Key facts Flashcards
<p>What are the conducting airways of the lungs?</p>
<p>Trachea -> Terminal bronchioles</p>
<p>What are the respiratory airways of the lungs?</p>
<p>Respiratory bronchioles -> Alveoli</p>
<p>What does the "Bucket handle" movement of the chest lead to?</p>
<p>Increased Lateral diameter</p>
<p>What does the "Pump handle" movement of the lead to?</p>
<p>Anterior-Posterior diameter increase</p>
<p>Name the 3 openings of the Diaphragm and their spinal levels</p>
<p>T8 - Vena Cava
T10 - Oesophagus
T12 - Aorta (aortic hiatus)</p>
<p>Where does the neurovascular bundle supply the rib run?</p>
<p>Along inferior of the bone (under the bone)</p>
What does the neurovascular bundle contain?
Intercostal vein, artery, nerve
What are the accessory muscles to breathing on inspiration?
- SCM (COPD sign)
- Pec Major, Minor, Serratus anterior
What are the accessory muscles to breathing on expiriation?
- Abdominal wall muscles
- Internal intercostal muscles
What does the Azygous system drain from and to?
From the intercostals, to the SVC
How many lobes do the right and left lungs have?
R = 3 L = 2
What is the organisation of the Hilum of the lungs?
Bronchi top
Arteries middle
Veins bottom
What blood system supplies the Lungs?
Bronchial
What nerve supplies the smooth muscle of the lungs?
Vagus
What is the Tidal volume?
Amount of air that enters and exits with each breath
What is Boyle’s law?
Inverse relationship between pressure and volume of contained - if volume goes up, pressure goes down
How are the lungs attached to the external pleura? (parietal)
Surface tension via pleuritic fluid
What is the pressure within the pleura?
Negative
On all graphs, what does an upward deflection mean?
Inspiration
What is the Inspiratory Reserve Volume?
From tidal volume max inspiration to the top of the graph
What is the Vital Capacity?
IRV + TV + ERV
What is the Inspiratory Capacity?
IRV + TV
What is the Residual Volume?
Total Lung Capacity - VC
Define Compliance
Volume change per unit pressure change
What is Compliance determined by?
Elastic recoil of the lung
Surface tension of the lung
What does surfactant do to compliance?
Reduces surface tension, raises compliance
What is surfactant made by and at what age does it start being produced?
Type 2 pneumocytes start at 24 weeks, make enough by 35 weeks
What is the role of surfactant?
Increase compliance
Prevent small alveoli from collapsing into larger ones
How does surfactant prevent small alveoli from collapsing into larger ones?
Law of Laplace - Pressure = 2 x Surface Tension / Radius
Normally, smaller has larger pressure, so collapses into larger one.
In a larger alveoli, surfactant molecules are further apart, so they reduce surface tension less
In a smaller alveoli, surfactant molecules are closer together, so they reduce surface tension more
Therefore pressure in both is the same, despite volume difference
Where is the highest resistance in the airways?
Trachea, as going from larger to smaller
What prevents bronchi from collapsing inwards due to lack of cartilage?
“Radial traction” from alveoli
What is the relationship between Compliance and Elasticity?
Compliance = 1/Elasticity as the elastance PUSHES BACK IN, reducing the ability to push out
What are the two types of lung disease?
Obstructive
Restrictive
Describe how diffuse lung fibrosis occurs and what type of lung disease it is
Increased deposition of matrix eg. elastic fibres/ collagen in the interstitium of the lungs
Reduces compliance and increases elastic recoil, causes reduced filling
Restrictive disease
Give a cause of Diffuse Lung Fibrosis
Asbestosis
What is COPD?
Chronic Bronchitis and Emphysema
Describe the pathophysiology of Emphysema
Protease mediated destruction of elastin, leads to reduced alveolar SA, reduced radial traction of alveoli
Loss of elastic tissue leads to increased compliance - less able to get air out
Obstructive defect
Give one cause of Emphysema
Smoking
When is airway obstruction more significant? (inspiration or expiration?)
Expiration (no negative pressure in pleuritic space to keep airways open)
What is Atelectasis?
Lung collapse
Name 4 causes for Atelectasis
Pneumothorax, Pleural effusion, RDS, Resorption collapse due to blockage
Describe the pathophysiology of Respiratory Distress Syndrome
Reduced surfactant, therefore increased surface tension, therefore reduced compliance, therefore reduced filling, therefore difficulty breathing
What is the treatment for RDS?
Give mother corticosteroids before birth/ surfactant replacement therapy
What does SVP stand for?
