Category Archives: Pulmonology (respiratory)

– Asthma
– Snoring and sleep apnea.
– Sinusitis.

Tuberculosis, Latent and Active Infections, with Video.

The videos on this page can be downloaded upon purchase of a license on Alila medical Media website. Click here!

Tuberculosis, or TB, is one of the oldest and most common infectious diseases. About one third of the world population is believed to be infected with TB. Fortunately, only about 5% of these infections progress to active disease. The other 95% of infected people are said to have a dormant or latent infection; they do not develop any symptoms, and do not transmit the disease.

Tuberculosis is caused by a rod-shaped bacterium, or a bacillus, called Mycobacterium tuberculosis. An infection is initiated following inhalation of mycobacteria present in aerosol droplets discharged into the atmosphere by a person with an active infection. The transmission process is very efficient as these droplets can persist in the atmosphere for several hours and the infectious dose is very low – less than 10 bacilli are needed to start the infection.

Once in the lung, the bacteria meet with the body’s first-line defense – the alveolar macrophages. The bacteria are ingested by the macrophages but manage to survive inside. Internalization of the bacilli triggers an inflammatory response that brings other defensive cells to the area. Together, these cells form a mass of tissue, called a granuloma, characteristic of the disease.

In its early stage, the granuloma has a core of infected macrophages enclosed by other cells of the immune system. As cellular immunity develops, macrophages loaded with bacteria are killed, resulting in the formation of the caseous center of the granuloma. The bacteria become dormant but may remain alive for decades. This enclosed infection is referred to as latent tuberculosis and may persist throughout a person’s life without causing any symptoms.

The strength of the body’s immune response determines whether an infection is arrested here or progresses to the next stage. In healthy people, the infection may be stopped permanently at this point. The granulomas subsequently heal, leaving small calcified lesions. On the other hand, if the immune system is compromised by immunosuppressive drugs, HIV infections, malnutrition, aging, or other factors, the bacteria can be re-activated, replicate, escape from the granuloma and spread to other parts of the lungs causing active pulmonary tuberculosis. This reactivation may occur months or even years after the initial infection.

In some cases, the bacteria may also spread to other organs of the body via the lymphatic system or the bloodstream. This widespread form of TB disease, called disseminated TB or miliary TB, occurs most commonly in the very young, the very old and those with HIV infections.

Tuberculosis is generally treatable with antibiotics. Several antibiotics are usually prescribed for many months due to the slow growth rate of the bacteria. It’s very important that the patients complete the course of the treatment to prevent development of drug-resistant bacteria and re-occurrence of the disease.

Paranasal sinuses and sinus conditions

The videos on this page can be downloaded upon purchase of a license on Alila Medical Media website. Click here!

Paranasal sinuses, or simply “sinuses” in common language, are air cavities in the bones of the skull. There are four pairs of sinuses (see Fig. 1, 2 and upper panel of Fig. 3):

– the maxillary sinuses are under the eyes, in the maxillary bones.
– the frontal sinuses are above the eyes, in the frontal bone.
– the ethmoid sinuses are between the nose and the eyes, in the ethmoid bone.
– the sphenoid sinuses are behind the nasal cavity, in the sphenoid bones.

Fig.1: The four pairs of sinuses. Red = frontal, green = ethmoid, blue = sphenoid, beige = maxillary. The right panel show normal sinuses on half of the head and inflamed sinuses on the other half. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

The sinuses are lined with respiratory epithelium producing mucus. The mucus drains into nasal cavity through small openings (Fig. 2 left panel, Fig. 3 upper panel). Impaired sinus drainage has been associated with inflammation of sinuses (sinusitis, see below).
Biological function of the sinuses remains unclear.

