Chapter 71: Care Of Pts With Acute And Chronic Kidney Disease Flashcards
Azotemia
Azotemia is the retention and buildup of nitrogenous wastes in the blood.
Prerenal azotemia is kidney injury caused by poor blood flow to the kidneys. Usually caused by hypovolemic shock and heart failure. Bowel preparation, NPO, and fluid lost during surgery can cause this.
Pathophysiology of acute kidney injury
Pathophysiology
Acute kidney injury (AKI) which use to be known as acute renal failure (ARF) is a rapid decrease in kidney function leading to the collection of metabolic wastes in the body.
Types:
ØPrerenal: AKI can result from conditions that reduce blood flow to the kidneys (prerenal acute kidney injury)
ØIntrarenal: damage to the glomeruli, interstitial tissue, or tublule (intrarenal/intrinsic acute kidney injury)
ØPostrenal: is obstruction of urine flow (postrenal acute kidney injury)
ØWhen AKI occurs in patients who already have reduced kidney function, it may lead to end-stage kidney disease (ESKD), or it may resolve to nearly the pre-AKI level of kidney function.
If BUN rises faster than the serum creatinine level, the cause is usually related to protein breakdown or volume depletion. When both the BUN and creatinine levels rise and the ratio between the two remains constant, this indicates kidney failure.
Causes of AKI
Causes: The most common problems leading to AKI are:
ØHypovolemic shock
ØHeart failure
Early AKI (levels R & I-see table 71-2) often can be reversed by correcting blood volume, increasing blood pressure, and improving cardiac output. When the reduced blood flow is prolonged, the kidneys are severely damaged and intrarenal kidney injury results.
Intra and post renal AKI
Intrarenal AKI is often referred to as oliguric AKI in the clinical setting (infections, bacteria, viral, fungi), drugs especially aminoglycoside antibiotics and NSAIDs), invading tumors can cause acute interstitial nephritis.
Postrenal azotemia develops from obstruction to the outflow of formed urine anywhere within the kidney or urinary tract.
Nonoliguric AKI
Nonoliguric form of AKI in which urine output remains near normal but serum creatinine levels rise. Interventions are to restore circulating volume, improve cardiac output, and increase blood pressure to prevent progression to a more severe level of kidney injury.
Phases of AKI
Rapid decrease in kidney function lead to collection of metabolic wastes in the body
Phases (see table 71-4)
ØOnset phase begins with precipitating event and continues until oligurai develops. Last hours to days
ØOliguric characterized by a urine output of 100-400 ml?24 hours that does not respond to fluid challenges or diuretics. Lasts 1-3 weeks.
ØDiuretic often has a sudden onset within 2-6 weeks after oliguric stage. Urine flow increases rapidly over a period of several days. The diuresis can result in an output of up to 10 L/day of dilute urine
ØRecovery in this phase the patient begins to return to normal levels of activity. Complete recovery may take up to 12 months
Acute syndrome may be reversible with prompt intervention
Manifestations of acute renal failure
They are related to the buildup of nitrogenous waste/azotemia As well as the underlying cause.
Prerenal azotemia are hypotension, tachycardia, decreased urine output, decreased cardiac output, decreased central venous pressure, lethargy. Similar to heart failure or dehydration
Intrarenal include oliguria or anuria, edema, hypertension, tachycardia, shortness of breath, distended neck veins, elevated central venous pressure, weight gain, respiratory crackles, anorexia, nausea and vomiting, lethargy, ECG changes from electrolyte imbalance.
Post Reno olguria or intermittent anuria, symptoms of uremia, lethargy. Report changes in urine stream or difficulty starting urination.
See chart 71-1 pg 1604
Interventions AKI
Nursing interventions for:
ØElectrolyte imbalances
ØThe patient with AKI may move from the oliguric phase (in which fluid and electrolytes are retained) to the diuretic phase. In the oliguric phase, the plan of care focuses on close monitoring for life-threatening electrolyte changes and nitrogen retention that may require intervention. During the diuretic phase, hypovelemia and electrolyte loss are the main problems. The patient in the diuretic phase of AKI needs a plan of care that focuses on fluid and electrolyte replacement and monitoring.
ØNutritional considerations
•Patients with AKI often have a high rate of protein breakdown. The cause of this is unknown. Need adequate caloric intake of protein, sodium, and fluids. For patient who does not require dialysis 40 g/day of protein, 60 to 90 mEq/day, if high blood potassium levels present, restrict dietary potassium to 60 to 70 mEq/day. The amount of fluid permitted is calculated to be equal to urine volume plus 500 mL.
•If too ill to eat, nutritional support such as TPN or hyperalimentation.
ØDialysis therapies
ØHemodialysis and peritoneal dialysis are used for patients with AKI. Indications for dialysis use include the presence of uremia, persistent high potassium levels, metabolic acidosis, continued fluid overload, uremic pericarditis, and encephalopathy.
Teach patients continuing dialysis to limit foods high in potassium and sodium and to observe protein restrictions. Teach about fluid intake limitation.
Med therapy for AKI
Preazotemia, fluid challenges and diuretics are often used to promote kidney blood flow. In patient without fluid overload, 500 ml to 1000 mL if NS may be infused over 1 hour. The patient responds by producing urine soon after the initial bolus. Diuretics such as Lasix may be prescribed. Assess for I & O may be at risk for hypovolemia due to increased urine output.