Saturated water vapour constant = 6.28kPa
What is the equation for the amount of gas dissolved in a fluid?
Partial pressure of gas x solubility coefficient of the gas
What is the definition of partial pressure?
Pressure exerted by a gas when in solution (dissolved)
What is the partial pressure of O2 in the lungs?
13.3kPa
What is the partial pressure of CO2 in the lungs?
5.3kPa
What is the partial pressure of both CO2 and O2 in the lungs from the bloodstream?
6kPa
What percentage of O2 is still bound in venous return?
67%
What is the difference between hypoxia and hypoxaemia?
Hypoxaemia = systemic reduction in O2 in the blood (like in anaemia) Hypoxia = reduction in O2 in a tissue
Where is an ABG taken from?
Radial artery needle puncture
What is the normal respiration rate/minute?
12-20
What is it called when the lungs constrict arteries in poorly perfused areas of the lung?
Hypoxic pulmonary vasoconstriction
Why does significant V/Q mismatch make up for CO2 levels in the other lung, but not O2?
CO2 can be blown off through hyperventilation
O2 cannot be increased, as 13.3kPa already reached
What is the carbonic acid equation?
CO2 + H2O -> H2CO3 -> H+ + HCO3-
What determines blood pH?
HCO3- to H+ determines pH
What controls pCO2 in the blood? What controls HCO3- levels in the blood?
CO2 = lungs HCO3- = produced constantly by the RBCs, but controlled by the kidneys
What is the enzyme that converts CO2 and H2O to H+ and HCO3-?
Carbonic anhydrase
Describe RBC HCO3- production
Carbonic anhydrase conversion of CO2 and H2O to HCO3- and H+
H+ binds to Hb
HCO3- exported
The amount of H+ that Hb can carry is based on what?
Amount of O2 carried - this means that when O2 dropped off at muscles, more CO2 can be converted to HCO3- (buffering), since more H+ can be carried by Hb
How can CO2 be carried back to the lungs?
- H+ stored Hb
- Carbamino compounds
- Dissolved in blood
What do Peripheral chemoreceptors detect and where are they? What nerves transmit to and from them?
O2 levels - carotid and aortic bodies
Glossopharyngeal and Vagus
What do Central chemoreceptors detect and where are they?
CO2 levels via pH of CSF - in medulla of brain, choroid plexus cells - choroid plexus cells secrete HCO3- into the CSF, as the BBB is impermeable
What does alkalosis cause? (not hypokalaemia)
Hypocalcaemia - leads to paraesthesia and tetany
How do the kidneys controlled HCO3- levels?
- 100% of HCO3- is reabsorbed in PCT (absorbed as H2O and CO2, then reabsorbed via Na+/HCO3- co-transporter)
- In PCT - Amino acids converted to HCO3- and NH4+ (eg. glutamine)
- In DCT - makes via CO2 + H2O - H+ buffered by phosphate and NH4+
Explain why severe acidosis cannot be dealt with by the kidney
Acidosis causes K+ to leave cells. Acidosis causes K+ to leave PCT cells. RECIPROCAL ION SHIFT. Therefore, low H+ in kidney tubules, kidney thinks it's alkalotic, when it isn't. Loses HCO3- - makes acidosis worse
Explain the relevance of the anion gap
Gap between cations and anions
Gap is increased if anions not replaced by Cl-
IN ACIDOSIS:
If renal cause - no anion gap, as Cl- will replace due to anion exchanger
If non-renal cause, will have keto or lactic acidosis
Give a cause of respiratory acidosis
High CO2, low O2
Type 2 respiratory failure
Severe COPD, severe asthma, respiratory distress from head injury or drug overdose
Hypoventilation
Give a cause of respiratory alkalosis
Low CO2, low O2
Type 1 respiratory failure
Eg. everything
Give a cause of metabolic acidosis
Increased anion gap: Ketoacidosis/Lactoacidosis
Normal anion gap: Kidney failure/ severe diarrhoea
Give a cause of metabolic alkalosis
Increased HCO3- from stomach acid production
What X-ray is done for lungs?
PA
What is functional reserve volume?
RV + ERV
What is FVC?
Forced vital capacity - total air breathed out after inhaling fully
What is FEV1?
Total amount breathed out in 1 second
What is the ratio used to check if restrictive/obstructive between FEV1 and FVC?
FEV1/FVC ratio
What is the FEV1/FVC ratio for an obstructive disorder?
<70% - FEV1 down, FVC same
What is the FEV1/FVC ratio for a restrictive disorder?
> 70% - FEV1 the same, FVC goes down
What are the Flow-volume loop signs for restrictive and obstructive disorders?
