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IV therapies for patients with fluid and electrolyte imbalances.

Hanging accurate IV solutions specific to medical conditions can significantly impact the health and healing of patients. This article describes accurate identification of a patient's fluid and electrolyte status, understanding tonicity, and knowing appropriate IV therapies.

Scenario One

A 32-year-old male athlete who had been participating in a local marathon was brought to the emergency department confused and lethargic. His vital signs on arrival were: temperature 103.5[degrees]F (39.6[degrees]C), heart rate (HR) 106, respirations (RR) 24. The patient was diagnosed with heat exhaustion. The emergency department nurse removed the patient's clothing and applied cool, moist sheets and ice packs to his groin and axilla. The emergency room physician wrote orders to initiate an intravenous (IV) infusion of chilled Lactated Ringer's (LR) at 100 mL/hour, administer 2 L oxygen (C[O.sub.2]) via nasal cannula, monitor heart rate, track urine output (UO) via an indwelling catheter, and observe neurological status.

Scenario Two

A 68-year-old female was admitted to the medical-surgical unit following a total abdominal hysterectomy for ovarian cancer. The patient arrived from the post-anesthesia recovery unit confused and with 2+ pitting edema in her bilateral extremities. Laboratory findings revealed potassium (K+) of 3.4 mEq/L, sodium (Na+) of 128 mEq/L, chloride ([Cl.sup.-]) of 93 mEq/L, carbon dioxide (C[O.sub.2]) of 25 mEq/L, blood urea nitrogen (BUN) of 8 mg/dL, creatinine of 0.7 mg/dL and a blood glucose of 108 mg/dL. The patient was lethargic, but denied pain. A large abdominal dressing was dry and intact. A peripheral IV of 5% dextrose in water (DSW) was infused at 120 mL/hour. The patient was on oxygen at 2 L per nasal cannula.

Scenario Three

A neurosurgical intensive care nurse was assigned to care for a 23-year-old male who sustained severe head trauma following a motor vehicle crash the day before. He had an intracranial pressure (ICP) monitor in place with readings between 15 and 22 mmHg. He was on a ventilator and was responsive to noxious stimuli, didn't follow commands or open his eyes during wake trials from sedation. He had an arterial line in place and a peripheral IV of 5% dextrose in 0.9% normal saline ([D.sub.5]/0.9% NS) infusing at 60 mL/hr.

Choosing the Correct IV Solution

If you were the nurse caring for any of the patients in the above scenarios, would you question any of the orders given? Would you know what to evaluate if the ordered IV solution was appropriate for the patient? Only one of the three scenarios has the appropriate IV therapy hanging given the patient situation. Fluid and electrolyte abnormalities account for numerous health-related complications, including patient mortality (Grossman et al., 2010). Understanding which type of IV fluid to give can improve health and healing and prevent complications, thus saving lives and money.

Categories of IV Solutions

There are two major types of IV solutions: crystalloids and colloids. Crystalloids are water solutions with electrolytes and other substances such as minerals added. An electrolyte is an element from the periodic table with either a positive or negative charge. Examples of positively charged electrolytes are sodium (Na+) and potassium (K+). Sodium is a common electrolyte added to crystalloids. Potassium can be added to the crystalloid solution if the patient's potassium level is low. Other substances without electrical charges such as glucose--usually infused as dextrose--can be added to water solutions (Phillips, 2010).

Crystalloids have different tonicities and are categorized as isotonic, hypotonic, and hypertonic types. It is important to understand the differences in the tonicity of the IV solution because tonicity significantly impacts the fluid and electrolyte status of the patient (Daniels & Nicoll, 2012; Phillips, 2010).These will be discussed further in subsequent paragraphs.

Crystalloids are readily available and less expensive to administer than colloids. Examples of crystalloids are LR, 0.9% normal saline (NS), 0.45% NS (.45 NS or 1/2 NS), [Dextrose.sup.5] Water ([D.sup.5]W),3.0% normal saline (3% NS), [D.sup.5]0.45% NS, and [D.sup.10]W. Water alone cannot be infused intravascularly because it moves too quickly into the red blood cells, causing them to rupture (Daniels & Nicoll, 2012).