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Fig. 2: Front view of the sinuses (left panel) showing connections to the nasal cavity. Right panel shows mid-sagittal section of the head. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Sinusitis or rhinosinusitis is inflammation of the paranasal sinuses (Fig. 1, right panel). This can be due to:
– allergy (allergic rhinitis): allergens such as pollen, pet dander,.. trigger overreaction of the mucosa of the nose and sinuses resulting in excess mucus, nasal congestion, sneezing and itching.
– infection: usually as a complication of an earlier viral infection of the nasal mucosa, pharynx or tonsils such as during a common cold. Impaired sinus drainage due to inflammation of nasal mucosa during a cold often leads to infection of the sinus itself. Cold-like symptoms plus headache and facial pain/pressure are common complaints.
– other conditions that cause blockage of sinus drainage: structural abnormality such as deviated nasal septum (Fig. 3); formation of nasal polyps (Fig. 4). When a sinus is blocked, fluid builds up making it a favorable environment for bacteria, viruses or fungi to grow and cause infection.

Fig. 3: Front view of the sinuses (upper panel) showing connections to the nasal cavity, also shown the nasal septum (light blue color). Lower panel shows deviated septum blocking drainage of the right maxillary sinus (your left). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Fig. 4: Nasal polyps – overgrowths of nasal mucosa – block sinus drainage. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Treatment depends on the cause of sinusitis:
– For viral infection : symptom relief medications such as nasal spray for irrigation and decongestion; other conservative treatment for common cold such as rest and drinking plenty of fluid.
– For bacterial infection: antibiotics may be prescribed.
– For allergy: intranasal corticosteroids are commonly used.
– For recurrent (chronic) sinusitis due to structural abnormalities or nasal polyps, nasal surgery may be recommended.

See all Respiratory topics

Asthma (with Animation Video)

The videos on this page can be downloaded upon purchase of a license on Alila Medical Media website. Click here!

Asthma is a chronic respiratory condition where the airway is inflamed and narrowed causing breathlessness, wheezing, chest tightness and coughing. Symptoms come as recurrent episodes called asthmatic attacks more commonly during the night and early morning. Asthma is usually diagnosed in childhood and lasts for life.

Anatomy of asthma

Our lungs consist of millions of air tubes or airways (bronchi and smaller bronchioles) bringing air in and out of the body. Each tube ends with a cluster of air sacs (alveolus, plural alveoli) where the gas exchange process takes place. The airways have a layer of smooth muscle in their wall which enables them to constrict or dilate. In response to the body’s higher demand of air, such as during exercise, the airways dilate to increase air flow. In response to presence of pollutants in the air, they constrict to prevent the lungs from being polluted. In people suffering from asthma these airways are inflamed, narrowed and become more sensitive to certain substances. Asthmatic attack (or exacerbation) happens when the airways react to these substances. During the attack smooth muscle contracts squeezing the airways making them even narrower, mucus secretion increases further obstructs the airways.

Causes of asthma

Causes of asthma are complex and not fully understood but likely involve a combination of genetic and environmental factors. Family history is a known risk factor for asthma. There are at least over twenty genes associated with asthma of which many are involved in the immune system. Most people who have asthma also have allergies. Many environmental factors such as air pollution, chemicals, smoking, allergens have been associated with development of asthma or triggering of asthmatic attacks.

Triggers of asthmatic attack

Triggers are factors that initiate the attack, these can be very different from person to person. Common triggers include :
– allergens (pollen, animal fur, pet dander, sulfites in preserved food..)
– irritants (cigarette smoke, industrial chemicals, dust, household chemicals,..)
– some medication (aspirin, beta blockers,..).
– physical activity, exercise.

Treatments

There is no cure for asthma. The most effective way to manage symptoms is to identify the triggers of asthmatic attack and avoid them.
There are two main classes of medication:
– bronchodilators – substances that dilate bronchi and bronchioles – are used as short-term relief of symptoms.
– inflammation moderators such as corticosteroids are used as long-term treatment.
Asthma inhalers are used to deliver medication to the lungs.

