1. Fluids, electrolytes, acid-base balance and intravenous therapy
Jennifer kean msn, rn, ccrn

2. water An adult’s body is about 45% water
Infants, children, and older adults are more likely to become dehydrated
Water in the body has 4 main functions:
Be a vehicle for the transportation of substances to and from the cells
Aid heat regulation by providing perspiration which evaporates and cools the body
Assist in maintenance of hydrogen (H+) balance in the body
Serve as a medium for the enzymatic action of digestion

3. diffusion
Diffusion is a process by which solutes pass through a semipermeable membrane from a higher concentration to a lower concentration until they are evenly distributed in the available space

4. osmosis
Osmosis is the movement of pure solvent (liquid) across a membrane
When there are differences in concentration on either side of the membrane, osmotic pressure will move solute particles from the area of greater concentration of solutes to the area of lesser concentration
This process takes place via a semipermeable membrane
Fluid moves between the interstitial and intracellular and between the interstitial and intravascular compartments by osmosis
Diffusion and osmosis are done via passive transport

5. osmosis

6. filtration
Filtration is the movement of water and solutes through a semipermeable membrane as a result of a pushing force (hydrostatic pressure) on one side of the membrane
In the body this happens in the capillaries
The pumping action of the heart creates this hydrostatic pressure in the body
Water and electrolytes move through the capillary wall to the interstitial fluid
Filtration also occurs in the kidney, where waste substances and excess water are eliminated
Filtration is accomplished through active transport

7. filtration

8. Passive and active transport
Diffusion and osmosis are all processes that occur with the process of passive transport (no cellular energy is required)
Glucose, oxygen, carbon dioxide, water and other small molecules move across cell membranes via passive transport
in active transport, these processes require cellular energy
Active transport moves solutes from areas of lower concentration to higher concentration (filtration)
The energy in the body is produced by adenosine triphosphate (ATP)

9. Fluid balance
Body fluids are continually moving in and out of the blood and lymph vessels (intravascular), through the spaces surrounding the cells (interstitial), and in and out of the cells (intracellular)
Osmoreceptors (volume sensors) in the hypothalamus control the fluid volume by sensing when the intake of fluid (thirst mechanism) is needed
Antidiuretic hormone, released by the posterior pituitary, controls how much fluid leaves the body through urination
Aldosterone regulates the reabsorption of water and sodium ions from the kidney tubules
Baroreceptors in the carotids and aortic arch sense blood pressure changes and stimulate the sympathetic or parasympathetic nervous system to return the pressure to normal via the release of these hormones

10. dehydration
Any seriously ill patient is at risk for a fluid and electrolyte imbalance
It is important to remember that water follows sodium in the body through osmosis
Water loss occurs through the processes of urination and perspiration (sensible water loss) and also through defecation and respiration (insensible water loss)
The processes of vomiting, diarrhea, hemorrhage, excessive wound drainage or diuretic therapy may cause excessive fluid losses

11. Signs and symptoms of dehydration
Thirst
Poor skin turgor
Weight loss
Weakness
Dizziness
Postural hypotension
Decreased urine production
Dark urine
Dry lips and tongue
Dry mucous membranes
Sunken eyeballs
Thick saliva
Dry, scaly skin
Flat neck veins when lying down
Rapid, weak, thready pulse
Elevated temp (>100.6)
Increased hematocrit
High urine specific gravity

12. Signs and symptoms of overhydration
Weight gain
Slow, bounding pulse
Elevated blood pressure
Firm subcutaneous tissues
Edema
Possibly crackles on lung auscultation
Lethargy, possible seizures
Possibly visible neck veins when lying down
Decreased serum sodium
Decreased hematocrit from hemodilution
Low urine specific gravity

13. edema
Localized: often occurs with inflammatory process (injury, surgery, etc.)
Dependent: noted in feet, ankles and lower legs in chf patients; is an effect of gravity
Pitting vs. non-pitting
1+, 2+, 3+, 4+
Generalized (anasarca): occurs in critically ill patients

14. Meds commonly used to treat nausea and vomiting
Hydroxyzine (vistaril)
Antihistamine and antiemetic
Never give iv-give by z-track method
Promethazine (Phenergan)
Depresses the cns
Monitor for dizziness and hypotension
Ondansetron (Zofran)
Blocks serotonin centrally and peripherally
Monitor for extrapyramidal symptoms
Metoclopramide (reglan)
Decreases reflux and stimulates stomach emptying
Monitor for extrapyramidal symptoms and renal function

15. Meds commonly used to treat diarrhea
Loperamide (immodium)
Slows intestinal motility
Monitor for constipation; d/c if ineffective after 2 days
Diphenoxylate atropine (lomotil)
Monitor for electrolyte imbalances
Contains narcotic; may be habit-forming
Kaolin/pectin (kaopectate)
Decreases gastric motility
Monitor bowel pattern

