In the course of systemic lupus erythematosus, pulmonary involvement is common and can affect any part of the respiratory tract.
Systemic lupus erythematosus (sle) is a systemic inflammatory disease characterized by an autoantibody reaction induced by the presence of a nuclear antigen reaction in the serum and clinical manifestations of damage and/or dysfunction of multiple organ systems. During these courses, up to 50% of patients with SLE will develop pulmonary manifestations. These include pleurisy (with or without effusions), inflammatory and fibrotic interstitial lung disease, alveolar hemorrhage, pulmonary atrophy syndrome, pulmonary hypertension, airway disease, and pulmonary thromboembolic disease.
Clinical manifestations and simulation of SLE lung disease
Cough, chest pain, and dyspnea are the most common respiratory symptoms of systemic lupus erythematosus, and although they may suggest lesions, they are not specific clinical manifestations of respiratory disease. Cough in patients with systemic lupus erythematosus can be caused by problems with the airway or lung parenchyma, but in the general population it is often caused by gastroesophageal reflux disease (GERD) or retronasal drip syndrome.
Vascular "part"
Pulmonary hypertension
In different studies, the incidence of pulmonary hypertension (PH) in SLE ranged from 0.5% to 17.5%, depending on the diagnostic criteria used.
The main mechanism that drives the development of SLE-PH is the autoimmune effect of changing organs directly against the pulmonary vasculature system.
Patients with suspicion of sle-ph can be evaluated by transthoracic echocardiography (tte) screening; however, tte is known to be inaccurate when estimating that right ventricular systolic blood pressure is not significantly elevated or lacks other signs of right heart pressure (eg, dilation, impaired systolic function). To confirm the pH, a right heart catheterization (RHC) is required. At the time of right heart catheterization, the hemodynamic definition of pulmonary hypertension is the mean pulmonary artery pressure ≥ 25 mmhg, even if the pulmonary capillary wedge insertion pressure < 15 mmhg.
There are currently no consensus guidelines for SLE-PH treatment. Overall, the 3-year survival rate for SLE-PH patients was 75%.
Diffuse alveolar bleeding
Diffuse alveolar hemorrhage (dah) is a rare and potentially catastrophic lung manifestation of sle. In patients with systemic lupus erythematosus, dah is a direct consequence of pulmonary capillaryitis, diagnosed pathologically by neutrophil infiltration and destruction of the vascular wall. Its clinical manifestations are often abrupt: patients often present with dyspnea and fever. Because haemoptysis occurs only in about 30% of patients with dah, it is missed far beyond what is diagnosed. Chest images show distinct diffuse, bilateral consolidation, or ground glass shadows (Figure 1). Patients may also have decreased hematocrit and/or significant anemia, depending on the amount of blood lost.
Fig. 1 Axial chest spiral scan image at odd vein level in patients.
Catastrophic antiphospholipid antibody syndrome and primary vasculitis overlap must be ruled out because their treatment differs from sle-associated alveolar diffuse bleeding. In addition to screening serum complement c3, c4, ana, and anti-DS-dna, all patients with DAH should be screened for the presence of antiphospholipid antibodies, anti-glomerular basement membranes, and anti-neutrophil cytoplasmic antibodies. Lung infections, as one of the causes of DAH, should also be evaluated accordingly. Pulsed methylprednisolone therapy, 1 g daily for 3 days, followed by an oral prednisone 1 to 2 mg/kg/day, which is the initial treatment of dah. Plasmapheresis and cytotoxic agents can also be used. Some researchers have used cyclophosphamide or rituximab to successfully treat SLE-associated DAH.
pulmonary embolism
Antiphospholipid antibodies (apla) are a heterogeneous group of autoantibodies, including anticardiolipin antibodies, lupus anticoagulants, and anti-glycoprotein-I antibodies. Apla appears in about 1/3 of patients with SLE. Patients with lupus anticoagulants or anticardiolipin antibodies are more likely to develop deep vein thrombosis (DVT) or pulmonary embolism (PE) than those without lupus anticoagulants or anticardiolipin antibodies.
As with most pulmonary embolism, pulmonary embolism occurs almost exclusively from venous thrombosis in the lower extremities; intracardiac thrombosis is rare in patients with SLE, even in those with antiphospholipid antibody syndrome. In patients with systemic lupus erythematosus presenting with dyspnea and/or chest pain, especially if they are apla positive, pulmonary embolism must be part of the differential diagnosis. Further diagnostic tests for pe should consider bilateral lower extremity venous Doppler ultrasound, apla screening, and CT angiography.
Acute reversible hypoxemia
Sudden onset of potentially severe hypoxemia in patients with SLE is extremely rare. The cause is the aggregation of leukocytes within the pulmonary vessels. A large increase in the concentration of c3a in the blood suggests complement activation, which plays a key role. Treatment includes glucocorticoids and aspirin. It is believed that the prognosis will be good.
Lung parenchyma "part"
Interstitial lung disease and pneumonia
Clinically pronounced iLD is far less common in patients with SLE than other connective tissue diseases, occurring in 1% to 15% of patients with SLE.