Obstructive: scalloping
Restrictive: X-axis reduced (volume lower)
Name 3 risk factors of PE
Pregnancy, COCP, DVT (immobilisation)
What does PE lead to pathologically?
RV overload, respiratory failure due to V/Q mismatch
What is the treatment for PE?
Oxygen, heparinisation, fibrinolytics
Describe Type 1 vs Type 2 respiratory failure
Type 1 - Low O2, Low or Normal CO2
Type 2 - Low O2, High CO2
What are the compensatory mechanisms for chronic hypoxaemia?
- Increased EPO production
- Increased 2,3-BPG production
- Hypoxic pulmonary vasoconstriction
List 2 Type 1 acute respiratory causes
- Pneumonia, PE
List 3 Type 1 chronic respiratory causes
- Asthma, COPD, fibrotic lung disease,
List 2 Type 2 acute respiratory causes
- Narcotics, life threatening asthma
List 1 Type 2 chronic respiratory causes
Chronic COPD
Describe the pathophysiology of Asthma
Type 1 -> Type 4 hypersensitivity reaction
Name 4 triggers of asthma
Pollen
Pets
Smoking
Dust mites
Name 2 Asthma treatments
- Corticosteroid inhaler (prednisolone)
- B2 agonist (salbutamol)
Severe asthma vs life-threatening asthma
Severe: High resp rate, tachycardia, O2>92%
Life-threatening: Silent chest, low resp rate, O2 < 92%
What is the treatment for life-threatening asthma?
- Oxygen
- Nebulised salbutamol
- Ipratropium
- Prednisolone
What is Chronic Bronchitis?
Chronic mucous hypersecretion due to inflammation in upper airways - remodelling and narrowing + destruction of mucociliary escalator
Name 3 early COPD signs
“Purse lip”
Accessory muscle usage
Hyperinflation
How are pack years calculated?
1 pack year = 20 cigarettes/ day
What is Bronchiectasis?
Chronic dilatation of bronchi, reduced mucous clearance, recurrent infections
What can be seen on an X-ray in Bronchiectasis?
Signet-ring sign
What are the symptoms of Bronchiectasis?
Chronic cough, sputum production, haemoptysis
What are the causes of Bronchiectasis?
Infection: whooping cough, TB, influenza, lung scarring
Name 3 LRT infections
- Bronchitis
- Pneumonia
- Bronchiestasis
What is pneumonia?
Lung parenchyma inflammation
Cellular exudate into alveolar spaces
What are the most common organisms for hospital and community acquired pneumonias? What are their treatments?
Community: Strep pneumoniae - co-amoxiclav and
Hospital: Staph aureus - co-amoxiclav
What type of Giant cells are present in TB?
Langerhans Giant Cells
What tests are there for TB?
Tuberculin skin test
Interferon-Gamma test
Sputum and microscopy - only way of seeing if active infection
What are the drugs to treat TB and how long are they taken for?
RIZE Rifampicin Isoniazid Pyrazinamide Ethambutol 6 months
Where is the fluid build-up in a pleural effusion?
Under the lung
What does a “bat-wing” appearance on an X-ray mean?
Congestive heart failure
What are the “crackles” heard on auscultation?
Alveoli opening (snapping open)
What type of breathing is normal?
Vesicular - not Bronchial
What are the causes of primary and secondary pneumothoraxes?
Primary: = bulla bursts Secondary = secondary to lung disease
Where is the chest drain placed in a normal pneumothorax?
5th mid axillary line
Where is the CANNULA placed in a tension pneumothorax?
2nd mid clavicular line
List the causes of pleural effusion and whether they are (lymphatic) absorptive failure or overproductive failures
Absorptive: Heart failure, Nephrotic syndrome
Overproduction: Infection from pneumonia
What types of lung cancer are there?
Small cell, non-small cell - small cell most aggressive
What is the minimum O2 the lungs need to be kept at to prevent damage?
8KPa
Give 2 reasons why giving a patient with Chronic Hypoxia Oxygen is bad
- Will remove respiratory drive from peripheral chemoreceptors in carotid and aortic bodies
- Will lead to increased perfusion of poorly ventilated alveoli, removing the effect of hypoxic pulmonary vasoconstriction
Where should a chest drain be inserted into a patient?
Just above the rib, avoid the neurovascular bundle
Why is asthma worse at night?
Parasympathetic drive constricts the airways - rest and digest
What is the main treatment for Small Cell lung cancer?
Chemo
What is the main treatment for Non-Small Cell lung cancer?
Surgery
