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From the Division of Internal Medicine (Dr. Allen), and Department of Pulmonary, Allergy, and Critical Care Medicine (Drs. Stoller and Minai), Cleveland Clinic, Cleveland, OH.
Correspondence to: Omar A. Minai, MD, FCCP, Department of Pulmonary, Allergy, and Critical Care Medicine, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44124; e-mail: minaio{at}ccf.org
A 45-year-old African-American woman presented to the pulmonary medicine clinic for evaluation of progressive dyspnea and pulmonary hypertension. She had a 3-month history of fatigue, progressive dyspnea on exertion, and orthopnea associated with a feeling of fullness in the neck, chest pressure, palpitations, and an infrequent dry cough. She had a medical history of systemic lupus erythematosus, superior vena cava obstruction due to antiphospholipid antibody syndrome (requiring warfarin therapy for the last 4 years), rheumatoid arthritis, asthma, complete heart block status-post pacemaker placement, and atrial fibrillation. The symptoms gradually started to interfere with her daily activities. Three weeks before her pulmonary appointment, she was evaluated by her primary care provider who prescribed an inhaled corticosteroid in addition to her usual ß-agonist with no relief. The patient denied tobacco, alcohol, or other recreational drug use.
Physical Examination
At the time of presentation, she had significant functional limitation and was short of breath with minimal activity such as walking across the room. Physical examination showed a BP of 152/98 mm Hg, regular pulse of 84 beats/min, pulse oximetry of 95% on room air at rest, regular heart sounds without murmurs, clear lung fields without wheezing or rhonchi, and a normal neurologic examination. The remainder of the physical examination was unremarkable. Blood test results consisted of a normal CBC and basic metabolic panel. A complete neurologic workup in the neurology clinic discounted neuromuscular disease as the cause of her dyspnea. A transthoracic echocardiogram was normal except for an estimated right ventricular systolic pressure of 40 mm Hg. Pulmonary function testing (Table 1 ) showed restrictive lung disease, increased residual volume, and a decreased diffusing capacity of the lung for carbon monoxide that normalized when corrected for alveolar volume. Figure 1 presents a chest radiograph taken at the time of presentation to the pulmonary clinic (left, A) compared to a chest radiograph from 3 years earlier (right, B).
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Diagnosis: Bilateral diaphragmatic dysfunction (shrinking lung syndrome)
Diagnostic testing: Erect and supine pulmonary function testing
Systemic lupus erythematosus is a multisystem inflammatory disorder that can produce a variety of pulmonary manifestations, including pleural disease, acute lupus pneumonitis, pulmonary vasculitis, diffuse alveolar hemorrhage, shrinking lung syndrome, pulmonary hypertension, interstitial pulmonary fibrosis, and antiphospholipid syndrome. Among these, the so-called "shrinking lung" syndrome is suggested by the presence of unexplained dyspnea, small lung volumes, extrapulmonary restriction, and diaphragmatic weakness. When considering a diagnosis of shrinking lung syndrome, it is important to look for alternate explanations for diaphragmatic dysfunction or paresis (Table 2
), none of which were evident in our patient.
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In contrast, in characterizing 12 patients with the shrinking lung syndrome using spirometry, sniff testing, and transdiaphragmatic pressure measurement, Laroche et al believed that the reduced vital capacity in shrinking lung syndrome was due to restricted chest wall expansion and not to diaphragmatic weakness. Also, although the pathophysiology of the oxygen desaturation in shrinking lung syndrome has not been fully elucidated, basilar atelectasis from diaphragmatic elevation and a concomitant increase in shunting are believed to contribute.
Because few cases have been described, optimal therapy of shrinking lung syndrome remains unclear. Most case reports describe the benefits of systemic glucocorticoids alone for the treatment of shrinking lung syndrome. While no available reports describe spontaneous resolution of shrinking lung syndrome, there are examples of patients who have not experienced further disease progression in the absence of treatment. Also, some case reports describe patients who do not respond to glucocorticoids but do respond to other agents, including ß-agonists, theophylline, and azathioprine. In one report, a 15-year-old girl with systemic lupus erythematosus presented to a hospital with tachypnea and a 2-month history of progressive dyspnea on exertion. She had initially tried a course of corticosteroids with no significant improvement in her exercise tolerance. After evaluation in the hospital, she was found to have a restrictive pulmonary process. She demonstrated a 12.6% improvement in FEV1 and a 10.4% improvement in FVC with albuterol nebulizers. Azathioprine was introduced later and the patient remained stable.
Based on our patient’s history of systemic lupus erythematosus, her clinical picture of progressive dyspnea on exertion, chest radiographic findings of lung volume loss, and pulmonary function findings of extrathoracic restriction, the systemic lupus erythematosus-related shrinking lung syndrome was strongly suspected. Fluoroscopic "sniff" testing showed minimal excursion of both diaphragms with deep breathing and sniffing. As further evidence of bilateral diaphragmatic dysfunction, the patient demonstrated a 24% reduction in FVC in the supine position vs the erect position (Table 3 ), exceeding the normal criterion for diaphragmatic dysfunction (ie, <20% decline in the FVC when supine).
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Based on anecdotal reports, our patient was placed on prednisone, 40 mg/d, and azathioprine, 100 mg/d. After 6 weeks, she achieved only a slight improvement in her dyspnea and still demonstrated a 41% decline in the FVC on assuming the supine position. However, significant improvement in her flows and volumes was evident (Table 4 ). The patient was continued on prednisone and azathioprine. Over the next 4 months, her flows and volumes continued to improve and the percentage decline in supine FVC normalized (Table 4).
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Footnotes
None of the authors report any conflicts of interest.
Received for publication April 24, 2006. Accepted for publication June 12, 2006.
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