Anatomy And Pattern Recognition Of Lower Respiratory System And Mediastinum

Question 1

What is the trachea?

Answer 1

The trachea is a tubular passageway connecting the upper respiratory tract to the lungs enabling gas exchange

Question 2

What are anatomical landmarks for the trachea?

Answer 2

• Inferior margin of the cricoid cartilage (C6)
• Braches into the left and right main bronchi at the carina (T4) - the plane of Ludwig.
• Is in a midline position but can be slightly displaced to the right by the arch of the aorta.
• 10-1cm with a width of 1.5 - 2 cm (wider in men).

Question 3

What does the trachea consist of?

Answer 3

• The fibro-elastic tissue is flexible and expands and contains “C” shaped cartilage rings which gives it rigidity. These are bridged by annular ligaments.
• Histology
 Outer layer – connective tissue
 Middle layer – tracheal cartilage, annular ligaments, connective tissue, trachealis muscle
 Inner layer – respiratory mucous membrane

Question 4

What is the carina?

Answer 4

The carina is a ridge of cartilage at the base of the trachea.
• It separates the openings of the right and left main bronchi
• Level of T4 / T5 but moves with breathing
• Lies to left of midline

Question 5

Why is the carina important?

Answer 5

Important marker for tube position
-ET tubes should be 5cm above the carina to supply air to both lungs
-NG tubes should go straight through the carina
- SVC is to the right side of the carina for CVC (central venous catheter) position.
- Marker for CTPA scans

Question 6

What can happen if the carina widened?

Answer 6

If widened (more than 100 degrees) can be a sign of:
o Left atrial enlargement
o Cardiomegaly
o Pericardial effusion
o A mass around the area

Question 7

What is the bronchi?

Answer 7

respiratory epithelium (shorter than trachea) – lamina propria (denser than trachea) –
separated by a discontinuous layer of smooth muscle from the submucosa (cartilage are flat plates)

Question 8

What are bronchioles?

Answer 8

no cartilage, airways must be kept open by radial traction. Prominent smooth muscle layer. Adjusting the tone of the muscle layer alters airway diameter so air flow can be controlled.

Question 9

What are respiratory bronchioles?

Answer 9

no goblet cells, alveoli for gaseous exchange. Have alveolar ducts (rings of smooth muscle, collagen and elastic fibres) – leading to alveolar sacs – leading to alveoli - Provide the majority of the lung volume and surface area.
Can communicate between adjacent alveoli through pores of Kohn. Lined with pneumocytes
(provide structure and surfactant)

Question 10

Fun fact of right main bronchus

Answer 10

Right main bronchus straighter so inhaled objects more likely to end up there

Question 11

What are the lung lobes?

Answer 11

• superior lobe
• middle lobe
• inferior lobe

Question 12

What are lung fissures?

Answer 12

• Lung fissures are a double fold of visceral pleura that either completely or incompletely invaginate (turned inside out) the lung parenchyma to form the lung lobes
• You will often see the horizontal fissure on a PA or AP CXR, and sometimes the oblique fissure on a lateral CXR.

Question 13

What is the left lung fissure?

Answer 13

• Oblique fissure separating the upper lobe from the lower lobe
• T4/T5 posterior to the hemidiaphragm anteriorly

Question 14

What is the right lung fissure?

Answer 14

• Oblique fissure separating the upper lobe from the lower lobe
• Horizontal fissure separates the upper lobe from the middle lobe
• 4th costal cartilage from the hilum to the anterior and lateral surfaces of the right lung.

Question 15

Why are the fissures important for us?

Answer 15

For CT lung biopsy
• They help protect infections affecting nearby lobes – good way to differentiate between infection and possible malignancy

Question 16

What do the lungs look like on CT?

Answer 16

Lung window’
• lungs W:1500 L:-600
Width is contrast and level is brightness - manipulate the grayscale in CT
• Axial slice

Question 17

What is the pleura?

Answer 17

Covers the lung, chest wall and mediastinum with 2 continuous layers of epithelium
• Visceral – covers the lungs inner layer
• Parietal – covers the chest wall and is the outer later. Nerve supply is the phrenic nerve so inflamed pleura can cause ipsilateral shoulder tip pain
• Separated by a thin layer of liquid.

Question 18

What is the pleura like on a X-ray?

Answer 18

You can only see the pleura and pleural spaces on plain film when they are abnormal.
• Lung markings should reach the thoracic wall on a CXR
• There should be no space between the pleura

Question 19

What is the mediastinum?

