Overview: The main symptoms of this disease are progressive dyspnea, cough and chest pain.
A disease characterized by inflammation and pulmonary fibrosis that occurs mainly in the interstitium of the lungs. The main symptoms are progressive dyspnea, cough, chest pain, etc. The etiology of the disease is related to the environment, medications, diseases, clinical treatments, etc., and there may be no clear cause of the disease. The treatments include general treatments, medications, and surgeries.
Definition
Interstitial pneumonitis is a group of diseases caused by a variety of reasons and characterized by inflammation and fibrosis of the interstitium of the lungs.
The interstitium is defined as the interalveolar, supporting tissue beyond the terminal airway epithelium, including vascular and lymphovascular tissue.
Staging
Interstitial pneumonia of known cause
Interstitial pneumonia associated with environmental factors
Caused by repeated inhalation of organic dust antigens, e.g., hypersensitivity pneumonitis.
Drug- or treatment-related interstitial pneumonias
Interstitial pneumonitis caused by drugs such as amiodarone, bleomycin, methotrexate, radiation therapy, and high concentration oxygen therapy.
Interstitial pneumonia associated with connective tissue disease or vasculitis
Caused by connective tissue disease or vasculitis involving the respiratory system.
For example, systemic scleroderma, rheumatoid arthritis, polymyositis/dermatomyositis, dry syndrome, systemic lupus erythematosus, necrotizing granulomatous vasculitis, allergic granulomatous vasculitis.
Interstitial pneumonia of unknown origin
Interstitial pneumonia of unknown cause, also known as idiopathic interstitial pneumonia, can be categorized into the following 3 main groups.
Common idiopathic interstitial pneumonia
Idiopathic pulmonary fibrosis: Prevalent in the elderly.
Idiopathic nonspecific interstitial pneumonia: It is interstitial pneumonia without a clear cause and difficult to classify.
Respiratory bronchiolitis with interstitial lung disease: most common in heavy smokers, with no significant difference in gender distribution.
Desquamative interstitial pneumonia: most common in heavy smokers, prevalent in males.
Cryptogenic mechanized pneumonia: refers to mechanized pneumonia of unknown etiology.
Acute interstitial pneumonia: of unknown etiology, with a rapid onset and critical illness.
Rare idiopathic interstitial pneumonia
Idiopathic lymphocytic interstitial pneumonia: very rare, less than 2% of idiopathic interstitial pneumonias.
Idiopathic pleuropulmonary parenchymal elastosis.
Idiopathic interstitial pneumonia that fails to be classified
Interstitial pneumonia that cannot be definitively diagnosed.
Etiology
Causes
There are numerous causes of interstitial pneumonia, most of which are not clearly defined and may be related to the following factors.
Environmental factors
Inhalation of organic dust: such as plant, animal and man-made organic dust, common cotton, tobacco, wood chips, feathers, fur, animal excreta and man-made fibers.
Inhalation of inorganic dust: such as quartz, asbestos, lead, manganese, cement, glass fiber, etc.
Inhalation of harmful gases: nitrogen oxides, sulfur dioxide, metal oxides, hydrocarbon compounds and diisocyanotoluene, etc.
Drug factors
e.g. furoantoin, amiodarone, hydralazine, bleomycin, methotrexate, etc.
Clinical factors
Such as receiving radiotherapy, long-term high concentration of oxygen therapy.
Disease factors
Secondary to connective tissue disease or vasculitis, e.g. systemic scleroderma, rheumatoid arthritis, polymyositis/dermatomyositis, dry syndrome, systemic lupus erythematosus, necrotizing granulomatous vasculitis, allergic granulomatous vasculitis.
High risk factors
Occupational exposure: those who are engaged in rock drilling, blasting, casting, farming and animal husbandry, or other long-term exposure to hazardous substances or gases.
Smoking: an important risk factor for interstitial pneumonia.
Infections: Pneumocystis carinii, cytomegalovirus, hepatitis C virus infection, etc.
Gastroesophageal reflux: Gastroesophageal reflux causes microscopic aspiration, which may increase the risk of developing the disease.
Genetic factors: a family history of interstitial pneumonia may increase the risk of the disease.
Pathogenesis
Inflammatory and immune responses due to a variety of known and unknown etiologic factors result in damage to the alveolar walls, blood vessel walls, and airways, followed by irreversible scarring of the lungs (fibrosis), which ultimately leads to impaired alveolar gas exchange.
