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Asthma

Definition : - asthma is a lung disease characterized by :
1 . Airway obstruction ( or airway narrowing ) that is reversible either with treatment or sometime spontaneously
2 . Airway inflammation
3 . Airway hyper-responsiveness to variety of stimuli .

Incidence :-

1- Asthma is the most common chronic lung disease of children .
As many as 10 -15 % of boys and 7 – 10 % girls may have asthma at some time during childhood .
2. before puberty twice as many boys are affected , but at puberty the incidence is equal .
3 .asthma is more severe in young children because they are more prone to viral infection and because the smaller airway size increase airway resistance .
4 . data on the inheritance of asthma are most compatible with polygenic or multifactorial .
5- a child with one affected parent has about 25% risk of having asthma, the risk increases to about 50 % if both parents are asthmatic .
6 . A genetic predisposition combined with environmental factors may explain most cases of childhood asthma .

Epidemiology :-

Asthma may have its onset at any age . 30 % of patients are symptomatic by one year .
80 – 90 % of asthmatic children have their first symptoms before 4-5 yrs of age ,
Most severely affected children have an onset of wheezing during the first year of life and family history of asthma and other allergic disease, these
children may have growth retardation unrelated to steroid therapy .

The prognosis for young asthmatic is generally good . About 50% of all asthmatic children are virtually free of symptom within 10 -20 yrs , but recurrence are common in children 1. In children who have mild asthma with onset between 2 yrs and puberty ,
The remission rate is about 50% and only 5% experience severe asthma .
2. In contrast ,resolution is rare in children with severe asthma characterized
By chronic steroid user with frequent hospitalization about 95 % become Asthmatic adult .

Risk factors for occurrence of asthma include :-
( poverty , black race , birth weight less than 2.5 kg , maternal smoking , Small home size , large family size , intense allergic exposure at infancy )

ETIOLOGY :-

Asthma is a complex disorder involving autonomic , immunogenic , Infectious , endocrine and psychological factors .

1-Vagal sensory ending in airway epithelium causing contraction of smooth muscles .

2-Immunological factors as extrinsic ( allergic asthma ) have increase IgE level .
3-Intrinsic asthma no increasing IgE level and negative skin test .
4-Viral agent are the most important infection triggers .
5-Endocrine effect on asthma may be worsen in relation to pregnancy and menses .
6-Thyrotoxicosis increase the severity of asthma .
7-Psychological factors affection are related more closely to poor control of asthma
Than to the severity of asthma .

Summary of asthma triggers in children :

1 . respiratory infections .
2 . irritant ( cigarette , air pollution .
3 . exercise .
4 . allergic ( inhaled or ingested )
5 . change in the weather .
6 . emotional stress .
7 . medication like aspirin .
8 . gasroesophageal reflux .

ASTHMA PATHOPHYSIOLOGY

The pathology of asthma include bronchoconstriction , bronchial smooth muscle hypertrophy , mucous gland hypertrophy , mucosal edema , infiltration inflammatory cells ( eosinopil , neutrophil , basophil , macrophage ) .
Obstruction is most severe during expiration because the intrathoracic airway become narrower during expiration .
Overinflation cause decrease compliance and then increase work of breathing .
Airway obstruction may lead to atelactasis and then ventilation – perfusion mismatch Further narrowing of airway may lead to pheumothorax .
Hypoxia may damage alveolar cells and then decrease surfactant which normally stabilized alveoli , thus this process may aggravate the tendency toward atelactasis

CLINICAL FEATURES

The acute episodes are most often caused by exposure to irritant such as cold air or exposure to allergins . Because airway patency decrease at night many children have acute asthma at night . 1-Cough is non productive early in the course of attack accompanied by wheezing , Tachypnea , dyspnea , prolonged expiration and use of accessory muscles of Respiration . 2-Hyperinflation of the chest , tachycardia and pulsus paradoxus may be present in severe asthma . 3-sometime Cough may present without wheezing or wheezing may be present without cough .
4- Asthma may present only with chronic night cough .
5- When the patient is in extreme respiratory distress the cardinal signs wheeze may be strikingly absent(silent chest) and appear only after bronchodilator treatment . 6-Abdominal pain is common due to contraction of abdominal muscles and diaphragm ,Vomiting is common .

