Asthma

 

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

 

 

 

 

 

 

 

 

 

 

 

 

 

Asthma in children

 

Introduction

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

 

Aetiology

Atopy

Allergens

More boys than girls in young children

 

Trigger factors

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

 

Pathophysiology

Immunological factors

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

 

Vagal stimulation

Antigens trigger reflex bronchoconstriction

Alteration in autonomic neural control of the airways

Increase in airway smooth muscle responsiveness

Spasm of smooth bronchial muscle

 

Ventilation

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

 

Gaseous exchange

Reduced alveolar ventilation, carbon dioxide retention, hypoxaemia, respiratory acidosis and eventual respiratory failure

 

 

Clinical features

Possible prodromal itching localized to front of the neck or over the upper part of the back

Exacerbations with SOB, cough, wheezing, chest tightness

Non productive cough caused by bronchiole oedema

Later cough becomes productive with frothy, clear, gelatinous sputum

Coughing at night

Decreased expiratory flow

Hyperinflation - hyperresonance

Hypoxaemia due to mismatch of ventilation and perfusion

Dyspnoea

Tachypnoea

Cyanosis

Recession

Grunting to increase PEEP

Bradycardia is a terminal feature

A second wave of symptoms may occur 6 8 hours after antigenic exposure

 

Classification

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.

 

Assessments

Pulmonary function tests

Peak expiratory flow rate

Pulse oximetry

 

Treatments

Prevent by avoiding allergens

Steroids

Bronchodilators

Chest physiotherapy

Hyposensitization

CPAP

IPPV