Asthma

Previous: Understanding ABGs

Chronic lung condition, inflammation and hypersensitivity of the airways.

Diagnosis is clinical

Ten facts
 * 1) Chronic lung condition, inflammation and hypersensitivity of the airways.

Symptoms
Worse at night
 * Wheeze
 * Cough
 * Chest tightness
 * Dyspnoea

3 questions use to determine severity...
 * 1) In the last month/week have you had difficulty sleeping due to your asthma?
 * 2) have you had your usual asthma symptoms during the day
 * 3) has your asthma interfered with your usual daily activities?

Pathophysiology

 * Airflow limitation (usually reversible spontaneously or with treatment)
 * Airway hyperresponsiveness (to a wide range of stimuli)
 * Inflammation of the bronchi (T lymphocytes, mast cells, eosinophils with associated plasma exudation, oedema, smooth muscle hypertrophy, matrix deposition, mucus plugging and epithelial damage)

In chronic asthma, inflammation may be accompanied by irreversible airflow limitation as a result of airway wall remodelling that may involve large and small airways and mucus impaction

Factors
NSAIDs-prevents certain prostaglandins
 * Smoking
 * Environmental
 * Allergens
 * Occupational sensitisers
 * non specific- everything else
 * Drugs-

Bblockers- airways have a direct parasympathetic innervation that cause bronchoconstriction. However there is no direct sympathetic innervation. Parasympathetic action is antagonised by circulating adrenaline which act through beta2receptors on the surface of the smooth muscle cells. Betablockers prevents this effect and causes bronchoconstriction and airflow limitation in asthmatic patients.

PEF/spirometry
FEV1/FVC <0.7

>400ml improvement in FEV1 after 400mcg inhaled salbutamol

exercise test

trial corticosteroids

Blood/sputum:
unexplained peripheral blood eosinophils

Skin prick test

Inhaled steroids
Consider if patients have any of the following:
 * exacerbation in the last 2 years
 * using inhaled β2 agonists three times a week or more
 * Symptomatic 3x a week or more
 * waking 1 night a week

Acute severe asthma
Asthma that has failed to resolve in 12 hours of therapy use

Complications
Tension pneumothorax

Brittle asthma
Brittle asthma is catastrophic sudden severe asthma. These patients are usually well controlled between attacks. The attacks can occur in hours/minutes and can cause sudden death.

These patients require optimised standard therapy, emergency supplies and equip including O2/ resus equip/ β2 agonists nebulizer/ self injectable adrenaline/ prednisolone tablets at home/work/car, and medic alert bracelet.

If these patients develop wheeze they must attend nearest hospital immedietly.

Asthma Questions

Next: COPD