Goodpasture's syndrome

THIS UNCOMMON PULMONARY-RENAL DISORDER CAN BE FATAL IF NOT CAUGHT EARLY. HERE'S WHAT YOU NEW TO KNOW.

Goodpasture's syndrome, a rare autoimmune disorder characterized by pulmonary hemorrhage, rapidly progressing glomerulonephritis, and antiglomerular basement membrane (GBM) antibody formation, has long been a challenge to clinicians.

The syndrome typically strikes young men, is rapidly progressive, and can be fatal if not diagnosed and treated early. This pulmonary-renal syndrome is caused by anti-GBM antibody-induced glomerulonephritis.

In this article, we'll describe how you can help pinpoint Goodpasture's syndrome in a patient by knowing the signs and symptoms to look for in anyone admitted with a pulmonary-renal syndrome.

The exact cause of Goodpasture's syndrome is unknown, but it's been attributed to one or more of the following:

upper respiratory infection or flulike illness, which may damage the pulmonary basement membrane and expose the Goodpasture antigen, causing antibody production in genetically predisposed individuals

cigarette smoking, which may lead to increased lung permeability and induce antibody formation or make the basement membrane "more antigenic"

exposure to hydrocarbons, which may injure the lungs or kidneys and stimulate antibody production

genetics, because Goodpasture's syndrome has been described in identical twins, siblings, and first cousins.

These factors are refer-red to as "triggers," which lead to exposure of the Goodpasture antigen. Once the antigen is recognized by immunocompetent cells, antibodies are produced. These anti-GBM antibodies are targeted to the Type IV collagen protomer, the building block of the basement membrane of both the kidney and the lung. Type IV collagen protomer is responsible for keeping the basement membrane intact.

The anti-GBM antibodies attack the alveolar and glomerular basement membranes, breaking down the collagen and interrupting the membrane's integrity. This permits blood leakage, resulting in hemoptysis and hematuria.

As the anti-GBM antibodies attack the lungs and kidneys, a triad of clinical findings evolves: antiGBM antibody formation, pulmonary hemorrhage, and glomerulonephritis.

AMUSING YOUR PATIENT

Pulmonary hemorrhage with hemoptysis is the presenting sign in more than 50% of cases. The hemoptysis may be mild to exsanguinating and usually precedes renal involvement. In some cases, the onset of pulmonary hemorrhage precedes glomerulonephritis by 8 months to a year. Flulike symptoms are associated with acute hemorrhage; fatigue and weakness are associated with chronic blood loss. The patient may be pale, which relates to the degree of anemia.

Pulmonary assessment reveals hemoptysis, dyspnea, and crackles or gurgles. The patient may be treated for an upper respiratory infection. In this case, Goodpasture's syndrome may be missed until further signs and symptoms develop.

Rapidly progressive glomerulonephritis is characterized by a rapid decrease in renal function caused by a decrease in glomerular blood flow. This decreased blood flow is secondary to the accumulation of monocytes-macrophages from peripheral blood and activation of the coagulation system, resulting in fibrin deposits. The fibrin deposits, in turn, stimulate epithelial crescent formation in the glomerulus.

The crescent, which is shaped like a crescent moon, tends to surround and compress the glomerular tuft. Renal failure, which may take from a few weeks to a few months, develops as glomerulonephritis advances.

As the syndrome progresses, serum levels of antiGBM antibodies rise and may cause more injury. Because the anti-GBM antibody test is a specialized diagnostic test, the specimen may need to be shipped to another lab, which may delay diagnosis. Therefore, if the patient has the other two clinical findings, treatment should be initiated.

COULD IT BE SOMETHING ELSE?

Pulmonary-renal syndrome is a broad category that includes Goodpasture's syndrome, systemic vasculitis, Wegener's granulomatosis, polyarteritis nodosa, and systemic lupus erythematosus. By being familiar with the signs of these syndromes, you'll be able to differentiate Goodpasture's syndrome from the others and help the physician make a definite diagnosis (see Differentiating Pulmonary-Renal Syndromes).

A definite diagnosis of Goodpasture's syndrome is reached when the anti-GBM antibody titer returns positive (greater than 20 units). A titer of 10 to 20 units is indeterminate, and 0 to 9 units is negative. Along with these results, a bronchoscopy specimen may return bloody, and a renal biopsy may show diffuse linear disposition of immunoglobulin G (IgG) along the peripheral capillary loop of the GBM.

DIANOSTIC EVALUATION TOOLS

The patient needs a thorough workup to determine the cause of his ailment. The lab studies in the initial evaluation are complete blood cell (CBC) count, prothrombin time, partial thromboplastin time (PTT), erythrocyte sedimentation rate, complete chemistry panel, urinalysis with culture and Gram's stain, sputum culture and Gram's stain, blood cultures, complement panel, enzyme-linked immunosorbent assay, antineutrophilic cytoplasmic antibody levels, arterial blood gas (ABG) measurements, and anti-GBM antibodies.

