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Asthma

Definition

  • Asthma is a chronic inflammatory disease of the airways characterized by hyper-responsiveness, mucosal edema, and mucus production.
  • This inflammation ultimately leads to recurrent episodes of asthma symptoms: cough, chest tightness, wheezing, and dyspnea.
  • Patients with asthma may experience symptom-free periods alternating with acute exacerbations that last from minutes to hours or days.
  • Asthma, the most common chronic disease of childhood, can begin at any age.

Causes

The main triggers for asthma are allergies, viral infections, autonomic nervous system imbalance that can cause an increase in parasympathetic stimulation, medications, psychological factors, and exercise. Of asthmatic conditions in patients under 30 years old, 70% are caused by allergies. Three major indoor allergens are dust mites, cockroaches, and cats. In older patients,the cause is almost always nonallergic types of irritants such as smog. Heredity plays a part in about one-third of the cases.


Pathophysiology
1. An asthma attack may occur spontaneously or in response to a trigger. Either way, the attack progresses in the following manner:
  • There is an initial release of inflammatory mediators from bronchial mast cells, epithelial cells, and macrophages, followed by activation of other inflammatory cells
  • Alteration of autonomic neural control of airway tone and epithelial integrity occur and the increased responsiveness in airways smooth muscle results in clinical manifestations (e.g. wheezing and dyspnea)
2. Three events contribute to clinical manifestations
  • Bronchial spasm
  • Inflammation and edema of the mucosa
  • Production of thick mucus, which results in increased airway resistance, premature closure of airways, hyperinflation, increased work of breathing, and impaired gas exchange
3. If not treated promptly, status asthmaticus – an acute, severe, prolonged asthma attack that is unresponsive to the usual treatment – may occur, requiring hospitalization.

Classification
1. Extrinsic Asthma – called Atopic/allergic asthma.
An “allergen” or an “antigen” is a foreign particle which enters the body. Our immune system over-reacts to these often harmless items, forming “antibodies” which are normally used to attack viruses or bacteria. Mast cells release these antibodies as well as other chemicals to defend the body.
Common irritants:
  • Cockroach particles
  • Cat hair and saliva
  • Dog hair and saliva
  • House dust mites
  • Mold or yeast spores
  • Metabisulfite, used as a preservative in many beverages and some foods
  • Pollen
2. Intrinsic asthmacalled non-allergic asthma, is not allergy-related, in fact it is caused by anything except an allergy. It may be caused by inhalation of chemicals such as cigarette smoke or cleaning agents, taking aspirin, a chest infection, stress, laughter, exercise, cold air, food preservatives or a myriad of other factors.
  • Smoke
  • Exercise
  • Gas, wood, coal, and kerosene heating units
  • Natural gas, propane, or kerosene used as cooking fuel
  • Fumes
  • Smog
  • Viral respiratory infections
  • Wood smoke
  • Weather changes

Clinical Manifestations

  • Most common symptoms of asthma are cough (with or without mucus production), dyspnea, and wheezing (first on expiration, then possibly during inspiration as well).
  • Asthma attacks frequently occur at night or in the early morning.
  • An asthma exacerbation is frequently preceded by increasing symptoms over days, but it may begin abruptly.
  • Chest tightness and dyspnea occur.
  • Expiration requires effort and becomes prolonged.
  • As exacerbation progresses, central cyanosis secondary to severe hypoxia may occur.
  • Additional symptoms, such as diaphoresis, tachycardia, and a widened pulse pressure, may occur.
  • Exercise-induced asthma: maximal symptoms during exercise, absence of nocturnal symptoms, and sometimes only a description of a “choking” sensation during exercise.
  • A severe, continuous reaction, status asthmaticus, may occur. It is life-threatening.
  • Eczema, rashes, and temporary edema are allergic reactions that may be noted with asthma.