Colloids are volume expanders and have larger molecules compared to crystalloids, so colloid molecules remain in the vascular spaces longer. In addition, colloids increase the osmotic gradient, meaning they draw fluid from the interstitial spaces back into the vascular spaces (Phillips, 2010). Less volume is required when using colloids to achieve the same effect compared to a larger amount of crystalloids. Colloids, such as albumin, blood, plasma, and Dextran 40, are useful for patients with fluid volume overload because they expand the intravascular spaces without adding significantly more fluid. Patients with edema can benefit from colloids because the increase in oncotic pressure exerted by colloids pulls fluid from the interstitial and intracellular spaces back into the intravascular spaces, where the kidneys can excrete the excess (Shafiee, Bohn, Hoorn, & Halperin, 2003). Patients with increased intracranial pressure are often treated with colloids because they move fluid from swollen brain cells into the intravascular spaces and do not add a significant amount of extra intravascular fluid. Patients with congestive heart failure are also good candidates for colloid therapy when intravascular expansion is needed, but additional fluid volume could worsen the patient's symptoms.

Tonicity of Crystalloids

Tonicity is the relationship between the amounts of water on both sides of a membrane. A membrane is any surface dividing two areas, for example, vascular walls or the covering of cells. Sometimes the membranes are semi-permeable, meaning they will allow substances (also known as solutes) of a certain size to enter the compartment. Sometimes when solutes are too large to move across a membrane, water will move across the membrane instead; this is referred to as osmosis (Daniels & Nicoll, 2012; Port, 2008). The body strives to maintain equilibrium, a place where there is no movement of solutes or water across the membranes. When equilibrium has occurred on both sides of the membranes, the patient is considered to be in an isotonic state. The goal of parenteral therapy is to achieve or maintain an isotonic state for the patient.


Hypotonic conditions occur when there is a lower concentration of solutes in relationship to water than is considered normal. Patients with fluid overload from excessive fluid intake are often in hypotonic states. Conditions that cause fluid retention such as liver, heart, and renal failure can lead to a hypotonic state for patients. Symptoms such as headache, confusion, twitching, irritability, hypertension, bounding pulses, increased central venous pressures, and jugular venous distention (JVD) are often noted in hypotonic patients. Electrolytes tend to be diluted and thus decreased in the hypotonic patient.


A hypertonic state occurs when there is a higher concentration of solutes in relation to water. Patients who are hypertonic have a deficit of extracellular fluid volume (Patanwala, Amini, & Erstad, 2010). Extracellular fluid loss or too much fluid in the interstitial spaces causes this deficit. Dehydrated patients are often hypertonic and may have these symptoms: thirst, dry mucous membranes, decreased skin elasticity, pale skin color, tachycardia, decreased urine output, postural hypotension, increased hematocrit, and elevated blood urea nitrogen (BUN) and creatinine. All body systems are affected when the patient is in a hypertonic state. Lethargy, confusion, thirst, irritability, and restlessness are common neurological signs evident in patients who are hypertonic. Nausea, vomiting, decreased tearing, dry eyes, dry skin with tenting, clear but rapid and shallow respirations, and weak pulses can be evident in other body systems in patients who have a deficit of extracellular fluid volume. Patients in diabetic ketoacidosis and burned patients are other patient groups who are often in a hypertonic state. Patients who have experienced prolonged vomiting, diarrhea, GI suctioning, surgical patients, prolonged periods of no food by mouth (NPO), excessive use of diuretics, excessive diaphoresis, or have inadequate fluid intake are also at risk for developing hypertonicity.

It is important for medical-surgical nurses to know the tonicity of their patients to understand the purpose of ordered parenteral therapy (Daniels & Nicoll, 2012). The general rule is to provide IV fluids opposite of the patient's tonicity. For example, if the patient is in a hyper tonic state, then an isotonic or hypotonic IV fluid should be administered. If a patient is in a hypotonic state, then a hypertonic or isotonic IV solution is a more appropriate infusion. Figure I depicts the concept of tonicity and appropriate IV therapies.