Oliguric kidney is diagnosed, the fluid challenges and diuretics are discontinued. Will require CVP monitoring or measurement of pulmonary arterial pressure by means of a pulmonary artery catheter for accurate evaluation of hemodynamic status. Watch for signs of fluid overload.
Calcium channel blockers may be used and work by preventing the movement of calcium into the kidney cells, maintain kidney cell integrity, and improve glomerular filtration rate by improving kidney flow.
Health promotion and maintenance for acute renal failure
Severe volume depletion can lead to renal failure. Urge all people to drink at least 2 to 3 L of fluid daily, especially athletes. In the hospital early recognize signs by physical assessment and laboratory values. Accurately measure I and O. Check bodyweight. Decreased specific gravity is the earliest sign of renal tubular damage. Be aware of nephrotoxic substances.
Continuous renal replacement therapy
The standard for acute renal failure. They are tolerated better than hemodialysis for critically ill patients. There used is temporary. They are used for patients who have fluid volume overload, are resistant to diuretics, have unstable blood pressures and cardiac output.
They must have a map of at least 60. Requires an arterial and a venous catheter. There is a risk for bleeding caused by anticoagulants.
Pathophysiology of chronic kidney disease
Progressive, irreversible kidney injury; kidney function does not recover
When kidney function is too poor to sustain life, CKD becomes end-stage kidney disease (ESKD)
Azotemia (buildup of nitrogen-based wastes in the blood)
Uremia (azotemia with clinical symptoms)
Uremic syndrome
The two main causes are hypertension and diabetes mellitus. Infection and genetic can lead to it. African-American patients are four times higher because of their hypertension.
Uremia
Azotemia: Build up of nitrogen-based wastes in the blood
Azotemia with clinical symptoms such as metallic taste in the mouth, anorexia, nausea and vomiting, muscle cramps, itching, fatigue, lethargy, hiccups, edema, dyspnea, paresthesias
Stages of CKD
5 stages:
- At risk; normal kidney function and GFR (> 90 ml/min)and no kidney disease, however, reduced renal reserve in which reduced kidney function occurs without buildup of wastes in the blood because the unaffected nephrons overwork to compensate for the diseased nephrons. Stress such as infection, fluid overload, pregnancy, or dehydration can appear to reduce kidney function.
- Mild CKD, GFR (60-89)is reduced and kidney nephron damage has occurred, and may be slight elevations of metabolic wastes in the blood because not enough healthy nephrons remain to compensate completely for the damaged nephrons. Increased output of dilute urine. Manage fluid volume, blood pressure, electrolytes, dietary intake, and other diseases can prevent further damage and slow progression
- Moderate CKD, GFR (30-59) reduction continues and nephron damage has continued ,and the remaining nephrons cannot manage metabolic wastes, fluid balance, and electrolyte balance. Restriction of fluids. Proteins, and electrolytes is needs.
- Severe CKD GFR continues to decline and interventions are to manage complications, and prepare for eventual renal replacement therapy
- End-stage kidney disease (ESKD) excessive amounts of urea and creatinine build up in the blood, and the kidneys cannot maintain homeostasis. Severe fluid., electrolyte, and acid-base imbalances occur. Without renal replacement therapy, fatal complications occur.
CKD kidney changes
Kidney dysfunction with greatly reduced GFR causes many problems, including abnormal urine production, poor water excretion, electrolyte imbalances, and metabolic abnormalities. As disease progresses, the ability to produce dilute urine is reduced. As kidney function continues to decline, the BUN increases and urine output decreases. The patient is at risk for fluid overload.
CKI metabolic changes
Metabolic changes include urea and creatinine excretion are disrupted by kidney dysfunction. Creatinine comes from proteins present in skeletal muscle. The rate of creatinine excretion depends on the muscle mass, physical activity, and diet. Without major changes in diet or physical activity, the serum creatinine level is constant.
CKD electrolyte changes
Electrolyte changes
ØSodium excretion changes are common. Early in CKD the patient is at risk for hyponatremia (sodium depletion) because there are fewer healthy nephrons to reabsorb sodium. Sodium is lost in the urine; the polyuria of early kidney dysfunction also causes sodium loss.
ØIn later stages of CKD, kidney excretion of sodium is reduced as urine production decreases. Then sodium retention and high serum sodium levels (hypernatremia) can occur with only modest increases in dietary sodium intake. Sodium retention causes hypertension and edema.
ØPotassium excretion occurs mainly through the kidney. Any increase in potassium load during the later stages of CKD can lead to hyperkalemia. If urine output is below 500 mL in 24 hours, high serum potassium levels develop quickly reaching 7 to 8 m Eq/L or greater and severe ECG changes result from this elevation and fatal dysrhythmias can occur. Other factors that can contribute to high potassium levels in CKD are ingestion of potassium drugs, failure to restrict dietary potassium, tissue breakdown, blood transfusions, and bleeding or hemorrhage.
Calcium and phosphorus balance is disrupted by CKD. In CKD, phosphate retention and a deficiency of active vitamin D disrupt the calcium phosphate balance. CKD reduces phosphate excretion and phosphate levels increase, calcium levels decrease. Bone reabsorption occurs as calcium is released from the bones, reduced production of vitamin D and less calcium absorbed from intestinal tract. Renal osteodystrophy occurs with bone mineral loss that causes bone pain, spinal sclerosis, fractures, bone density loss, osteomalacia, and tooth calcium loss.