Page 2 - Physiological Adaptation Study Guide for the NCLEX-RN Exam

Fluids and Electrolytes

Proper nursing care is essential with regard to a patient’s balance of fluid and/or electrolytes.

Signs and Symptoms of Imbalance

Recognize the signs and symptoms associated with both excess and deficient fluid volume (hypovolemia and hypervolemia) and important electrolytes (sodium, potassium, calcium, magnesium, phosphate, and chloride). Understand the most likely cause of these imbalances given the current health state of the patient as well as the proper management of these conditions.


Hypervolemia is an excess of body fluids (plasma). Underlying causes can vary. Common causative factors include an increased sodium level (hypernatremia), the inability to clear excessive fluids/supplementation effectively, and organ failure (heart, renal, and/or hepatic). Hypervolemic patients may demonstrate hypertension, dyspnea/shortness of breath, abdominal ascites, peripheral edema, distended jugular veins, and tachycardia. Monitor for bounding pulses and adventitious breath sounds (rales, crackles) throughout the exam.

Hypovolemia is the deficit of body fluids and may occur in response to loss via hemorrhage, dehydration, vomiting, and diarrhea. Clinical signs of hypovolemia may include hypovolemic shock, decreased cardiac output, metabolic acidosis, multisystem organ failure, coma and death, if uncorrected. Weak, thready pulses, shallow breath sounds, sunken facial features, and poor skin turgor may be assessed during episodes of hypovolemia.


  • Sodium: 135–145 mEq/L. Understand the most likely causes and manifestations of excess sodium (hypernatremia) and sodium deficits (hyponatremia). Understand the direct inverse relationship to fluid. Know the likely endocrine disorders that primarily manifest with sodium imbalances (diabetes insipidus, syndrome of inappropriate antidiuretic hormone/SIADH). Symptoms of hypernatremia include thirst, confusion, neuromuscular excitability, seizures, and coma. Symptoms of hyponatremia include nausea/vomiting, headache, confusion, fatigue, restlessness/irritability, muscle weakness, seizures, and coma.

  • Potassium: 3.7–5.2 mEq/L. Understand the most likely causes and manifestations of excess potassium (hyperkalemia) and deficits (hypokalemia). Hypokalemia may occur in the event of diuretics, laxatives, corticosteroids, vomiting/diarrhea, hypomagnesemia, dialysis, insulin overdose, alkalosis, refeeding syndrome, and anorexia. Hyperkalemia may occur in the event of acute/chronic kidney disease, heparin, lithium, congestive heart failure, cirrhosis, sickle cell disease, insulin deficiency, acidosis, digoxin toxicity, and potassium supplementation. Peaked T-waves are often noted with hyperkalemia, whereas decreased T-wave amplitude is characteristic of hypokalemia. Neuromuscular changes are also common in the event of either hypo or hyperkalemia.

  • Calcium: 8.5–10.6 mg/dL. Understand the endocrine feedback system responsible for calcium regulation. Know the most common pathophysiologic causes of calcium excess (hypercalcemia) and deficits (hypocalcemia) as well as common medications that can trigger calcium imbalance (thiazides, lithium, phenobarbital, corticosteroids, etc.). Symptoms of hypercalcemia include fatigue, depression, confusion, anorexia, nausea, constipation, renal tubular defects, polyuria, short QT interval, and arrhythmias. Symptoms of hypocalcemia include fatigue, cramping, weakness, paresthesias, altered mental status, hypotension, prolonged QT interval, and arrhythmias.

  • Magnesium: 1.7–2.2 mg/dL. Understand the underlying endocrine and disease processes that commonly affect magnesium levels along with medications that can potentially trigger hypermagnesemia (antacids and laxatives) as well as hypomagnesemia (diuretics, antibiotics, cisplatin, PPIs, etc.). Symptoms of hypermagnesemia include neuromuscular symptoms, muscle weakness, nausea/vomiting, shortness of breath, cutaneous flushing, hypotension, bradycardia, and hypocalcemia. Symptoms of hypomagnesemia include muscle cramps, hyperreflexia, depression, generalized weakness, anorexia, vomiting, convulsions, apathy, hypertension, ventricular arrhythmia, and death.

