respiratory Flashcards
what FEV1/FVC ratio indicates obstructive lung disease
< 70% or FEV1 <80%
what FEV1/FVC ration indicated restrictive lung disease
> 80%
define transfer coefficient, which conditions is it low and high in?
measure of ability of oxygen to diffuse across the alveolar membrane low in - emphysema -fibrosing alveoli's -anaemia high in -pulmonary haemorrhage
why might we perform a bronchoscopy on a patient
- lobar collapse, mass or persistent consolidation detected on X-ray
- haemoptysis
- cough, wheeze, stride, dyspnoea
- suspected aspiration of foreign body
- therapeutic e.g stent
what is the definition of chronic bronchitis
- productive cough for 3 months in two consecutive years
what are the symptoms and signs of chronic bronchitis
- mucus hyper secretion with bronchial mucus gland hypertrophy
- hypercapnia and hypoxaemia
- cyanosis (blue bloaters) - rely on hypoxic drive
- right heart failure
what are the main organisms associated with chronic bronchitis
- haemophilus influenzae
- streptococcus pneumoniae
- viruses (adeno, respiratory syncytial)
describe the pathophysiology of emphysema
- enlargement of alveolar airspaces with destruction of elastin in walls
- permanent enlargement of airspaces distal to terminal bronchioles due to destruction of walls
- gas trapping effect prevents full exhalation
- pulmonary hypertension and poor oxygen delivery to tissues
- neutrophils recruited and release IL8, TNF and destructive enzymes = tissue damage
- reduced paCO2, normal PaO2 due to over ventilation
- pink puffers
- weight loss due to metabolic demands
- right heart failure
- over inflated chest
what is the main genetic abnormality linked to emphysema
alpha -1 - antitrypsin deficiency
what are the features of bronchiectasis
- permanent dilation of bronchi and bronchioles due to obstruction and inflammation
- caused by h. influenzae, strep penumoniae, staph aureus
- chronic cough with expectation of large quantities of foul smelling sputum with intermitted haemoptysis
- clubbing
- wheeze
- complications include: pneumonia, fungal colonisation, metastatic abscess, amyloidosis, pneumothorax
- treatment to reduce symptoms rather than cause - mucolytics for hyper secretion
in interstitial lung diseases what happens to TCO, VC, FEV1, FVC and PEFR
reduced TCO, VC FVC
high FEV1/FVC ratio
normal PEFR
give one acute and 3 chronic interstitial lung diseases
acute - Adult respiratory distress syndrome
chronic - fibrosing alveolitis (Idiopathic pulmonary fibrosis)
- pneumoconiosis
- sarcoidosis
what are the main causes of ARDS
- Trauma
- shock
- gastric aspiration
- drug abuse
- pneumonia
what are the clinical features of ARDS
Tachypnoea, arterial hypoxaemia, cyanosis
what are the features of IPF
- symptoms - dry cough, exertion dyspnoea, clubbing, cyanosis
- abnormally large irregular spaces separated by thick fibrous septa (honeycomb lung)
- restrictive lung function tests
- scarring
- myofibroblasts secrete exaggerated amounts of ECM that remodel lung architecture
what are the different ways the lung can respond to inhaled dust (causes pneumoconiosis)
- inert - coal workers pneumoconiosis (coal in alveolar macrophages)
- fibrous - asbestosis, silicosis, progressive massive fibrosis
- allergic - EAA - granulomatous inflammation
- neoplastic - mesothelioma, lung cancer
what is the Kviem test for sarcoidosis
subcutaneous injection of sterile homogenised sarcoid tissue induces granulomas in affected patients
using an FEV1/FVC ratio what is the definition of COPD
< 70% or 0.7
which two diseases does COPD encompass
- emphysema and chronic bronchitis
what are the different delivery systems for inhaled drugs
- pressurised measured dose inhalers (PMDIS) - device activated by user pressing down on the top of container, resulting in the release of a fine spray containing propellant and drug
- spacer devices - slow down the particles of the drug and allow more time for evaporation of the propellant
- dry powder inhalers (DPIS) - device releases a small amount of drug in powder form which is then inhaled
- nebulisers - disperse a liquid into a fine mist which can be inhaled through a mask or mouthpiece
what factors need to be considered to prolong absorption of therapeutic agents from the lungs
- solubility
- charge and tissue retention
- encapsulation - allow controlled release by use of excipients (molecules that modify properties of medicines)
what are the advantages of using inhaled drugs
- lungs are robust
- act directly on lung or enter systemic circulation
- rapid absorption
- large sa
- lungs naturally permeable
- fewer drug metabolising enzymes
- non invasive
- fewer systemic side effects
what is bronchoconstriction due to
- tightening of ASM
- lumens occlusion by mucus and plasma
- airway wall thickening
- in asthma ASM is both primed to contract an is resistant to relaxation
what drugs can we use to relieve bronchoconstriction
- B2 adrenoreceptor agonists - act on sympathetic nervous system to cause bronchodilation :
smooth muscle relaxation and bronchodilation
inhibit histamine release from lung mast cells
SABA - salbutamol
LABA - formoterol and salmeterol - Anticholinergics: block bronchoconstriction (PSNS)
block Ach binding to muscarinic receptors M1-M5 on ASM glands and nerves
e,g atropine = naturally occurring anticholinergic (ipratropium bromide and tiotropium bromide are synthetic derivatives with fewer side effects)