| definition
* populaton Etiology & Onset Symptoms Pathophysiology Work of Breathing Diagnosis Treatment Prevention Complications, Prognosis Links |
A S T H M A |
 |
- I. Definition: A severe airway disorder characterized by hyperactive airways that result in severe airway obstruction due too
- A) Constricting and bronchospactic airways
- B) Swelling airways
- C) The pouring of secretions into the lumen of airways
- II Population:
- A) Children
- 1) 5-10% effected in the United States
- 2) Most frequent cause of hospitalization in the United States among children
- 3) Effects 1 in 12 school children
- B) Adults
- 1) 3-5% effected in the United States
- 2) Half of the adult asthma patients effected before the age of 10
- III Etiology: The exact etiology of the disease is unknown, but several participating factors have been identified.
- A) Allergens
- 1) Molds
- 2) Pollens
- B) Outdoor irritants
- 1) Smoke
- 2) Air pollution
- C) Indoor irritants
- 1) Animal dander
- 2) Dusts
- D) Exercise
- E) Viral infections
- F) Foods
- G) Emotions
- H) Aspirin
- IV Onset
- A) Sudden onset
- 1) Higher amounts of neutrophils and less eosinophils in airway mucosa
- B) Slow onset
- 1) More common
- 2) Possible different mechanism of action for sudden onset
- V Pathophysiology:
- A)Can be broken down into two phases
- 1) Allergic
- a) Triggering stimuli (Listed above) of airways rupture or degranulate mast cells
- b) Mast cells release chemical mediators including histamine, leukotrienes, eosinophilic chemotactic factor of anaphylaxis, and prostaglandins.
- c) These mediators promote bronchospasm, vasodilatation, edema, increased secretions, and accumulation of eosinophils.
- 2) Inflammatory phase
- a) Mediators are released by eosinophils, neutrophils, macrophages, and lymphocytes.
- b) These mediators initiate the inflammatory response of the airways.
- B Work of Breathing
- 1) Inhalation
- a) Resistance increases
- b) Ventilation and perfusion mismatches increase
- c) Arterial blood gasses diminish
- d) Patient status deteriorates
- 2) Exhalation
- a) Narrowing of airways causes air trapping and an increased FRC
- b) The patient must exert an increasing amount of intraplural pressure to maintain normal tidal volume, increasing patient fatigue.
- 3) V/Q mismatching leads to hypoxemia
- a) Hypoxemia causes the patient to hyperventilation and become hypocarbic
- b) Hypocarbia limits conservation of bicarbonate by the kidney which leads to metabolic acidosis
- 4) Derangement of both cardiovascular and metabolic function
- a) Patient becomes dehydrated due to
- i) A decreased ability to take fluids
- ii) A increased metabolis rate from tachypnea and possible fever
- b) The patient experiences lactic acidosis due to
- i) Hypoxemia
- ii) Dehydration
- iii) Increased metabolism due to tachypnea
- 5) Respiratory failure
- a) As the patient becomes exhausted maintaining ventilation, PaCo2 begins to rise causing the patient to enter acute respiratory failure
- VI. Diagnosis
- A STEPS FOR DIAGNOSING ASTHMA IN CHILDREN
- 1. MEDICAL HISTORY
- Family history of allergy and asthma
- Child’s symptoms
- Coughing wheezing shortness of breath or rapid breathing chest tightness
- Frequency and severity of the child’s symptoms
- Medications the child is using
- 2. PHYSICAL EXAM
- Wheezing (may or may not be present)
- Hyperexpansion of the thorax, use of accessory muscles, tachypnea
- Presence of other allergic diseases
- atopic dermatitis/eczema
- swelling of and/or pale nasal mucosa
- clear nasal discharge
- 3. OBJECTIVE MEASUREMENTS
- Spirometry for children > 4 years of age
- FEV1, FVC, FEV1/FVC
- Presence of ANY indicators from the history and physical examination
- VII ASSESSMENT OF ASTHMA IN CHILDREN
- A. ROLE OF ASSESSMENT IN ASTHMA
- 1 Initial diagnosis and determination of severity
- 2 Ongoing monitoring and management
- 3 Components of assessment
- a Medical history
- b Physical assessment
- c Objective measures of pulmonary function
- B. MEDICAL HISTORY
- 1 Physician usually will be the primary historian
- 2 Therapist history
- a. less “formal”
- i. “What do you think made you have to be admitted to the hospital?”
- a. less “formal”
- 3 use information to assess educational needs
- 4 Family history of asthma and allergy
- a Patient’s symptoms
- i. When do symptoms occur?
- ii. What causes symptoms (triggers)?
- iii. What makes symptoms worse?
- iv. Frequency and severity of symptoms
- v. Do symptoms limit physical activity?
- vi Do symptoms interfere with sleep?
- vii Do symptoms interfere with school performance or activities
- viii ER visits or hospital admissions needed?
- ix Medication usage
- x What and how much?