Answer 19

It is the space in the midline of the chest between the pleura of each lung and extends from the sternum to the vertebral column.
• Contains all the thoracic viscera except the lungs
• Which are Heart
• Great vessels
• Oesophagus
• Trachea
• Phrenic nerve
• Cardiac nerve
• Thoracic duct
• Thymus
• Mediastinal lymph nodes

Question 20

What is the mediastinum divided into?

Answer 20

Can be divided into parts based on their relationship to the pericardium.
• Superior mediastinum – above the level of the pericardium and plane of Ludwig
• Inferior mediastinum – below the plane of Ludwig:
• Anterior mediastinum – anterior to pericardium
• Middle mediastinum – within the pericardium
• Posterior mediastinum – posterior to the pericardium

Question 21

What is the hila/hilum?

Answer 21

May be at the same level but commonly the left is higher than the right
• Should look similar in appearance
• Anatomical landmark – anteriorly 3-4th costal cartilage, posteriorly T5-T7
Hila = 2 and hilum = 1

Question 22

Why do we have the sternum?

Answer 22

• Protect your heart and mediastinum

Question 23

What is the diaphragm?

Answer 23

C shape structure
Separates chest from abdomen
Main muscle of respiration - how we breathe

Question 24

What is chilaiditi sign?

Answer 24

It is a condition in which a segment of the intestine is interposed between the liver and diaphragm
. Is the anterior interposition of the colon to the liver reaching the under surface of the right hemi- diaphragm
• One of the cause of pseudopneumoperitonuem
• Can have Chilaiditi syndrome where patients experience pain

Question 25

What is dextrocardia

Answer 25

Dextrocardia means the heart is on the right side

Question 26

What is hiatus hernia

Answer 26

Occurs when there is herniation of the abdominal contents through the oesophageal hiatus of the diaphragm

Question 27

Where the causes and symptoms of hiatus hernia

Answer 27

Causes = increases with age and slight female predilection Symptoms = chest/abdominal pain Nausea and vomitting Sometimes GORD gastro-oesophageal reflux disease

Question 28

What is the diagnosis of hiatus hernia

Answer 28

Plain film – retrocardiac opacity with air fluid level CT – fat collection in middle mediastinum, may see hernia or widened oesophageal hiatus

Question 29

What treatments are used for hiatus hernia

Answer 29

Surgery in severe cases

Question 30

What is pulmonary embolic disease

Answer 30

Most commonly a blood clot (which often starts in the leg), which travels through the circulatory system and then causes a blockage in the pulmonary artery – can be partial or complete

Question 31

What are the causes and symptoms of pulmonary embolic disease

Answer 31

Causes o Recent surgery o Immobility o Diseases with a risk of thrombus formation e.g. lupus, HIV, Covid o Drugs such as the contraceptive pill, o Pregnancy o Malignancy Symptoms o History fitting any of the causes above o Tachycardia, dyspnea (breathing difficulty), chest pain, hemoptysis o Signs of a DVT

Question 32

What are the treatments of pulmonary embolic disease

Answer 32

o Anticoagulation o CPR if necessary

Question 33

What are complications of pulmonary embolic disease

Answer 33

o PEA in the case of a cardiac arrest o Right ventricular strain o Pulmonary infarction o Pulmonary hypertension Damage heart Part of the lung can die off Stops blood getting to lungs

Question 34

Which imaging is used for pulmonary embolic disease

Answer 34

CXR •Nonspecific, not suggested CT CTPA immediately if possible depending on Wells score. • If wells is <4 D-dimer – if high = CTP (how likely it is a patient has PED) MRI Magnetic resonance imaging findings in acute pulmonary embolism - PMC (nih.gov) VQ • Looks for that mismatch from ventilation and perfusion • Have to have a CXR first

Question 35

What is pulmonary oedema

Answer 35

• Accumulation of fluid in the interstitial and alveolar spaces – very broad term! it manifests in 2 types – alveolar and interstitial

Question 36

What are the causes of pulmonary oedema

Answer 36

Cardiogenic o Congestive heart failure o Cardiomyopathy o Arrythmias o Mitral regurgitation Non cardiogenic o Near drowning o O2 (post intubation) o Trauma o CNS o Alveolitis (hypersensitivity pneumonitis) o Renalfailure o Drugs o Inhaled toxins o Altitude o Contusion

