ASTHMA Amy Higgins Stephanie Kimbrel Diane Morris

ASTHMA

Amy HigginsStephanie Kimbrel

Diane Morris

Definition of Asthma

• Chronic inflammatory disorder of the airways in which many cells and cellular elements play a role, in particular mast cells, eosinophils, T-lymphocytes, neutrophils, and epithelial cells. This inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness and cough. These episodes are usually associated with widespread but variable airflow obstruction that is often reversible either spontaneously or with treatment. The inflammation also causes and associated increase in the existing bronchial hyper responsiveness to a variety of stimuli.

ANATOMY

• Upper Respiratory Tract: major passages and structures of the upper respiratory include the nose or nostrils, nasal cavity, mouth, throat (pharynx), and the voice box (larynx).

Upper Respiratory Tract

• Breathing in through your nose or mouth filters the air to protect you against illness and irritation of the respiratory tract. Nasal hairs (vibrissae) trap large particles so they are not inhaled. The entire respiratory tract is lined with a mucous membrane that secrets mucous and traps smaller particles like pollen and smoke.


• The pharynx is a muscular, funnel shaped tube about five inches long that connects the nasal and oral cavities to the larynx.

• The pharynx houses the tonsils and adenoids, which are lymphatic tissues that guard against infection by releasing white blood cells.


• The larynx forms the entrance to the lower respiratory system.

• The epiglottis helps to prevent food or liquid from entering the lower respiratory tract while swallowing.

• There are two pairs of connective tissue that are stretched across the larynx and vibrate to produce sounds while talking or singing.

Lower Respiratory Tract

• The lower respiratory tract includes the windpipe (trachea) and within the lungs, the bronchi, bronchioles and alveoli.


• Inhaled air moves through the larynx and into the trachea, which is a rigid muscular tube about 4.5” long and 1” wide.

• Inside the trachea there are C-shaped cartilage rings that allow the trachea rigidity to stay open all the time.

• Airflow from the trachea branches off into two bronchi. One bronchus leads into the right, the other into the left lung. C-shaped rings are also present in the bronchi.


• Deeper in the lungs the bronchus further divides into secondary and tertiary bronchi, which leads into smaller airways called the bronchioles.

• In the bronchioles there are no cartilage rings so they are subject to constriction and obstruction, as during an asthma attack.

• The bronchioles end in air sacs called alveoli, which are bunched together into clusters to from alveolar sacs.


• Each alveolus has a network of capillaries carrying blood that has come through veins from other parts of the body.

• At this point gas exchange occurs-carbon dioxide from the blood is exchanged for oxygen from the alveoli.


• After the blood is oxygenated it goes to the heart where it is pumped out into the bodies tissues and extremities.

• When you breath out, carbon dioxide is exhaled and expelled from the body.

The Diaphragm

• The diaphragm is the major muscle of respiration. It is a large dome shaped muscle that contracts and rhythmically and continually, and usually involuntarily.

• During inhalation the diaphragm contracts and flattens and the chest cavity enlarges.

The Diaphragm

• This contraction creates a vacuum, which pulls air into the lungs.

• During exhalation the diaphragm relaxes and returns to the dome like shape, and air is forced out of the lungs.

Physiology of Asthma

• The allergic process of asthma is basically a result in the hyper responsiveness that is inherent in certain individuals.

• This disease process can manifest itself with a variety of symptoms. This includes wheezing, cough, chest tightness, shortness of breath and sputum production.


• Whenever the body recognizes an antigen that is foreign, it tries to minimize its effect on the body’s cells by a mechanism known as inflammation.

• This is actually an immune response that is exaggerated and can leads to allergic asthma.

• There are two types of responses which the body can produce, primary response and secondary response.


• Primary response occurs on the first exposure to an antigen or a foreign body.

• This is normally short lived, produces less mediators or chemical substances, but is capable of causing sensitization.

• Secondary response happens when the body is exposed to the same antigen.

• This is normally more severe and produces more inflammatory mediators, leading to more signs and symptoms.


• Signs and symptoms of inflammation include redness, heat production, pain and swelling at the site and the inability of the tissue to perform their function.

• When these symptoms happen in the lungs, symptoms of asthma occur.

• This causes swelling and tightening of the smooth muscle around the airways. This causes restriction in the amount of airflow and the normal function of the lungs is affected and breathing becomes more difficult.

• It is not known whether all cases of asthma require a specific stimulus or not.

Pathophysiology of Asthma

• Recognition that asthma is an inflammatory process that involves multiple cell types and mediators have revolutionized the approach to prevention and management.

• Inflammation is the underlying abnormality present in patients, even with mild asthma.

• Inflammatory changes may include submucusal infiltration with activated lymphocytes and eosinophils, activation of mast cells, epithelial changes and basement membrane thickening.


• These changes can occur along a continuum from mild to severe asthma.

• In fatal asthma, findings of mucus plugging in airways, goblet cell hyperplasia, and smooth muscle hypertrophy/hyperplasia are usually present and represent extension of the inflammatory continuum.


• Mast cell activation releases histamine and leukotrienes, these are responsible for the immediate brochospastic response to allergen exposure.

• Studies demonstrate the inflammatory nature of allergic asthma, the role of multiple cell types and cytokines, and the biphasic response to allergen provocation.

• These concepts have provided the foundation for current understanding of therapeutic approach.


• The seminal role of allergy and atopic sensitization is related to specific IgE fixed to airway mast cells and basophils and their activation causing release of multiple mediators of inflammation and bronchospasm.

• Mast cells release histamine and leukotrines which are responsible for the immediate bronchospastic response to allergen exposure.



Epidemiology of Asthma


• African-American children have an increase in being diagnosed with asthma. In 2000 the ratio was 2:1 when comparing African-Americans to Caucasian children.

• This could be due to lack of access to health care or by the use of episodic care rather than appropriate, consistent preventive management.

• Other contributing factors may include early and high exposure to allergens, particularly dust mites and cockroaches often found in urban settings that have poor hygiene, and a higher exposure rate to tobacco smoke.


• The primary risk factor for transient early wheezing was maternal smoking.

• These children also showed to have reduced pulmonary function in the first postnatal year, but normalized by the age of six.

• Late-onset wheezing was associated with maternal asthma and male gender. This is also associated with elevated serum (Ig) E and positive allergy tests at 6 years of age.

Epidemology of Asthma

• Allergies also play an important role in childhood asthma. Predominant risk factor for persistent asthma in children is personal or family history of allergies.

• 40% to 80% of children who have asthma had at least one positive allergen skin test.

• Early education focuses on limiting allergen exposures in the home by controlling the presence of dust mites, mold, cockroaches, and indoor pets.


History and Physical Examination Findings

History• What are your symptoms• Do you have hay fever or

any other allergies• Blood relatives with hay

fever or other allergies• Health problems now or in

the past• Medications or herbal

supplements that you take now or in the past

Physical Exam• Examination of the upper

respiratory tract • Listening to lung sounds:

wheezing or high-pitched whistling while exhaling-main signs of asthma

• Examination of skin for signs of allergic conditions such as eczema and hives, often associated with asthma

Documents

ASTHMA Amy Higgins Stephanie Kimbrel Diane Morris