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Pulmonary ventilation (Capacties (Inspiratory capactiy (Sum of TV and IRV)…
Pulmonary ventilation
Capacties
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Total lung capactiy
Maximum amount air lungs accomodate, sum all four volumes
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Intro
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Pressure differnces
- Inspiration
- Intrapulmn press < atmospheric pres
- Expiration
- Intrapulm pressure > atmospheric pressure
- Transpulmonary pressure
- Diff between intrapulmonary and interpleural pressure (keeps lungs against thoracic wall, allows lungs to expand as thoracic wall does
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Spirometry
- Most common form lung function test
- Volume and flow of air inhaled and exhaled within lungs + overall effort
- Identify obstructive, restrictive + mixed disease
- Normal spir result: 0.7-0.8
- FEV1 % Predicted:> or equal to 80%
- FVC % predicted: > or equal to 80%
% predicted average equivalen in healthy popn of same gender, age + height
Obstructive diseases
- Impair passage air into and out of respiratory tract
- Could be a result various factors reduce size passageway for air: mucus plugs, contraction smoth muscle, oedema presence various inflammatory cells
- E.g COPD, asthma, cystic fibrosis
FEV1:FVC RATIO LESS THAN OR EQUAL TO 0.7
Asthma
- Inflammatory condition airways:
- Bronchospasm
- Breathlessness
- Chest tightness
- Wheeze
Results in
- Oedema
- Epithelial cell shedding
- Mucus plug formation
Restrictive
- Impairs lung expansion, reduces lung volume + results inadequate ventilation
- Pulmonary and extra pulmonary issues
- Pulmonary: interstitial lung disease e.g. pulmn fibrosis, p oedema
- Extra pulm causes: obesity, pregnancy, neuromuscular
FEV1:FVC MORE THAN 0.8
Pulmonary causes
- Group disorders affects pulmonary interstitial tissue + alveoli
- Inflam cells + fibroblasts infiltrate tissue resulting in inflam and fibrosis
- Final effect formation of scar tissue + thickening alveoli walls: impairs effective gas exchange
- Lung compliance reduced + work of breathing increases + imparis ventilation: perfusion ratio
DLCO/TLCO and KCO
- DLCO (diffusing capacity lungs for CO)
- DLCO Measure of lung's ability transport oxygen inhaled air to pulmonary capillaries
- CO greater affinity for HB compared to O2,
feature assess lung ability to transfer oxygen from alveoli to blood
- Efficiency gas transfer 2 factors
- SA, diff in partial pressure of gas, diff coefficiecnt and barrier thickness
Hb levels
- Patient exhale as much as possible, inhale mixture 0.3% CO and 10% He. Hold breath for 10s
- Composition He and CO in air exhaled assessed for changes when inspired
- Condition which affects alveolar SA, alters DLCO (e.g. COPD)
- KCO is TLCO corrected for alveolar volume
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Control breathing
Receptors:
- Central chemoreceptors (ventral surface medulla)
- Increase rate and depth with increase CO2
- Peripheral chemoreceptors (carotid bodies, aortic arch)
- Increase rate and depth with decrease O2 and pH
- Stretch receptors (bronchi)