Choosing the Correct IV Therapy

Isotonic IV Solutions

Isotonic IV solutions include any IV therapy that does not cause osmosis or diffusion, meaning there is no change in the composition of body fluids. Two isotonic fluids commonly used to replace fluid loss in patients who do not have tonicity problems are 0.9% NS and LR. Infusing isotonic fluids does not generally alter the fluid concentrations of the patient when given as maintenance fluids (Criss, 2007). Hypotensive and hypovolemic patients are excellent candidates for isotonic fluid infusions due to the increased fluid volume associated with isotonic fluids. Patients who are hyponatremic benefit from isotonic IV solutions.

The nurse will assess signs and symptoms of isotonic losses such as hypotension, tachycardia, weak peripheral pulses, sunken eyeballs, poor skin turgor, oliguria, and hemo-concentration. Isotonic fluid volume deficits are caused by hemorrhage, gastrointestinal losses, fever, environmental heat, diaphoresis, burned patients, and overuse of diuretics (Phillips, 2010). The nursing care of patients with a fluid volume deficit diagnosis focuses on increasing fluid intake with 0.9% NS, LR or hypotonic solutions, replacing electrolytes, restricting sodium in cases of hypernatremia, and offering oral free water (Daniels, 2010; Daniels & Nicoll, 2012).

Isotonic solutions are appropriate for patients suffering from extracellular fluid deficits such as in hemorrhaging or hypovolemic shock. The nurse can determine if the fluid volume deficit is in the intravascular space or interstitial space based on assessment data of the patient. Patients who have a fluid deficit in the intravascular space often present with orthostatic hypotension, dizziness, syncope, tachycardia, decreased urine output, and thready pulses. The nurse will assess poor skin turgor and dry mucous membranes in patients who have insufficient amounts of fluid in their interstitial spaces. Weight loss is a common assessment finding in generalized extracellular fluid volume deficits (Daniels, 2010; Shafiee et al., 2003).

0.9% NS should be used cautiously in patients with congestive heart failure (CHF) and those who are hypertensive and have left ventricular dysfunction because of the risk of fluid overload. Causes of isotonic fluid volume overload include excessive administration of fluids and excessive irrigation of body cavities (enemas, peritoneal dialysis, gastric lavage, etc.). LR should be used with caution in patients who may be at risk for acidosis such as diabetic ketoacidosis (DKA) and chronic obstructive pulmonary disease (COPD) patients. LR should be avoided in hyperthermic and febrile patients because the breakdown of lactate found in LR is lactic acid, which compounds the acidosis due to body temperature elevation. The liver is unable to metabolize lactate when the body temperature is elevated as in heat exhaustion, heat stroke, and high fevers. Diabetic patients receiving Metformin[R] (glucophage) should not be given LR due to Metformin's common side effect of metabolic acidosis, which would potentiate a lactate complication from an LR infusion (Criss, 2007). LR can worsen cerebral edema, so it is not the fluid of choice in a patient with head trauma (Criss, 2007; Thompson, 2005).

Hypotonic IV Solutions

Hypotonic IV solutions are fluids with solutes less than 0.9% NS. Examples of hypotonic solutions include 0.45% NS and D5/0.45% NS. Hypotonic solutions cause fluid to move into the cells from the interstitial spaces and are useful for increasing total fluid volume and maintaining body fluids. Dehydrated patients, hypernatremic patients, and patients using diuretics are good candidates for hypotonic solutions. Patients with renal disorders, such as diabetes and those on dialysis, benefit from hypo tonic solutions because they help restore renal functioning. The hypotonicity of the fluids provides electrolytes and free water to help renal excretion of metabolic wastes (Phillips, 2010). Hypotonic solutions dilute blood serum and thus decrease the osmolarity of the patient.

Hypotonic solutions should be used cautiously or avoided in patients who are fluid overloaded as hypotonic solutions will compound the problem by moving more fluid into the interstitial spaces to attempt to achieve equilibrium (Phillips, 2010). Patients with fluid overload problems due to syndrome of inappropriate antidiuretic hormone (SIADH), hyponatremia, head trauma, water intoxication, and heart failure would not benefit from a hypotonic solution. Patients with elevated central venous pressure (CVP), rales/crackles, dyspnea, edematous, galloping or extra heart sounds, polyuria, and weight gain would benefit from an IV solution other than hypotonic (Shafiee et al., 2003). Patients who have been receiving hypotonic IV solutions or who have any of the aforementioned conditions should be assessed closely for hyponatremia. Hypotonic IV fluids can dilute sodium, leading to level of consciousness changes such as headache, confusion, twitching, irritability, agitation, and lethargy.

