Pathophysiology
Bronchial asthma is a chronic
inflammatory disorder causing reversible airway limitation.
Clinical features are produced by
three pathophysiological features;
*
Contraction of the smooth muscular walls of the small bronchi and bronchioles.
*
Swelling of the surface mucosa reducing the lumen of the air passages.
*
Over production of viscid secretions further narrowing the lumen and
obstructing air flow to the alveoli.
Chronic asthma may lead to
irreversible airway limitation
Aetiology
extrinsic - a definite external cause intrinsic - cryptogenic
airway hyperactivity allergy
to inhalants - histamine
occupational sensitisers atmospheric
pollution
NSAIDs eg aspirin viral
infections
cold air emotion
irritant dust/vapour/fumes house
dust mite faeces
animals foods
Clinical Features
Condition may occur at any age, often
affecting children Attacks
may be of sudden onset
Recurrent episodes of dyspnoea and
wheezing often with coughing
Expiration is often more difficult
than inspiration, chest tightness
Use of the accessory muscles of
respiration Increase
in respiratory and pulse rate
Severe anxiety/restless, a fear of
suffocation Central
cyanosis may develop
Hypoxia may embarrass essential organs
such as the heart and brain.
Complications may occur such as
pneumothorax and respiratory failure.
Attacks may last from hours to weeks Wide
variation in frequency of attack
Asthma occurs in otherwise healthy
people. The condition is relatively
common, some studies have revealed a prevalence in the second decade of life as
high as 15-20%.
Untreated asthma is potentially fatal. 1 858 people died from asthma in 1990 in
the UK. Many of these deaths occurred in children and young people and were preventable.
Management Principles
No cure
Admit to hospital if peak flow is less
than 150 l/min or 30% lower than expected
* Salbutamol
or terbutaline by inhaler - 2 puffs
* Oxygen
therapy
* Position
the individual upright supported by pillows
* Take
all possible measures to reduce anxiety;
Calm unhurried approach Project
professional competence
Give appropriate explanations prior to
treatments
Allow parent or significant other to
stay with the patient
Stay with the individual at all times
Pay attention to verbal and non verbal
aspects of communication
* Nursing
Observations;
- Temperature,
pulse, blood pressure, respiratory rate
- Recordings
of peak expiratory flow rate, (PEFR) regularly, and before and after administration of
medication
- Effects
and side effects of medication
- Changes
in the difficulty experienced in breathing, observation of the use of accessory
muscles
-
Degree of cyanosis
- Degree
of patient distress and anxiety
- Level
of consciousness
- Close
observation should be maintained for possible cardiac complications such as heart failure or
ventricular fibrillation
* Physiotherapy
Acute severe asthma
Status asthmaticus is the old term and
describes a severe asthmatic attack which has not responded to self-treatment.
In status the patients life is at risk
Clinical Features;
Wheezing Severe
distressing dyspnoea
Developing central cyanosis Tachycardia
>110
Pulsus paradoxicus, (fall in pulse and
BP during inspiration)
Management;
Position upright
Oxygen therapy at high concentrations,
40 - 60 %
Nebulized salbutamol 5 mg is given
initially
Hydrocortisone 200 mg I.V. is given
four hourly for 24 hours
Nebulized salbutamol 5 mg in saline is
given every 4 hours
Reassure
Monitor peak expiatory flow rates
Arterial blood gases may be monitored
Intermittent positive pressure
ventilation if indicated
Hypnotics or opiate analgesic must
never be given as they may cause respiratory arrest
Chest X Ray may be performed when
patients condition allows
Drugs in severe asthma
At home;
Nebulized 5 mg salbutamol or 10 mg
terbutaline Hydrocortisone
200 mg iv.
Prednisolone 60 mg orally
In hospital
Nebulized 5 mg salbutamol or 10 mg terbutaline
every 4 hours
Add nebulized ipratropium bromide 0.5
mg to nebulized salbutamol or terbutaline
Hydrocortisone 200 mg iv. is given 4
hourly for 24 hours
Prednisolone 60 mg orally daily for 2
weeks
If no significant improvement
Salbutamol 3 - 20 ug/min or
terbutaline 1.5 - 5 ug/min by intravenous infusion
Patient Education
Airway hyperresponsiveness -
prophalatic drugs and behaviour
Medication
Give full instruction of the use of
medication in prophylaxis and treatment.