  • Phosphate: 0.81–1.45 mmol/L. Be able to identify the disease processes, medications, and endocrine dysfunctions that produce phosphate imbalances. Be able to identify the clinical manifestations of both hypo and hyperphosphatemia. Symptoms of hyperphosphatemia include muscle cramps, numbness around the mouth, bone and joint pain, weak bones, rash, and itchy skin. Symptoms of hypophosphatemia include weakness, trouble breathing, bone fractures, anorexia, tooth decay, and irritability.

  • Chloride: 97–107 mEq/L. Understand the main metabolic causes for low chloride levels or hypochloremia (metabolic alkalosis, respiratory acidosis, hyponatremia, etc.), as well as disease processes that can produce it (cystic fibrosis, etc.). Be able to recognize the clinical signs and symptoms of hypochloremia including fluid loss, dehydration, weakness, fatigue, increased work of breathing, and diarrhea or vomiting. Increased chloride levels, or hyperchloremia, can be the result of numerous disease processes (renal disease, diabetes, hyperparathyroidism, etc.) and through fluid losses (diarrhea, dehydration, diuresis). Be familiar with the common clinical manifestations of hyperchloremia such as fatigue, muscle weakness, excessive thirst, dry mucous membranes, and hypertension l.

Pathophysiology Application

Caring for a patient with either fluid or electrolyte imbalances or both requires you to carefully consider and anticipate both the pathophysiologic responses to the condition and its treatment. In addition to recognizing the signs and symptoms of these disorders, you must also be aware of the risk factors for their development. This should be an important part of your overall assessment and evaluation.

Patient Care Management

Care of hypervolemia generally includes fluid/sodium restriction and diuretic medications to clear excess fluid. In hypovolemia, treatment is directed at correction of the underlying cause and is dictated by the patient’s severity. This may range from intravenous fluid supplementation to proper patient positioning (Trendelenburg), plasma expanders, and the administration of blood and blood products.

Management of a patient with electrolyte imbalance(s) will rely heavily on correcting the underlying cause (when applicable) along with replacement of depleted electrolytes when indicated and interventions to deplete excesses when applicable. Some of these management scenarios can include emergent interventions, so be familiar with these (cardiac manifestations, seizures, etc.).

Evaluation of Patient Response to Treatment

As with any treatment given, ongoing patient evaluation will be necessary to ensure patient safety and effectiveness. This will include monitoring for clinical signs and symptoms of normalization of fluids and electrolytes as well as over or undercorrection. Serial lab draws and values will be utilized as well. Certain lifestyle modifications (diet, fluid restriction, medications, etc.) may be necessary for long-term maintenance.


The care of patients who require hemodynamic monitoring is complex. Understand the unique pathophysiologic changes of each patient, as well as the basic aspects of care for patients that require routine and advanced hemodynamic monitoring and intervention.

Patient Assessment for Decreased Cardiac Output

Understand the physiological principle of: cardiac output (CO) = stroke volume (SV) x heart rate (HR). Normal cardiac output of 4 to 8 L/min is necessary to meet the body’s physiological demands. When this falls short, impairment (mild to severe) will occur. Be familiar with the clinical signs of diminished cardiac output such as diminished peripheral pulses, hypotension, hypoxia, and reduced organ/tissue perfusion (and its sequelae).

Cardiac Rhythm Strip Abnormalities

Being able to read a cardiac rhythm strip and identify abnormalities is essential for prompt identification and intervention of potentially fatal arrhythmias. Know the proper steps for reading a rhythm strip and the proper timing for all of the waveforms, intervals, and complexes. Understand how to interpret abnormalities in sinus rhythms (tachycardia, bradycardia, etc.), atrial arrhythmias [atrial flutter, atrial fibrillation, supraventricular tachycardia (SVT), and premature atrial contractions/complexes (PACs)], and ventricular arrhythmias [idioventricular rhythm, ventricular tachycardia, agonal rhythm, ventricular fibrillation, Torsades de Pointes, premature ventricular contractions (PVCs), and asystole]. Also be able to recognize the various types of heart block (first, second-type I and II, and third degree as well as bundle branch).

