Breathing Flashcards
what investigations should we use In assessing respiratory function?
NON-INVASIVE:
Peak flow, Pulse oximetry , Capnogrpahy, sputum sample
Spirometry - FEV1/FVC should be >80%
DLco = transfer factor = measures transfer of low carbon monoxide concentrations in inspired air to Hb Kco = DLco corrected for alveolar volume
CXR, CT, Echo
INVASIVE: ABG Bronchoscopy - rigid or flexi Lung biopsy Mediastinoscopy - if need tracheobronchial LNs PET scan
Applications of flexible bronchoscopy?
Diagnostic = biopsy via direct sampling or brushings, visualising obstruction
Therapeutic = Removing obstruction, argon coagulation therapy, difficult intubations, stenting
Advantage ov rigid brocnhosocpy over flexible?
Rigid bronchoscope permits simultaneous instrumentation, good if need to suction or remove foreign body
Outline the measurable lung volumes?
TV = volume of inspired air - 500ml OR 7ml/kg
ERV = volume that can be forcibly expired after quiet expiration
- 1.3L
IRV = volume that can be forcibly inspired above TV
- 3L
What lung volumes are there that are non measurable with spirometry?
Anything that involves residual volume.
Residual volume = Volume in lung after maximal expiration
- 1.2-1.5L
Total lung volume = VC + RV
Functional residual capacity = ERV + RV = volume left after quiet expiration
2.5-3L
Equation for FRC, normal range, and what can increase it or decrease it?
FRC = Functional residual capacity = ERV + RV
normal range = 2.5-3L
Increased in:
Obstructive disorders e.g. COPD / asthma
PEEP e.g CPAP
Decreased with: Age Obesity Pregnancy Factors limiting expansion = Effusions, abdo swelling, restrictive lung disease
Obstructive vs restrictive on spirometry?
Obstructive has reduced FEV1 = FEV1/FVC is low <0.8
Restrictive both are low but FVC is more low:
FEV1/FVC >0.8
What is atelectasis?
absence of gas from all or part of the lung
Plain CXR can be sub-segmental, segmental, lobar or pulmonary collapse
Causes of atelectasis?
Bronchial obstruction - sputum, FB or tumour
Alveolar hypoventilation leading to progressive airway collapse
Parenchymal compression due to oedema or effusions
Bronchial intubation collapses contralateral side
Why does airway obstruction cause atelectasis?
The gas trapped distally is absorbed as it has a higher partial pressure than the mixed venous blood = progressive collapse
Risk factors for post-op atelectasis?
Abdominal or thoracic surgery BMI > 27 Age >59 ASA >2 COPD IPPV > 1 day Smoking in the preceding 8 weeks
Management of post-op atelectasis?
Pre-op - breathing exercises
Intra-op:
Humidified air
Avoid unnecessarily high FiO2
Post-op: Upright position and breathing exercises Mobilise early Adequate analgesia CPAP Bronchoscopy for mucus plugs / secretions
What is CPAP and its effect on respiratory system?
Continuous positive airway pressure
Has a valve with set pressure.
On inspiration and expiration positive pressure cannot fall below this set pressure, if it does then pressure given.
Improves ventilation by: Opening of collapsed airways + prevention of collapsing on expiration Increases FRC Increases lung compliance Decreases work of breathing Increases V/Q ratio = improved perfusion
Disadvantages of CPAP?
Tight uncomfortable mask - pressure sores
Risk of barotrauma
Gastric dilation due to swallowed air
What is bronchiectasis?
The irreversible dilation of bronchi due to chronic inflammatory processes
name the types of bronchiectasis?
Follicular = loss of bronchial elastic tissue + multiple lymphoid follicles
Atelectatic = localised dilation of airways, associated with parenchymal collapse
Saccular / cystic = patchy dilation of airways, with loss of bronchial subdivisions
Aetiology of bronchiectasis?
Congenital:
Ciliary dyskinesia e.g. Kartageners
Cystic fibrosis
Ig deficiencies (will see recurrent infections in infancy)
Acquired: Post-infective bronchial damage e.g measles, pertussis, TB Bronchial obstruction - tumour, FB, LN's Immunodeficiency e.g. AIDS Autoimmune - RA, UC
What bacteria may colonise bronchiectasis?
Haem. Influenzae
Staph aureus
Strep pneumo
Complications of untreated bronchiectasis?
Early =
- haemoptysis
- infections > abscess and empyema
- metastatic infection e.g. cerebral abscesses
Late:
- Cor pulmonale
- Respiratory failure
- Secondary amyloidosis with protein A deposition
Mx of bronchiectasis?
Manage reversible airway obstruction with neb and steroids
Chest physio
Treat underlying cause and treat any infection
Surgery - lung transplant in CF
What is pneumonia?
Inflammatory process of lung characterised by consolidation due to exudate in alveolar space
Types of pneumonia?
Lobar - confined to one lobe, linear demarcation.
Exudate forms in bronchioles and alveoli and spills over to adjacent segments via pore of Kohn.
Bronchopneumonia = starts at bronchioles and extends into alveoli > numerous foci of consolidation
Interstitial = chronic alveolar inflammation, not necessarily infective in origin - may be immune based
Pathological classes of pneumonia?
1 = acute congestion, day 1-2
- lobe is heavy, dark and firm.
- inflame exudate and cellular infiltrate including erythrocytes
2 = red hepatisation, day 2-4
- lung is firm, red and consolidated
- neutrophils fibrin and extravasated erythrocytes
3 = grey hepatisation, day 4-8
- Heavy, consolidated and grey
- Extensive fibrin network and degenerating erythrocytes
4 = resolution > day 8
- Macrophage action liquefies exudate
- can take 3 weeks
Organsims involed in ICU pneumonias?
Ventilator related
Within 1-4 days of intubation = early onset:
- Strep. pneumonia, s. aureus and h influenza
Lates onset >4 days = gram negative
- Pseudomonas, enterobacter, aeruginosa
What are the normal respiratory defence mechanisms?
Nasal humidification of air Nascociliary action Intact cough reflex Alveolar macrophages Secretory IgA
RF’s for nosocomial pneumonia when intubated?
Breakdown of anatomical barriers Impaired cough reflex Re-intubation Colonisation of instruments Staff hygiene Aspiration of gastric contents Epithelial trauma due to airway / suction
