Chapter 8. Intravenous Therapy Show
Patients are prescribed an IV solution (fluids) based on their electrolyte and fluid volume status. IV fluids are commonly categorized as colloids and crystalloids. Colloid solutions contain large molecules that cannot pass through semi-permeable membranes and are used to expand intravascular volume by drawing fluid from extravascular space via high osmotic pressure. Examples of colloid solutions are albumin, dextrans, and hydroxyethyl starches (Crawford & Harris, 2011). Crystalloid solutions contain solutes such as electrolytes or dextrose, which are easily mixed and dissolvable in solution. Crystalloids contain small molecules that flow easily across semi-permeable membranes, which allows for transfer from the bloodstream into the cells and tissues (Crawford & Harris, 2011). They may increase fluid volume in interstitial and intravascular space. Examples of crystalloid solutions are isotonic, hypotonic, and hypertonic solutions. Isotonic solutions have an osomolality of 250 to 375 mOsm/L. Isotonic solutions have the same osmotic pressure as plasma, creating constant pressure inside and outside the cells, which causes the cells to remain the same (they will not shrink or swell) and does not cause any fluid shifts within compartments. Isotonic solutions are useful to increase intravascular volume, and are utilized to treat vomiting, diarrhea, shock, and metabolic acidosis, and for resuscitation purposes and the administration of blood and blood products. Examples of isotonic solutions include normal saline (0.9% sodium chloride), lactated Ringer’s solution, 5% dextrose in water (D5W), and Ringer’s solution. It is important to monitor patients receiving isotonic solutions for fluid volume overload (hypervolemia) (Crawford & Harris, 2011). Hypotonic solutions have a lower concentration, or tonicity, of solutes and have an osomolality equal to or less than 250 mOsm/L. The infusion of hypotonic solutions lowers the osmolality within the vascular space and causes fluid to shift to the intracellular and interstitial space. Cells will swell but may also delete fluid within the vascular space. Examples of hypotonic solutions include 0.45% sodium chloride, 0.33% sodium chloride, 2.5% dextrose in water, and 0.2% sodium chloride. Monitor for hypovolemia and hypotension related to fluid shifting out of the vascular space, and do not administer to patients with increased intracranial pressure (ICP), as it may exacerbate cerebral edema. Use cautiously in patients with burns, liver failure, and traumas (Crawford & Harris, 2011). Hypertonic solutions have a higher concentration, or tonicity, of solutes and have an osomolality equal to or greater than 375 mOsm/L. The osmotic pressure gradient draws water out of the intracellular space into the extracellular space. Examples of hypertonic solutions include D5W and 0.45% sodium chloride, D10W, and 3% sodium chloride. Hypertonic solutions may cause intravascular fluid volume overload and pulmonary edema, and they should not be used for an extended period of time. Hypertonic solutions should not be used in patients with heart or renal disease who are dehydrated (Crawford & Harris, 2011). Read the article IV fluids: what nurses need to know for more in-depth information regarding colloid and crystalloid solutions. Although all IV fluids must be administered carefully, hypertonic solutions are additionally risky. An order for IV fluids may be continuous or as a bolus, depending on the needs of the patient. IV solutions are available in 25 ml to 1000 ml bags. The frequency, duration, amount, and additives to solution must be ordered by a physician or nurse practitioner; for example, an order may be “give NS at 125 ml/hr.” The most common types of solutions include normal saline (NS) and D5W. Patients may also have medications, such as potassium chloride, thiamine, and multivitamins, added to IV solutions. To discontinue an IV infusion, an order must be obtained from the physician or nurse practitioner (Perry et al., 2014). IV Administration EquipmentWhen a peripheral vein has a cannula inserted, an extension tubing is connected to the hub on the cannula and flushed with normal saline to maintain patency of the cannula. Most peripheral intravenous cannulas will have extension tubing, a short, 20 cm tube with a positive fluid displacement/positive pressure cap attached to the hub of the cannula for ease of access and to decrease manipulation of the catheter hub (Vancouver Coastal Health, 2008). The extension tubing must be changed each time the peripheral catheter is changed. When the peripheral cannula is not in use, the extension tubing attached to the cannula is called a saline lock. Intravenous