Learning Objectives
By the end of this section, you will be able to:
- Discuss the pathophysiology, risk factors, and clinical manifestations of acute tubular necrosis (ATN) and chronic kidney disease.
- Describe the diagnostics and laboratory values used to diagnose ATN and chronic kidney disease.
- Apply nursing concepts and plan associated nursing care of patients with ATN and chronic kidney disease.
- Evaluate the efficacy of nursing care of patients with ATN and chronic kidney disease.
- Describe the medical therapies that apply to the care of patients with ATN and chronic kidney disease.
The kidneys are arguably one of the most important body organs because they participate in many functions necessary for life. The major functions of the kidney include
- blood pressure control
- erythropoietin production for red blood cell regulation
- filtration of waste products and excretion as urine
- regulation of acid-base balance
- regulation of electrolytes
- regulation of water/fluid balance
- synthesis of vitamin D to its active form
Most individuals are born with two kidneys, which are located within the abdominal cavity. They are composed of several different components that are labeled in Figure 20.15. Each kidney has approximately one million nephrons (the functional unit of the kidneys), which assist in the formation of urine for excretion. Without optimal functioning of the kidneys, patients are unable to maintain blood pressure, fluid and electrolyte balance, and many other life-sustaining body system processes. This highlights the importance of providing effective treatment and care for disorders that result in dysfunction of the renal system. Two of the most common disorders that affect the kidneys are acute tubular necrosis (ATN) and chronic kidney disease (CKD), both of which are discussed in more detail in this section.
Patient Populations at Risk for Kidney Disease
One of the biggest risk factors for kidney disease is diabetes mellitus because this condition often results in nephropathy, or problems with the kidney vasculature. Other major risk factors for kidney disease are (American Kidney Fund, n.d.):
- African, American Indian, or Asian heritage
- diabetes mellitus
- family history of kidney disease
- glomerulonephritis
- hypertension
- increasing age
- medication use (e.g., nonsteroidal anti-inflammatory drugs, antibiotics)
- obesity
- polycystic kidney disease
- pyelonephritis
- smoking
- urinary tract obstruction (e.g., urinary tumors, enlarged prostate, kidney stones)
Pathophysiology of ATN
Acute tubular necrosis occurs when there is a lack of adequate oxygen and nutrients being delivered to the kidneys. Without adequate oxygen and perfusion, the kidneys can quickly become necrotic, resulting in kidney failure. Often, the cause of ATN is related to thrombosis, or clot formation, or a buildup of myoglobin that blocks blood flow to the kidneys. This condition is transient, but without prompt intervention and adequate treatment, it can become permanent, resulting in chronic kidney problems.
Clinical Manifestations of ATN
Recognizing and Analyzing Cues
Clinical manifestations of ATN are directly related to a lack of blood flow and perfusion to the kidneys, resulting in their suboptimal functioning. Common clinical manifestations of ATN are
- cardiac dysrhythmias
- confusion
- edema in the extremities
- electrolyte imbalances (e.g., hyperkalemia, elevated serum creatinine and blood urea nitrogen levels, decreased glomerular filtration rate)
- fatigue
- nausea/vomiting
- oliguria (urine output less than 30 mL/h)
- weight gain
Pathophysiology of CKD
The term chronic kidney disease is used to describe long-standing kidney dysfunction lasting longer than three months (Cleveland Clinic, 2020a). If left untreated, CKD can quickly turn into end-stage renal disease, which may require permanent dialysis or even a kidney transplant. Although the specific pathophysiologic mechanism of CKD is poorly understood, specific risk factors have been linked to its development. Patients with any of the risk factors listed in Table 20.12 are at a higher risk than the general population for developing CKD.