Symptoms
Main Symptoms
Progressive dyspnea
Most patients present with chest tightness and shallow, rapid breathing, which occurs after activity in the early stages of the disease and then, as the disease progresses (slow progression), with light activity or quietness.
Acute interstitial pneumonitis often starts suddenly (within a few days to weeks), and symptoms such as chest tightness and shallow, rapid breathing may appear rapidly, and in severe cases, may be followed by respiratory failure.
Cough
Early stage is not serious.
In the late stage, there may be irritating dry cough due to labor or hard breathing.
In secondary infection, there may be pus sputum.
A few patients may have blood in sputum.
Chest pain
Chest pain is uncommon and is usually seen in patients with interstitial pneumonitis due to rheumatoid arthritis, systemic lupus erythematosus, mixed connective tissue disease, and certain medications.
Other symptoms
Systemic symptoms: some patients may present with fever, malaise, weight loss, muscle aches, joint swelling and pain.
Pestle-like fingers (toes): manifested as hyperplasia and hypertrophy of the ends of the fingers or toes, with a pestle-like expansion.
Cyanosis: obvious cyanosis may appear in the late stage of the disease, manifesting as blue-purple color of lips, fingers (toes) and nail beds.
Complications
Pulmonary hypertension
The most common first symptom is shortness of breath and weakness after activity.
Other symptoms include chest pain, hemoptysis, vertigo or fainting, and dry cough.
Lung infections
Mostly related to the application of glucocorticoids or immunosuppressants in treatment.
Mostly manifested as fever, cough, and increased sputum volume.
Respiratory failure
Mainly manifested as dyspnea, cyanosis, etc., and may appear unconsciousness, involving all systems of the body, causing multi-organ dysfunction.
Consultation
Department of Medicine
Respiratory medicine
When symptoms such as cough, sputum, chest tightness, chest pain and shallow breathing occur, it is recommended to consult a doctor promptly.
Emergency Department
When symptoms such as respiratory distress, cyanosis, or impaired consciousness occur, immediate medical attention is recommended.
Preparation for medical treatment
Consultation: registration, preparation of documents, common problems
Tips for seeking medical treatment
Chest X-rays or chest CT are often needed, so avoid wearing clothing made of metal, and inform your doctor if you are pregnant or planning to become pregnant.
Preparation Checklist
Symptom list
Pay particular attention to the time of onset of symptoms and special signs and symptoms.
Is there fever? What is the highest temperature?
Is there a cough? How long has the cough lasted?
Is there any sputum? What kind of phlegm?
Is there chest tightness or chest pain? Under what circumstances is it aggravated or relieved?
How long have the symptoms been present?
List of medical history
Are there any diseases such as rheumatoid arthritis?
What kind of work are you engaged in? Any long-term exposure to dust, harmful gases, etc.?
Has radiotherapy or oxygen been administered?
Checklist
Test results in the past six months, which can be brought to the doctor’s office
Laboratory tests: routine blood test, C-reactive protein, erythrocyte sedimentation rate (sedimentation), urine routine, sputum culture, blood gas analysis
Imaging tests: Chest X-ray, Chest CT scan
Specialized examination: lung function test
Medication List
Medication used in the last 3 months, if there is a box or package, you can bring it with you to the doctor’s office
Anti-fibrotic drugs: pirfenidone, nidaneb
Glucocorticoids: prednisone, methylprednisolone
Others: methotrexate, amiodarone, dextromethorphan
Diagnosis
Diagnosis is based on
Medical history
History of respiratory disease, connective tissue disease, or vasculitis.
History of exposure to dust, harmful gases or substances, etc. (The doctor should be informed of the workplace, type of work, etc.)
History of chemotherapy, radiotherapy, long-term high concentration oxygen therapy.
History of infection.
History of drug application, especially some drugs that can induce pulmonary fibrosis, such as amiodarone and methotrexate.
Clinical manifestations
Symptoms
Progressive dyspnea, dry cough, chest pain, chest tightness, fever, cyanosis and other symptoms.
Physical signs
In some patients, examination reveals hyperplasia and hypertrophy of the ends of the fingers or toes, with pestle-like enlargement.