Initially, you'll see few abnormalities in the lab studies. Significant findings commonly occur in the urinalysis with the appearance of red blood cells, white blood cell (WBQ casts, and proteinuria. The chemistry panel commonly reveals an elevation in the blood urea nitrogen and creatinine levels. The CBC count shows an elevated WBC count and a drop in the hemoglobin and hematocrit levels. The MIT may be prolonged.

If these initial results are significant and the patient is experiencing signs and symptoms of renal compromise or respiratory distress, he may be admitted directly to the critical care unit for further studies and supportive care.

Once the patient is admitted to the unit, more tests are completed to confirm the diagnosis and rule out other causes. These studies include chest X-rays, bronchoscopy, computed tomography (CT) scans, a renal biopsy if the patient's condition permits, and possibly a lung biopsy.

Chest X-rays reveal numerous infiltrates. If the hemorrhage is significant enough, the film may show acute respiratory distress syndrome (ARDS). Bronchoscopy reveals hemorrhage from the lung lining. The CT scans are done to rule out other disease processes such as tumors. Renal and lung biopsies, if done, reveal IgG deposition and crescent formation in the glomeruli.

The patient is admitted to the critical care unit for close observation and aggressive therapy: Goodpasture's syndrome has a 50% mortality rate caused by rapidly progressive glomenlonephritis and pulmonary failure. If the patient is experiencing respiratory distress, mechanical ventilation may be instituted. If the renal system is failing, the patient may need dialysis to help preserve the kidneys until therapy is completed.

SUPPORTING VENTILATION

The breakdown of the permeability of the alveolar basement membrane causes pulmonary infiltrates and hemorrhage, so the patient with Goodpasture's syndrome may need to be intubated and mechanically ventilated to maintain a patent airway. You may need to try multiple ventilator modes before optimal oxygenation is achieved, so you should be familiar with the various modes of ventilation and types of ventilators. Frequent suctioning may be required secondary to massive pulmonary hemorrhage.

Continual observation and assessment of the patient's pulmonary status through the use of pulse oximetry and ABG measurements are your best tools in this area of patient care.

SUPPORTING RENAL FUNCTION

Once the patient is determined to be in renal failure or volume overload, hemodialysis may be started. The access line usually is placed in the subclavian, internal jugular, or femoral vein. Although you aren't totally responsible for placing the line or running the equipment, you must be familiar with the procedure and must anticipate possible complications, such as hypotension, air embolism, hypoxemia, infection at the catheter insertion site, or ischemia of the area distal to the insertion site.

Constantly monitor the patient's hemodynamic status and electrolyte and acid-base balance and maintain the sterility of the closed system. After hemodialysis is completed, watch for complications such as bleeding from the site. Maintain accurate records of the patient's intake and output.

During this phase of evaluation, you play an important role in patient and family care. Watch for physical changes in the patient as well as significant changes in lab findings. Ongoing patient education and support throughout the hospitalization can minimize stress for the patient and his family.

PREVENTING COMPLICATIONS

Once the diagnosis is confirmed, an aggressive course of therapy is initiated to reverse the abnormalities seen in the patient with Goodpasture's syndrome. Therapy consists of

plasmapheresis to reduce the level of anti-GBM antibodies

immunosuppressive chemotherapy to halt the inflammatory process

high-dose corticosteroids to decrease the amount of tissue destruction.

This aggressive therapy itself can cause many problems (see Treating Goodpasture's Syndrome). Being familiar with the therapy and its adverse effects will help you effectively care for the patient.

Because of its rarity, Goodpasture's syndrome is difficult to diagnose, and if treatment isn't started early enough, the mortality rate is greater than 50%. As a critical care nurse, your ability to detect, early on, the signs and symptoms related to Goodpasture's syndrome can be key to improving patient outcomes.

SELECTED REFERENCES

Ball, J., and Young, K.: "Pulmonary Manifestations of Goodpasture's Syndrome. Antiglomerular Basement Membrane Disease and Related Disorders," Clinics in Chest Medicine. 19(4):777-791. December 1998. Heltmark, T., et al.: "Characterization of Anti-GBM Antibodies Involved in Goodpasture's Syndrome," Kidney International. 46(3):823-829, September 1994.

Kelley, P., and Haponik, E.: "Goodpasture Syndrome: Molecular and Clinical Advances," Medicine. 73(4):177-178, July 1994.

BY PHYLLIS AVELLA, RN, CCRN, ADN, AND MARY WALKER, RN,C, CCRN, BSN

Phyllis Avella and Mary Walker are clinical staff nurses in the medical intensive rare unit at Brooke Army Medical Center at Fort Sam Houston, Tex. The views expressed in this article are those of the authors and not necessarily those of the Department of the Army or the Department of Defense.

Copyright Springhouse Corporation Mar 2000
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