Cough

A cough is an inborn protective reflex mechanism. A reflex is when your body produces an automatic response to a stimulus, for example, an irritant. Our airways and the throat have the nerves, which sense these irritants. Once an irritant stimulates the nerves, they send a signal to the brain. The brain sends a signal to the chest wall muscles and the abdomen, which in response take a deep breath, which is quickly and forcefully also breathed out while trying to eliminate the irritant. This entire response is almost rapid, occurs within a fraction of a second, and is very effective. A cough can push the particles and air out of the throat and lungs at a speed of nearly 50 miles per hour.

A chronic cough and persistent production of phlegm are important indicators of respiratory illness. These symptoms hold significance in various epidemiologic studies that have shown a strong connection between these symptoms and fatal respiratory diseases like COPD.

Cough is a symptom of an underlying disease, which might originate from the respiratory system, cardiovascular (heart) system, digestive system or others. It will typically be associated with other symptoms that guide the diagnosis of the original cause. Some of the most commonly seen symptoms associated with a cough are:

• Sore throat
• Difficulty in swallowing while eating, especially in children
• Burning sensation in your chest or heartburn
• Sweating at nights
• Fever and chills
• Weight loss
• Chest pain
• Ear pain
• Blood in the sputum while coughing
• Decreased ability to perform physical activity
• Difficulty in breathing
• Whistle-like sound while exhaling, i.e., wheezing.

Causes

The causes of cough can be classified based on the site of origin.

Respiratory causes

• Infectious causes

  • Upper Respiratory Tract Infections (URTIs): Upper respiratory infections are extremely common and spread rapidly from person to person by droplet infection. Common examples are common cold, sinusitis, and infection the influenza virus causing flu. Of these, flu is the most serious cause.

  • Lower Respiratory Tract Infections (LRTIs): LRTIs affect the airways and the lung tissue called alveoli. These infections can progress to collapse of a lobe of the lung if not treated in time. Common examples include pneumonia, bronchitis, and bronchiectasis. Tuberculosis is potentially lethal but common LRTI. Flu can affect both the upper and lower respiratory tract and is a common cause.
• Heart-related causes
  Heart failure: Failure of the heart to pump adequate blood is termed as heart failure. A number of chronic heart diseases can lead to heart failure. Accumulation of excess blood in the heart leads to fluid buildup in the lungs as well, causing cough, especially at night as one lies down.

• Non-infectious causes

  • Allergic conditions: Inhalation of toxic chemical fumes can lead to an allergic reaction in the nose and respiratory tract causing allergic rhinitis and cough. Allergy to common environmental allergens like pollen, dust, environmental pollutants or animal dander too can incite an allergic cough. This is also termed as hay fever.

  • Asthma: Asthma is a severe allergy and inflammation of the airways of the lungs leading to a triad of cough, wheezing and shortness of breath due to narrowing down of the airway passage. Common triggers for asthma include exercise, cold weather, pollen, dust, certain chemicals, dyes and others.

  • Chronic Obstructive Pulmonary Disease (COPD): This is usually observed in smokers as a chronic cough that worsens with exertion. Lung tissue inflammation leads to prolonged cough with shortness of breath and phlegm production.

  • Lung clot: Presence of clot in the arteries of the lungs, also known as pulmonary embolism, is medical emergency leading to sudden and severe shortness of breath along with a cough. Blood clots travel from the veins of the leg to the lungs.

  • Lung collapse: Collapse of one or more lobes of the lungs, also known as pneumothorax, occurs when a part of the lung deflates in the chest. An injury to the chest or genetic syndromes, like Marfan’s syndrome, increases the risk of lung collapse quite spontaneously. It is more commonly seen in smokers who have been diagnosed with emphysema

  • Nasal drip: Continuous dribbling of mucus into the throat leads to a cough, especially while lying down. This generally occurs in case of a URTI or allergic rhinitis.

  • Lung cancer: Uncontrolled growth of cells of any lung tissue can lead to lung cancer, which is a common cause for cough. Metastasis or spread of a tumour from other organs to the lungs too can lead to a cough. Such cough might contain blood.

• Digestive causes
  Gastro-oesophageal reflux disease (GERD): A common cause of a cough is the acid produced from the stomach travelling upwards into the food pipe. This is due to a condition called GERD.
• Other causes
  Medications: Some medications like angiotensin-converting enzyme inhibitors (ACE-I) which are used to treat high blood pressure can cause a dry cough.

Risk Factors

Following are some of the risk factors for developing a cough:

Internal causes like the following increase the risk of having a cough:

• Allergy to certain substances
• Female gender
• Existing lung diseases
• Existing heart diseases

External causes as mentioned below increase the risk of having a cough:

• Smoking
• Environmental pollutants and irritants like asbestos, coal, silica
• Close contact with a person having an infectious lung disease.