16. Major electrolytes Sodium (na+): normal range 135-145 mEq/L
Potassium (K+): normal range mEq/L
Calcium (Ca++): normal range mg/dL
Magnesium (Mg++): normal range mg/dL
Phosphate (po4-): mg/dL
Chloride (Cl-): mEq/L
Bicarbonate (hco3-): normal range mEq/L

17. Hyponatremia (<135 meq/l)
Causes: Occurs from inadequate sodium intake, excessive intake of water, loss of bile, burns, or inappropriate iv therapy
s/s: cns and neuromuscular changes resulting from failure of swollen cells to transmit electrical impulses, Fatigue, lethargy, headache, confusion, altered level of consciousness, anxiety, anorexia, nausea, vomiting, muscle cramps, seizures, Decreased sensation and decreased bp
Treatment: restrict water intake, administer iv fluids containing sodium, provide salty foods

18. Hypernatremia (>145 meq/l)
Occurs from high-sodium diet, inadequate water intake, excessive sweating, diarrhea; high-protein, hyperosmotic tube feedings, dehydration
s/s: dry mucous membranes, taut skin turgor, intense thirst, flushed skin, oliguria, weakness, lethargy, irritability, seizures, coma
Treatment: encourage increased fluid intake, monitor i&o, give water between tube feedings, restrict sodium intake, monitor temp

19. Hypokalemia (<3.5 meq/l)
Causes: Inadequate intake of potassium-rich foods, diarrhea, vomiting, diuretics
s/s: muscle weakness. Cardiac dysrhythmias, decreased reflexes, lethargy, confusion
Treatment: instruct pt. on diet in potassium-rich foods, observe for digitalis toxicity on patients taking digoxin

20. Hyperkalemia (> 5.0 meq/l)
Causes: kidney failure, digitalis toxicity, overuse of salt substitutes
s/s: muscle weakness, fatigue, hypotension, nausea, paralysis, cardiac dysrhythmias, EKG changes
Treatment: decrease intake of potassium-rich foods, increase fluid intake (will enhance excretion via urination), instruct pt. in proper use of salt substitutes

21. Hypocalcemia (<8.4 mg/dl)
Causes: metastatic cancer, inadequate dietary intake, impaired absorption in intestinal tract (overuse of laxatives), hyposecretion of pararthyroid hormone (thyroidectomy)
s/s: paresthesias, abdominal cramps, weak pulse, hypotension, seizures, positive Chvostek sign, positive Trousseau sign, cardiac dysrhythmias, dyspnea, wheezing
Treatment: encourage intake of calcium-rich foods, have 10% calcium gluconate at bedside of thyroidectomy patient, give calcium supplements 30 minutes before meals to aid in absorption

22. Hypercalcemia (>10.6 mg/dl)
Causes: excess intake of calcium (antacids), excess intake of vitamin D, bone tumor, multiple fractures (both cause movement of calcium out of bone and into extracellular fluid), immobility, osteoporosis
s/s: anorexia, nausea, constipation, muscle weakness, oliguria, confusion, renal calculi, pathologic fractures, dysrhythmias
Treatment: administer diuretics as prescribed to enhance excretion via urination, monitor i&o, encourage high fluid intake ( ml per day)

23. Hypomagnesemia (<1.3 meq/l)
Causes: chronic malnutrition, bowel resection with colostomy/ileostomy, chronic alcoholism, thiazide diuretic use, prolonged gastric suction, acute pancreatitis, osmotic diuretic therapy, diabetic ketoacidosis
s/s: insomnia, hyperactive reflexes, leg and foot cramps, twitching, tremors, seizures, cardiac dysrhythmias, vertigo, hypocalcemia, positive Chvostek and trousseau signs, hypokalemia
Treatment: provide diet counseling to at-risk patients to increase their magnesium levels (milk and cereals), monitor iv infusions closely, monitor i&o

24. Hypermagnesemia (>2.1 meq/l)
Causes: overuse of antacids and cathartics containing magnesium, aspiration of sea water as in near-drowning, chronic kidney failure
s/s: hypotension, sweating and flushing, nausea, vomiting, muscle weakness, respiratory depression, cardiac dysrhythmias
Treatment: teach patient to avoid overuse of laxatives and antacids, encourage fluid intake to increase urinary excretion, monitor i&O, administer diuretics as ordered

25. Hypophosphatemia (<3.0 mg/dl)
Causes: vitamin d deficiency or hyperparathyroidism, use of aluminum- containing antacids
s/s: confusion, seizures, numbness, weakness, possible coma, osteomalacia (chronic state)
Treatment: assess for vitamin d deficiency, hyperparathyroidism, overuse of antacids containing aluminum (amphogel)

26. Hyperphosphatemia (>4.5 mg/dl)
Cause: renal insufficiency
s/s: anorexia, nausea, vomiting
Treatment: assess for restlessness, confusion, chest pain, and cyanosis, monitor respirations, check all electrolyte levels

