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A novel therapeutic strategy using extracorporeal membrane oxygenation in patients with anti-neutrophil cytoplasmic antibodies-associated vasculitis: a case report and literature review

Diffuse alveolar hemorrhage (DAH) secondary to anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) often results in severe respiratory failure which requires emergent management. In patients who are resistant to traditional mechanical respiratory support, extracorporeal membrane oxygenation (ECMO) can be used to maintain gas exchange, thereby providing time for the administration of immunosuppressive therapy to control the inflammation. Herein, we report the application of ECMO to support an adult patient with AAV complicated by severe respiratory failure due to DAH. Similar cases in the literature were identified and discussed. The patient in our case study was successfully treated with ECMO in the acute phase and relieved by immunosuppressive therapy after withdrawal of ECMO. A search in the PubMed database revealed 32 similar cases with DAH, of which 11 cases were microscopic polyangiitis (MPA), 2 cases were eosinophilic granulomatosis with polyangiitis (EGPA), and 19 cases were granulomatosis with polyangiitis (GPA). These patients were all treated with ECMO. Therefore, to date, we identified 33 patients who were effectively treated with ECMO, including 13 (39.4%) males and 20 (60.6%) females, with a ratio of 1:1.54. The average age was 32.4±17.5 and 36.0±16.1 years for males and females, respectively (t=0.610, P=0.547). Most patients received ECMO on the first day of admission to the intensive care unit (ICU) and it appeared that early initiation of ECMO was associated with a shorter duration of ECMO. In general, complications of ECMO in these patients were mild and were not often seen in the clinical setting. This study suggested that early recognition of respiratory failure and referral for ECMO are vital to achieve a satisfactory outcome in AAV patients with DAH.


Introduction
Anti-neutrophil cytoplasmic antibodies (ANCAs) are autoantibodies specific for antigens located in the cytoplasmic granules of neutrophils and the lysosomes of monocytes (1,2). ANCA-associated vasculitis (AAV) is a group of systemic disorders characterized by inflammation and necrosis of small and medium size vessels, and is the major cause of vasculitis affecting the lungs. There are three types of AAV including microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). As the disease progresses, the disruption of the alveolar-capillary basement membrane accelerates the extravasation of red blood cells into the alveolar spaces (3), resulting in diffuse alveolar hemorrhage (DAH). DAH is the most serious complication of AAV and is one of the strongest predictors of early mortality (4,5). Extracorporeal membrane oxygenation (ECMO) is an efficient method to correct hypoxemia in patients with severe acute respiratory failure, especially when conventional mechanical ventilation fails or when there is insufficient time to treat the underlying pathology (6,7). Recent technological advances have allowed for the application of ECMO in AAV-related DAH, in addition to traditional immune-suppressors and corticosteroids, even if a certain degree of systemic anticoagulation is required. Therefore, the fine balance between bleeding and anticoagulation is crucial. Herein, we present a case report of a 56-year-old patient presenting with AAV-related DAH who was successfully supported with ECMO. In addition, a review of the literature was conducted to further understand the utilization of ECMO in DAH. We present the following article in accordance with the CARE reporting checklist (available at https://dx.doi.org/10.21037/atm-21-3133).

