Random Resp Questions Flashcards
What is normal PaO2?
10.5 - 13.5 pKa
What is normal PaCO2?
4.8 - 6.0 pKa
What is the PaO2 and PaCO2 level in type I respiratory failure?
PaO2 is < 8 pKa
PaCO2 is normal or low (below 4.8)
What is the PaO2 and PaCO2 level in type II respiratory failure?
PaO2 is usually low (hypoxaemia) (< 10.5)
PaCO2 is > 6.5 pKa
How can hypoxaemia be corrected?
By small increases in FIO2 (fraction of inspired air which is oxygen) which increases PAO2 in poorly ventilated alveoli, thus increasing diffusion rate
What is shunt?
Blood passing from R to L side of heart without contacting ventilated alveoli therefore not taking part in gas exchange
What is deep vein thrombosis (DVT)?
When thrombus forms in the venous system, usually in the deep veins of legs
What is pulmonary embolism (PE)?
Acute disease when thrombus forms in the deep veins of the legs, dislodges and embolises to pulmonary arteries
What is venous thromboembolism (VTE)?
A disease that includes both deep vein thrombosis (DVT) and pulmonary embolism (PE)
What is pulmonary hypertension?
A chronic disease where blood pressure is elevated in the pulmonary arterial tree. Defines by mean pulmonary artery pressure of >25mmHg.
What is a pleural effusion?
Collection of fluid in pleural space
What is a pneumothorax?
Collection of air in the pleural cavity
What is a hydropneumothorax?
The collection of both air and water in the pleural cavity
What is mesothelioma?
Primary pleural malignancy
What is empyema?
Pus in the pleural space
What is a haemothorax?
Blood in the pleural space
Give examples of pleural disease
Pleural effusion (most common), pneumothorax, hydropneumothorax, mesothelioma, empyema, haemothorax
What is COPD
Chronic obstructive pulmonary disease, includes chronic bronchitis and emphysema
What is chronic bronchitis?
Cough productive of sputum most days in at least 3 consecutive months for 2 or more consecutive years
What FEV1:FVC ratio is considered obstructive?
<0.7
What is a bulla?
Abnormal emphysematous air space in the lung greater than 1cm diameter. Patient with a bulla should avoid air travel. Called bleb if less than 1cm diameter or if under the pleura
What is asthma?
A disease characterised my increased responsiveness of trachea and bronchi to various stimuli manifested by widespread narrowing or airways that changes in severity spontaneously/ as a result of therapy. Characteristics are wheezing, panting/gasping, variability
Where are central chemoreceptors located?
Medulla
Where are peripheral chemoreceptors located?
Carotid and aortic bodies
What do central chemoreceptors respond to?
Respond directly to changes in hydrogen ion concentration, detect changed in arterial partial pressure of CO2 (PCO2)
What do peripheral chemoreceptors respond to?
Primarily respond to PO2 (less to PCO2) and plasma (H+)
What is the primary ventilatory drive?
Central chemoreceptors
What is the secondary ventilatory drive?
Peripheral chemoreceptors
What is fibrosis?
Increased thickening of the alveolar membrane, decreased gas exchange
What is oedema?
Fluid in the interstitial space increasing the diffusion distance
What is emphysema?
Air spaces become bigger than normal, distal to the terminal bronchiole arising either from dilatation or from destruction of their walls and without obvious fibrosis
Reduced SA for gas exchange
Easy to get air in but elasticity lost
What values cannot be measured by spirometry?
RV, TLC and FRC cannot be measured by spirometry
What is pulmonary (minute) ventilation?
Total air moving in and out of the lungs
What is alveolar ventilation?
Fresh air moving into the alveoli and therefore available for gas exchange (more significant)
What has an impact on alveolar ventilation?
Anatomical dead space
Where is alveolar ventilation highest?
At the base of the lung are the lungs where compliance is highest due to the lungs being slightly compressed by the diaphragm
What is infant respiratory distress syndrome?
Insufficient surfactant production
Where is intrapleural pressure lowest (most negative)?
At the apex of the lung, least negative at base due to gravity pulling down the lung
What is anaemia?
Defined as any condition where O2 carrying capacity of the blood is compromised and is decreased
Does anaemia affect the oxyhemoglobin binding curve?
No, the oxyhemoglobin binding curve is unaffected in anaemia
What is Nitrous oxide used for in ventilation?
A common sedative/ light anaesthetic agent, blunts peripheral chemoreceptors response to falling PaO2. Problematic if given t hypoxia patients and can aggregate their situation
What do barbiturates and opioids do in ventilatory control?
Depress the respiratory centres, overdoses often cause death due to respiratory failure. Decrease sensitivity to pH and decrease peripheral chemoreceptors response to decreased PO2, respond to PCO2
What is the main function of CFTR?
Transport of Cl ions from the interstitium into the airway lumen
The activation of which channel results in a reduction in airway surface liquid (ASL) volume?
ENaC
What does standing up do?
Decreases EDV, preload, SV, CO & MAP
What is normal FEV1?
3.5 - 4L
What is normal FVC?
5L
What is a normal FEV1:FVC ratio?
0.7-0.8
Characteristics that would define fluid as an exudate
Protein - pleural fluid/ serum fluid ration > 0.5
LDH - pleural fluid/ serum fluid ration > 0.6
Pleural fluid LDH >2/3rd ULN serum LDH
Are exudates or transudates mostly caused by pulmonary causes?
Exudates