Nurses should assess for fluid volume overload in patients who have been receiving hypotonic solutions for an extended period of time. Hypertension, bounding pulse, weight gain, tachycardia, and skeletal muscle weakness can occur if patients become hyponatremic or fluid overloaded as a result of hypotonic fluids. When nurses identify a patient has fluid volume overload, they should anticipate the primary care provider ordering interventions such as restricting fluids, reducing IV infusion rates, switching to an isotonic or hypertonic IV solution, administering ordered diuretics, and treating the underlying cause should be implemented to restore homeostasis.

Hypertonic IV Solutions

Hypertonic IV solutions are fluids with solutes greater than 0.9%, such as 3.0% NS, [D.sub.5] NS, and [D.sub.5]LR, which pull fluid from cells into the intravascular space. Hypertonic solutions are useful for patients with elevated intracranial pressure (ICP) and some trauma patients (Patanwala et al., 2010; Phillips et al., 2009). Hypertonic IV solutions are useful in stabilizing blood pressure, increasing urine output, and correcting hyponatremia in edematous patients. Patients with inadequate electrolytes could benefit from a hypertonic solution, which helps replace the lost electrolytes. If prolonged use of hypertonic solutions is expected, administering the solution through a central line should be considered (Daniels, 2010).

The nurse should assess often for fluid volume overload in patients receiving hypertonic solutions as the fluid moves out of the cells and into the intravascular space. Assessment findings such as auscultated rales or crackles in the lung fields, shortness of breath, dyspnea, and jugular vein distention might indicate the patient is developing fluid volume overload. The nurse should notify the health care provider and anticipate a reduction or change in the type of IV solution being infused. Hypertonic solutions should not be infused rapidly.


Now that you have more information regarding appropriate IV fluid choices, do you know which of the three patient scenarios presented at the beginning of this article has the correct solution hanging? The answer is the patient in the third scenario. This patient has an elevated ICP following head trauma, so the hypertonic solution of [D.sub.5].9% NS is a good choice for this patient. [D.sub.5].9 NS will help to pull fluid from the cells and into the intravascular space where the excess fluid can be excreted by the kidneys. The shrinking of the brain cells will provide more intracranial space, which will help reduce the ICP. In addition, the IV is infusing at a slower rate, appropriate for hypertonic solutions and patients following head trauma.

The patient in the first scenario is suffering from heat exhaustion, and his liver will not be able to metabolize the lactate in the ordered LR. While it is appropriate to hang chilled IV solutions in an attempt to cool him down, a solution without lactate would be a better choice for this patient. Hypertonic solutions would not be a good choice because patients with dehydration, excessive diaphoresis, and inadequate amounts of fluid intake (all common following intense activities in hot conditions) are likely to be in a hypertonic state.

The patient in the second scenario is post-operative, a common risk factor for hypotonicity. She is showing signs of being in a hypotonic state as evidenced by her lethargy, edematous extremities, hyponatremia, and decreasing BUN and creatinine. The IV solution the patient is getting is a hypotonic fluid, which will make her symptoms worse. The patient would benefit from an isotonic solution at a lower rate or a hypertonic solution until she is returned to an isotonic state.

Understanding osmolality, tonicity, and IV solutions can improve nursing assessment and intervention skills, as well as lead to enhanced patient outcomes (Grossman et al., 2010; Phillips et al., 2009). Because administering and managing IV solutions is a common nursing function, knowledge of the types and reaction of intravenous fluids is essential. Table I depicts the types of fluids, their properties, uses, and cautions presented to be used as a quick reference guide when you are caring for your next patient who has an order to initiate IV fluids.


Criss, E. (2007). A comparison of normal saline and Lactated Ringer's IV solution in the treatment of shock. (Master's thesis). Retrieved from http://www.nursing.