Case presentation
A 56-year-old Chinese man presenting with cough, expectoration and chest tightness was admitted to the Department of Pulmonology at The First Medical Center of PLA General Hospital on Sep 29, 2017. Two months earlier, the patient experienced cough and expectoration, accompanied by left chest pain and chest tightness. The chest computed tomography (CT) scan showed bilateral lower lung field interstitial fibrosis ( Figure 1A,1B). While the patient had been evaluated and treated empirically by antibiotics several times outside our department, the dyspnea persisted and was gradually aggravated with dizziness. Past medical history included hypertension with regular treatment. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). This study was approved by the local Ethics Committee of the Chinese PLA General Hospital (Beijing, China) (No. S2020-141-01). The patient provided written informed consent for the publication of any associated data and accompanying images.
On physical examination, the patient's temperature was 38.7 ℃, pulse rate was 106 beats per minute, respiratory rate was 46 breaths per minute, and blood pressure was 135/79 mmHg. The breath sounds of double lungs had coarse crackles, a small number of wet rales could be auscultated in the left lower lung and no dry rales and pleural frictions could be heard. The cardiovascular, abdominal, musculoskeletal, and neurologic examinations were normal. The chest radiograph ( Figure 1C) revealed multiple patchy lesions and diffuse alveolar infiltration. Laboratory data on admission included the following: a hemoglobin count of 87 g/L, a white blood cell (WBC) count of 16.77×10 9 cells/L, and a platelet count of 389×10 9 cells/L. Analysis of infectious indicators revealed 10.61 mg/dL C-reactive protein, 0.717 ng/mL procalcitonin, and 118.10 pg/mL interleukin-6. The biochemical indicators showed creatinine levels at 325 mmol/L, blood urea nitrogen (BUN) levels at 12.5 mmol/L, lactate dehydrogenase levels at 307 units/L, and plasma N-terminal pro-B-type natriuretic peptide (BNP) levels at 1,046 pg/mL. Initial arterial blood gas analysis showed that pH was 7.45, partial pressure of carbon dioxide (PaCO 2 ) was 28 mmHg, partial pressure of oxygen (PaO 2 ) was 42 mmHg, bicarbonate (HCO 3− ) was 19.5 mmol/L, and oxygen (O 2 ) saturation was 80%, suggesting acute respiratory failure.
On the first day of admission, the patient was administered oxygen via a face mask and the pulse oxygen saturation was maintained 80%.   The preliminary diagnosis was pulmonary infection with pulmonary interstitial fibrosis, pending examination of rheumatic immune-related antibodies. Treatment with methylprednisolone 80 mg once daily, moxifloxacin, ganciclovir, meropenem, caspofungin, linezolid, and gamma globulin were commenced immediately to control infection, suppress inflammation, and regulate immunology. Meanwhile, continuous renal replacement therapy (CRRT) was administered to remove the inflammatory mediators and reduced oxygen consumption in the organs. Bronchoscopy was performed to detect airway hyperemia ( Figure 2A) and to remove the stained bloody secretions ( Figure 2B). Gross hematuria was visible ( Figure 2C). Despite the continuous mechanical ventilation on an FiO 2 of 100%, hypoxemia failed to improve and oxygen saturation and the PaO 2 /FiO 2 ratio continued to deteriorate.
The patient was transferred to the intensive care unit (ICU) on the day of admission, and on hospital day 4, the decision was made to initiate emergency veno-venous ECMO (V-V ECMO) for respiratory support. The ECMO unit was established at the beside of the ICU, and consisted of a centrifugal pump, Oxygenator (Sorin Group, Italy), and tubes. A 21F cannula was penetrated into the patient's right femoral vein and a 17-Fr cannula was placed in the patient's right internal jugular vein. The optimal location of the cannulas was confirmed by transthoracic echocardiography (TTE) to minimize recirculation. The blood was then circulated from the femoral vein and returned through the internal jugular vein. At beginning of ECMO, the average flow rate was set at 3.5 L/min, the sweep gas flow rate was set at 8 L/min, and the rotation rate was set at 2,500 rpm. Despite the risk of re-bleeding, a maintenance dose of heparin was applied until termination of ECMO. There was no further bleeding from the lungs, and the low dosage unfractionated heparin kept the activated clotting time (ACT) at about 200 seconds and the activated partial thromboplastin time (APTT) at about 50 seconds. During his support of extracorporeal circulation, flows were maintained between 3.5 and 3.8 L/min, and the gas at about 8 L/min. The ventilator settings were adjusted as follows: mode was pressure control ventilation positive, end expiratory pressure 12 cmH 2 O, respiratory rate 10 breaths per minute, and FiO 2 at 30%. Due to the changes in pharmacokinetics, the dosage and time of drug administration were adjusted, with the dose of methylprednisolone increased to 120 mg daily from hospital day 4 to day 12.
The patient remained stable on hospital day 11 (ECMO day 8), and was able to remain without ECMO for 6 hours with an oxygen saturation in the mid-95% range and PEEP at 8 cmH 2 O. The ECMO unit was removed successfully and mechanical ventilation support was continued. The patient's bleeding had stopped, the oxygenation had improved, and chest imaging also shown improvements. On the 17 th hospital day, the tracheal intubation was removed.
On hospital day 9 of intubation, the laboratory data showed that the patient was positive for cytoplasmic ANCA antibodies (C-ANCA), perinuclear ANCA antibodies (P-ANCA), antimyeloperoxidase antibodies (anti-MPO), and anti-cardiolipin antibodies. However, he was negative for anti-glomerular basement membrane antibodies (anti-GBM). Combined with the previous results, a diagnosis of AAV was confirmed (MPA). Thus, the dose of methylprednisolone was increased to 500 mg daily from hospital day 13 to day 14 and decreased to 80 mg daily from hospital days 15 to 21. When the methylprednisolone was decreased to 40 mg, an equal dose was administered orally until discharge. Blood, sputum culture, excrement, and urine were tested daily to assess for infections and guide the use of antibiotics. The major events of therapy during the hospital stay are summarized in Table 1. The patient gradually improved and the chest radiographs also gradually showed improvements (Figure 3). Thus, he was discharged to the Department of Rheumatology and where his treatment continued. The patient has since recovered well.