Asthma is an inflammatory disease so
anti-inflammatory drugs should be given even in mild cases, eg. sodium
cromoglycate, nedocromil sodium.
In cases with persistent symptoms
beclomethasone, (a corticosteroid) may be given
Use Bronchodilators only when
necessary - long term use may make condition worse
Guide-lines on use of inhaled therapy;
First shake the canister The
patient exhales
The aerosol nozzle is placed in the
mouth - forming a good seal with the lips
The patient simultaneously activates
the aerosol and inhales rapidly
The breath is in held for 10 seconds
if possible
The aim is to get as much of the drug
as far into the bronchial tree as possible to exert a local bronchodilatory
effect
Make patient independent - peak flow
technique
Encourage sufferers to seek early medical
advice during attacks
Avoid dehydration
Manage infections
Avoid any situations, drugs or agents
which may precipitate an attack
Trigger factors may include,
respiratory tract infections, house mite dust, pollens, moulds from house plants,
occupational exposure, animals, exercise in cold air, certain foods, emotional
stress, dust and fumes.
There may also be an association with
pregnancy and menstruation.
Asthma often improves with age
Care plan/problems
Difficulty in breathing
Excessive sputum production
Anxiety focused on breathlessness and
hospital admission
Potential dehydration due to inability
to drink because of breathlessness
Exhaustion due to effort of breathing
Unable to maintain own hygiene needs
due to exhaustion
Possible deep vein thrombosis
Patient smokes cigarettes
Patients occupation may be
exacerbating condition
Patient is anxious about
financial/social issues due to his hospitalisation
The most common chronic disease in
children
Increasing in prevalence, morbidity
and mortality in western countries
80 – 90% of sufferers have their
first episode before 4 – 5 years of age
A chronic inflammatory disorder
Inflammation in the airways causes
hyperresponsiveness to a variety of stimuli
Recognition of the inflammatory
component has made steroid therapy important
Recurrent episodes of cough,
breathlessness, chest tightness, wheezing, particularly at night or early
morning
Airflow limitation or obstruction
which is reversible - spontaneously or with treatment
Atopy Allergens
More boys than girls in young children
Pollens, moulds, pollution Dust
and dust mites
Tobacco smoke Smoke,
odours, sprays
Exercise Environmental
chemicals
Animals Medications
Strong emotions Food
additives
Foods, nuts, dairy products
Effects can be instant or delayed for
several hours
Allergic reaction in the airways
An initial release of inflammatory mediators
from bronchial mast cells, macrophages and epithelial cells
Inflammatory oedema
Accumulation of tenacious secretions
from mucous glands
Antigens trigger reflex
bronchoconstriction
Alteration in autonomic neural control
of the airways
Increase in airway smooth muscle
responsiveness
Smooth
muscle in walls of bronchial passages constrict
Causes
forced expiration through increased airway resistance
Air is trapped in the lungs behind
occluded, narrowed airways
Hyperinflation
Reduced alveolar ventilation, carbon
dioxide retention, hypoxaemia, respiratory acidosis and eventual respiratory
failure
Non
productive cough caused by bronchiole oedema
Later cough
becomes productive with frothy, clear, gelatinous sputum
Coughing at
night
Decreased
expiratory flow
Hypoxaemia
due to mismatch of ventilation and perfusion
Tachypnoea
Cyanosis
Mild intermittent
Mild, persistent
Moderate persistent
Severe persistent
This classification gives guidelines
for treatments appropriate to the severity of the disease, with the possibility
of movement up or down the classification.
Pulmonary function tests
Peak expiratory flow rate
Pulse oximetry
Prevent by avoiding allergens
Steroids
Bronchodilators
Chest physiotherapy
Hyposensitization