Clinical Manifestations of CKD
In many cases, the early stages of CKD are asymptomatic. Symptoms may not even become noticeable until the patient is in the later stages of the disorder that require complex intervention and medical care. Some of the clinical manifestations of CKD are like those seen with ATN, because both conditions result in kidney dysfunction and eventual failure. Clinical manifestations associated with CKD are the following:
- anorexia, nausea, and/or vomiting
- chest pain
- confusion
- edema and swelling of hands and feet
- fatigue
- hypertension
- muscle cramps
- oliguria
- shortness of breath (from fluid build-up in the lungs)
Assessment and Diagnostics
The diagnoses of both ATN and CKD are usually made on the basis of certain laboratory findings. Specific laboratory values that can indicate how well the kidneys are functioning include serum creatinine and blood urea nitrogen (BUN) level, and glomerular filtration rate (GFR). Serum creatinine is a byproduct of skeletal muscle metabolism and breakdown, and this value remains stable from person to person. If the kidneys are unable to filter and excrete creatinine effectively, it can build up in the blood and increased values may indicate kidney damage. Blood urea nitrogen is a byproduct of protein metabolism; elevations of this value may also indicate poor functioning of the kidneys and an inability to excrete the protein product in the urine. However, it is important to note that serum creatinine tends to be a more specific indicator of renal dysfunction than BUN, because other conditions (e.g., dehydration, increased protein intake) can also increase BUN levels. The GFR represents how quickly the kidneys can filter the blood and excrete it as urine. With kidney dysfunction, GFR increases, indicating that it takes a lot longer for the kidneys to filter out and excrete waste products.
Medical Therapies and Related Care
The underlying principles for the treatment of kidney disorders are restoring optimal functioning and treating the underlying cause and associated symptoms. Because the kidneys play such an important role in the maintenance of fluid balance, treatment often revolves around interventions that help to restore optimal fluid balance. Most patients with kidney disorders will experience fluid overload because the kidneys are unable to filter out excess fluid effectively, resulting in manifestations such as edema and weight gain. These patients are often prescribed diuretic medications to remove the excess fluid from the body as urine. However, these medications are used cautiously because they may inadvertently cause worsening of the renal disease. It is important to closely monitor patients receiving diuretic therapy for electrolyte imbalances (e.g., hypokalemia), worsening renal failure, and hypotension, the latter two of which are common with the use of diuretics.
One of the most common electrolyte imbalances associated with kidney disease is hyperkalemia, or elevated potassium levels in the blood. Hyperkalemia occurs because the kidneys are unable to effectively excrete the potassium from the body, so it builds up in the blood. This is a significant issue because hyperkalemia can result in deadly ventricular dysrhythmias and, eventually, cardiac arrest, if left untreated. Often, the provider will order medications (e.g., sodium polystyrene [Kayexalate]), which work to pull out excess potassium, in turn excreted in the feces, bringing the electrolyte level back into normal range. If the potassium level is dangerously high, intravenous medications, including regular insulin, intravenous dextrose, and calcium can be administered to quickly cause an influx of potassium out of the vessels and into cells, restoring potassium balance much more quickly than with medications that cause potassium to be excreted in the feces. Another type of medication commonly used to treat patients with kidney disorders is phosphate binders (e.g., sevelamer [Renvela]). These medications bind with phosphate to prevent hyperphosphatemia that commonly occurs with kidney disorders.
For patients with more severe or end-stage kidney disease, dialysis, or the use of a dialyzer machine to filter the blood and remove toxins when kidney function is decreased, is often indicated. There are three main types of dialysis; they are described in Table 20.12. Though they all work by slightly different mechanisms, the goal of their use is to remove toxins and electrolytes that the kidneys are unable to excrete and to restore fluid volume to a normal level. Hemodialysis (HD) can be performed as an emergency procedure or as a long-term intervention for patients with CKD. For emergency situations such as life-threatening fluid overload or hyperkalemia, a temporary dialysis catheter can be placed in a central vein, allowing for immediate vascular access. Figure 20.16 shows a picture of a temporary dialysis catheter. For more permanent, long-term dialysis solutions, an arteriovenous fistula can be created. Arteriovenous (AV) fistulas are created through the surgical connection of an artery and a vein in the patient’s arm and can be used to perform HD on a long-term basis. The downside to using an AV fistula is that they take several months to mature before they can be used, so a temporary dialysis catheter often must be used first until the fistula is ready. An illustration of an AV fistula is depicted in Figure 20.17.
| Type | Description |
|---|---|
| Hemodialysis | Artificial kidney (hemodialyzer) machine is used to filter the blood and remove excess fluid and toxins. These treatments typically occur three times a week. |
| Peritoneal dialysis (PD) | Catheter is placed into peritoneal space in the abdomen. Dialysate fluid is administered through catheter into peritoneal space, where it remains in place for several hours to filter out toxins. Dialysate is then drained from the catheter into a drainage bag. The benefit of PD is it can occur while the patient sleeps in the comfort of their home. |
| Continuous renal replacement therapy | Similar mechanism to HD but filtration occurs continuously, allowing for slower removal of fluid and toxins. This type of dialysis is indicated for patients who are hemodynamically unstable and unable to tolerate large amounts of fluid and waste removal over a short time. |
Nursing Care of the Patient with ATN and CKD
While evaluating interventions and the effectiveness of treatment options, the nurse should also be constantly aware of the signs of complications of ATN or CKD. Complications can quickly lead to poor patient outcomes, and the nurse must be ready to address issues as they arise. The nurse should also be prepared to handle the patient’s psychosocial and educational needs, and provide resources for the patient as needed.
