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The airways become obstructed from either inflammation of the lining of the airways or constriction of the bronchial smooth muscles (bronchospasm). A knownallergen, for example, pollen—is inhaled, causing activation of antibodies that recognize the allergen. Mast cells and histamine are activated, initiating a local inflammatory response. Prostaglandins enhance the effect of histamine. Leukotrienes also respond, enhancing the inflammatory response. White blood cells responding to thearea release inflammatory mediators.
Astimulus causes an inflammatory reaction, increasing the size of the bronchial linings; this results in restriction of the airways. There may be a bronchial smoothmuscle reaction at the same time. There are two kinds of asthma:
• Extrinsic asthma, also known as atopic, caused by allergens such as pollen,animal dander, mold, or dust. Often accompanied by allergic rhinitis and eczema; this may run in families.
• Intrinsic asthma, also known as nonatopic, caused by a nonallergic factor such as following a respiratory tract infection, exposure to cold air, changes in air humidity, or respiratory irritants.
PROGNOSIS
Triggers for the asthmatic patient can often be identified and avoided. Patients can learn to check peak flow levels and manage symptoms in conjunction with their caregiver. Well controlled asthma typically has temporary, reversible exacerbations that can be controlled with medications, often in an outpatient setting. With frequent attacks, a mild exposure to a known trigger will often be sufficient to exacerbate an attack. Patients who do not respond to medications or who use medications improperly may die during an asthma attack.
SIGNS AND SYMPTOMS
• Wheezing initially present on expiration continues throughout respiratory cycle as inflammation progresses. Air has difficulty moving through the narrowed airways, making noise. Not all asthmatics will have wheezing.
• Asymptomatic between asthma attacks. Symptoms resolve when there is no inflammation present.
• Difficulty breathing (dyspnea) as airways narrow due to inflammation. This is typically progressive as inflammation increases.
• Respiration greater than 20 breaths per minute (tachypnea) as the body attempts to get more oxygen into the lungs to meet physiologic needs.
• Use of accessory muscles to breathe as the body tries harder to get more air into the lungs.
• Tightness in the chest due to narrowing of the airways (bronchoconstriction).
• Cough.
• Tachycardia—heart rate greater than 100, as the body attempts to get more oxygen to the tissues.
TEST RESULTS
• Decreased oxygen and increased carbon dioxide present in arterial blood gas due to inability to move adequate air, which results in inadequate gas exchange.
• Decreased force on expiration [either forced expiratory volume in the first second (FEV1) or peak expiratory rate flow (PERF)] during attack shown in pulmonary function test. Narrowed airways make it more difficult for the patient to exhale, prolonging time of exhalation and decreasing force of exha-
lation. Patients can check expiratory effort at home on a peak flow meter.
• Hyperinflated lungs shown in chest x-ray due to air trapping.
• Pulse oximetry shows diminished oxygen saturation.
• CBC—elevated eosinophils.
• Sputum—positive for eosinophils.
TREATMENT
The focus of treatment is to return the respiratory status to normal, deliver adequate oxygen, and limit the number of recurrences. Patient education should focus on understanding the disease, its management, and when emergency care may benecessary.
• Administer supplemental oxygen to help meet body’s needs.
• Identify and remove allergens and known triggers to avoid causing an asthma attack.
• Give patient 3 liters/day of fluid to help liquefy any secretions.
• Administer short-acting beta2-adrenergic drugs to bronchodilate:
• albuterol, pirbuterol, metaproterenol, terbutaline, levalbuterol
• Administer long-acting beta2-adrenergic drugs to manage symptoms day to day; keep airways open, not for acute symptoms:
• salmeterol, formoterol
• Administer leukotriene modulators to reduce local inflammatory response in lung to reduce exacerbations; does not have immediate effect on symptoms:
• zafirlukast, zileuton, montelukast
• Administer anticholinergic drugs
• ipratropium inhaler, tiotropium handihaler
• Administer antacid, H2 blocker, or proton pump inhibitor to decrease the amount of acid in the stomach, reducing the possibility of ulcers due to stress of disease or medication effects.
• Antacids: aluminum hydroxide/magnesium hydroxide, calcium carbonate • H2 blockers: ranitidine, famotidine, nizatidine, cimetidine
• Proton pump inhibitors: omeprazole, lansoprazole, esomeprazole, rabeprazole, pantoprazole
• Administer mast cell stabilizer to retain an early component of the initial response to allergens, which will prevent further reactions from occurring;this is not for acute symptoms. This is useful for pretreatment for allergenexposure or chronic use to improve control of symptoms.
• cromolyn, nedocromil
• Administer steroids to decrease inflammation, which will help open airways;
these are not for acute symptoms:
• hydrocortisone, methylprednisolone intravenously
• beclomethasone, triamcinolone, fluticasone, budesonide, flunisolide, mometasone inhalers
• prednisolone, prednisone orally
• Administer methylxanthines to assist with bronchodilation, often used when
other medications not effective:
• aminophylline, theophylline
NURSING DIAGNOSES
• Impaired gas exchange
• Ineffective airway clearance
• Ineffective tissue perfusion
NURSING INTERVENTION
• Monitor respiration: patient’s respiratory status can continue to deteriorate;
look at respiratory rate, effort, use of accessory muscles, skin color, breath sounds.
• Place patient in high Fowler’s position to ease respirations.
• Monitor vital signs, look for changes in BP, tachycardia, tachypnea.
• Explain to the patient:
• How to use a peak flow meter.
• How to use the metered dose inhaler or dry powder and in which order to take inhaled medication.
• Avoid exposure to allergen.
• How to recognize the early signs of asthma.
• How to perform coughing and deep-breathing exercises.
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