SLE-associated interstitial lung disease (SLE-ILD) typically presents with dyspnea on exertion and a dry cough may be present.
Diagnosis of sle-ILD relies primarily on a combination of clinical features, chest imaging, histopathology, and lung physiology. Before making a SLE-ILD diagnosis, it is important to rule out other causes including drug therapy-related iLD. Disease-modifying drugs used to treat sle, such as methotrexate, leflunomide, azathioprine, tumor necrosis factor inhibitors, rituximab, cyclophosphamide, and sulfasalazine, have all been associated with the development of ild.
Although surgical lung biopsy is the gold standard used to diagnose ild, it is not performed very often. The most common histological type of SLE-ILD is nonspecific interstitial pneumonia (NSIP); less common types include organic pneumonia (OP), lymphocyte interstitial pneumonia (LIP), common interstitial pneumonia (UIP), desquamation interstitial pneumonia, and diffuse alveolar injury (DAD). Alternative to invasive testing, high-resolution computed tomography of the chest (HRCT) combined with restrictive physiology [lung function test (PFT) finding a decrease in forced vital capacity (FVC), total lung volume, and/or carbon monoxide diffusion (DLCO)] and/or corresponding clinical features can confirm the diagnosis of iLD. However, clinicians must be vigilant to rule out ild-like conditions such as diffuse alveolar hemorrhage, drug poisoning, congestive heart failure, uremia, or infection.
Treatment of sle-ILD is mainly based on the advice of specialists. Patients with severe ild are often treated with oral high-dose corticosteroids (oral prednisone 1 mg/kg, up to 60 mg, or their equivalent) and hormone abstrictors, often with cyclophosphamide (1 to 2 mg/kg orally daily, depending on renal function and age or intravenous equivalent dose). Treatment in mild to moderate ild sometimes begins with the use of moderate doses of corticosteroids in combination with azathioprine or mycophenolate modulators. Tapering on corticosteroid therapy is often modulated based on good clinical symptoms, physiology, and/or imaging response.
Lupus pneumonia and its association with ild
Lupus pneumonia (LP) in patients with SLE may be most characteristic of an acute interstitial pneumonia (AIP)-like response. It is a fatal syndrome characterized by acute onset of fever, pleuritic chest pain, shortness of breath; this rare disease currently has a mortality rate of up to 50%. lp is often accompanied by auscultation crackles, while haemoptysis may rarely occur. Chest imaging usually shows bilateral shadows.
Physiological disorders: restrictive lung disease and pulmonary atrophy syndrome
Restrictive lung disease
Lung dysfunction in patients with SLE is common and can occur in patients who have no suspicion of lung involvement.
Pulmonary atrophy syndrome
Dyspnea and physiological limitations, and the absence of parenchymal lesions on chest imaging, are the main features of shrink-ing lung syndrome (sls).
SLS is generally considered a rare manifestation in patients with SLE and occurs in 0.5% of patients with SLE.
Information on the treatment and prognosis of SLS is limited. Corticosteroids (moderate to high doses), cytotoxic drugs, biological therapies (rituximab), theophylline, and high-dose β-receptor agonists have all been successfully used to treat this condition.
How to evaluate patients with sle who present with dyspnea
In any patient with sle who has breathing problems, especially dyspnea, infection must be ruled out. Patients with breathing difficulties who are receiving long-term immunomodulatory therapy should be given further attention to infection. Patients treated with glucocorticoids alone or in combination with immunomodulators may not have the typical symptoms of infection, so there is a high degree of vigilance against infection with typical pathogens (bacteria) and atypical pathogens (mycobacteria, fungi, Pneumocystis carinii). Bronchoscopy should be considered in any patient treated with immunosuppressive drugs and with a shadow on chest imaging. In addition to confirming or excluding lung infection, as in the typical cases discussed, what is seen on bronchoscopy may be useful in determining the true cause of a patient's symptoms (e.g., dah).
If infection can be definitively ruled out, other underlying causes of dyspnea are considered; pe is the first to bear the brunt of sle in patients with risk factors for thromboembolism (e.g., hypercoagulable state or history of thromboembolism). Where appropriate, CT angiography, with or without venous Doppler ultrasound of the lower extremities, is useful for identifying or excluding thromboembolic disease. The added benefit of ct angiography is that it can show the lung parenchyma as well as the vasculature very well. However, due to intravenography and the low volume techniques designated for CT angiography, the lung parenchyma is less likely to transmit rays than high-resolution CT scans; this can make it quite challenging to distinguish the presence or absence of terrazzo. Severe symptoms, lung function during exertion, and peripheral oxygen saturation (spo2) can be used as important supplemental information for directly assisted assessment. DLCO may be elevated in diffuse alveolar hemorrhage and decreased in interstitial lung disease or pulmonary hypertension. Pulmonary vascular disease should be considered and evaluated for any other patient with unexplained dyspnea or decreased oxygen saturation at exertion (≥4 compared to decreased oxygen saturation at rest, and the lowest point during exercise is still > 90%).