Recognizing and Analyzing Cues
When caring for patients with kidney disorders, the nurse will assess for signs and symptoms indicating the kidney damage is progressing. One of the first signs may be a decreased urine output, highlighting the need for maintaining accurate intake and output documentation. Other signs to monitor for include alterations in laboratory values (e.g., elevated serum creatinine level or decreased GFR) and mental status changes, which are most likely related to electrolyte imbalances.
Prioritizing Hypotheses, Generating Solutions, and Taking Action
Caring for patients with kidney disorders is complex and involves a high level of attention to detail. The nurse must monitor the patient closely for signs and symptoms that indicate worsening kidney function. Without prompt intervention, kidney disorders can quickly become life-threatening, highlighting the importance of thorough assessments and attention to small changes in the patient’s condition.
As part of the assessment process, the nurse will closely monitor fluid balance through accurate recording of intake and output as well as electrolyte balance with regular assessments of kidney values, including serum creatinine and BUN levels, and GFR. The nurse should monitor the patient closely for signs of fluid overload, such as edema, shortness of breath, or crackles in the lungs. In these situations, the nurse must act quickly, such as by elevating the head of the bed to alleviate the shortness of breath and improve the pulmonary congestion. The nurse will also alert the provider so appropriate interventions may be started to restore optimal fluid balance and hemodynamics. Nurses caring for patients receiving dialysis must be alert to potential complications associated with this kind of treatment. Hypotension is one of the most common complications because dialysis often removes large amounts of fluid from the body at one time. With these quick fluid shifts, the patient may experience low blood pressure and associated symptoms such as lightheadedness or dizziness. For this reason, the nurse should consider withholding medications such as antihypertensives before dialysis treatment to prevent hypotension. The nurse should also monitor for cardiac dysrhythmias during and after dialysis that may result from the changes in electrolyte balance, so continuous telemetry monitoring is often indicated. Though most hospitals have specialized dialysis units and nurses, patients will often return to their initial room right after treatment, so all nurses need to be aware of these potential complications and be ready to intervene appropriately.
Evaluation of Nursing Care of the Patient with ATN and CKD
When evaluating care of a patient with ATN and CKD, the nurse must consider the effectiveness of any intervention and treatment options. The nurse should assess all aspects of the patient’s well-being, including psychological and educational needs, as well as assessing for any signs of complications of ATN or CKD.
Evaluating Outcomes
The optimal patient outcome for patients with kidney disorders is restoration of kidney function to baseline level. With ATN, this is often possible if treatment is initiated early and complications do not occur. This would be indicated by normal serum creatinine and BUN levels, and GFR values, as well as a normal urine output. Patients with CKD have more advanced disease, so it is unlikely that their kidney function will return to baseline. With CKD, the goal would be to maintain as much function of the kidneys as possible, even if that means using therapies such as HD on a long-term basis. Other nursing goals include maintaining a baseline “dry” weight, reducing edema, and maintaining normal electrolyte balance. It is important for the nurse to evaluate how the patient is coping with their CKD, especially if they are receiving long-term HD. This disorder significantly affects everyday life, often requiring HD to be performed multiple times a week for several hours at a time. The nurse should provide these patients with the necessary social support and resources like support groups to help improve coping skills and life outlook.
Read the Electronic Health Record
Laboratory Profile of a Patient with Chronic Kidney Disease
Nurse’s note: Patient arrived to ED at 0700 with complaints of nausea and vomiting and sudden weight gain. Patient reports a new onset of shortness of breath when walking.
0730 Vital signs and laboratory test results:
BP: 145/87 mm Hg
HR: 99
O2: 92 percent
Laboratory test results: Serum creatinine (1.4 mg/dL), BUN (28 mg/dL), GFR (45 mL/min/1.73 m2)
0930 Vital signs and laboratory test results:
BP: 155/92 mm Hg
HR: 110
O2: 89 percent
Laboratory test results: Serum creatine (1.8 mg/dL), BUN (35 mg/dL), GFR (41 mL/min/1.73 m2)