Question 37

What are the symptoms and diagnosis of pulmonary oedema

Answer 37

Symptoms = breathlessness and distress and increased heart rate due to fluid in lungs Diagnosis = • CXR – increased cardio/thoracic ratio, upper lobe pulmonary venous diversion, alveolar signs (batwing shadowing, airspace shadowing, consolidation), interstitial signs (Kerley B lines, thickening of the fissures), pleural effusion. • CT – ground glass opacification, septal thickening • US – B lines

Question 38

What are the treatments of pulmonary oedema

Answer 38

Depends on the underlying cause

Question 39

What is aortic dissection (type a)

Answer 39

Separation in the aortic wall intima (tear), allowing blood to flow between the layers of the aortic wall (inner and outer walls of the media). Type A – ascending aorta with or without the aortic arch and descending aorta. Type B – mainly descending aorta and / or abdominal aorta.

Question 40

What are the causes and symptoms of aortic dissection

Answer 40

o Causes • Risk factors include: ▪ Hypertension ▪ Marfan syndrome - connective tissue disorder ▪ Ehlors-Danlos syndrome - connective tissue disorder o Symptoms • Acute severe chest pain • Left right blood pressure differential • Pulse deficit • Dyspnoea . Struggling to breathe . Low pulse in wrist

Question 41

Treatment of aortic dissection

Answer 41

. Aggressive blood pressure control with beta blockers to reduce blood pressure and heart rate •Immediate surgical repair

Question 42

What is pneumonia

Answer 42

• Broad term to describe acute infection on the lung parenchyma (functional tissue e.g. alveoli

Question 43

Causes + symptoms of pneumonia

Answer 43

Causes • Infection e.g. COVID 19, bacteria, viral or fungal Symptoms • Productive cough / breathlessness / chest pain • High temperature (pyrexia), sometimes associated with tachycardia • Malaise

Question 44

Diagnosis of pneumonia

Answer 44

• CXR – air space opacification • CT – not generally used as the initial diagnostic tool, but useful in cases with complications or for follow up

Question 45

Treatment of pneumonia

Answer 45

Antibiotics Potentially follow up imaging - ecg

Question 46

primary lung cancer:

Answer 46

o Broad term referring to primary lung malignancy. You may also see the term bronchogenic

Question 47

Causes + symptoms of PLC

Answer 47

Causes o Tobacco smoking o Asbestos o COPD Symptoms o Patients may be asymptomatic in up to 50% of cases o Hemoptysis o Cough and dyspnoea o Pleural effusion o pneumonia

Question 48

Diagnosis for plc

Answer 48

CXR CT PET CT MRI

Question 49

Treatments for plc

Answer 49

Surgery chemotherapy radiotherapy depending on tumour Molecular testing can help with targeted treatments

Question 50

What is pleural effusion

Answer 50

Is any accumulation of fluid in the pleural cavity – this could be simple fluid, blood, pus etc. Results from many pathological processes which overwhelm the pleura's ability to reabsorb fluid

Question 51

Causes and symptoms of pleural effusion

Answer 51

Causes . Most common are cardiac failure and malignancy Symptoms •Small amount may have no symptoms •As volume increases symptoms include breathlessness especially when active •Causes are generally split into transudate and exudate

Question 52

Diagnosis of pleural effusion

Answer 52

US - allows detection of small amounts CT - excellent in detecting small amounts CXR - most commonly used imaging method

Question 53

Complications and treatment of pleural effusions

Answer 53

Complications = lung collapse, scarring (fibrotic changes) Treatment = may drain if it large

Question 54

What is transudate fluid

Answer 54

Lower protein content (<30g/L) o Occurs when there is an increase in hydrostatic pressure o Cardiac failure o Cirrhosis o Trauma o Post coronary surgery

Question 55

What is exudate fluid

Answer 55

Exudate o Higher protein content (>30 g/L) o Occurs due to an alteration in the pleural space drainage to lymph nodes o Bronchial cancer o Lung metastases o PE o Pneumonia o TB o Mesothelioma

Question 56

Pleural effusion – AP / Pa erect

Answer 56

Erect films are insensitive to small amounts of fluid • May see blunting of the costophrenic angle • Blunting of the cardiophrenic angle • Fluid within the horizontal or oblique fissure • Eventually a meniscus will be seen, (not with a hydropneumothorax) • Lateral images can identify a smaller amount of fluid