fluids are administered through thin, flexible plastic tubing called an infusion set or primary infusion tubing/administration set (Perry et al., 2014). The infusion tubing/administration set connects to the bag of IV solution. Primary IV tubing is either a macro-drip solution administration set that delivers 10, 15, or 20 gtts/ml, or a micro-drip set that delivers 60 drops/ml. Macro-drip sets are used for routine primary infusions. Micro-drip IV tubing is used mostly in pediatric or neonatal care, when small amounts of fluids are to be administered over a long period of time (Perry et al., 2014). The drop factor can be located on the packaging of the IV tubing. Primary IV tubing is used to infuse continuous or intermittent fluids or medication. It consists of the following parts:
IV solution bags should have the date, time, and initials of the health care provider marked on them to be valid. Add-on devices (e.g., extension tubing or dead-enders) should be changed every 96 hours, if contaminated when administration set is replaced, or as per agency policy. Intravenous solution and IV tubing should be changed if:
Primary and secondary administration sets (see Figure 8.4) should be changed regularly to minimize risk and prevent infection (CDC, 2011; Fraser Health Authority, 2014). Change IV tubing according to agency policy. Table 8.5 lists the frequency of IV tubing change. Table 8.5 Frequency of IV Tubing Changes
Infusing IV Fluids by Gravity or an Electronic Infusion Pump (EID)To ensure therapeutic effectiveness of IV fluids, a constant, even flow is necessary to prevent complications from too much or too little fluid. A physician must order a rate of infusion for IV fluids or for medications. The rate of infusion for medications (given via a secondary or primary infusion) can be found in the Parenteral Drug Therapy Manual (PDTM). If an order for IV fluids is “to keep vein open” (TKVO), the minimum flow rate is 20 to 50 ml per hour, or according to physician’s orders (Fraser Heath Authority, 2014). A health care provider is responsible for regulating and monitoring the amount of IV fluids being infused. IV fluid rates are regulated in one of two ways:
An IV pump must be used for:
To calculate the drops per minute for an infusion by gravity, follow the steps in Table 8.6. Table 8.6 Calculating the Drops per Minute (gtts/min) for an Infusion by Gravity
Take the IV calculations quiz for more practice with IV fluid dose calculation. When an infusion is by gravity, there are several factors that may alter the flow/infusion rate (Fulcher & Frazier, 2007). In addition to regulating the flow rate, assess the IV system to ensure these factors are not increasing or decreasing the flow of the IV solution. These factors are listed in Table 8.7. Table 8.7 Factors Influencing the Flow Rate of Infusions
Assessing an IV SystemAll patients with IV fluid therapy (PIV and CVC) are at risk for developing IV-related complications. The assessment of an IV system (including the IV site, tubing, rate, and solution) (see Figure 8.6) often depends on what is being infused, the patient’s age and medical condition, type of IV therapy (PIV or CVC), and agency policy. Generally, an IV system should be assessed as described in Checklist 65. Figure 8.6 Assess IV site prior to use Checklist 65: Assessing an IV System
Which action would the nurse take when finding that the intravenous IV fluid has extravasated from an IV line?At the first sign of extravasation, nursing intervention with following steps is recommended: stop administration of IV fluids immediately, disconnect the IV tube from the cannula, aspirate any remaining drug from the cannula, administer drug-specific antidote, and notify the physician.
Which physical findings can be seen in a patient with extracellular fluid volume deficit?Important findings include orthostatic hypotension, tachycardia, prolonged capillary refill time and decreased skin turgor. These are defined to students as signs of ECF volume depletion, as dehydration cannot be reliably determined by use of clinical examination.
What assessment findings would indicate circulatory overload from a too rapid IV infusion?Transfusion-associated circulatory overload is characterised by acute respiratory distress, tachycardia, increased blood pressure, acute pulmonary oedema and/or evidence of positive fluid balance occurring within 6 hours after transfusion.
Which body fluid is considered an intravascular fluid?Intravascular fluid is whole blood volume and also includes red blood cells, white blood cells, plasma, and platelets. Intravascular fluid is the most important component of the body's overall fluid balance.
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