DIFFERENTIAL DIAGNOSIS :


1 . Respiratory ( infection , foreign body aspiration , tracheomalacia , cystic fibrosis Bronchiectasis , alpha 1 – anti trypsin deficiency ) .
2 . cardiac ( congenital heart disease with failure , vascular ring ) .
3 . G.I.T ( gastro- esophageal reflux , H type fistula ) .
4 . Miscellaneous ( immune deficiency , psychogenic cough ) .

LAB. FINDING IN ASTHUMA 1-Complete blood count , generally normal but esonophelia suggest atopy .
2 . sputum whitish with esonophilia and purulent sputum suggest infection .
3 . chest x-ray normal between episodes Hyperinflation , atelactasis , pneumomediastinum or presence of pneumothorax . May be present .
4 . pulmonary function test .
5 . serum IgE
6 . Allergy skin test .
7 . arterial blood gas analysis .

CLASSIFICATION OF ASTHMA SEVERITY IN GENERAL

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C/F before R symptoms night time symptoms lung function

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Step 4 severe continual symptoms frequent FEV or PEFR <60%_
Persistent limited activity
frequent exacerbation

Step 3 moderate daily symptoms >one time/wk FEV or PEFR>60-80%

Persistent exacerbation affect activity
Exacerbation >2times/wk

Step2 mild symptoms>2times/wk >2times/mon. FEV or PEFR>80%
persistent but < one time a day

Step1 mild symptoms<2times/wk <2times/mon. FEV or PEFR>80%
Intermittent exacerbation breif

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FEV =Forced expiratory volume in 1st second

PEFR = Peaked expiratory flow rate

CLASSIFICATION OF SEVERITY OF ACUTE ASTHMA EXACERBATION ____________________________________________________________________
Mild moderate severe resp. arrest imminent
_____________________________________________________________________ ,
1-Symptoms:
_breathlessness at walking at talking at rest
_ talk in sentences phrases word
_alertness may be agitated agitated usually agitated drowsy confused
2-Signs :
_ R.R increased increased >30/min.
_Accessory not used common used usually paradoxical thoracoabd mov muscles
_wheeze end of expiration throughout throughout absent
Exhalation respiratory
_pulse/min: <100 100 -120 >120 bradycardia
_pulsus paradoxus absent may be present often present absent
3-Functional assessment:
SO2 >95% 91-95% <91% often cyanosis

TREATMENT OF BRONCHIAL ASTHMA

1 . Mild intermittent asthma .
A- *long term control uually no daily medication needed B-*quick relief by short acting bronchodilators in form inhaled beta 2 agonist .
2 . Mild persistent asthma .
A- * long term control by anti-inflammatory therapy inform of low dose inhaled corticosteroid or bronchodilators , cromolyn or nedocromil may be used .
B- some evidence suggest that leukotrien antagonism are effective .
C-* quick relief by short acting bronchodilators in form of inhalers .
3 . Moderate persistent asthma . A- * long term control by daily anti –inflammatory treatment inform of inhaled corticosteroid and long acting bronchodilators .
B- *quick relief by short acting bronchodilators .
4 . Severe persistent asthma .
A- * long term control daily anti-inflammatory therapy inform of inhaled
corticosteroid ( high dose )and long acting bronchodilators , anti-leukotien or B- theophyline .
C- * quick relief by short acting bronchodilator.

Treatment of severe asthma ( status asthmaticus )

1 . Admission and continuous oxygen to keep saturation more than 90 % .
2 . Aerosilized albuterol ( salbutamol ) in a dose 0.15 mg /kg may be repeated hourly
3 . Methyl prednisolone 1-2 mg/kg intravenously 6 hourly or Hydrocortisone 10 mg /kg
4 . Aminophyline administral either loading dose 5 mg /kg followed by continuous
infusion or bolus therapy 1mg /kg 6 hourly ( slow infusion ) .
Beside that laboratory work should include blood gas analysis and electrolytes .
5- Chest x-ray is advisable if there are localized abnormalities on auscultation or
failure response to the treatment .
6- Fluid therapy may be needed due to loss that result from ( hyper ventilation , poor
oral intake , diuretic effect of theophyline ) .
7- Mechanical ventilation may be needed if medical therapy failed .

