Renal Failure :

Renal failure occurs when the kidneys are unable to do their job: to filter wastes from the blood, help regulate blood pressure, and regulate salt and water balances in the body. As blood flows through the kidneys, it is filtered, and wastes are removed and sent to the bladder as urine.

Background

Chronic renal failure (CRF) requiring dialysis or transplantation is known as end-stage renal disease (ESRD). In the United States, diabetic nephropathy, hypertension, and glomerulonephritis cause approximately 75% of all adult cases. Certain geographic areas have a high incidence of HIV nephropathy.

Patients with ESRD are commonly encountered in the ED with problems related to the metabolic complications of their renal disease or dialysis complications. Various problems related to vascular access in patients on hemodialysis and to abdominal catheters in patients taking continuous ambulatory peritoneal dialysis (CAPD) are also common. Patients who have undergone renal transplantation may experience a variety of transplant-related conditions.

Patients with CRF may present to the ED with an unrelated condition. In these cases, the level of renal function may have important implications for diagnosis and treatment.

Pathophysiology

All major organ systems are affected by renal failure. Prevalence of symptoms is a function of the glomerular filtration rate (GFR), which averages 120 mL/min in a healthy adult. As the GFR falls to less than ~20% of normal, symptoms of uremia may begin to occur. They almost are invariably present when the GFR decreases to less than 10% of normal.

Signs and symptoms of renal failure are due to overt metabolic derangements resulting from inability of failed kidneys to regulate electrolyte, fluid, and acid-base balance; they are also due to accumulation of toxic products of amino acid metabolism in the serum. Signs and symptoms include the following:

• Malaise, weakness, and fatigue are very common.
• GI disturbances include anorexia, nausea, vomiting, and hiccups. Peptic ulcer disease and symptomatic diverticular disease are common in patients with CRF.
• Peripheral neuropathy and restless legs syndrome are the most common neurologic complications of CRF.
• Anemia is inevitable in CRF because of loss of erythropoietin production. Abnormalities in white cell and platelet functions lead to increased susceptibility to infection and easy bruising.
• Pruritus is a common dermatologic complication assumed to be secondary to accumulation of toxic pigments (urochromes) in the dermis.
• Volume overload, a common cardiovascular complication of renal failure, occurs when salt and water intake exceeds losses and excretion. Hyperkalemia is the most common immediately life-threatening metabolic complication of renal failure and may develop suddenly when GFR is severely reduced. Anion gap acidosis results from decreased hydrogen ion excretion and may exacerbate hyperkalemia. Hypocalcemia is potentially life threatening and results from loss of vitamin D and increased parathyroid hormone levels. Hypermagnesemia also may occur.
• Vascular access complications are similar to those seen in any patient with a vascular surgical procedure (eg, bleeding, local or disseminated intravascular infections, vessel [graft] occlusion).
• A peritoneal dialysis catheter subjects patients to the risks of peritonitis and local infection. The catheter acts as a foreign body and provides a portal of entry for pathogens from the external environment.
• Patients who have received renal transplants may experience recurrent renal failure due to rejection or other graft complications. In addition, chronic immunosuppression makes them prone to infection.

Frequency

In the US: The government of the United States funds treatment of ESRD universally for US citizens. As a consequence, the population of patients receiving dialysis or who have had a renal transplant in the United States is large. Approximately 150 cases of CRF per million persons are newly diagnosed per year in the United States. Approximately half of these patients go on to require dialysis or transplantation. As a result, patients with ESRD are encountered on a regular basis in most US EDs.

Internationally

Resources allocated for treatment of ESRD vary throughout the world. Very few patients with ESRD are encountered in countries where ESRD treatment is not funded by the government because of the high mortality rate when dialysis or transplantation is not widely available.

Mortality/Morbidity

Patients in renal failure are prone to all of the complications of any underlying condition, such as diabetes and hypertension. In addition, renal failure causes a variety of metabolic and physiologic derangements.

The most common cause of sudden death in patients with ESRD is hyperkalemia, which is often encountered in patients who have missed dialysis or commit dietary indiscretion. Serum potassium also rises when the serum is acidemic, even though total body potassium is unchanged. Hyperkalemia is usually asymptomatic and should be treated empirically when suspected and when arrhythmia or cardiovascular compromise is present. Iatrogenic complications related to fluid administration (fluid overload) or medications are frequently encountered in patients in renal failure.