Associated conditions

A number of conditions tend to occur more frequently in people with asthma:
– Allergies : eczema and hay fever. These individuals are considered hyperallergic (high tendency to develop allergic reactions). The combination of these conditions is called atopy or atopic symdrome.
– Gastroesophageal reflux disease (GERD): a condition in which stomach acid backs up and damages the mucosal lining of the esophagus. GERD may worsen asthma symptoms and medications for asthma often worsen GERD symptoms. Treating GERD usually improves asthma and must be included in asthma treatment plan.
– Obstructive sleep apnea (OSA): asthmatic patients tend to develop OSA. The mechanism is not fully understood but it’s likely due to nasal obstruction. Click on the link to read more about OSA.
– Sinusitis: inflammation of paranasal sinuses. Sinusitis commonly worsens asthma symptoms and makes treatment less effective.

See all Respiratory topics

See all Immunology topics

Snoring and Sleep Apnea

Below is a narrated animation of snoring, sleep apnea and treatment with a mandibular advancement device. Click here to license this video and/or other related videos on Alila Medical Media website.

No one likes to share a bedroom with a person who snores. Snoring is definitely well established as a social/marital problem. Not many are aware, however, that snoring maybe a sign of, or might progress to, a more serious, potentially life threatening health problem: obstructive sleep apnea (OSA).
Sleep apnea is a sleep disorder characterized by instances of cessation of breathing (apnea).

Anatomy of snoring and sleep apnea

In normal breathing, air enters the nostrils and goes through the throat and the trachea (the windpipe) to the lungs (blue arrow in Fig. 1). In people who snore this airway is partially obstructed by excess tissue of the throat (large tonsils, soft palate, tongue). Another common cause of obstruction is the dropping of the tongue into the throat due to over- relaxation of tongue muscles during sleep. To get enough air the body reacts by breathing through the mouth. The two air currents from the nose and the mouth competing through narrow spaces in the throat cause the soft palate (essentially a piece of soft tissue hanging in the throat) to vibrate. This vibration is the source of the noise we hear when someone is snoring.

Fig. 1: Anatomy of snoring and sleep apnea. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Sleep apnea happens when the airway is completely obstructed, no air can go through and the person stops breathing (apnea). This cessation of breathing triggers the brain to response by waking up the person just enough to take a breath. This repeats itself again and again during the course of the night and may result in sleep deprivation.

How do I know if i have sleep apnea?

Not everyone who snores has sleep apnea. It’s hard to self diagnose when one is sleeping. The biggest tell-tale to look for is daytime drowsiness together with other signs of sleep deprivation such as loss of concentration, loss of memory, headache in the morning,…It would also help to have a bed partner observing for episodes of breathing pauses. If you suspect that you may have sleep apnea based on those symptoms, it’s important that you visit your doctor immediately. The doctor will examine your throat and if a sleep disorder is suspected, you will be sent to a sleep clinic where your sleep will be monitored and data about your breathing patterns will be collected.

Treatments for snoring and sleep apnea

(in order from mild to severe)

Life style changes: Snoring and mild sleep apnea may be treated with life style changes such as losing some weight, avoiding alcohol and heavy meals. In some people, sleeping on the side instead of on the back might be a solution.
Oral appliances (snoring mouthpiece) are small devices that can be worn in the mouth at night. An oral appliance prevents the tongue and other soft tissue from falling back into your throat and thus keeps the airway open. It’s best to have the device made to measure to ensure fitting to your mouth.
Continuous Positive Airway Pressure (CPAP) is the first line treatment for patients with severe OSA. In this case a small machine is used to generate a constant air flow that is delivered to the patient through a mask fitted on the nose. It looks pretty much like a snorkeling mask except that the tube is connected to a machine.
It is important to note that CPAP and oral appliances help to keep your airway open and enable you to sleep at night but they do not cure the condition. The symptoms will return as soon as you stop using them.
Surgery: Various surgical procedures are available for treatment of sleep apnea. Surgery can be performed on the soft palate, the tongue, the hyoid bone, the jaws or a combination of those. Your surgeon will advice which is best for each patient.

See all ENT topics

Medical Information Illustrated

Medical and health topics fully illustrated with pictures and videos for easy understanding.