DRUGS USED IN ASTHMA

1 .Bronchodilators :- A . B2-adrenergic agonist include albuterol ( sabutamol ) , terbutaline , epinephrine and isoproterenol .
for example albuterol ( o.1-0.15 mg/kg / dose ) 3 times daily orally .
aerosol ( 0.01-0.03 ml/kg ) diluted with 2 ml of normal saline up to 4 times daily .
side effects tachycardia , tremor .
B . Xanthine ( theophyline and its derivatives ) are effective bronchodilators but have significant side effect like irritability , hyperactivity , hematemesis and seizure this can be minimized by beginning with small dose and increase slowly available as rapid release and slow release .
C . Anticholinergic such as ipratropium bromide as atropine derivative , have slower onset of action and provide less maximal bronchodilation .
2- Cromolyn :-
Is a mast cell stabilizers that inhibit pulmonary histamine release . It given to prevent ( not treat ) asthma .
3 . nedocromil :-
Is effective in long term asthma ( 4 mg by inhalation ) but has no clear cut advantage over cromolyn .

5 . Leukotriene inhibitors :-

These agent improve pulmonary function by afford protection
against bronchospasim induced by exercise cold air and allergens.

Zafirlukast and Zileutin given above 12 yrs .
Montelukast can be given in children above 2 yrs .

6 . Ketotifen :-

Antihistamine with mass cell stabilizers used for prevention .

7 . Methotrexate :-
Remain as experimental therapy for patient with severe steroid
dependent asthma .

8 . Future therapy :-
Monoclonal Anti IgE antibodies are undergoing clinical trial in
patients with allergen induced asthma

4-Corticosteroid :-

They have significant side effect when used orally for long period Oral preparation are extremely effective , however low dose thera Usually 3-5 days . Low dose ( alternative day ) steroid therapy can be used effectively for patient whose asthma can not be controlled with inhaled steroid because o high effective and can be used safely for chronic asthma .
Mode of action of steroid :
1 . suppression of mediators .
2 . enhance response to agents that increase cyclic AMP .
3 . Enhance response to B2 agonist .
5 . Leukotriene inhibitors :-
These agent improve pulmonary function by afford protection against bronchospasim induced by exercise cold air and allergens. Zafirlukast and Zileutin given above 12 yrs . Montelukast can be given in children above 2 yrs .
6 . Ketotifen :-
Antihistamine with mast cell stabilizers used for prevention .
7 . Methotrexate :-
Remain as experimental therapy for patient with severe steroid dependent asthma .
8 . Future therapy :- Monoclonal Anti IgE antibodies are undergoing clinical trial in patients with allergen induced asthma

4

INHERITED LUNG DISEASES

CYSTIC FIBROSIS :-
The most common lethal inherited disease of whitish that defined as a disease of the exocrine gland that cause viscoid secretion ,the GIT , and pulmonary system are most commonly and most severely affected .
Pathogenesis :-
Cystic fibrosis is inherited as autosomal recessive gene that located on chromosome no. 7 .The defect in cystic fibrosis is thought to be blocked or closed chloride channel in the cell membrane of epithelial cells . this blockage traps chloride ions inside the cell and draws ions and water into the cell . this process results in dehydration of the mucous secretion .
Clinical features :-
1 . respiratory insufficiency , occurs eventually in more than 95 % of all patients and caused by abnormal mucous gland secretion in the airway producing airway obstruction and secondary infection , cough , dyspnea , bronchiectasis , pneumothorax and finely corpulmonale is a late complication .
2.GIT , chronic diarrhea and malabsorption .
3- reproductive defect including sterile male and reduce fertility in females .
4.hepatic manifestation , that ends with portal hypertension .
5.pancreatic with diabetic mellitus .
6.skeletal abnormalities with arthritis and joint pain .
7.nasal including chronic sinusitis with nasal polyps .

Diagnostic criteria of cystic fibrosis :-


1 . positive sweat test by skin test > 6 MEq /L .
2 . typical pulmonary manifestation .
3 . typical GIT manifestation ( meconium ileus , chronic diarrhea , rectal prolapse ,
billiary cirrhosis ) .
4 . positive family history .

