Respiratory Flashcards
Stimulators of central chemoreceptors
High CO2, Low pH
Stimulators of peripheral chemoreceptors (carotid bodies>aortic bodies)
Low oxygen
High Co2
Low pH
Group of neurons most important for inspiration
Dorsal inspiratory group neurons in the medulla
Communicates with somatic neurons working of the diaphragm
Arterial baroceptors action
Increase in arterial blood pressure can cause refle hypoventilation
Conducting airway dead space volume
150ml
First site of diffusion of oxygen
Respiratory bronchioles
Muscles important for active expiration
abdominal muscles
Total lung capacity
6L
Residual volume
20% TLC
Volume post forced expiration
Functional residual volume
40% of TLC
Volume after passive expiration
Major site of airway resistance
medium-sized bronchi
Lowest point of PVR
At FRC
Tidal volume
7ml/kg ~700mls
Elderly LFTs
Lvel of obstruction with increased residual volumes
Lung volume that cannot be measured with a spirometer
Residual volume
Therefore TLC and functional residual capacity
Measures with body plethysmograph
FEV1 / FVC ratio for obstruction
< 0.7
Reduction in TLC
Reduction in RV
Intrinsic RLD (ILD)
TLC decrease
RV normal
Extrinsic RLD
Mixed obstruction/restriction
Decreased TLC
FEV1/FVC <0.7
Indicator of gas trapping in COPD
Functional residual capacity
Increased RV/TLC
Consistent with extrinsic restriction
Mild increase with morbid obesity
Marked with NMD
The partial pressure of oxygen
Amount of oxygen dissolved in the blood
Not affected by Hb
Right shift of oxygen dissociation curve
Causes a reduced affinity of O2 to Hb Increase in Temp Increased pCO2 decreased pH Increased 2,3- DBG
Left shift of oxygen dissociation curve
Carbon Monoxide
High HbF
Met-Hb
Decreased temp, high pH, low pCO2
3 forms of CO2 carriage in the bloods
HCO3 (majoirty)
Carbamino Hb
Dissolved
Cause of left/right shift of CO2 curve
More HbO2, the less bound CO2 to Hb
Increment of HCO3 in acute respiratory acidosis
1 - 1.5 for every 10mmHg increase in CO2
Increment of HCO3 in chronic respiratory acidosis
3 - 4 for every 10mmHg increase in CO2
Normal A-a gradient age adjusted
Age/4 + 4
e.g. 60/4 + 4 = 19
pAO2
150 - paCO2 / 0.8
Increased A-a gradient
V/Q mismatch
Diffusion abnormality
Shunts
NOT pure hypoventilation
Carbon monoxide poisoning
Lactic acidosis
Normal Sats and pO2
Smokers reach toxic level faster
Anatomical shunt fraction
Ideal pO2 at 100% oxygen for 20 mins:
= (670 - pO2) / 20
= % shunt
Effect on V/Q mismatch of bronchodilators
Vasodilation before bronchodilatation resulting in V/Q mismatch
Indication for ICU in asthma
Hypercapnia
the calculation to use when FiO2 >40% instead of A-a gradient
pO2 / FiO2 > 500 is normal
Volume that may change on lying supine
Functional residual capacity
Dyspnoea worse on standing
Atria-atria shunt
Hepatopulmonary syndrome causing a pulmonary shunt - dilation of the arteries
Effect of PEEP
Reduces shunt
Increases FRC
Increase deadspace
Reduced CO due to decrease in venous return
Lung volume parameter affected most in pregnancy
Decrease in ERV and RV, therefore, FRC most affected
High DLCO
Alveolar haemorrhage
Asthma
MIP
strength of inspiration musleca
Gene mutation A1ATD
Serpina1
MM - normal
ZZ- common A1ATD levels 15%
MZ - vulnerability to smoking
No sex linkage
Indications for O2 for COPD
PaO2 <55
PaO2 55-59 with PC or PHTN
Improves survival in these patients
Indication for bipap COPD
pH <7.35
pCO2 >45
COPD DECAF Score
Dyspnoea Eisinopaenia Consolidation Acidaemia Atrial fibrillation
Worse outcomes
Exhaled NO
Suggests steroid responsive asthma
Anti IL5
Mepolizumab
Severe asthma with eosinophilia
Steroid sparing, reduces exacerbation
IL4Ra inhibitor
Dupilumab
Eisinophilia and elevated FeNO
Features of early aging
Family Ajax IPF
Short telemere
Familial interstitial pneumonia
Pulmonary LAM
Women
Tuberous sclerosis complexes (seizures, cutaneous lesions, ID delay)
Autosomal dominant
Birt Hogg Dube
Multiple benign skin lesions Pulmonary cysts Renal neoplasia Asymptomatic until PTx Lower zone
Langerhans Cell histiocytosis
Smoking
Upper and mid zone cysts
Hypersensitivity pneumonitis CT
Ground glass
Hypo dense on expiratory imaging
Gas trapping
Diffuse
Bird fanciers and farmers lung
Silicosis
ILD
Stone Mason
Starry night on CT
Autoimmune features
Best predictor of clinical response to treatment of OSA
Hypersomnolence
IPF CT
Honey combing Reticular changes Basal predominant Digital clubbing Older age
Emphysema lower zones
A1ATD
Gram-negative cocci that commonly causes respiratory infections in those with underlying lung disease
Morexella catarrhalis
Indication for CPAP
T1RF
Benefit in APO
Indications for BiPAP
T2RF/mixed
In whihc COPD patients has long term O2 therapy shown benefit
paO2 <55 or SpO2 <88%
Bronchiectasis on HRCT
Dilatation of the lumen of airway more than the nearest blood vessel (signet ring sign) Varicose construction of airways Balloons cysts (bunch of grapes sign)
Bronchiectasis clinical features
Sputum production
Clubbing
Coarse crackles
Shape of flow-volume loop seen with tracheal stenosis
Box shaped
Flattening of inspiration amd exploratory limbs
Treatment of aspergillosis
Voriconazole
Amphotericin
Caspofungin
Diagnosis of OSA
AHI/RDA greater than 15 and asymptomatic
Or
> 5 and symptomatic
NSIP CT
Basal predominant Ground glass opacity Subpleural sparing (most specific, distinguish from UIP)
Organising pneumonia CT
Ground glass
Consolidation
Modular
Atoll sign (reverse halo)
Only small percentage with fibrosis
Treatments for IPF
Nintedanib - tyrosine kinase blocker
Pirfendirone - TGF-b blocker
Treatment of NSIP
Systemic glucocorticoid
Refractory- Azathioprine Mycophenalate Cyclophosphamide Rutixumab
Rapid score for empyema risk of mortality
Renal Age Purulent fluid Infection source (com good hosp bad) Diet (albumin)