- a Patient’s symptoms
- C. PHYSICAL ASSESSMENT
- 1 Indicators of respiratory distress and
severity
- a Respiratory Rate
- b Use of accessory muscles
- c Breath sounds
- d Respiratory rate
- e Increased respiratory rate is a reliable indicator of respiratory distress
- f “Norms” and acceptable ranges are age dependent
- g Accessory Muscle Use
- h None with no distress
- i Intercostal and tracheosternal retractions with moderate distress
- j Retractions and accessory muscle use (particularly sternocleidomastoids) with severe distress
- k Breath Sounds
- l Expiratory wheezes with mild exacerbation
- m Inspiratory / expiratory wheezes with more severe exacerbation
- n “Silent chest” is ominous sign
- o Aeration may be decreased locally or throughout
- p Absence of wheezing does not rule out asthma (cough may be the only symptom)
- 1 Indicators of respiratory distress and
severity
- D. OBJECTIVE MEASURES OF PULMONARY FUNCTION
- 1 Spirometry
- a Airflow obstruction indicated by ¯ FEV1 and FEV1/FVC relative to predicted values
- b Significant reversibility is indicated by an increase of at least 12% and 200 ml in FEV1 post short-acting bronchodilator.
- c. Indications for Spirometry
- d Initial diagnosis
- e Periodic assessment (every 1 - 2 years)
- f Peak Expiratory Flow (PEF)-long term monitoring
- g To evaluate response to changes in therapeutic regime
- h Primarily a measure of large airway function
- i Published reference values vary widely and according to brand of meter
- j Valuable as a serial measurement related to patient’s PERSONAL BEST (PB) or predicted
- k PB is the highest peak flow number a patient can achieve over a 2 - 3 week period with his/her asthma under good control
- l PEF variability (%) is a factor in asthma severity
- m. Peak Flow Monitoring
- n PEF may be useful for any child (generally over 5 years of age)
- o Particularly recommended for patients with
- p poor symptom perception
- q moderate to severe asthma
- r history of severe exacerbation
- s Part of daily routine
- t Every morning , before taking medications, or
- u In the morning and late afternoon or evening; > 20% difference between measurements suggests inadequate control
- v When having symptoms of an attack (and after taking medications for the attack)
- 1 Spirometry
- VIII Asthma Treatment:
- A. Avoid Triggers (see prevention)
- B. Oxygen
- C. Heliox (80/20 mix of helium/oxygen)
- D. Drugs:
- 1. Sympathomimetics (Beta 2 Adrenergic Agonists)
- Method of action: cause bronchodilation, inhibit mast cell degranulation, reduce permeability of pulmonary vasculature, and improve mucociliary transport of secretions.
- Examples: epinephrine, isoproterenol, isoetharine (these have been show to cause tremors, palpitations, and anxiety), bitolterol, metaproterenol, terbutaline, fenoterol, albuterol, pirbuterol, carbuterol, procaterol, salmeterol xinafoate and formoterol.
- Action mainly in the small innervated peripheral bronchioles and therefore should be given second.
- b. Beta 2-adrenergic sites
- Bronchodilation
- Inhibit mast cell degranulation
- Reduce permeability of pulmonary vasculature
- Improve mucociliary transport of secretions
- 2. Parasympatholytics (Anticholenergics)
- Method of action: actively bind to muscarinic receptors (antagonist of nerve impulses) and block transmission of nerve impulses.
- Examples: atropine, glycopyrrolate, ipratopium bromide, and oxitropium bromide.
- Action mainly in the large airways and therefore should be given first.
- 3. Corticosteroids
- Method of action: suppress the release of inflammatory mediators and reversal of airway hyperactivity.
- Examples: beclomethasone dipropionate, fluticosone, trimcinolone acetonide, funisolide, and budenoside.
- 4. Xanthine
- 5. Antibiotics
- 6. Cromolyn sodium and Nedacromil Stabilize mast cells and prevent degranulation
- E. Fluid administration
- F. Humidification
- IX Prevention
- A. Avoid the following precipitating factors that lead to an asthma attack:
- 1. Allergens
- 2. Molds
- 3. Pollens
- B. Outdoor Irritants
- 1. Smoke
- a. especially prenatally
- 2. Air pollution
- 3. Molds and Fungi
- C. Indoor Irritants
- 1. Animal danders
- a. If you must have a pet in the house:
- i. wash them often
- ii. keep them out of the asthmatics room
- 2. Dusts
- a. dust mites
- i. found in mattresses, pillows, sheets and stuffed animals
- ii. to prevent dust mites wash the above items with hot water often
- 3. Cockroaches
- a. to prevent cockroaches:
- i. keep a clean house
- ii. do not leave food out
- iii. place traps
- 4. Molds and Fungi
- a. to prevent molds from growing:
- i. fix leaky pipes
- ii. clean areas with bleach
- D. Exercise
- 1. take meds prior to exercising
- F. Cold Air
- 1. wear a scarf around nose and mouth
- E. Viral Infections
- 1. RSV
- F. Foods
- G. Emotions/Stress
- H. Aspirin and related drugs
- I* Other methods important in preventing asthma attacks: patient compliance to medications, use of preventative medications, use of spacer with MDI’s, use of proper technique when taking MDI’s and nebs, and patient education.