Therapy :-
1 . treatment of pulmonary problems .
2 . chest physiotherapy ( postural drainage , active cycle of breathing ) .
3 . antibiotics given orally , I.v or aerosol especially for staph. And pseudomonas
infection ( aminoglycosides , cephalosporin can be used ) .
4 . bronchodilators and steroid .
5 . pancreatic enzymes replacement .
6 . vitamins supplement , high calorie and protein diet .
7 . treatment of complication accordingly .
8 . lung transplant .

DISEASES OF PLEURA

PLEURAL EFFUSION :--
Accumulation of fluid in the pleural space whenever the local hydrostatic forces pushing fluid out of the vascular space exceed osmotic forces pulling fluid back into the vascular space .

Etiology :-

1 . congestive heart failure .
2 . hypoprotienemia .
3 . obstruction of lymphatic drainage .
4 . malignancy .
5 . collagen vascular disease .
6 . infection of pleura is due to strepto cocus , pneumonaie , H . influenza or T .B .

Clinical features :-

In general clinical features of primary disease is the presenting symptoms , but the patient may complain from pain , dyspnea , and sings of respiratory insufficiency resulting from compression of the underling lung tissues .
Physical finding include :-
Dullness to percussion , decrease breath sounds , mediastinal shift and decrease tactile fremitus .

Diagnosis :-

Is confirmed by chest x-ray . postero- anterior shows uniform opacity with acurved upper border , when air is also present the fluid line is horizontal . decubitus views may be helpful to distinguish fluid collection from other densities
in the thorax . diagnostic thoracocetesis may be necessary to establish the cause of the effusion and to exclude infection .
Most patients with effusion should undergo diagnostic thoracocentesis unless the:- 1 . underling causes for the effusion are clearly evident .
2 . the patient does not have significant respiratory distress .
3 . infection not suspected .
Comparison between transudates and exudates pleural effusion :
Transudate exudates
1 . low specific gravity < 1.015 high specific gravity
2 . low protein ( < 2.5 g/ dl high protein > 3g / dl
3 . decrease lactic dehydrogenase increase lactic deh.
4 . low cell count high cell count
5 . high PH low PH
6 . normal glucose low glucose

Treatment : -

Treatment directed to the underlying condition that cause the effusion and at relief of mechanical consequences of the fluid collection .
Small effusion especially if they are trnsudate usually require no treatment
Large effusion may require drainage with chest tube especially if the fluid is
purulent ( empyema ) .
If the underlying condition is treated successfully the prognosis for patient with pleural effusion including empyema is excellent .

PNEUMOTHORAX:-

Is the accumulation of air in the pleural space that may result from external trauma or from leakage of air from the lung or air way ,it may occur spontaneously Predisposing condition include :-
1 . mechanical ventilation .
2 . asthma .
3 . disorder of collagen .
4 . cystic fibrosis .
5 . infection especially staph. Pneumonia , T.B.
6 . Iatrogenic ( tracheostomy , thorachocentesis ) .
Symptoms of pneumothorax :-
Chest pain , dyspnea , and cyanosis . If the air leak accumulate with mediastinum , subcutaneous emphysema may become apparent .
Physical finding :-
Decreased breath sounds , tympanic percussion note , sings of mediastinal shift and subcutaneous crepitance . Few or no physical sings of pneumothorax may be present if the amount of air collection is small , but symptoms may progress rapidly if the air in the pleural space is under pressure ( tension pneumothorax ) with death resulting if the tension not relieved

DIAGNOSIS :-

The radiography usually confirms the diagnosis ,although in the infant there may be difficulty in distinguishing pneumothorax from a large diaphragmatic hernia or giant emphysematous bulla , drink of gastrografin usually resolve the difficulty .

TREATMENT OF PNEUMOTHORAX :-

The treatment depend on the amount of air collected and the nature of the underling cause ,
Small pneumothorax often do not need treatment and resolve spontaneously .
Large pneumothrax and tension peumothorax require immediate drainage of air .
In emergency situation a simple needle aspiration may sufficient , but placement of chest tube may be require for resolution .
Sclerosing the pleural surfaces to obliterate the pleural space may benefit patient with recurrent pneumothoraces .




رفعت المحاضرة من قبل: Mubark Wilkins
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