Literature review
A detailed search in the PubMed database revealed 32 similar cases with DAH, of which 11 were MPA, 2 were EGPA, and 19 were GPA. These patients were all treated with ECMO (see Table 2 for details). Thus, in total, we reported 33 patients who were successfully treated with ECMO. Of these patients, there were 13 (39.4%) males and 20 (60.6%) females, with a ratio of 1:1.54. The average age was 32.4±17.5 and 36.0±16.1 years for males and females, respectively (t=0.610, P=0.547).

Discussion
ANCA are a family of autoantibodies which can cause a potentially life-threatening systemic necrotizing small vessel  vasculitis referred to as AAV. This group of autoimmune diseases involve both small and medium vessels, and includes GPA, MPA, and EGPA (1). When AAV affects other organs, diagnosis and treatment tend to be delayed due to its nonspecific clinical manifestations. In a systematic review, the authors enrolled 56 studies on 1,422 AAV patients treated with Rituximab (RTX). Complete or partial remission rates over 80% were reported in most studies. The total relapse rate was 30%. Main adverse events included infections and infusion reactions (35). DAH is one of the most serious complications of AAV.
The main clinical manifestations are hemoptysis, or unexplained dyspnea, and an abrupt drop in hemoglobin levels. Although hemoptysis is a characteristic symptom, it is not observed in about one-third of cases (36,37). The major diagnostic criteria include assessment of ANCArelated antibodies and bronchoalveolar lavage fluid, radiology examinations, and lung biopsies (38). Despite surgical lung biopsies representing the gold standard (39), it is not commonly recommended. The common causes of DAH are related to ANCA-related vasculitis, drugs (especially anti-thyroid drugs such as propylthiouracil), infections, connective tissue diseases such as systemic lupus erythematosus (SLE), or other small vasculitis (40). Once DAH is diagnosed, it requires pulse corticosteroids, intravenous cyclophosphamide, and rituximab. Moreover, plasma exchanges can be used in patients who suffer from anti-GBM disease, AAV, SLE, and occasionally in patients with other autoimmune disorders (41,42). In some cases, DAH complications can affect vital organs, and in such cases, invasive mechanical ventilation, CRRT, and ECMO may be used as temporary adjunctive therapy (12). ECMO is frequently used in the management of critical diseases, especially cardiogenic shock, cardiac arrest, fulminant myocarditis, and rejection of heart transplantation therapy (43,44). ECMO manages the task of gas exchange so that the lungs can remain in a resting state, thereby facilitating the patient's rehabilitation. For hypoxemia caused by DAH, mechanical ventilation is usually the first-line treatment of choice in clinics. For more severe refractory cases, ECMO may be used as a short-term supporting method (12).
Herein, we described a patient with AAV-related DAH who suffered from severe respiratory failure. This patient was successfully supported by ECMO which was an essential part of his treatment and evidently improved his prognosis. Mechanical ventilation support is provided to patients who experience persistent hypoxia and respiratory failure. When conventional mechanical ventilation fails, ECMO is used to provide oxygenation immediately (indications for use: oxygenation index less than 80%, ventilation failure in the prone position, life-threatening pneumothorax or hemoptysis). After 2 days of support with V-V ECMO, the patient's pulse oxygen increased and was maintained above 95%. The alveolar hemorrhage did not deteriorate and was resolved after ECMO therapy. These results demonstrated that while the application of ECMO is not suitable for etiological treatment, it confers life-supporting benefits which allows crucial time for immunosuppressive agents to take effect and terminate the pathophysiological processes of the underlying disease. Therefore, ECMO may be the essential strategy to sustain life in patients with acute respiratory failure if conventional therapy fails or if there is insufficient time to treat the primary disease. Different from the case in a report by Goel et al. (24), ours progressed relatively slow, which perhaps help us to save his life.