Daniels, R. (2010). Nursing fundamentals: Caring and clinical decision-making. Clifton Park, NY: Delmar Cengage Learning.

Daniels, R.,& Nicoll, L. (2012). Fluid, electrolyte and acid-base imbalances. In R. Daniels & L. Nicoll, Contemporary medical-surgical nursing (2nd ed., pp. 240-267). Clifton Park, NY: Delmar Cengage Learning.

Grossman, R., Mukherjee, D., Chaichana, K.L, Salvatori, R., Wand, G., Brem, H., ... Quinones-Hinojosa, A. (2010). Complications and death among elderly patients undergoing pituitary tumour surgery. Clinical Endocrinology, 73(3), 361-368. doi: 10.1111/j. 1365-2265.2010.03813.x

Patanwala, A.E., Amini, A., & Erstad, B. (2010). Use of hypertonic saline injection in trauma. American Journal of HealthSystem Pharmacy, 67(22), 1920-1928. doi: 10.2146/ajhp090523 Phillips, C.R., Vinecore, K., Hagg, D.S., Sawai, R.S., Differding, J.A., Watters, J.M., & Schreiber, M.A. (2009). Resuscitation of haemorrhagic shock with normal saline vs. Lactated Ringer's: Effects on oxygenation, extravascular lung water, and haemodynamics. Critical Care, 13(2), R30. doi.10.1186/cc7736

Phillips, L.D. (2010). Manual of IV therapeutics: Evidence-based practice for infusion therapy (5th ed.). Philadelphia: F.A. Davis Company.

Port, T. (2008). LesTout Science and Nature: What are diffusion, osmosis and tonicity? Retrieved from news-society/science-nature/what-arediffusion-osmosis-tonicity.html Shafiee, M.A., Bohn, D., Hoorn, E.J., & Halperin, M.L. (2003). How to select optimal maintenance intravenous fluid therapy. Quarterly Journal of Medicine, 96(8), 601 610. doi: 10.1093/qjmed/hcg 101

Thompson, R.C. (2005). Physiologic 0.9% saline in the fluid resuscitation of trauma. Journal of the Royal Army Medical Corps, 151(3), 146-151.

Molly McClelland, PhD, MSN, RN, CMSRN, ACNS-BC, is an Associate Professor of Nursing, University of Detroit Mercy, Detroit, MI. She is the MedSurg Matters! Editor.

Table I.

Reference Guide for Care of the Patient on IV Fluids

Category                   Crystalloids

Type           Isotonic               Hypotonic

Examples       0.9% NS                0.45% NS
               LR                     D5W *
                                      D5.45 NS

Properties     No movement of fluid   Causes fluid to move
                 between spaces         from interstitial
                                        spaces into cells

Useful for     Hemorrhage             Dehydration
               Hypovolemia            Hypernatremia
               Shock                  Excessive diuretic use
               Hypotension            Renal disorders

Cautious In    CHF                    SIADH
               HTN                    Hyponatremia
               Avoid LR in:           Head trauma
                 DKA                  CHF
                 COPD                 Increased CVP
                 Hyperthermia         Pulmonary edema
                 Febrile              Edema
                 Head trauma
                 Metformin use

Category            Crystalloids                  Colloids

Type           Hypertonic

Examples       3.0% NS                   Albumin
               D5.9% NS                  Blood
               DIO                       Plasma
                                         Dextran 40

Properties     Causes fluid to move      Increases intravascular
                 out of cells and into     space without excess
                 intravascular space       fluid
                                         Causes intravascular

Useful for     Head Trauma               Edema
               Increased ICP             Expansion of intravascular
               Hyponatremia                spaces
               Edema                     Improving tissue perfusion
               Acid/base imbalances      Prevention of vasospasm
                                         Severe anemia

Cautious In    Increased PAWP            CHF
               Increased CVP             Hypervolemia
               JVD                       Hemoconcentration

* D5W is isotonic in the bag, but quickly becomes hypotonic
when administered intravascularly (Phillips, 2010).
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Author:McClelland, Molly
Publication:MedSurg Nursing
Article Type:Report
Geographic Code:1USA
Date:Sep 1, 2014
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