Respiratory Flashcards
Oxygen dissociation curve
LEFT = HIGHER AFFINITY - binds more in lungs LEFT = LOW!! (everything except pH) - LOW TEMP - LOW CO2 (hyperventilation) - LOW 2,3 DPG - HIGH pH (alkaloic) - FOETAL HB - CO
RIGHT = LESS AFFINITY - more O2 to tissues e.g. sickness, exercising muscles RIGHT = HIGH!! (everything except pH) - HIGH TEMP - HIGH CO2 (hypoventilation) - HIGH 2, 3 DPG - LOW pH (acidotic)
Ventilation
Oxygenation = PaO2
- Depends on MAP + FiO2
- Increase LV, iTime
- P50 = 27mmHg
Ventilation = PaCO2
- Frequency (F up = PaCO2 up)
- Minute volume (MV up = PaCO2 down)
MV = TV + RR
Compliance = change in volume/change in pressure
- FRC
Airway resistance e.g. asthma
- slow rate, moderate volume
Decreased compliance e.g. RDS, pneumonia, CCF
- rapid rate, small volume
Equations
PRESSURE (gas) inversely proportional to volume
VOLUME (gas) proportional to temperature
FLOW = CHANGE IN PRESSURE / RESISTANCE
RESISTANCE = VISCOSITY x LENGTH/RADIUS^4
PiO2 = 0.21 x (Patm - Pwater)
Water = 47mmHg
Sea level atm = 760mmHg
PiO2 at sea level = 0.21 x (760-47) = 150
PiO2 on mountain Patm = 650mmHg: 0.21 x (650-47) = 126
FRC, RV, TV, VC
FRC = What is left after tidal volume released in standard breath (need whole body plethysmography)
Residual volume = volume left after maximum possible exhalation
Tidal volume = volume with each standard breath
Vital capacity = volume with maximum breath
Restrictive lung disease
Problem with INTERSTITIAL tissue/lung PARENCHYMA
Restrict the expansion of lung -> stiff, less compliant
No significant problem in the airways
“Smaller lung” / smaller volume but more dense parenchyma e.g. neuromuscular weakness, interstitial lung disease (DCLO2 NORMAL in neuromuscular, LOW in interstitial)
Obstructive lung disease
Problem is with the AIRWAYS
Increased airway resistance - difficult expiration
No problem with parenchymal or lung tissue e.g. asthma, CF
Important values
FEV1/FVC 80% = normal (restrictive - same, obstructive <70%)
Bronchodilator response - 12% improvement in FEV1
Histamine response - 20% reduction in FEV1
Monitoring: FEV1 = obstructive. FVC = restrictive
FEF25-75 = small airway obstruction
Restrictive flow volume
LESS! TLC less / FRV less TV less / RV less VC less / FEV1 less FVC less
Compliance less, stiffness more
FEV1/FVC normal or increased
FEF25-75 normal or increased
Obstructive flow volume
TLC high (air trapping) FRC high RV high FEV1 less (most reproducible in CF) VC less
compliance more, stiffness less
FEV1/FVC less
FEF25-75 less
Flow volume loops
Obstructive lung disease
- Scooped out curve e.g. asthma, CF
Restrictive lung disease
- Similar shape but smaller e.g. interstitial lung disease, chest wall deformity
Neuromuscular weakness
- Small circle graph
Fixed upper airway obstruction
- Both inspiratory and expiratory flattened e.g. goitre, tracheal stenosis
Variable extrathoracic upper airway obstruction
- Inspiration flattened e.g. laryngomalacia, subglottic haemangioma, vocal cord palsy (bilateral normal cry, resp distress. Unilateral - weak cry, minimal resp distress, choke with feeds)
Variable intrathroacic upper airway obstruction
- Fixed inspiration e.g. tracheomalacia
Thumb sign
Epiglottis
Steeple sign
Croup
Irregular trachea
Bacterial tracheitis
Multi cystic lesion in lung
CCAM
Dextrocardia, sinusitis, bronchiectasis
Kartageners
Finger and glove extensing bronchograms
Aspergillus
Affected side hyperventilation/flat diaphragm, other lung collapsed
Congenital lobar pneumonia
Round lesion with air fluid level
Lung abscess
Thin walled air sac within parenchyma, no air fluid level
Pneumatocele
Solitary coin lesion in lung
Harmatoma
Bowel in chest, scaphoid abdomen, barrel chest
CDH
Unilateral diaphragm up with bowel under
Diaphragmatic eventration
Large round upper lobe mass
Neuroblastoma
Halo on Ct, post stem cell transplant
Aspergillus fumigatus
Ground glass middle lobe, FTT, recurrent URTI
Neuroendocrine cell hyperplasia of infancy
