Asthma 2010

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Asthma Definition Reactive airway disease Chronic inflammatory lung disease Inflammation causes varying degrees of obstruction in the airways Asthma is reversible in early stages

description

pahophysiology

Transcript of Asthma 2010

Page 1: Asthma 2010

Asthma DefinitionReactive airway diseaseChronic inflammatory lung disease

Inflammation causes varying degrees of obstruction in the airways

Asthma is reversible in early stages

Page 2: Asthma 2010

Asthma

Affects approx 15% of New Zealanders which equates to 1 in 6 of the population

Incidence in New Zealand is increasingAsthma hospitalization rates have

markedly increasedPrevalence is higher in Maori & Pacific

Island adults with hospital admissions twice as likely for Maori than non-Maori adults

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Asthma

High morbidity due to:1. Underdiagnosis and inappropriate therapy2. Limited access to healthcare3. Inaccurate assessment of severity4. Delay in seeking help5. Inadequate medical treatment6. Nonadherence to prescribed therapy7. Increase in allergens in the environment

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TriggersPollensDustDust mitesFood colouringMoulds/fungiAnimalsFeathersJob-related factorsCold/flu viruses

Stress, emotionsChange of weatherChange of seasonSmokeCold airMedicinesFumesExercise

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AsthmaPathophysiologyEarly-Phase ResponseEarly-Phase Response

Triggered when IgE receptors on mast cells beneath the bronchial wall are activated

Release inflammatory mediators (histamine, bradykinin, leukotriene, prostaglandins, chemotactic factors, and cytokines)

Mediators cause• bronchial smooth muscle constriction• increased vasodilation and permeability• epithelial damage

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AsthmaPathophysiology

Early-Phase ResponseEarly-Phase Response Bronchospasm,increased mucous secretion, oedema formation, and increased amounts of tenacious sputum

Patient experiences wheezing, cough, chest tightness, and dyspnoea

Peaks within 30-60mins of exposure to trigger & subsides in another 30-90mins

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Factors Causing Expiratory Obstruction in Asthma

1. Reduction in airway diameter

2. ↑ in airway resistance related to mucosal inflammation

3. Constriction of bronchial smooth muscle

4. Excess production of mucous

Fig. 28--3

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Late-Phase ResponsePeaks in 5 – 6 hrsInfiltration with eosinophils & neutrophilsInflammation as more inflammatory

mediators producedBronchial reactivityMore severe than early-phase response & can

last 24 hrs or more

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Early and Late Phases of Responses of Asthma

Fig. 28--1

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AsthmaClinical ManifestationsUnpredictable and variableRecurrent episodes of:wheezing breathlessness coughtight chestExpiration may be prolonged from an

inspiration-expiration ratio of 1:2 to 1:3 or 1:4Between attacks may be asymptomatic with

normal or near-normal lung function

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AsthmaClinical ManifestationsWheezing is an unreliable sign to gauge

severity of attackSevere attacks can have no audible wheezing

due to reduction in airflow“Silent chest” is ominous sign of impending

respiratory failure

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AsthmaClinical Manifestations

Difficulty with air movement can create a feeling of suffocationPatient may feel increasingly anxiousMobilizing secretions may become difficult

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AsthmaClinical Manifestations Examination of the patient during an acute Examination of the patient during an acute

attack usually reveals signs of hypoxaemiaattack usually reveals signs of hypoxaemiaRestlessnessIncreased anxietyInappropriate behaviorIncreased pulse and blood pressure

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Features of Acute Severe AsthmaUnable to complete a sentence in 1 breathRR > 25 breaths per minPulse rate > 110 beats per minPERF (peak expiratory flow rate) <50%

predicted normal value or pt’s best-known value

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Life Threatening FeaturesPERF <33% of predicted normal value or pt’s

best known valueSilent chest – absence of wheezeDiminished respiratory effortBradycardiaHypotensionExhaustionConfusion & agitation due to hypoxiaSigns of hypercarbia (sweating, red florid

complexion, bounding pulse, peripheral tremorsComa