Question 57

Pleural effusion - supine

Answer 57

Large amounts fluid can be present on supine image with minimal imaging changes as the fluid is dependent and collects posteriorly There is no meniscus and only a veil like increased density of the hemithorax may be visible Can be very diffuse to identify bilateral effusions as the density will be similar

Question 58

What is a pneumothorax

Answer 58

Air in the pleural space

Question 59

Causes and symptoms of pneumothorax

Answer 59

o Causes o Many! Primary generally in younger patients, secondary in older/ • Primary spontaneous – no underlying lung disease • Secondary spontaneous – underlying lung disease is present • Iatrogenic / traumatic - caused by medical device o Symptoms • Pain and breathlessness

Question 60

Diagnosis of pneumothorax

Answer 60

Plain film imaging CT

Question 61

Complications and treatment of pneumothorax

Answer 61

o Complications • Tension pneumothorax o Treatment • Observation • Aspiration • Chest drain • surgery

Question 62

Pneumoperitoneum

Answer 62

. Gas within the peritoneal cavity • Generally, from a perforated hollow viscus, post operative, from peritoneal dialysis, due to mechanical ventilation, pneumothorax or pneumomediastinum, and many diseases • Patient will often be very ill • On CXR (most sensitive): • Sub diaphragmatic free gas • Continuous diaphragm sign

Question 63

What is copd

Answer 63

Is a general term with 2 key disease features – chronic bronchitis and emphysema

Question 64

Causes and symptoms of COPD

Answer 64

Causes . Smoking – most common •Cystic fibrosis •Industrial exposure e.g. mining Symptoms Dyspnoea on extertion •Wheezing •Productive coughSymptoms

Question 65

Diagnosis of COPD

Answer 65

CXR - hysema predominent CT – may be as for CXR and also fibrotic changes and bronchial wall thickening for bronchitis and for emphysema

Question 66

Complications and treatments of COPD

Answer 66

Treatments = Condition is irreversible, but can manage symptoms and delay progression Complications = Exacerbation – infection, and acute breathlessness •Pulmonary hypertensionComplications

Question 67

What are rib fractures

Answer 67

Most commonly due to trauma. When rib is fractured twice it is termed a floating rib. When there are 3 or more, this is a flail chest which indicates severe chest trauma

Question 68

Causes and symptoms of rib fractures

Answer 68

causes = Trauma • Osteoporosis • Pathological fracture Symptoms = Relevant clinical history • Pain on inspiration or movement

Question 69

Diagnosis of rib fractures

Answer 69

CXR – fracture and displacement seen • CT – better at diagnosing a flail chest

Question 70

Complications and treatment of rib fractures

Answer 70

Complications = Fracture of 1st rib is an indicator for severe chest trauma as this is protected by the clavicle and scapula Treatments = O2 therapy as infection is a common complication • Surgery is rare

Question 71

What is goitre

Answer 71

Enlargement of the thyroid gland. It can be caused by multiple conditions including – iodine deficiency, thyroid cancer, Hasimotos

Question 72

Causes and symptoms of goitre

Answer 72

Causes It can be caused by multiple conditions including – iodine deficiency, thyroid cancer, Symptoms Visible swelling •Tight feeling in throat •Coughing •Difficulty in swallowing or breathing

Question 73

Diagnosis of goitre

Answer 73

US can give accurate measurements •CXR – may see deviation of the trachea and a soft tissue mass in the upper mediastinum •CT – as for chest. Also mixed density mass

Question 74

Complications and treatments of goitre

Answer 74

Complications = •Difficulty in swallowing and breathing •May need thyroid surgery Treatment = may need it if it is large

Question 75

What is Mesothelioma

Answer 75

o Rare malignancy that mostly arises from the pleura

Question 76

Causes and symptoms of mesothelioma

Answer 76

Causes Asbestos exposure o Symptoms o Vague o Dyspnoea o Back pain o Pleural effusion

Question 77

Diagnosis of mesothelioma

Answer 77

PET CT is often used for staging as metastases are common o CXR – non specific. Will see pleural thickening with / without a pleural effusion. May see rib destruction. o CT – most commonly used for diagnosis. Will see a pleural, nodular mass. May see invasion into chest wall lung or bones. May see metastases in lung and lymphadenopathy o MRI – not commonly used but may provide more accurate staging

Question 78

Treatments and complications of mesothelioma

Answer 78

Complications From metastases o Pleural effusion o Treatment o Long term survival is poor. Surgery, chemotherapy and radiotherapy can be used