Race

Etiology of ESRD differs among racial groups primarily because of the prevalence of predisposing conditions, such as diabetes and hypertension. In populations with problematic access and utilization of primary medical care for treatment of predisposing conditions, ESRD often is encountered in relatively young patients. While the costs of treatment for ESRD are borne by the entire population (through government funding), relatively inexpensive preventive treatments often are funded poorly. Diseases such as diabetes and hypertension are much less likely to lead to renal failure when appropriately treated. The cost of primary care for these conditions is far lower than for dialysis or transplantation, yet primary care remains poorly funded while ESRD treatment is reimbursed completely by the government. This conundrum is reflective of the often illogical and capricious nature of health care spending in the United States.

Sex: Presentation and treatment of CRF and ESRD do not differ significantly between men and women. Differences in causes of renal failure are related to the types of underlying conditions prevalent in men and women.

Age: While the etiology of CRF differs among age groups, the presentations and nature of complications are similar. Young children with ESRD often are treated with transplantation because of difficulties related to vascular access for dialysis.

Procedures

• In an immediately life-threatening emergency, prehospital personnel may use a hemodialysis access site for IV access with the precautions noted in Procedures. The site should not be used for routine IV access.
• IV fluids should not be administered except for cases of frank shock. When used, the preferred regimen is small bolus doses (~200-250 mL) with reevaluation for effect between doses. Lactated Ringer solution should not be used because of the potassium content.
• Most medications used in prehospital care are used in the usual dosages.
• Do not give diuretics in the field to dialysis patients with ESRD. They usually are not effective and may have more than the usual toxicity.
• Cardiac arrest in a patient with CRF or ESRD may be due to hyperkalemia. Consider treatment with IV calcium and IV bicarbonate.

• Cardiac arrest in patients with CRF or ESRD may be due to hyperkalemia. In most medical arrests, treat hyperkalemia empirically with IV calcium and bicarbonate while awaiting laboratory confirmation.
• Consider pericardial tamponade, especially in the setting of pulseless electrical activity (PEA). Consider pericardiocentesis if tamponade is suspected.
• Pulmonary edema is frequent in renal failure and usually is due to volume overload. Also consider myocardial dysfunction.

  • Volume overload is best treated by hemodialysis or by use of hypertonic dialysate in CAPD patients.
  • Nitrates administered by the sublingual, topical, or IV routes are effective in the usual doses.
  • Loop diuretics (eg, furosemide) may be effective at promoting diuresis in patients with residual renal function. They also may be effective because of a pulmonary venodilation effect. Ototoxicity is potentially increased because of delayed excretion and higher blood levels.
  • IV morphine is useful for its vasodilating effects. Take care to avoid precipitating respiratory depression.
• Hypertension in patients with renal failure (as in other patients) usually requires no treatment in and of itself.

  • When indications for treatment exist, such as myocardial ischemia or hypertensive encephalopathy, usual treatments may be used with appropriate dosage adjustment.
  • Dialysis may be needed if hypertension is due to volume overload.
  • Nitroprusside may be used to treat severe hypertension in patients with renal failure. Risk of thiocyanate toxicity is increased and levels must be monitored in cases of prolonged infusion.
• Hypotension in dialysis patients may be due to any of the causes encountered in any other patient. Consider serious causes such as bleeding, cardiac dysfunction, and sepsis. The most common cause is dialysis. After more serious causes are ruled out, IV isotonic saline in small bolus doses (~200 mL) may be used for treatment.
• Bleeding may be due to uremic coagulopathy or from anticoagulation during hemodialysis. In the latter case, the heparin effect may be reversed with protamine.
  • Desmopressin (DDAVP) by nasal, subcutaneous, or IV routes and cryoprecipitate are effective in correction of uremic coagulopathy.
  • Applying firm but nonocclusive pressure for 10-15 minutes best treats bleeding from a vascular access site.
• CAPD-associated peritonitis is treated with a loading dose of parenteral antibiotic followed by a period of intraperitoneal antibiotics. Most institutions that treat CAPD patients have a standard protocol for treatment.
• Cutaneous herpes zoster infection in renal transplant patients should be treated with systemic antiviral therapy to prevent or ameliorate possible dissemination.

• Need for urgent dialysis
• Signs of transplant rejection, infection, or obstruction
• Significant deterioration from baseline renal function
• CAPD-associated peritonitis or catheter-associated infection
• Infection, obstruction, or expanding aneurysm/pseudoaneurysm of the vascular access

• Anemia
• Changes in calcium and phosphorous metabolism, hyperkalemia, hyponatremia, acidosis
• Lipid disorders
• Pericarditis
• Serositis
• Gout, pseudogout
• Hypothyroidism, seizures, fractures
• Accelerated hypertension
• Infertility, impotence, spontaneous abortion
• Bleeding, GI mucosal ulcerations, arteriovenous malformations