Pathophysiology Application

Be able to recognize the common physical signs and symptoms of cardiac abnormalities and correlate them with abnormal electrocardiogram (EKG) findings. Also be able to describe the altered path of electrical impulse/cardiac depolarization from normal in each of the above disorders and correlate that with the findings on an EKG (missing P waves, wide QRS complexes, etc.). Understand and be able to distinguish between potentially life-threatening arrhythmias and more benign ones.

Patient Care

Nursing care of patients undergoing altered hemodynamics is usually specialized, but every nurse must have a basic knowledge of the principles of cardiac care.

Providing Patient Strategies

Patients with decreased cardiac output will require physical and psychological modifications to cope with their condition. Provide patients with the proper strategies for activity modification, rest, diet, pain modification in addition to ways to deal with cognitive/emotional changes that may result from impaired cardiac function. Also remember that these patients may need proper planning for safety and reduction of risk due to their condition.


Be familiar with emergent intervention protocols for cardiac emergencies (CPR, ACLS protocols, etc.) and be able to initiate them. Also be familiar with the monitoring and maintenance of cardiac pacemakers/defibrillators for patients with chronic cardiac arrhythmias. When caring for patients who have just undergone placement of a pacemaker, be familiar with the common complications of pacemaker placement including insertion site infection, swelling, bleeding, damage to the blood vessels or nerves, and collapsed lung.

Managing Care of Patients in Special Circumstances

Some cardiac patients will require special care and management depending on their specific care plan and/or condition.

Arterial lines— The most common vessels used for surgical placement of arterial lines include the radial and femoral arteries. Indications for arterial lines include need for continuous hemodynamic monitoring, frequent blood sampling, and arterial blood gas sampling. Absolute contraindications to arterial lines include absent pulse, full-thickness burns over the insertion site, inadequate circulation to the extremities, and Raynaud syndrome. Risk versus benefit should be assessed in clients with anticoagulation therapy, atherosclerosis, coagulopathy, infection at the insertion site, partial-thickness burns, previous surgery in the area, and synthetic vascular graft.

Pacing device— There are numerous external cardiac pacing devices available to patients. Some familiar types include transcutaneous, transvenous, and epicardial. Indications for external cardiac pacing devices include symptomatic bradycardia, sinus node or AV node dysfunction, and traumatic cardiac injury. Common problems with pacing devices include failure to trigger the appropriate cardiac chamber, underdetection or overdetection of cardiac signals, and unusual EKG findings due to incorrect pacing. Pacing devices are programmed prior to and throughout therapy as indicated and may need routine battery changes and software updates. Review other interventions that may also be indicated in the management of pacing devices.

Telemetry— Care of patients on telemetry devices (i.e., continuous cardiac monitoring) may be done solely by the nurse or in conjunction with a specially trained technician. Ultimately, the nurse is responsible for the analysis, interpretation, and intervention(s) provided based on the telemetry reading.

Hemodialysis or continuous renal replacement therapy (CRRT) — Understand and be familiar with the various types of venous access that may be used for these patients (arteriovenous shunt, fistula, dialysis catheter, or graft) and the care that they require (anticoagulant therapy, careful fluid balance, central line management, etc.) as well as how to properly monitor a patient before, during, and after therapy. Common complications from hemodialysis and CRRT include hypovolemia, hypotension, hypertension, infection, and electrolyte imbalance.

Alteration in hemodynamics, tissue perfusion, and hemostasis— Understand and be able to recognize patients with impaired perfusion of the cerebral, cardiac, and peripheral tissues/organs. Be able to identify the signs and symptoms for each and properly intervene when necessary. Nurses must frequently assess skin turgor, capillary refill and monitor clients’ intake and output. Understand and be able to recognize the risk factors for cerebral, cardiac and peripheral hemostasis, and when it is a desired outcome (i.e., hemorrhage prevention postoperatively). The goal of care of patients with any of these issues is to correct and treat any identifiable, underlying cause and promote good tissue perfusion.

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