Obstructive Airway Diseases Flashcards
What are the obstructive airway diseases?
Chronic bronchitis
Emphysema
Asthma
What are chronic bronchitis and emphysema known as?
COPD
What is FEV1?
Forced expiratory volume of air exiting the lung in the first second
What is FVC?
Final total amount expired
FEV vs FVC
FEV1 usually about 70 - 80% of FVC
FEV 1 - 3.5 - 4 litres
FVC - 5 litres
Normal FEV1:FVC ratio
0.7- 0.8
What is predicted FVC based on?
Age
Sex
Height
What does PEFR stand for?
Peak expiratory flow rate
What is PEFR used to monitor at home?
Bronchial asthmatics respiratory function
Normal PEFR
400 - 600 L/min
Normal range of PEFR
80 - 100% of best value
What is a moderate fall of PEFR?
50 - 80%
What is a marked fall of PEFR?
< 50%
Features of obstructive lung disease
Airflow limitation
PEFR reduced
FEV1 reduced
FVC reduced
FEV1 less than 70% of FVC
Pathology of bronchial asthma
Type 1 hypersensitivity in the airway
Allergic (associated) reactions
Constriction of bronchial smooth muscle
Inflammation response
What type of obstruction is bronchial asthma? In response to what?
Reversible
In response to
- spontaneously
- pharmacological intervention
Causes of chronic bronchitis / emphysema
Any chronic irritant being inhaled into the lungs
Smoking
Atmospheric pollution
Occupation (dust)
Alpha 1 antiprotease (antitrypsin) deficiency (emphysema)
Which gender gets chronic bronchitis /emphysema?
M > F
Definition of chronic bronchitis
Cough productive of sputum most days in at least 3 consecutive months for 2 or more consecutive years
What does chronic bronchitis result in?
Natural decline in FEV1
What is complicated bronchitis?
Mucopurulent (mucus and pus) in an acute infective exacerbation
FEV1 falls
Morphological changes in chronic bronchitis
Large airways
- mucous gland hyperplasia
- goblet cells hyperplasia
- inflammation and fibrosis
Smaller airways
- goblet cells appear
- inflammation and fibrosis in long standing disease
Definition of emphysema
Increase beyond the normal size of the airspaces distal to the terminal bronchiole arising either from dilation or from destruction of their walls and without obvious fibrosis
What is the terminal bronchiole?
Last conducting airway of sub mm in size which is completely lined by respiratory epithelium
Pathology of emphysema
Increase in size of airspaces distal to terminal bronchiole
Loss of alveolar tissue (making spaces bigger)
Loss of alveolar walls may take place in the acinus
What is the acinus?
The region of the lung supplied with air from one of the terminal bronchioles
Types of emphysema
Centriacinar
Paracinar
Periacinar
Bullous
What is centriacinar emphysema?
Begins with bronchiolar dilatation
Gough wentworth section of the lung
Upper regions of the lung
What is paracinar emphysema?
Lower regions of the lung
Massive destruction
All gas tissue disappears and left with tubes and airways suspended in space
What is periacinar emphysema?
Enlarged air spaces along the edge of the acinar unit but only where it abuts against a fixed structure such as pleura or a vessel
What is a bulla?
Emphysematous space greater than 1cm
What is used to describe bullae under the pleura?
Bleb
Causes of emphysema
Smoking
Ageing
Alpha - 1 - antitrypsin deficiency
Pathology of smoking causing emphysema
Protease : antiprotease imbalance
Leads to malfunction of alpha 1 antitrypsin and similar enzymes
Causes inflammation in the lungs which also causes damage
These enzymes try to repair the damaged tissue but they cant so the tissue damage occurs and stays
Most important factor in the pathology of emphysema
Loss of alveolar attachments
Causes of respiratory alkalosis
PE
Anxiety leading to hyperventilation
CNS disorders e.g. stroke, SAH, encephalitis
Altitude
Pregnancy
Causes of respiratory acidosis
COPD
Opiate overdose
Life threating decompensated asthma
NM disease
Obesity hypoventilation syndrome
Benzodiazepines overdose
