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CO2 movement impairment, dyspnoea and airflow limitation - Coggle Diagram
- CO2 movement impairment, dyspnoea and airflow limitation
- Patients with airflow limitation (obstructive) are more likely to have CO2 impairment
Note: CO2 impairment is increased demand with no way to cope with it (no balance)
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DYSPNOEA
- distressing awareness of breathing
- mismatch between afferent and efferent
MECHANISM:
- Afferent info. from receptors is processed with the respiratory motor command (in response to increased CO2)
- Mismatch between the motor command and afferent info causes dyspnoea
- Afferent = efferent = no dyspnoea
AIRFLOW LIMITATION (OBSTRUCTION)
Definition: Obstruction is partial or complete blockage of airways = airway resistance (Raw)
Note: length and radius of airway determine AR --> increase/decrease load
- Can't get air OUT
- expiratory flow can't be increased by increasing expiratory muscle effort
MECHANISMS OF AIRWAY OBSTRUCTION:
- Lumen obstructed by secretion
- airway thickened by mucosal oedema, muscle hypertrophy or contraction
- loss of parenchyema, elastic tissue & radial traction
Why patient develop CO2 impairment?
- Increased Raw --> increased expiratory load
- hyperinflation: muscles are shortened (stretched?), which decreases pressure changing ability
PATHOPHYSIOLOGY OF AIRWAY OBSTRUCTION
Airway narrowing --> prolonged expiratory time --> inspires before expiration is complete --> gas trapping (increased FRC) --> flattened diaphragm --> inappropriate length-tension --> decreased efficiency --> increased PaCO2 --> increased drive to breath --> increased RR --> inspires before expiration is complete
NOTE: the drive makes the cycle repeat, making it worse
SIGNS & SYMPTOMS
- prolonged expiratory time
- gas trapping/hyperinflation (CXR)
- dyspnoea
- barrel chest
- increased accessory muscle use (because diaphragm is ineffective)
- lean forward position (curves diaphragm to optimise LTR)
- Decreased FEV1/FVC ratio
- Increased PaCO2 and possibly PaCO2
OBSTRUCTIVE CONDITIONS
ASTHMA
- inflammation and smooth muscle bronchoconstriction --> narrows airways
- Bronchodilators effective
Differentiating S&S:
- Reversible with bronchodilators (>12% improvement)
- wheeze
- cough with sputum (yellow from eosinophils)
- SOB is episodic
MEDICAL MANAGEMENT:
- Aims to prevent acute episodes
- Preventers (inhaled steroids or anti-allergy) ~ taken after BD
- Relievers (relaxes smooth muscle)
- Bronchodilators (ventolin) -- should use spacer!
- Crisis management plan
- monitor peak flow meter
CHRONIC BRONCHITIS - can't see it, just symptoms
- excessive mucus production
- causes excessive sputum (expectoration on most days for at least 3 months in a year for at least 2 consecutive years)
Differentiating S&S:
- cough with sputum (commonly get infections)
- frequent exacerbations
- common to see cor pulmonale (advanced)
- some reversibility
- crackles
COR PULMONALE:
- RHF due to respiratory pathology
- hypoxic vasocontriction
MEDICAL MANAGEMENT:
- Stop smoking
- treat acute infections
- improve QOF, pulmonary rehab
EMPHYSEMA
- enlargement of airspaces distal to terminal bronchiole with destruction of their walls
Differential S&S
- cough is rare except with acute exacerbation
- SOB is main symptoms
- reduced breath sounds (no added sounds)
- hyperinflation with barrel chest
- non reversible
MEDICAL MANAGEMENT:
- stop smoking
- treat acute exacerbation
- pulmonary rehab