T h e s t a n d a r d t r e a t m e n t o f A AV-r e l a t e d D A H comprises of high doses of glucocorticoids in combination with cyclophosphamide. The recommended dosage of methylprednisolone ranges from 0.5 to 1.0 g per day for 1-3 days or 15 mg/kg (maximum dose per pulse of 1 g) per dose for 1-3 days (45). In our case, the dose of methylprednisolone (80-120 mg per day) during ECMO was less than the recommended dose. However, the patient's condition improved gradually, suggesting that the application of ECMO can decrease the dose of glucocorticoids required and it may have a direct beneficial effect in improving the outcomes of DAH. The optimization of glucocorticoid therapy with ECMO warrants further investigation.
In addition, due to the rarity and the high mortality rate of DAH secondary to AAV, there have been few cases detailing the use of ECMO in this condition. The comprehensive clinical data of fifteen cases from the literature are listed in Table 2.
Although we were successful in treating this patient, there are a few noteworthy points. First, AAV-related DAH may be misdiagnosed as pulmonary interstitial fibrosis according to chest imaging. Second, the patient's pulmonary hemorrhage with renal function was easily misdiagnosed as Good-pasture syndrome. Third, when combined with organ dysfunction such as acute respiratory distress syndrome (ARDS), it is necessary to support the vital organs in a timely manner, especially with the application of ECMO which can allow for valuable time for the diagnosis and treatment of the primary disease.
This report also summarized 33 patients with AAV who were treated with ECMO. Most of these patients received ECMO on the first day of admission to the ICU and there appeared be a trend that early initiation of ECMO was associated with a shorter duration of ECMO therapy. In general, complications of ECMO in these patients were mild and not often seen in practice. In a retrospective analysis, Seeliger et al. reported 12 patients with GPA and 3 patients with MPA who received ECMO therapy. However, the clinical details of each patient were not provided (46). In addition, there were other similar case reports which did not provide full text articles and thus, could not be incorporated into our literature review (47,48). Nonetheless, to the best of our knowledge, there have been least 48 cases of AAV which have been successfully treated with ECMO therapy. These 48 cases provide valid support for similar patients to receive ECMO as early as possible.
Our patient expressed his satisfactory for our service and hoped to do follow-up regularly.

Conclusions
The emergent condition caused by AAV-related DAH can be effectively managed by ECMO. In our case study, supporting respiratory function with ECMO effectively improved the potentially fatal hypoxemia caused by pulmonary hemorrhage. With the improvement of oxygenation, effective control of underlying disease allowed for the removal of extracorporeal circulation and extubation. In the past case reports, no life-threatening hemorrhage events occurred during ECMO intervention. Although ECMO is a highly invasive procedure with a significant risk of bleeding complications, early initiation of ECMO and meticulous care during treatment may be a novel and lifesaving strategy in patients with AAV-related DAH who fail to respond to conventional mechanical ventilation.

Acknowledgments
Funding: None. Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was approved by the local Ethics Committee of the Chinese PLA General Hospital (Beijing, China) (No. S2020-141-01). The patient provided written informed consent for the publication of any associated data and accompanying images. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013).
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