Chest auscultation can mostly hear bilateral lung base bursting rales, occasionally can hear wheezing and wet rales, can also be completely normal. In the area of pulmonary artery auscultation, the presence of a hyperactive second heart sound is suggestive of pulmonary hypertension.
Increased pulse rate and irregular pulse beat may be present.
Laboratory Tests
Routine blood tests
To find out the changes in blood cells (red blood cells, white blood cells, platelets) and hemoglobin.
If bacterial infection is present, elevated white blood cells and neutrophils may be present.
Fasting is not required before the test.
Erythrocyte Sedimentation Rate and C-Reactive Protein
Changes in erythrocyte sedimentation rate and C-reactive protein can be detected.
Increased erythrocyte sedimentation rate and elevated C-reactive protein are often seen.
Urine routine
In the presence of renal damage, erythrocytes may be present in the urine and there may be an abnormal increase in urinary protein.
Sputum Pathogenesis
Helps to clarify the presence of a respiratory infection and the nature of the infection.
Sputum specimens are collected by rinsing the mouth with water and coughing up sputum deep in the trachea.
Arterial blood gas analysis
Helps to understand the patient’s ventilation, oxygenation and acid-base balance.
Others
Serum autoantibodies, serum immune complexes, and tumor marker tests are also helpful in the identification and diagnosis of the disease.
Imaging
Chest X-ray
Changes in the structure of the lungs can be detected, and certain signs may suggest a diagnosis.
It is common to see ground-glass-like changes in the lungs, reticular changes, honeycomb lungs, and enlarged mediastinal and hilar lymph nodes.
Avoid wearing metal jewelry or clothing with metal buttons.
Chest CT
CT is more sensitive than conventional chest X-ray and can detect lesions that are not easily detected by conventional chest X-ray.
Echocardiogram
Helps to check the structure and function of the heart, as well as pulmonary artery pressure.
Specialized Tests
Pulmonary Function Test: To determine the nature of ventilation dysfunction (obstructive, restrictive or mixed) and whether it is combined with diffusion dysfunction, and to judge the severity of ventilation and diffusion dysfunction through pulmonary function.
Histopathology: Samples can be obtained by bronchoscopy, bronchoalveolar lavage, or open chest surgery for histopathologic examination as needed. This test helps in the diagnosis of the disease.
Differential Diagnosis
Bacterial pneumonia
Similarities: Fever, cough, sputum, chest pain, etc.
Differences: Bacterial pneumonia is an inflammatory disease mainly caused by pneumococcus with diffuse fibrinous exudation in the alveoli, and the lesions usually involve some or all of the lobes of the lungs. Patients are mostly young adults, and cold, fatigue, and alcoholism are often the triggers.
Bronchopneumonia
Similarities: fever, cough, shortness of breath, etc.
Differences: Bronchopneumonia is an inflammation of the bronchial walls and alveoli caused by bacterial and viral infections. It occurs in critically ill patients who are bedridden for a long period of time, children and the elderly who are weak. Chest auscultation can be heard in the middle and fine wet rales, combined with imaging, laboratory tests, etc. can help differential diagnosis.
Treatment
Treatment objectives and principles
Treatment objectives
To delay disease progression, improve quality of life and prolong survival.
Principles of treatment
Actively carry out clinical comprehensive treatment, the main treatment modalities include general treatment, drug treatment and so on.
General treatment
Health management
Interstitial pneumonia caused by clear environmental factors should be removed from the adverse working or living environment as soon as possible and kept away from allergens (allergens).
Interstitial pneumonia induced by drugs should immediately stop using the suspected drugs.
Actively treat connective tissue disease, gastroesophageal reflux and other primary diseases.
Reasonable oxygen therapy
Nasal catheter oxygen administration: applicable to mild hypoxemia.
Mask oxygenation: generally applicable to patients who need higher oxygen concentration.
If necessary, long-term home oxygen therapy can be carried out under the guidance of doctors.
Do not adjust the oxygen flow rate when performing oxygen therapy.
Nutritional support
Patients are in a high metabolic state, and adequate nutrition should be ensured.
For critically ill patients who cannot eat normally by mouth, a nasogastric tube or nasojejunal tube can be placed.
The specific nutritional regimen should be based on the patient’s general condition, access, hepatic and renal function, and glucose and lipid metabolism.
