Isotonic Fluids PDF

11/27/23, 4:33 AM Realizeit for Student Isotonic Fluids Fluids that are classified as isotonic have a total osmolality close to that of the ECF and do not cause cells to shrink or swell. When isotonic fluids are administered they expand the ECF volume. One liter of isotonic fluid expands the ECF b...

11/27/23, 4:33 AM Realizeit for Student Isotonic Fluids Fluids that are classified as isotonic have a total osmolality close to that of the ECF and do not cause cells to shrink or swell. When isotonic fluids are administered they expand the ECF volume. One liter of isotonic fluid expands the ECF by 1 L; however, isotonic solution expands the plasma component of ECF by only 0.25 L. An isotonic solution is a crystalloid solution (water containing soluble mineral salts). Plasma is a colloidal solution. A colloidal solution is a mixture of fluid containing insoluble large particles, such as proteins. Colloidal solutions exert oncotic pressure; crystalloids do not exert oncotic pressure (Siparsky, 2019; Sterns, 2018a). Because isotonic fluids expand the water volume in the intravascular space, patients with heart failure or hypertension who receive isotonic solutions should be carefully monitored for signs of fluid overload (Siparsky, 2019). D 5W A solution of D5W is unique in that it may be both isotonic and hypotonic (Hoorn, 2017). Once given, the glucose is rapidly metabolized, and this initially isotonic solution (same osmolality as serum) then disperses as a hypotonic fluid—one third extracellular and two thirds intracellular. It is essential to consider this action of D5W, especially if the patient is at risk for increased intracranial pressure. During fluid resuscitation, this solution should not be used because hyperglycemia can result. Therefore, D5W is used mainly to supply water and to correct an increased serum osmolality. About 1 L of D5W provides less than 170 kcal and is a minor source of the body’s daily caloric requirements (Hoorn, 2017). Normal Saline Solution Normal saline (0.9% sodium chloride) solution contains water, sodium, and chloride. Because the osmolality is entirely contributed by electrolytes, the solution remains within the ECF and expands the intravascular volume. For this reason, normal saline solution is often used to correct an extracellular volume deficit but is not identical to ECF. It is used with administration of blood transfusions and to replace large sodium losses, such as in burn injuries. It should not be used in heart failure, pulmonary edema, renal impairment, or sodium retention. Normal saline does not supply calories (Hoorn, 2017). Other Isotonic Solutions Several other solutions contain ions in addition to sodium and chloride and are somewhat similar to the ECF in composition. Lactated Ringer’s solution contains potassium and calcium in addition to sodium chloride. It is used to correct dehydration, blood loss, and sodium depletion and to replace GI losses. Hypotonic Fluids One purpose of hypotonic solution is to replace fluid, because it is hypotonic compared with plasma. Another purpose of hypotonic solution is to provide free water. At times, hypotonic sodium solutions are used to treat hypernatremia and other hyperosmolar conditions. Half-strength saline (0.45% sodium chloride) solution is frequently used. Hypertonic Fluids Hypertonic fluids include 3% NaCl and IV mannitol. If a patient is sodium depleted, a hypertonic sodium IV solution might be used. If a patient is experiencing acute cerebral edema, IV mannitol is often used. Hypertonic solutions pull water from the interstitial and intracellular compartments into the bloodstream. These solutions draw water out of intracellular compartments causing cellular dehydration (Hoorn, 2017). Normal saline and lactated Ringer’s solution are considered isotonic solutions. When 5% dextrose (D5W) is added to normal saline solution or lactated Ringer’s solution, the total osmolality exceeds that of the ECF. With the added dextrose, these are then considered hypertonic solutions. However, the dextrose is quickly metabolized, and after the dextrose is depleted, only the isotonic solution remains. Therefore, any effect on the intracellular compartment is temporary. Similarly, with hypotonic electrolyte solutions containing 5% dextrose, once the dextrose is metabolized, these solutions disperse as hypotonic fluids. However, higher concentrations of dextrose, such as 50% dextrose (D50W) in water, are strongly hypertonic. Hypertonic solutions should be administered into central veins so that they can be diluted by large amounts of rapid blood flow (Hoorn, 2017). Saline solutions are also available in osmolar concentrations greater than that of the ECF. These solutions draw water from the ICF to the ECF and cause cells to shrink. If given rapidly or in large quantity, they may cause an extracellular volume excess and precipitate circulatory overload and dehydration. As a result, these solutions must be given cautiously and usually only when the serum osmolality has decreased to dangerously low levels. Hypertonic solutions exert an osmotic pressure greater than that of the ECF (Hoorn, 2017). https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 1/2 11/27/23, 4:33 AM Realizeit for Student Quality and Safety Nursing Alert The nurse must assess the patient for a history of allergic reactions to medications. Although obtaining drug allergy information is important when administering any medication, it is especially critical with IV administration, because the medication is delivered directly into the bloodstream. This can trigger an immediate hypersensitivity reaction. Other Intravenous Therapies When the patient is unable to tolerate food, nutritional requirements are often met using the IV route. Solutions may include high concentrations of glucose (such as 50% dextrose in water), protein, or fat to meet nutritional requirements. The IV route may also be used to administer colloids, plasma expanders, and blood products (Hoorn, 2017). Examples of blood products include whole blood, packed RBCs, fresh-frozen plasma, albumin, and cryoprecipitate. Many medications are also delivered by the IV route, either by continuous infusion or by intermittent bolus directly into the vein. Because IV medications enter the circulation rapidly, administration by this route is potentially hazardous. All medications can produce adverse reactions; however, medications given by the IV route can cause these reactions quickly after administration, because the medications are delivered directly into the bloodstream. Administration rates and recommended dilutions for individual medications are available in specialized texts pertaining to IV medications and in manufacturers’ package inserts; these should be consulted to ensure safe IV administration of medications (Institute for Safe Medication Practices [ISMP], 2019). https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IZsc2gfB3djkaGXwQ9ctgb2A3gz%2bCKrCW4cKwIi8CIqb… 2/2