Primary Nursing Diagnosis
Ineffective airway clearance related to obstruction from narrowed lumen and thick mucus

OUTCOMES
. Respiratory status: Gas exchange; Respiratory status: Ventilation; Symptom
control behavior; Treatment behavior: Illness or injury; Comfort level
INTERVENTIONS. Airway management; Anxiety reduction; Oxygen therapy; Airway suctioning;Airway insertion and stabilization; Cough enhancement; Mechanical ventilation; Positioning;Respiratory monitoring


Assessment and Diagnostic Methods

  • Family, environment, and occupational history is essential.
  • During acute episodes, sputum and blood test, pulse oximetry, ABGs, hypocapnia and respiratory alkalosis, and pulmonary function (forced expiratory volume [FEV] and forced vital capacity [FVC] decreased) tests are performed.
  • Spirometry will detect:
a. Decreased for expiratory volume (FEV)
b. Decreased peak expiratory flow rate (PEFR)
c. Diminished forced vital capacity (FVC)
d. Diminished inspiratory capacity (IC)

Steps of Clinical and Diagnostic as per National Asthma Education and Prevention Program
Mild Intermittent Asthma
  • Symptoms ? 2 times per week
  • Brief exacerbations
  • Nighttime symptoms ? 2 times a month
  • Asymptomatic and normal PEF (peak expiratory flow) between exacerbations
  • PEF or FEV, (forced expiratory volume in 1 second) ? 80% of predicted value
  • PEF variability < 20%
Mild Persistent Asthma
  • Symptoms > 2 times/week, but less than once a day
  • Exacerbations may affect activity
  • Nighttimes symptoms > 2 times a month
  • PEF/FEV ? 80% of predicted value
  • PEF variability 20%-30%
Moderate Persistent Asthma
  • Daily Symptoms
  • Daily use of inhaled short-acting ?2 - agonists
  • Exacerbations affect activity
  • Exacerbations ? 2 times a week
  • Exacerbations may last  days
  • Nighttime symptoms > once a week
  • PEF/FEV > 60%-<80% of predicted value
  • PEF variability > 30%
Severe Persistent Asthma
  • Continual symptoms
  • Frequent exacerbations
  • Frequent nighttime symptoms
  • Limited physical activity
  • PEF or FEV ? 60% of predicted value
  • PEF variability > 30 %

Medical Management

Pharmacologic Therapy
There are two classes of medications—long-acting control and quick-relief medications—as well as combination products.
  • Short-acting beta2-adrenergic agonists
  • Anticholinergics
  • Corticosteroids: metered-dose inhaler (MDI)
  • Leukotriene modifiers inhibitors/antileukotrienes
  • Methylxanthines


Nursing Management

The immediate nursing care of patients with asthma depends on the severity of symptoms. The patient and family are often frightened and anxious because of the patient’s dyspnea. Therefore, a calm approach is an important aspect of care.
  • Assess the patient’s respiratory status by monitoring the severity of symptoms, breath sounds, peak flow, pulse oximetry, and vital signs.
  • Obtain a history of allergic reactions to medications before administering medications.
  • Identify medications the patient is currently taking.
  • Administer medications as prescribed and monitor the patient’s responses to those medications; medications may include an antibiotic if the patient has an underlying respiratory infection.
  • Administer fluids if the patient is dehydrated.
  • Assist with intubation procedure, if required.
Teaching Points
  • Teach patient and family about asthma (chronic inflammatory), purpose and action of medications, triggers to avoid and how to do so, and proper inhalation technique.
  • Instruct patient and family about peak-flow monitoring.
  • Teach patient how to implement an action plan and how and when to seek assistance.
  • Obtain current educational materials for the patient based on the patient’s diagnosis, causative factors, educational level, and cultural background.
Continuing Care
  • Emphasize adherence to prescribed therapy, preventive measures, and need for followup appointments.
  • Refer for home health nurse as indicated.
  • Home visit to assess for allergens may be indicated (with recurrent exacerbations).
  • Refer patient to community support groups.
  • Remind patients and families about the importance of health promotion strategies and recommended health screening.
Documentation Guidelines
  • Respiratory status: Patency of airway, auscultation of the lungs, presence or absence of adventitious breath sounds, respiratory rate and depth
  • Response to medications, oxygen therapy, hydration, bedrest
  • Presence of complications: Respiratory failure, ruptured bleb that may result in a pneumothorax

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