Acute phase treatment
Patients with acute exacerbation of interstitial pneumonia have severe conditions and high mortality rates, and high doses of hormones and immunosuppressive agents are generally recommended for clinical treatment.
Oxygen therapy, prevention and control of infection, symptomatic supportive therapy and other treatments can be adopted, and noninvasive mechanical ventilation and invasive mechanical ventilation can be used as appropriate.
Drug therapy
There are many types of interstitial pneumonia, and the following drug treatments should be mainly applied to slow down disease progression and reduce symptoms. Specifically should be used under the guidance of a doctor, do not believe in unidentified treatments such as local remedies, secret prescriptions, and biased remedies.
Anti-fibrosis drugs
Pirfenidone or nidanib are used under the supervision of a doctor to slow down the decline of lung function in patients.
Adverse effects of pirfenidone include photoallergy, malaise, rash, and stomach upset; common adverse effects of nidaneb are mainly diarrhea.
Some patients can apply N-acetylcysteine, which has antioxidant effects and also relieves cough symptoms.
Anti-inflammatory treatment
Glucocorticoid
Prednisone and methylprednisolone can be used.
In severe cases, high-dose glucocorticoid shock therapy can be applied as appropriate.
If the clinical symptoms are relieved and stabilized, the dosage can be reduced or stopped according to the doctor’s opinion.
Long-term application of glucocorticosteroids should be aware of adverse reactions such as infection, osteoporosis, gastrointestinal bleeding and hypokalemia.
Immunosuppressant
Some patients need immunosuppressive drugs combined with glucocorticoid therapy.
Cyclophosphamide, methotrexate and azathioprine are commonly used.
In the treatment, attention should be paid to check the blood routine, urine routine and liver function, renal function, in order to monitor the occurrence of adverse reactions.
Cough suppressants
Central cough suppressants
They work by directly inhibiting the medullary cough center and are suitable for patients with dry cough.
Codeine and dextromethorphan are available.
Codeine: strong cough suppressant, not conducive to phlegm expectoration, and addictive and dependent, so only used for dry cough and irritating cough with chest pain.
Dextromethorphan: non-addictive and analgesic effect. It is suitable for cough with little or no sputum, and should not be used for those with much sputum.
Peripheral cough suppressants
Act by inhibiting cough reflex receptors as well as effectors.
Nyquiline is available, non-dependent and suitable for coughs of different causes.
Anti-infective treatment
If infection is present, anti-infective treatment should be active.
Under the condition of smooth drainage of respiratory secretions, effective antibacterial drugs should be selected with reference to the results of sputum bacterial culture and drug sensitivity test.
Quinolones (e.g., levofloxacin) or β-lactams (e.g., cephalosporins, penicillins) combined with macrolides (e.g., erythromycin, azithromycin) can be used for treatment, or carbapenems alone can be used for anti-infective treatment.
Surgical treatment
Lung transplantation can be considered for end-stage patients, patients with severe lung fibrosis and severely affected respiratory function, in order to improve the quality of life and survival rate of patients.
Prognosis
Cure
The prognosis of different types of interstitial pneumonia is different, as follows.
Allergic Pneumonia
In some patients, the symptoms may disappear on their own and lung function may recover a few days after they are removed from the adverse environment and away from allergens (allergens).
Drug-related interstitial pneumonia
It can be cured after stopping the suspected drugs in time.
Interstitial pneumonia associated with connective tissue disease or vasculitis.
Prognosis is related to the severity of the primary disease.
Idiopathic pulmonary fibrosis
The average survival time after diagnosis is 3 to 5 years, and the most common cause of death is respiratory failure.
Idiopathic nonspecific interstitial pneumonia
The vast majority of patients have a good clinical prognosis and their disease may stabilize or improve with treatment.
However, some patients continue to progress to end-stage or even die.
Respiratory bronchiolitis with interstitial lung disease
Most patients have a good prognosis, and their condition may stabilize or improve after active or forced smoking cessation.
Desquamative interstitial pneumonia
Most of the patients have a good prognosis, and some of them may resolve on their own after quitting smoking.
Cryptogenic Mechanized Pneumonia
Most patients may have complete remission after treatment, and a few patients may remit on their own.
Acute interstitial pneumonia
Patients with sudden onset and rapid progression can develop respiratory failure in a relatively short period of time, and the average survival time is very short, with most of them dying within 1 to 2 months.