In order to prevent a cough, it is important that you take enough protective measures to protect yourself from infectious agents and allergens, This can be done in the following manner:

• While going out, it is advisable to wear a protective mask to shield you from environmental pollutants and allergens. This will further protect you from the risk of developing respiratory tract infections. Using protective devices like a mask is all the more important if you suffer from recurrent coughs or are prone to lung infections.
• Avoid any known allergens and stay away from environmental triggers.
• Avoiding contact with a person who is suffering from a communicable infection and washing your hands regularly will also help in the prevention of an infection.
• Keep your environment clean and dispose off used tissues carefully.
• Another way in which you can avoid a cough is by working on your immunity. Increase the intake of immunity-boosting foods like those rich in vitamin C in your diet.
• Vaccination is another important measure, which helps to avoid future infections. So, make sure your children are vaccinated for respiratory infections like pertusis, well in time.

Your doctor will diagnose a cough by eliciting history related to your occupation, lifestyle, past medical history, and current symptoms. This will be followed by chest auscultation with the help of a stethoscope, to identify the exact cause, which will be later confirmed by diagnostic tests.

Your doctor may or may not recommend you some of the following tests:

Laboratory tests

• Complete blood count
• Sputum culture and microscopic examination
• Specific tests to look for certain infections
• Throat swab
• Spirometry – this is a test to determine the lung function and breathing capacity

Imaging studies

• Chest X-ray
• CT scan of the chest
• Bronchoscopy – this is a procedure where a camera-fitted thin tube is passed into the lung airways (bronchi) to look for the cause of a cough. This is sometimes also used to treat a cough by removing a foreign body. A bronchoscopy might also be used to collect a tissue sample, called a biopsy, for further assessment.

Treatment options for a cough depend on the cause. Following is a list of therapeutic options for a cough:

• Antibiotics and antifungals are used to treat infections of the respiratory tract.
• Expectorants might be advised to help remove phlegm accumulated in the airways. Anti-tussives are also commonly prescribed.
• Antihistamines and decongestants are used to treat allergic causes of a cough. Avoiding allergens; however, remains the prime step in treating allergic conditions.
• Drugs called bronchodilators that help in widening narrowed airways are used to treat asthma, which also helps in reducing the associated symptom of a cough.
• Steroids like prednisone might be used to treat severe episodes of asthma and COPD.
• Proton pump inhibitors and H2- receptor blockers are used when GERD is the cause of a cough.
• Changing the drug or dosage is the treatment in cases where medication is the ascertained cause.
• Blood thinners, oxygen and other emergency treatment, are needed in case of lung collapse or a blood clot in the lungs. A chest drainage tube might be inserted to reinflate the collapsed lung and drain any fluid in the chest cavity.

Tips to manage a cough

• Use a fresh paper tissue or a napkin to cover your nose and mouth while coughing or sneezing. Discard the tissue right away. In case, you have nothing available, cough into the crook of your elbow or upper sleeve and not into your hand.
• Always clean and disinfect the surfaces you touch at work or home.
• Thoroughly wash your hands for a least 15 to 20 seconds using hot water and soap after touching your nose, eyes and mouth. You can also use alcohol-based rubs.
• Quitting smoking is extremely important to prevent worsening of existing cough. Avoid inhaling smoke due to passive smoking.
• You can use steam inhalation or a hot shower to reduce cough and congestion.
• Drinking warm water over cold is another way in which you can manage cold and a sore throat.
• Sucking on hard candy or lozenges can help relieve a sore throat and dry cough by increasing saliva production. Avoid giving them to children aged three or less as it poses a choking hazard.
• Warm teas like ginger tea or lemon tea can also help in relieving a cough.
• Honey can help reduce the frequency of coughing and soothe an inflamed throat. Do not give it to children under the age of one as there might be a high risk of botulism, which is a severe infection.

Prognosis

A cough usually is not a sign of something serious.  But, sometimes, a short-term cough may be the first sign of a disease that causes a persistent cough. Yet in rare cases, a persistent cough can be a symptom of lung cancer, tuberculosis, or heart failure. In children, a persistent cough can be a sign of cystic fibrosis, a severe long-term infection. In most people, coughs clear up within three weeks; thus, they don't need much of a therapy. If cough persists, it is a good idea to see your doctor so that they can find the underlying cause of a cough.

Complications

The complications of a cough seem to arise from factors like the pressure and force produced during forceful coughing. Some of the adverse complications of coughing include:

• Constitutional symptoms: Sweating, anorexia, exhaustion, and excessive sweating.
• Skin: Disruption of any surgical wounds.
• Musculoskeletal symptoms: Rib fractures, diaphragm rupture etc.
• Cardiovascular: Low blood pressure in the arteries, decreased heart rate, increased heart rate etc.
• Neurological: Headache, dizziness, seizures.

Effects are also seen in the respiratory tract, cardiovascular system, gastrointestinal tract, and the eyes. Severe coughing can also have psychological effects and adverse effects on the person’s quality of life. Persistent dry cough can cause the following complications:

• Urinary incontinence in pregnant women.
• Interrupted sleep.
• A cough can cause intense fits which can result in vomiting at times.
• Headaches.