq/L)
Hyponatremia
• Treatment:
• Oral/IV Na+ (3%) supplements
• Encourage foods high in Na+
• Fluid restriction
• Monitor I&Os
• Daily weights
• Monitor Neuro Status
• Monitor for Arrhythmias
Hypernatremia
• Treatment:
• Hypotonic IV Fluids
• Encourage foods low in Na+
• Push P.O. Fluids
• Monitor I&Os
• Monitor Neuro Status
• Monitor for Arrhythmias

15. Potassium (3.5 – 5.0 mEq/L)
Hypokalemia
• Causes:
• Increased Urine Output
• Malnutrition
• Vomiting and/or Diarrhea
• Hypomagnesemia
• DKA
Hyperkalemia
• Causes:
• Renal Failure
• Meds (ACEIs, ARBs, K+ sparing
diuretics, NSAIDs)
• Addison’s Disease
• Aldosterone Insufficiencies
• Digoxin Overdose
• Beta-Blocker Therapy

17. Potassium (3.5 – 5.0 mEq/L)
Hypokalemia
• Treatment
• Oral/IV Potassium Chloride
Replacement
• D/C or adjust meds causing  K+
• Reverse alkalosis, if cause
• Monitor closely for arrhythmias
• Monitor Respiratory Status
• Monitor LOC
• Monitor GI symptoms
Hyperkalemia
• Treatment:
• Medications: (D/C meds that may
cause hyperkalemia)
• Restrict foods with K+
• Dialysis for renal failure
• Monitor closely for arrhythmias
• Monitor Blood Pressure
• Monitor GI symptoms

18. Calcium (9.0 – 10.5 mg/dL)
Hypocalcemia
• Causes
• Inadequate calcium intake (ETOH,
malnutrition)
• Increased calcium loss (pancreatic
insufficiency)
• Malabsorption of calcium
• Decrease in serum protein levels
• Increased binding of calcium
Hypercalcemia
• Causes:
• Malignancy
• Hyperparathyroidism
• Prolonged immobilization
• Milk-alkali syndrome (Too many
Tums)

19. Calcium (9.0 – 10.5 mg/dL)
Hypocalcemia
• Signs & Symptoms
• Tetany
• Muscle spasms/convulsions &
seizures
• Trousseau’s & Chvostek’s signs
• Dyspnea & laryngospasm (stridor)
• Torsades de pointes (v. tach)
• Hyperactive bowel sounds
• Brittle hair/nails
Hypercalcemia
• Signs & Symptoms:
• Muscle weakness/Incoordination
• Anorexia/Constipation
• Hypertension
• Severe thirst/polyuria
• Bone pain/Kidney stones
• Psychiatric symptoms
• Cardiac standstill > 18 mg/dL

20. Calcium (9.0 – 10.5 mg/dL)
Hypocalcemia
• Treatment:
• PO or IV calcium replacement
(depends on severity of symptoms
or deficiency)
• Vitamin D supplement
• Encourage foods high in calcium
Hypercalcemia
• Treatment:
• Hydration
• Increased Salt Intake
• Diuretics
• Dialysis (renal failure)
• Glucocorticoids

21. Magnesium (1.3-2.3 mEq/L)
Hypomagnesemia
Causes:
• Alcoholism (#1)
• Malnutrition/malabsorption
• Chronic Diarrhea
• Diuretics
• DKA
• Pancreatitis
• Sepsis/burns/hypothermia
Hypermagnesemia
Causes:
• Renal Failure (#1)
• Untreated DKA
• Adrenocortical insufficiency
• Lithium toxicity

22. Phosphorus (2.5 – 4.5 mg/dL)
Hypomagnesemia
Causes:
• Use of nutritional supplements
(enteral or parenteral feedings)
• s/sx: neuro/muscular symptoms
• Treatment:
• Phosphorus supplementation
Hypermagnesemia
Causes:
• Renal failure (asymptomatic)
• Treatment focuses on underlying
disorder

23. Chloride (97-107 mEq/L)
Hypochloremia
Rarely occurs in the absence of
other abnormalities.
• S/Sx: associated with:
• Hyponatremia
• Hypokalemia
• Metabolic alkalosis.
• Treatment: Correct the cause.
Hyperchloremia
Causes r/t :
• Hypernatremia
• Bicarbonate loss
• Metabolic acidosis
Treatment: correct the cause.
*Restore fluid, lytes, & acid-base
balance.

24. Acid–Base Balance
• Homeostatic mechanisms keep pH within a normal range (7.35 to
7.45)
• Buffer systems prevent major changes in the pH of body fluids by
removing or releasing H+
• The major extracellular buffer system is the bicarbonate–carbonic acid
buffer system
• The kidneys regulate the bicarbonate level in the ECF
• The lungs, under the control of the medulla, regulate the CO2 and the
carbonic acid content of the ECF

25. Metabolic Acidosis (Base Bicarbonate Deficit)
• pH is >7.45 and PaCO2 is <35 mm Hg
• Always caused by hyperventilation
• Signs consist of lightheadedness due to vasoconstriction and
decreased cerebral blood flow, inability to concentrate, numbness
and tingling from decreased calcium ionization, tinnitus, and
sometimes loss of consciousness
• Treatment depends on the underlying cause of respiratory alkalosis

26. Arterial Blood Gases:
Blood gas analysis is often used to identify the
specific acid–base disturbance and the degree
of compensation that has occurred