Idiopathic lymphocytic interstitial pneumonia
Some patients experience complete remission with treatment, and some may be relatively stable for months or years before progressing to pulmonary fibrosis and pneumogenic heart disease.
Idiopathic pleuropulmonary parenchymal elastosis
The prognosis is poor; patients may experience a short-term worsening of clinical symptoms, a gradual decline in the level of lung function, and a high mortality rate.
Hazardous
Interstitial pneumonia mostly manifests as progressively aggravated dyspnea, which seriously affects normal work and life, and may even develop into respiratory failure, thus endangering life.
Interstitial pneumonia is prone to complications such as lung infections and pulmonary heart disease, which can affect disease progression and prognosis, further affecting health and quality of life.
Daily
Daily Management
Dietary management
Patients with interstitial pneumonia are in a state of high metabolism and should be supplemented with adequate nutrition.
For those who can eat normally by mouth, it is advisable to increase the intake of high-quality and high-protein diet (such as eggs, milk, lean meat, etc.), diversify food and ensure the intake of other nutrients.
Eating should be chewed and swallowed slowly to avoid breathlessness caused by excessive satiety.
Avoid eating spicy and stimulating foods, such as wine, strong tea, coffee, raw garlic, ginger, chili peppers, curry and so on.
Gastrointestinal nutrition may be given to critically ill patients if they are unable to eat normally by mouth. The overall body condition, access, liver and renal function, and glucose and lipid metabolism should be closely monitored in order to formulate a specific nutritional supply program.
If cardiac or renal insufficiency is not present, more water can be consumed in moderation.
Life management
Rest
Combine work and rest, pay attention to rest, and avoid staying up late.
In order to reduce physical exertion and oxygen consumption, those who are more seriously ill should rest in bed and minimize self-care activities and unnecessary operations.
Long-term bedridden patients should regularly perform active or passive activities of the lower limbs to prevent the formation of lower limb deep vein thrombosis.
Appropriate exercise
Perform respiratory control training, respiratory muscle training, thoracic relaxation training, strength endurance training and aerobic exercise under doctor’s guidance to improve respiratory efficiency and help restore lung function.
Avoid exercises with high oxygen consumption and start with low-intensity exercises such as walking according to your situation.
Keep your airways clear
Learn effective breathing and coughing and phlegm techniques under the guidance of your doctor, such as lip-contraction breathing and abdominal breathing, to slow down the deterioration of lung function.
When breathing is labored, try adopting a semi-recumbent or sitting position, lying on your stomach on a bed table, to improve breathing.
Long-term bedridden people should be given regular turning and back patting to keep the airway open.
Contact your doctor if you notice a peculiar smell in the sputum, or changes in the amount, color and consistency of sputum.
Avoid cold stimulation
Observe the weather changes and increase clothing appropriately in cold weather.
Wear warm hats, masks, gloves and warm socks when going out.
Prevention of infection
Avoid going to places where people gather.
Pay attention to personal hygiene and wash hands frequently.
Get vaccinated against influenza and pneumonia in winter and spring.
Smoking cessation
Smoking will further damage the bronchial mucosa and weaken the function of alveolar macrophages, which will easily lead to lung and bronchial infections, thus accelerating pulmonary fibrosis. Therefore, patients with interstitial pneumonia must quit smoking and avoid inhaling second-hand smoke.
Psychological support
Facing the disease with a positive and optimistic mindset and establishing confidence in overcoming the disease.
Family members should give more psychological care to the patient, and may encourage him/her to name the factors that cause or aggravate anxiety.
Disease monitoring
Monitor the respiratory rate, blood pressure, heart rate, sputum volume and character, and so on.
If symptoms worsen, or new symptoms appear, consult the doctor promptly.
Follow the doctor’s prescribed schedule for follow-up visits.
Prevention
Reasonable dietary arrangement, strengthen nutrition and improve physical fitness.
Avoid triggers and stay away from allergens.
People engaged in dust work and long-term exposure to toxic and hazardous gases should pay attention to protection at work.
Quit smoking and drinking.
Have regular medical checkups and actively treat other diseases of the respiratory system and systemic diseases.
Go to crowded places as little as possible to avoid contact with respiratory tract infected people and reduce the chance of infection.
Wear a mask when going out and wash your hands frequently.