Asthma 2010

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Asthma 2010

  1. 1. Asthma Definition <ul><li>Reactive airway disease </li></ul><ul><li>Chronic inflammatory lung disease </li></ul><ul><ul><li>Inflammation causes varying degrees of obstruction in the airways </li></ul></ul><ul><li>Asthma is reversible in early stages </li></ul>
  2. 2. Asthma <ul><li>Affects approx 15% of New Zealanders which equates to 1 in 6 of the population </li></ul><ul><li>Incidence in New Zealand is increasing </li></ul><ul><li>Asthma hospitalization rates have markedly increased </li></ul><ul><li>Prevalence is higher in Maori & Pacific Island adults with hospital admissions twice as likely for Maori than non-Maori adults </li></ul>
  3. 3. Asthma <ul><li>High morbidity due to: </li></ul><ul><ul><li>Underdiagnosis and inappropriate therapy </li></ul></ul><ul><ul><li>Limited access to healthcare </li></ul></ul><ul><ul><li>Inaccurate assessment of severity </li></ul></ul><ul><ul><li>Delay in seeking help </li></ul></ul><ul><ul><li>Inadequate medical treatment </li></ul></ul><ul><ul><li>Nonadherence to prescribed therapy </li></ul></ul><ul><ul><li>Increase in allergens in the environment </li></ul></ul>
  4. 4. Triggers <ul><li>Pollens </li></ul><ul><li>Dust </li></ul><ul><li>Dust mites </li></ul><ul><li>Food colouring </li></ul><ul><li>Moulds/fungi </li></ul><ul><li>Animals </li></ul><ul><li>Feathers </li></ul><ul><li>Job-related factors </li></ul><ul><li>Cold/flu viruses </li></ul><ul><li>Stress, emotions </li></ul><ul><li>Change of weather </li></ul><ul><li>Change of season </li></ul><ul><li>Smoke </li></ul><ul><li>Cold air </li></ul><ul><li>Medicines </li></ul><ul><li>Fumes </li></ul><ul><li>Exercise </li></ul>
  5. 5. Asthma Pathophysiology <ul><li>Early-Phase Response </li></ul><ul><ul><li>Triggered when IgE receptors on mast cells beneath the bronchial wall are activated </li></ul></ul><ul><ul><li>Release inflammatory mediators (histamine, bradykinin, leukotriene, prostaglandins, chemotactic factors, and cytokines) </li></ul></ul><ul><ul><li>Mediators cause </li></ul></ul><ul><ul><ul><li>bronchial smooth muscle constriction </li></ul></ul></ul><ul><ul><ul><li>increased vasodilation and permeability </li></ul></ul></ul><ul><ul><ul><li>epithelial damage </li></ul></ul></ul>
  6. 6. Asthma Pathophysiology <ul><ul><li>Early-Phase Response </li></ul></ul><ul><ul><li>Bronchospasm,increased mucous secretion, oedema formation, and increased amounts of tenacious sputum </li></ul></ul><ul><ul><li>Patient experiences wheezing, cough, chest tightness, and dyspnoea </li></ul></ul><ul><ul><li>Peaks within 30-60mins of exposure to trigger & subsides in another 30-90mins </li></ul></ul>
  7. 7. Factors Causing Expiratory Obstruction in Asthma <ul><li>Reduction in airway diameter </li></ul><ul><li>↑ in airway resistance related to mucosal inflammation </li></ul><ul><li>Constriction of bronchial smooth muscle </li></ul><ul><li>Excess production of mucous </li></ul>Fig. 28 - 3
  8. 8. Late-Phase Response <ul><li>Peaks in 5 – 6 hrs </li></ul><ul><li>Infiltration with eosinophils & neutrophils </li></ul><ul><li>Inflammation as more inflammatory mediators produced </li></ul><ul><li>Bronchial reactivity </li></ul><ul><li>More severe than early-phase response & can last 24 hrs or more </li></ul>
  9. 9. Early and Late Phases of Responses of Asthma Fig. 28 - 1
  10. 10. Asthma Clinical Manifestations <ul><li>Unpredictable and variable </li></ul><ul><li>Recurrent episodes of: </li></ul><ul><li>wheezing </li></ul><ul><li>breathlessness </li></ul><ul><li>cough </li></ul><ul><li>tight chest </li></ul><ul><li>Expiration may be prolonged from an inspiration-expiration ratio of 1:2 to 1:3 or 1:4 </li></ul><ul><li>Between attacks may be asymptomatic with normal or near-normal lung function </li></ul>
  11. 11. Asthma Clinical Manifestations <ul><li>Wheezing is an unreliable sign to gauge severity of attack </li></ul><ul><li>Severe attacks can have no audible wheezing due to reduction in airflow </li></ul><ul><li>“ Silent chest” is ominous sign of impending respiratory failure </li></ul>
  12. 12. Asthma Clinical Manifestations <ul><li>Difficulty with air movement can create a feeling of suffocation </li></ul><ul><ul><li>Patient may feel increasingly anxious </li></ul></ul><ul><ul><li>Mobilizing secretions may become difficult </li></ul></ul>
  13. 13. Asthma Clinical Manifestations <ul><li>Examination of the patient during an acute attack usually reveals signs of hypoxaemia </li></ul><ul><ul><li>Restlessness </li></ul></ul><ul><ul><li>Increased anxiety </li></ul></ul><ul><ul><li>Inappropriate behavior </li></ul></ul><ul><ul><li>Increased pulse and blood pressure </li></ul></ul>
  14. 14. Features of Acute Severe Asthma <ul><li>Unable to complete a sentence in 1 breath </li></ul><ul><li>RR > 25 breaths per min </li></ul><ul><li>Pulse rate > 110 beats per min </li></ul><ul><li>PERF (peak expiratory flow rate) <50% predicted normal value or pt’s best-known value </li></ul>
  15. 15. Life Threatening Features <ul><li>PERF <33% of predicted normal value or pt’s best known value </li></ul><ul><li>Silent chest – absence of wheeze </li></ul><ul><li>Diminished respiratory effort </li></ul><ul><li>Bradycardia </li></ul><ul><li>Hypotension </li></ul><ul><li>Exhaustion </li></ul><ul><li>Confusion & agitation due to hypoxia </li></ul><ul><li>Signs of hypercarbia (sweating, red florid complexion, bounding pulse, peripheral tremors </li></ul><ul><li>Coma </li></ul>

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