If you are a nursing student, you need to understand the physiology of fluids & electrolyte balance as well as acid-base balances in order to anticipate, identify & respond to possible imbalance of each. For student nurses who will be exposed to clinical areas with patients attached to IV fluids, it is very important to know why such an IVF is indicated for a particular patient.
IVF or intravenous fluid therapy is a common practice today. It is an efficient and effective method of supplying fluids directly into the ECF compartment, specifically the venous
Purposes of IV Fluids
1. to supply fluids when clients are unable to take in an adequate volume of fluids by mouth.
Example: patients who are vomiting, patients with altered level of consciousness, patients with disabilities or patients under certain conditions cannot take in fluids orally.
2. to provide salts needed to maintain electrolyte balance.
You have to understand that electrolytes in the body were placed in such a way that it should maintain cellular equilibrium to achieve normal body functioning. If there will be an imbalance to these electrolytes, it will result to a serious disorder or malfunctioning....that's why IVF may come in a form of prevention --- to prevent electrolyte imbalance to occur.
3. to provide glucose (dextrose), the main fuel for metablism.
Glucose is NOT an electrolyte. It is a form of sugar. When carbohydrate is metabolized, it turns into glucose which the cell absorbs for cellular energy production and consumption.
4. to provide water-solube vitamins and medications.
Patients who cannot take in medications or even vitamins orally, may still be given through intravenous route. Either incorporated in an intravenous fluid or as an IV bolus.
5. to promote a life line for rapidly needed medications.
In cases patients develop convulsions or life-threatening conditions, the intavenous line is a helpful medium to give medications for rapid effects.
Common Type of Intravenous Solutions
IV solutions may come in different forms:
1. Depending on its TONICITY (the ability of the solute to cause water movement from one compartment to another)
- Isotonic Solutions
- Hypotonic Solutions
- Hypertonc solutions
2. May also come in a form of:
- Nutrient solutions
- Electrolyte solutions
- Alkalyzing solution
- Acidifying solutins
-solutions that have a concentration of dissolved particles or tonicity equal to that of ICF. Osmotic pressure is equal both in ICF & ECF.
- there is no water displacement, thus, no effect on the cell.
Examples of IVfluids:
- NSS (NOrmal Saline Solution/ 0.9% NaCl) - contains only electrolytes Na&Cl.
- D5W (5% dextrose in water) - contains no electrolytes
- Ringer's solution - &
- Lactated Ringer's Solution - contains Na, K, Ca, Cl & Lactate
- used to maintain fluid intake and reestablish water volume because these fluids stays in the vascular compartment, therefore, it expands the vascular volume. Example...patients who are vomiting, patients with acute diarrhea and fever.
- take note: D5W is an isotonic fluid on initial administration, but when glucose is metabolized, it produces free water.This water may expand both the ICF & ECF fluid volume, thus, acts as a hypotonic solution.
- D5W when given in large amounts may cause hyperglycemia.
Hypotonic solutions have lesser tonicity than that of the ICF because it has lesser solute concentration. ICF becomes more concentrated, it pulls water from the ECF, thus, makes the cell swell.
Examples of Hypotonic Fluids:
- 0.45% NaCl (half strength normal saline)
- 0.33% NaCl ( one third strength normal saline)
- 2.5% Dextrose in water
- used to provide free water and treat cellular dehydration.
- Note: Free water is desirable to aid the kidneys in elimination of solute via urine output.
Hypertonic solutions have tonicity or solute concentration in ECF greater than that of the ICF. Therefore, it pulls fluids out of the ICF...... and the cell shrinks.
Examples of Hypertonic Fluids:
- D5NSS (5% Dextrose in normal saline solution)
- D5 in 0.45% NaCl ( 5% Dextrose in half strength normal saline)
- D5LR (5% Dextrose in Lactated Ringer's Solution)
- D10W ( 10% Dextrose in water)
- D50W50 (50% Dextrose in 50 ml of water)
Aside from being isotonic, hypotonic & hypertonic. IVF may also come in a form of nutrient solution, electrolyte solution, alkalyzing solution & acidifying solution....
Nutrient solutions contain some form of carbohydrates and water. Water is supplied for fluid requirements and CHO for calories and energy requirement. Example... 1 liter of 5% Dextrose provides 170 of calories.
Common Nutrient Solutions are:
- D5W (5% Dextrose in water)
- 3.3% Glucose in 0.3% NaCl (Glucose in saline)
- 5% Dextrose in 0.45% NaCl (Dextrose in half strength saline)
- Nutrient solutions are useful in preventing dehydration. However, it is a wrong notion to say that dextrose increases weight, or promotes normal growth in children or promotes wound healing or healing disorders. The calories it provide are not for such purposes but mainly for prevention of dehydration and ketosis.
Electrolyte solutions are either NaCl (saline solutions) or multiple electrolyte solutions containing varying amounts of cations and anions.
Commonly Used Solutions are:
- Normal Saline Solution (0.9% NaCl Solution) - contains electrolytes Na & Cl only
- Ringer's Solution - contains Na, Cl, K, Ca
- Lactated Ringer's Solution - contains Na, Cl, K, Ca & Lactate( a salt of lactic acid that is metabolized in the liver to form bicarbonate)
NOte: Normal saline solutions are frequently used as initial hydrating solutions. Multiple electrolyte solutions are useful to prevent dehydration or to restore or correct fluid and electrolyte imbalances.
Alkalyzing solutions are administered to counteract or prevent Metabolic Acidosis. Example....Lactated Ringer's Solution
Acidifying slutions are administerd to counteract or prevent Metabolic Alkalosis. Example... 0.9% NaCl &/or D5NSS.