More than half of patients with idiopathic pulmonary fibrosis (IPF) have obvious cough symptoms.
When a patient develops chronic cough, it will affect the patient's psychological state and lead to a significant reduction in the quality of life.
cough in patients with IPF may be caused by comorbidities such as gastroesophageal reflux; may also be caused by IPF disease itself, which may be caused by various mechanisms such as mechanical and neurosensory changes.
Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with an estimated median survival of 3-5 years. The purpose of IPF treatment includes stopping disease progression and limiting the burden of symptom, including limited activity, difficulty breathing, fatigue, nagging, stubborn cough, etc. Although there are currently two anti-fibrotic drugs to slow the progression of IPF, no treatment can significantly prolong the survival of IPH patients except for lung transplantation (only for some eligible patients).
IPF The cause of coughing in
About 50% of patients with
Coughing is caused by other causes other than fibrotic interstitial lung disease (ILD), including upper airway cough syndrome (UACS), asthma, eosinophilic bronchitis (NAEB), gastroesophageal reflux disease (GERD) and other non-IPF causes. In addition, comorbidities such as obstructive sleep apnea (OSA), emphysema, lung cancer, etc. also need to be considered. Several studies have shown that the proportion of GERD and OSA in patients with IPF is much higher than that in ordinary people.
and IPF itself can also cause coughing, and its possible mechanism: coughing is caused by thermal, chemical or mechanical factors stimulating receptors. After stimulating cough receptors in the upper and lower respiratory tracts, pericardial, esophagus, diaphragm, stomach, and chest walls, accommodating pulses pass through the vagus nerve to reach the "cough center" in the medulla. The efferent pulses are then triggered through the vagus, phrenic nerves and motor nerves of the spine to coordinate the contraction of the diaphragm, abdominal wall and chest wall expiratory muscles, causing cough. The medulla is also affected by the higher cortical centers, so the cough may be spontaneous or reflexive. In IPF, cough stimulation and inhibition response imbalances include: upregulation of thermally sensitive fibers and chemosensory fibers, mechanical deformation changes sensory fibers, and intrinsic properties of the respiratory epithelium.
IPFEvaluation of cough
IPF patients need to undergo a detailed medical history and examination to determine the duration, severity and frequency of cough. Screen for common causes and risk factors for cough, including UACS, GERD, asthma, etc. Esophageal impedance detection or bile reflux monitoring, barium meal, sinus CT, bronchodilation test, sputum culture, bronchial examination, etc. can be performed.
If these tests do not indicate coughs that are not caused by IPF, lung function tests and chest CT can be performed, which can be inferred as coughs that progress at the same time as IPF disease.
IPFCough treatment
At present, there is relatively little evidence to guide the treatment of chronic cough in patients with IPF.
For UACS, saline rinsing and nasal corticosteroids can be selected to start treatment with saline, and when allergies cause nasal symptoms, increase nasal antihistamines and/or non-seducation oral antihistamines and/or leukotriene antagonists. If vasomotor rhinitis occurs, nasal anticholinergic drugs can also be added. Sterile saline nasal rinsing is a simple and inexpensive treatment that reduces symptoms related to irritating or allergic rhinitis by removing inflammatory mediators and enhancing mucus removal.
For GRED patients, anti-acid therapy can be performed by changing their lifestyle and using proton pump inhibitors. Life includes avoiding GRED-induced diet, losing weight, raising the head of the bed, avoiding diet and drinking plenty of water 3 hours before going to bed. If the patient still has persistent gastroesophageal reflux symptoms after receiving antacid therapy, gastrogenic motivation drugs can be increased.
Inhaled glucocorticoids can be used in patients with asthma and NAEB. If the cough is not completely relieved during the treatment process, it indicates that there are other comorbidities.
For cough caused by IPF itself, it is necessary to consider that the sensitivity of afferent airway neurons is a possible mechanism. Neuromodulators such as gabapentin, pregabalin, amitriptyline and baclofen can be used, but only gabapentin has passed the randomized double-blind trial.
Opioids such as morphine can also be used to relieve cough through neuromodulation. They are generally only used in patients whose treatment is ineffective and whose cough symptoms seriously affect the quality of life.
Speech pathology treatment is a non-drug treatment method that effectively improves cough symptoms in patients with refractory chronic cough. It mainly includes education, suppression of cough exercises, reducing throat stimulation and psychological counseling. Speech pathology treatment combined with pregabalin and other drugs can be more effective. It is also recommended that all patients with IPF-related cough undergo speech pathology.
In addition, some patients have coughs during hypoxia. For these patients, supplementing oxygen can significantly improve the cough and completely cure it. Short-term (2 weeks) and low doses (10~20mg) prednisone can also significantly improve the symptoms of cough.
For anti-fibrotic drugs such as pirfenidone, observational data showed that their objective and subjective cough severity can be improved after 12 weeks of treatment, but there is no strong clinical study to confirm that anti-fibrotic drugs have reliable effects on cough. In addition, no research has been published on the treatment of Nidanibu in the field of cough.
Summary
Chronic cough is very common in patients with IPF (as well as other fibrotic ILD) and can severely reduce the quality of life of patients. The mechanism of IPF causing cough has not been fully elucidated, but it is currently believed that multiple mechanisms are involved, including airway deformation, parenchymal, related nerve fibers, and afferent nerve allergies. IPF is associated with a variety of comorbidities that can cause chronic cough, such as GRED, OSA, lung cancer, etc. Others such as UACS, asthma, respiratory infections, post-infection coughs, etc. also need to be considered. After these reasons are ruled out, it can be considered that cough is caused by the IPF disease itself, and cough may be a signal of the progression of IPF disease. For cough caused by the disease itself, speech pathological treatment is recommended, and neuromodulation drugs are used. Short-term (2 to 3 weeks) medium and low doses of cortisone can be considered. Anesthetic drugs can be used in specific situations such as cough severely affecting sleep quality.
References: Wakwaya Y, Ramdurai D, Swigris JJ. Managing Cough in Idiopathic Pulmonary Fibrosis. Chest. 2021 Nov;160(5):1774-1782.
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