27. Acid-base system
An acid is a substance capable of giving up a hydrogen ion during chemical exchange
a base is a substance capable of accepting a hydrogen ion
Acids react with bases to form water and a salt
A reaction such as this is called a neutralization reaction: both the acid and the base become neutralized
Acids react with carbonates and bicarbonates to form carbon dioxide gas

28. Acid-base system and ph
The term ph refers to the concentration of hydrogen ions (h) in a solution
The higher the concentration of hydrogen ions, the lower the ph
A higher ph indicates the opposite
Acidic solutions are lower on the ph scale (<7.0)
Basic (alkaline) solutions are higher on the ph scale (>7.0)
A chemically neutral solution has a ph of 7.0
The ph of most body fluids are between 7.35 and 7.45; a ph of below 7.25 or above 7.55 is considered life-threatening and a ph<6.8 (acidosis) or >7.8 (alkalosis) is incompatible with life
Acidosis is the result of either a loss of base or an accumulation of acid

29. Acid-base imbalances
Most of the body’s metabolic activity produces carbon dioxide gas, which is acidic
The body takes care of this excess of acidic substance by way of the respiratory tract or the renal system

30. The respiratory system
Hypoventilation produces excess carbon dioxide gas
If the body senses an excess of acids (low ph), the respiratory system will increase the respiratory rate to “blow off” the excess carbon dioxide and return the body to a neutral state
If the body senses an excess of bases (high ph), the respiratory system will slow down the respiratory rate to conserve carbon dioxide and thus lower the ph to a neutral state
“neutral state” meaning a ph between

31. The renal system
Hydrogen ions are either conserved or excreted via the kidneys
So, if the body senses an acidic state, the glomeruli will conserve more bicarbonate (Hco3) to raise the ph to a neutral state
And, if the body senses a basic state, the glomeruli will excrete bicarbonate ions to restore a neutral state with a ph between
Bicarbonate ions are a basic substance
But, carbon dioxide ions are acidic. The body undergoes chemical reactions to form bicarbonate from carbon dioxide by adding water
Water + carbon dioxide= bicarbonate

32. Respiratory acidosis
Causes: slow, shallow respirations due to respiratory congestion or obstruction
Blood gas values
Ph <7.35
Paco2 >45 mm Hg
In respiratory acidosis, the carbon dioxide value will be increased, as carbon dioxide (co2) is an acidic substance; co2 is retained as it is not being exhaled

33. Respiratory alkalosis
Cause: hyperventilation due to anxiety or excitement
In respiratory alkalosis the carbon dioxide is being “blown off” in excess
Slowing down the respiratory rate will conserve carbon dioxide and lower the ph to a neutral level
This can also be accomplished by breathing into a paper bag
Ph >7.45
Paco2 >35 mm Hg

34. Metabolic acidosis
Causes: shock (due to poor circulation), diabetic ketoacidosis, renal failure, diarrhea, hyperkalemia
Ph <7.35
Hco3 (bicarbonate) < 22 meq/l
The kidneys accomplish ph control by excreting or conserving bicarbonate
Bicarbonate is a strong base

35. Metabolic alkalosis
Causes: vomiting, excessive antacid intake, hypokalemia
Ph >7.45
Hco3 >26 meq/l
Example: vomiting causes loss of potassium ions; potassium ions are + (k+); therefore, loss of the positive (acidic) ions cause a base state

36. Arterial blood gases
The levels of these percentages of gases (oxygen and carbon dioxide) and hydrogen ions in the blood are useful in assessing the status of both respiratory and metabolic acid-base balances
Blood gas studies are useful in assessing a patient’s progress toward recovery, or lack of it, and also the respiratory and renal systems’ abilities to regulate the retention or elimination of carbon dioxide and bicarbonate
Lungs= carbon dioxide
Kidneys= bicarbonate

38. Intravenous fluid therapy
The three types of solutions:
Isotonic: a solution that has the same osmotic pressure as the intracellular fluid
Example: 0.9% normal saline
Hypotonic: a solution that has a lower osmotic pressure (is less concentrated) than the intracellular fluid
Example: d5w or 0.45 % normal saline
Hypertonic: a solution that has a higher osmotic pressure (is more concentrated) than the intracellular fluid
Example: d5w + 0.9% normal saline
The blood has a 0.9% sodium concentration; therefore 0.9% saline solution is isotonic

39. When to use which fluid
If the patient is dehydrated: the physician will most likely order 0.9% normal saline solution, % normal saline or d5 % water (d5W)
Rationale: the osmolarity (concentration) of the solutes in the blood is high and these fluids will provide hydration to dilute the solutes and restore homeostasis
If the patient is a surgical or medical patient with no severe fluid imbalances: the physician will most likely order 0.9% normal saline
Rationale: maintain homeostasis
If the patient is fluid overloaded: probably no fluids will be ordered
If the patient is malnourished: the physician will most likely order d5% w+ 0.9 ns
Rationale: provide the patient with fluids and dextrose for nutrition while maintaining homeostasis