RESPIRATORY REVISION
OBSTRUCTIVE VS RESTRICTIVE LUNG DISEASE
- Obstructive - ‘ABCCF’ - Asthma, Bronchiectasis, COPD, Cystic fibrosis, Foreign body
- Difficult to exhale due to narrowed airway (harder to blow out)
- Total lung capacity - normal
- FEV1 reduced, FVC reduced or normal, FEV1/FVC ratio reduced
- Restrictive - ‘PAINT’ - Pleural (pleural effusion), Alveolar, Interstitial (interstitial lung
disease), Neuromuscular problems (muscular dystrophy, ALS), Thoracic cage disorders
(scoliosis)
- Difficult to inhale due to stiff lungs (less to blow out)
- Total lung capacity - reduced
- FEV1 reduced, FVC reduced, FEV1/FVC ratio normal
Normal Obstructive Restrictive
FEV1 >80% Reduced Reduced
FVC >80% Reduced or normal Reduced
FEV1/FVC ratio >70 Reduced Normal
Total lung capacity 4-6L Normal Reduced
RESPIRATORY FAILURE
Type I respiratory failure
- PaO2 low (<8kPa), PaCO2 normal/low (<6kPa) ie. hypoxia without hypercapnia
- Give controlled O2 via venturi device
- CPAP used if PaO2 <8kPa despite green 60% venturi device
Type II respiratory failure
, - PaO2 low (<8kPa), PaCO2 high (>6kPa) ie. hypoxia with hypercapnia
- Give controlled O2 starting at blue 24% venturi device, care needed
- BiPAP used if PaCO2 rising >1.5kPa and still hypoxic despite O2 therapy
ASTHMA
- Chronic reversible inflammation of the airways caused by increased sensitivity to various
stimuli leading to variable airflow obstruction
- Bronchial muscle contraction
- Mucosal swelling/inflammation
- Increased mucus production
- Samter’s triad - asthma + nasal polyps + aspirin sensitivity
- Sx: wheeze, non-productive cough, dyspnoea, chest tightness
- Dx: <5 years - clinical judgement; ≥5 years - spirometry with BDR ± FeNO (use in children
with diagnostic uncertainty and all adults)
- But no single way to dx asthma, most important to demonstrate reversibility
- PEF - variability >20%
- Spirometry with BDR - (obstructive pattern with reversibility) FEV1/FVC ratio <75,
reversibility ≥12%
- FeNO (fractional exhaled nitric oxide) - NO produced by 3 types of nitric oxide
synthases (NOS), once of the types is inducible (iNOS) and levels rise in
inflammatory cells, particularly eosinophils, so level of NO correlated with level of
inflammation
<5 years ≥5 years
1 SABA SABA
2 Trial of moderate-dose ICS Add low-dose
Review at 8w: ICS
- Sx didn’t resolve → review if asthma likely
- Sx resolved but recurred within 4w of stopping ICS → restart low-dose ICS
- Sx resolved but recurred after 4w of stopping ICS → repeat trial
3 Add LTRA Add LTRA
4 Stop LTRA and refer to specialist Add LABA
Acute asthma exacerbation
Moderate Severe Life-threatening Near-fatal
PEF 50-75% PEF 33-50% PEF <33% Needs ventilation
OBSTRUCTIVE VS RESTRICTIVE LUNG DISEASE
- Obstructive - ‘ABCCF’ - Asthma, Bronchiectasis, COPD, Cystic fibrosis, Foreign body
- Difficult to exhale due to narrowed airway (harder to blow out)
- Total lung capacity - normal
- FEV1 reduced, FVC reduced or normal, FEV1/FVC ratio reduced
- Restrictive - ‘PAINT’ - Pleural (pleural effusion), Alveolar, Interstitial (interstitial lung
disease), Neuromuscular problems (muscular dystrophy, ALS), Thoracic cage disorders
(scoliosis)
- Difficult to inhale due to stiff lungs (less to blow out)
- Total lung capacity - reduced
- FEV1 reduced, FVC reduced, FEV1/FVC ratio normal
Normal Obstructive Restrictive
FEV1 >80% Reduced Reduced
FVC >80% Reduced or normal Reduced
FEV1/FVC ratio >70 Reduced Normal
Total lung capacity 4-6L Normal Reduced
RESPIRATORY FAILURE
Type I respiratory failure
- PaO2 low (<8kPa), PaCO2 normal/low (<6kPa) ie. hypoxia without hypercapnia
- Give controlled O2 via venturi device
- CPAP used if PaO2 <8kPa despite green 60% venturi device
Type II respiratory failure
, - PaO2 low (<8kPa), PaCO2 high (>6kPa) ie. hypoxia with hypercapnia
- Give controlled O2 starting at blue 24% venturi device, care needed
- BiPAP used if PaCO2 rising >1.5kPa and still hypoxic despite O2 therapy
ASTHMA
- Chronic reversible inflammation of the airways caused by increased sensitivity to various
stimuli leading to variable airflow obstruction
- Bronchial muscle contraction
- Mucosal swelling/inflammation
- Increased mucus production
- Samter’s triad - asthma + nasal polyps + aspirin sensitivity
- Sx: wheeze, non-productive cough, dyspnoea, chest tightness
- Dx: <5 years - clinical judgement; ≥5 years - spirometry with BDR ± FeNO (use in children
with diagnostic uncertainty and all adults)
- But no single way to dx asthma, most important to demonstrate reversibility
- PEF - variability >20%
- Spirometry with BDR - (obstructive pattern with reversibility) FEV1/FVC ratio <75,
reversibility ≥12%
- FeNO (fractional exhaled nitric oxide) - NO produced by 3 types of nitric oxide
synthases (NOS), once of the types is inducible (iNOS) and levels rise in
inflammatory cells, particularly eosinophils, so level of NO correlated with level of
inflammation
<5 years ≥5 years
1 SABA SABA
2 Trial of moderate-dose ICS Add low-dose
Review at 8w: ICS
- Sx didn’t resolve → review if asthma likely
- Sx resolved but recurred within 4w of stopping ICS → restart low-dose ICS
- Sx resolved but recurred after 4w of stopping ICS → repeat trial
3 Add LTRA Add LTRA
4 Stop LTRA and refer to specialist Add LABA
Acute asthma exacerbation
Moderate Severe Life-threatening Near-fatal
PEF 50-75% PEF 33-50% PEF <33% Needs ventilation
